Language：English   Publisher：Skeletal Radiology  

Objective: Although some patients may experience collapse progression while others may not in post-collapse osteonecrosis of the femoral head (ONFH) with a necrotic lesion located within the weight-bearing part of the acetabulum (Type B/C1), few studies have focused on the natural course after collapse. This study aimed to clarify the correlation between necrotic volume (NV) and necrotic depth (ND) in predicting collapse progression in patients with post-collapse ONFH Type B/C1. Materials and methods: We retrospectively reviewed 54 hips with post-collapse ONFH Type B/C1 from 52 consecutive patients who were conservatively followed up for more than 1 year. We measured the amount of femoral head collapse using biplane radiographs at each follow-up period, and produced Kaplan–Meier survival curves with collapse progression (≥ 1 mm) as the endpoint. We compared NV and ND, which were calculated as the ratio of the distance from the articular surface of the femoral head to the deepest point of a necrotic lesion to the femoral head diameter in the mid-coronal slice of T1-weighted magnetic resonance imaging (MRI). Results: We observed collapse progression in 31 hips (57.4%). The NV and ND were significantly greater in hips with collapse progression than in those without collapse progression (p = 0.0127 and 0.0047, respectively). Necrotic volume was significantly correlated with ND　(rs = 0.56, p < 0.0001). Conclusion: This study suggests that necrotic depth on the mid-coronal slice of T1-weighted MRI can be a substitute for necrotic volume to predict collapse progression in ONFH Type B/C1.

DOI： 10.1007/s00256-024-04741-0

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Publisher：Journal of Bone and Joint Surgery  

Background:The incidence of developmental dysplasia of the hip (DDH) in Japanese newborns has reduced drastically following a primary prevention campaign initiated around 1972 to 1973; this perinatal education campaign promoted maintaining the hips of newborns in the naturally flexed-leg position. The purpose of the present study was to describe the life course epidemiology of hip osteoarthritis (OA) in adolescent and adult patients and to assess its association with exposure to the primary prevention campaign for DDH.Methods:We included new patients with hip OA diagnosed from January 1, 2022, to December 31, 2022, at 12 core hospitals (8 special-function hospitals and 4 regional medical care support hospitals). The trend in the percentage of hips with a history of DDH treatment in childhood was estimated with use of a centered moving average using the birth year of the patient. We compared the prevalence of severe subluxation (Crowe type II, III, or IV) between patients with secondary hip OA due to hip dysplasia who were born in or before 1972 and those who were born in or after 1973.Results:Overall, 1,095 patients (1,381 hips) were included. The mean age at the time of the survey was 63.5 years (range, 15 to 95 years). A total of 795 patients (1,019 hips; 73.8% of hips) were diagnosed with secondary OA due to hip dysplasia. Approximately 13% to 15% of hips among patients born from 1963 to 1972 had a history of DDH treatment in childhood; however, the percentage decreased among patients born in or after 1973. The prevalence of severe subluxation (Crowe type II, III, or IV) among patients born in or after 1973 was 2.4%, which was significantly less than that among patients born in or before 1972 (11.1%; odds ratio, 0.20; p < 0.001).Conclusions:As of 2022, secondary hip OA due to hip dysplasia is still responsible for most new cases of adolescent and adult hip OA seen in core hospitals in Japan. However, the perinatal education campaign initiated 50 years ago, which utilized a population approach and advocated for maintaining the hips of newborns in the naturally flexed-leg position, may have improved the environmental factors of DDH, as indicated by the apparently reduced need for treatment of DDH in childhood and the associated severe subluxation. This may result in a reduced need for challenging hip surgery later in life.Level of Evidence:Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

DOI： 10.2106/JBJS.23.01044

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publisher：BMJ Open  

Objectives This study documents the time elapsed from the diagnosis of osteonecrosis of the femoral head (ONFH) to surgery, exploring the factors that influence ONFH severity. Design Retrospective observational study of a nationwide database. Setting The Kaplan-Meier method with log-rank tests was applied to examine the period from definitive diagnosis of ONFH to surgery using any surgery as the end point. For bilateral cases, the date of the first surgery was the endpoint. Participants This study included 2074 ONFH cases registered in 34 university hospitals and highly specialised hospitals of the multicentre sentinel monitoring system of the Japanese Investigation Committee between 1997 and 2018. Main outcome measure The primary outcome was the time from diagnosis to surgery. The secondary outcome was the proportion of subjects remaining without surgery at 3, 6 and 9 months, and at 1, 2 and 5 years after diagnosis. Results The median time to surgery was 9 months (IQR 4–22 months) after diagnosis of ONFH. The time to surgery was significantly shorter in the alcohol alone group and the combined corticosteroid and alcohol group than in the corticosteroid alone group (p=0.018 and p<0.001, respectively), in early stage ONFH with no or mild joint destruction (stages II and III, p<0.001), and with joint preserving surgery (p<0.001). The proportion without surgery was 75.8% at 3 months, 59.6% at 6 months, 48.2% at 9 months, 40.5% at 1 year, 22.2% at 2 years and 8.3% at 5 years. Conclusion ONFH has been considered to be an intractable disease that often requires surgical treatment, but the fact that surgery was performed in more than half of the patients within 9 months from diagnosis suggests severe disease with a significant clinical impact. Trial registration number Chiba University ID1049.

DOI： 10.1136/bmjopen-2023-082342

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Language：English   Publisher：Journal of Orthopaedic Science  

Background: The location of the lateral boundary of the necrotic lesion to the weight-bearing portion of the acetabulum (Type classification) is an important factor for collapse in osteonecrosis of the femoral head (ONFH). Recent studies also reported the significance of the location of the anterior boundary of the necrotic lesion on the occurrence of collapse. We aimed to assess the effects of the location of both anterior and lateral boundaries of the necrotic lesion on collapse progression in ONFH. Methods: We recruited 55 hips with post-collapse ONFH from 48 consecutive patients, who were conservatively followed for more than one year. Using a plain lateral radiograph (Sugioka's lateral view), the location of the anterior boundary of the necrotic lesion to the weight-bearing portion of the acetabulum was classified as follows: Anterior-area I (two hips) occupying the medial one-third or less; Anterior-area II (17 hips) occupying the medial two-thirds or less; and Anterior-area III (36 hips) occupying greater than the medial two-thirds. The amount of femoral head collapse was measured by biplane radiographs at the onset of hip pain and each follow-up period, and Kaplan–Meier survival curves with collapse progression (≥1 mm) as the endpoint were produced. The probability of collapse progression was also assessed by the combination of Anterior-area and Type classifications. Results: Collapse progression was observed in 38 of the 55 hips (69.0%). The survival rate of hips with Anterior-area III/Type C2 was significantly lower. Among hips with Type B/C1, collapse progression occurred more frequently in hips with Anterior-area III (21 of 24 hips) than in hips with Anterior-area I/II (3 of 17 hips, P < 0.0001). Conclusions: Adding the location of the anterior boundary of the necrotic lesion to Type classification was useful to predict collapse progression especially in hips with Type B/C1.

DOI： 10.1016/j.jos.2023.01.011

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Language：Japanese   Publisher：西日本整形・災害外科学会  

【目的】脚長・オフセットがforgotten joint score(FJS)-12を含めた患者立脚型アウトカムに影響するか否かを明らかにすること.【対象】当科の初回THAで,対側健常な203例203股を対象とした.術前後の単純X線画像評価と術後の患者立脚型評価(FJS-12,Oxford hip score:HS,満足度)を行い,脚長・オフセットが及ぼす影響について多変量解析した.【結果】FJS-12が有意に低スコアを示す因子は,術後の脚長が健側より長いこと,術前の重度大転子高位例であった.脚長はOHS,満足度には有意な影響を認めず,オフセットは全てに有意な影響を認めなかった.【考察】THAの際に,安定性に懸念がある場合は過延長になるよりも,オフセットを延長する方が,FJS-12への負の影響は少ないと考えられた.(著者抄録)

Language：English   Publisher：Journal of Orthopaedics  

Purpose: The dislocation rate after total hip arthroplasty for osteonecrosis of the femoral head is higher than that after total hip arthroplasty for osteoarthritis. However, few reports have investigated the factors contributing to dislocation after total hip arthroplasty for osteonecrosis of the femoral head. The aim of this study was to assess radiological factors associated with posterior dislocation after total hip arthroplasty for osteonecrosis of the femoral head. Methods: We retrospectively reviewed 179 cementless total hip arthroplasties for osteonecrosis of the femoral head using a posterolateral approach between 2002 and 2020 with a minimum follow-up period of 24 months. The following radiological factors were examined for a possible association with posterior dislocation after total hip arthroplasty: cup anteversion angle, cup inclination angle, femoral offset, and stem anteversion angle. Results: Posterior dislocation occurred in seven hips (3.9 %). Compared to hips without posterior dislocation, those with posterior dislocation exhibited a significantly smaller cup anteversion angle (p = 0.045) and a nonsignificantly greater decrease in femoral offset (p = 0.089). Based on receiver operating characteristic curve analyses, the cutoff values for predicting posterior dislocation were 9.9° for the cup anteversion angle and 8.1 mm for the decrease in femoral offset. Logistic regression analysis showed a significantly higher risk of posterior dislocation among hips with a cup anteversion angle less than 9.9° (odds ratio = 7.1, p = 0.022) or with a decrease in femoral offset over 8.1 mm (odds ratio = 5.0, p = 0.040). Conclusions: A small cup anteversion angle and a decreased femoral offset are suggested to be associated with posterior dislocation after total hip arthroplasty in patients with osteonecrosis of the femoral head.

DOI： 10.1016/j.jor.2023.11.015

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publisher：Clinical Biomechanics  

Background: In the natural course of osteonecrosis of the femoral head, sclerotic changes at the boundary of necrotic lesion gradually occur until femoral head collapse. This study aims to examine the effects of bone mineral density at the lateral boundary of necrotic lesion on a subsequent femoral head collapse. Methods: We developed patient-specific finite element models of 9 hips with subsequent collapse and 10 hips without subsequent collapse. Cubic regions of interest were selected at both subchondral areas of the lateral boundary and the adjacent necrotic lesion. Bone mineral density values of the regions of interest were quantitatively measured, and a ratio of bone mineral density values (lateral boundary/necrotic lesion) was calculated. Stress values at the lateral boundary were also evaluated. Findings: The ratio of bone mineral density values was significantly higher in hips with subsequent collapse than that without subsequent collapse (p = 0.0016). The median equivalent stress and shear stress were significantly higher in hips with subsequent collapse than that without subsequent collapse (p = 0.0071, and p = 0.0143, respectively). The ratio of bone mineral density values showed a promising value in predicting the occurrence of subsequent femoral head collapse (AUC = 0.97). Interpretation: Our results indicated that bone mineral density value at the lateral boundary of necrotic lesion may be associated with the occurrence of subsequent femoral head collapse in pre-collapse stage osteonecrosis of the femoral head.

DOI： 10.1016/j.clinbiomech.2023.106156

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Language：English   Publisher：Journal of Orthopaedic Science  

Background: This study assessed the hip survival rate and patient-reported outcome measures (PROMs) of transtrochanteric curved varus osteotomy (CVO) for osteonecrosis of the femoral head (ONFH) compared with those of conservative management. Methods: The CVO group comprised 32 consecutive patients (39 hips) who underwent CVO for ONFH between 2000 and 2011. The conservative group consisted of 36 consecutive patients (37 hips) who were managed conservatively for at least 1 year after collapse and who had ONFH classified by the Japanese Investigation Committee of Health and Welfare as type B or C1, for which CVO is indicated. Kaplan–Meier analysis of hip survival used any ONFH-related therapeutic surgery as the endpoint. PROMs were evaluated for all patients with surviving hips and radiographs available at the latest follow-up. Result: The 10-year hip survival rate in the CVO group was 86.7%, which was significantly higher than the 51.0% 5-year survival rate in the conservative group (p < 0.0001). The Oxford Hip Score and UCLA Activity Score were significantly better in the CVO group without joint space narrowing than in the conservative group, with no significant differences between the CVO group with joint space narrowing and the conservative group. Conclusion: CVO could preserve hip joints more effectively than conservative follow-up after collapse, although the presence of joint space narrowing could reduce satisfaction levels even in patients with long-term hip survival.

DOI： 10.1016/j.jos.2024.03.010

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Language：English   Publisher：Elsevier B.V.  

股関節全置換術(THA)を施行された変形性股関節症(股OA)の日本人患者における患者申告アウトカム尺度(PROMs)の適用状況について検討した。PROMsを取り上げた文献をレビューし、ガイドラインの有無、質問票日本語版の妥当性、治療効果の評価方法などを評価項目とした。患者申告アウトカム(PROs)/PROMsに関するガイドラインとして、Consensus-based standards for the selection of health measurement instruments(COSMIN)チェックリスト、Standard protocol items:recommendations for interventional trials-PRO extension(SPIRIT-PRO extension)、the consolidated standards of reporting trials-PRO extension(CONSORT-PRO extension)が存在することが示され、方法論的な質や試験プロトコルが評価されていた。簡易36/12項目健康サーベイが多次元的評価に用いられており、EuroQol 5 dimension(EQ-5D)は患者選好性をベースとする有用性の評価に最も多く使用されていた。疾患特異的QOLの評価にはWestern Ontario and McMaster Universities変形性関節症指数、Oxford股関節スコア、股関節障害度・変形性関節症アウトカムスコア、Forgotten関節スコア-12、日本整形外科学会股関節疾患評価質問票が用いられていた。このほか、中枢神経感作症候群の評価には中枢神経感作尺度、「生きがい」の評価にはIkigai-9が活用されていた。THAを受けた股OA患者に対して、さまざまな手法によってQOLが評価されていることが明らかになった。

Language：Japanese   Publishing type：Research paper (scientific journal)  

Publisher：メジカルビュー社  

DOI： 10.18885/jjs.0000001562

CiNii Research

Language：English   Publisher：Scientific Reports  

This study aimed to clarify the clinical utility of the sourcil roundness index (SRI), a novel index for quantifying the asphericity of the acetabular concavity, by determining (1) the difference in the SRI between dysplastic and normal hips and (2) the correlation between the SRI and radiographic parameters of hip dysplasia. We reviewed standing anteroposterior pelvic radiographs of 109 dysplastic and 40 normal hips. The SRI was determined as the ratio of the distance from the medial edge of the sourcil to the most concave point of the acetabular sourcil (A) to the distance from the medial to the lateral edge of the sourcil (B). The formula for SRI is (A/B) × 100–50 (%), with an SRI of 0% indicating a perfectly spherical acetabulum, and higher SRI values indicating a more aspherical shape. The median SRI was greater in patients with hip dysplasia than in normal hips (5.9% vs. − 1.4%; p < 0.001). Furthermore, the median SRI was greater in the severe dysplasia subgroup (18.9%) than in the moderate (3.5%) and borderline-to-mild (− 1.3%) dysplasia subgroups (p < 0.05). Quantification of acetabular concavity asphericity by the SRI showed that dysplastic hips had a more lateral acetabular concave point than normal hips, and that the severity of hip dysplasia had an effect on the acetabular concavity asphericity.

DOI： 10.1038/s41598-023-42630-z

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publisher：Journal of Orthopaedic Research  

Articular surface irregularities are often observed in collapsed femoral heads with osteonecrosis, while the effects of the degree of collapse on the articular surface are poorly understood. We first macroscopically assessed the articular surface irregularities on 2-mm coronal slices obtained using high-resolution microcomputed tomography of 76 surgically resected femoral heads with osteonecrosis. These irregularities were observed in 68/76 femoral heads, mainly at the lateral boundary of the necrotic region. The mean degree of collapse was significantly larger for femoral heads with articular surface irregularities than for those without (p < 0.0001). Receiver operating characteristic analysis showed that the cutoff value for the degree of collapse in femoral heads with articular surface irregularities at the lateral boundary was 1.1 mm. Next, for femoral heads with <3-mm collapse (n = 28), articular surface irregularities were quantitatively assessed based on the number of automatically counted negative curvature points. Quantitative evaluation showed that the degree of collapse was positively correlated with the presence of articular surface irregularities (r = 0.95, p < 0.0001). Histological examination of articular cartilage above the necrotic region (n = 8) revealed cell necrosis in the calcified layer and abnormal cellular arrangement in the deep and middle layers. In conclusion, articular surface irregularities of the necrotic femoral head depended on the degree of collapse, and articular cartilage was already altered even in the absence of macroscopically determined gross irregularities.

DOI： 10.1002/jor.25539

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Language：Japanese   Publisher：日本股関節学会  

後方アプローチで人工股関節全置換術(THA)を行い、1年以上経過した関節リウマチ(RA)21例25関節(RA-THA群)と、変形性股関節症(OA)246例308関節(OA-THA群)の患者立脚型評価(PROMs)を比較した。PROMsとしてVAS satisfaction、Oxford hip score、Forgotten Joint Score-12、UCLA activity scaleを用いた。その結果、いずれのPROMsでも有意な群間差を認めず、RA-THA群では活動性に課題が残るもののOA-THA群に劣らない良好なPROMsが達成された。RA-THAでは除痛効果や歩行能力改善、疾患活動性のコントロールが良好なPROMs達成の要因と考えられ、疾患活動性をコントロールし骨破壊が進む前に手術をすることで良好なPROMsが得られる可能性が示された。

Language：Japanese   Publisher：日本股関節学会  

2018年7月～2020年10月に寛骨臼移動術を施行したlateral center-edge angle(LCEA)<20°の症候性股関節形成不全(DDH)40例40関節(全例女性、平均年齢37.8歳)の術前に撮影した臥位と立位の骨盤正面X線像を用いて骨頭被覆、および寛骨臼と骨頭の位置関係について検討し、LCEA≧25°の正常健常者16例16関節(全例女性、平均年齢35.6歳)と比較した。DDH患者・正常健常者ともにLCEAとanterior wall indexは臥位から立位で減少し、posterior wall indexは臥位から立位で増加した。寛骨臼と骨頭の位置関係として、最小関節裂隙幅とmodified lateralization distanceはDDH患者では臥位から立位で減少したが、正常健常者では変わらなかった。DDH患者では臥位から立位で骨頭が寛骨臼に対して内側上方に移動する一方、正常健常者では移動しなかった。

Language：English   Publisher：HIP International  

Background: No studies have compared patient satisfaction between periacetabular osteotomy (PAO) and total hip arthroplasty (THA) for osteoarthritis (OA) secondary to developmental dysplasia of the hip (DDH) in Asian cohorts. Methods: Multivariate analyses were applied to determine whether patient demographics and postoperative patient-reported outcomes were correlated with postoperative patient satisfaction in 737 DDH patients (251 PAO and 486 THA patients). Additionally, postoperative patient satisfaction, Oxford Hip Score (OHS), University of California-Los Angeles (UCLA) activity score, and sports participation were compared between propensity-matched PAO and THA patients for OA secondary to DDH (Kellgren-Lawrence grade II: 32 PAO and 16 THA patients, grade III: 20 PAO and 40 THA patients). Results: Of the 737 patients, 663 patients (90%) were postoperatively satisfied. Multivariate analysis demonstrated that THA was positively correlated with patient satisfaction. Furthermore, high postoperative OHS-pain, OHS-ADL, and UCLA scores were positively correlated with satisfaction. In propensity-matched PAO and THA patients, PAO elicited greater patient satisfaction than THA for KL grade II OA secondary to DDH, with comparable postoperative OHS (including the pain and ADL subscale), UCLA score, and sports participation rate. In contrast, THA resulted in better satisfaction and OHS-pain for KL grade III OA secondary to DDH, with comparable postoperative OHS-ADL, UCLA score, and sports participation rate in the 2 surgeries. Conclusions: Both PAO and THA procedures offer distinct patient satisfaction advantages based on preoperative OA severity. These findings can assist in the clinical decision-making process for the surgical treatment of middle-aged patients with symptomatic DDH.

DOI： 10.1177/11207000221114272

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Language：Japanese   Publisher：(一社)日本関節病学会  

目的:寛骨臼形成不全(DDH)に対するperiacetabular osteotomy(PAO)の至適な骨片の移動方向・移動量については定まった指標がない。本研究の目的は,PAOにおいて,股関節の力学的環境を最適化する骨片の移動方向・移動量を明らかにすることである。方法:DDH患者(LCE角<25°)の32例32股(全例女性,平均年齢40歳,平均LCEA9°)を対象とした。股関節CT DICOM dataを用い,立位骨盤傾斜を再現した上で有限要素解析を行った。LCEA30°・35°・40°に前方回転0°・5°・10°・15°を追加した12通りのPAOシミュレーションを行い,片脚立位想定時の寛骨臼軟骨の接触面積・最大接触圧力(Max CP)を算出した。正常ボランティア16例16股の結果からMax CPの正常範囲は4.1MPa未満とした。結果:前方回転(-)よりも前方回転(+)で接触面積は増加し,Max CPは減少した。12通りのPAOシミュレーションの中で,Max CPが正常化する割合はLCE角30°+前方回転15°のときで87.5%(27/32股)と最も多く,続いてLCE角35°+前方回転15°のときで84.4%(27/32股)であった。考察:PAOの際,寛骨臼の側方回転に前方回転を追加することで接触面積は増大し,接触圧力は減少した。症例により骨片の至適位置は異なるが,LCE角30°～35°に前方回転を15°追加した際,Max CPは最も正常化しやすいことが示唆された。(著者抄録)

Language：English   Publisher：Scientific Reports  

There are no reports on hip kinetics including contact forces and muscle activities during the golf swing after total hip arthroplasty (THA). The aim of this study was to identify the characteristics of three-dimensional dynamics during the golf swing. Ten unilateral primary THA patients participated in motion capture test of their driver golf swing. The driver swing produced approximately 20–30° of rotation in both lead and trail replaced hips. The mean hip contact forces (HCFs) of lead and trail replaced hips were 5.1 and 6.6 × body weight, respectively. Left and right THAs showed similar HCFs of lead and trail hips. More than 60% of the Percent maximum voluntary isometric contraction was found in bilateral iliopsoas muscles in all unilateral THA. Three factors [female sex, lower modified Harris Hip Score, and higher HCF of surgical side] were associated with the golf-related replacement hip pain. Golf is an admissible sport after THA because driver swings do not contribute excessive rotation or contact forces to hip prostheses. HCF could be reduced through swing adjustments, which may allow patients with golf-related replacement hip pain to develop a comfortable golf game free from pain.

DOI： 10.1038/s41598-023-35484-y

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Language：English   Publisher：Scientific Reports  

This study aimed to (1) set a reference value for anterior center edge angle (ACEA) for preoperative planning of periacetabular osteotomy (PAO), (2) investigate the effects of pelvic rotation and inclination from false profile (FP) radiographs on the measured ACEA, and (3) determine the “appropriate range of positioning” for FP radiograph. This single-centered, retrospective study analyzed 61 patients (61 hips) who underwent PAO from April 2018 and May 2021. ACEA was measured in each digitally reconstructed radiography (DRR) image of the FP radiograph reconstructed in different degrees of pelvic rotation. Detailed simulations were performed to determine the “appropriate range of positioning” (0.67 < ratio of the distance between the femoral heads to the diameter of the femoral head < 1.0). The vertical-center-anterior (VCA) angle was measured on the CT sagittal plane considering the patient-specific standing positions, and its correlation with the ACEA was investigated. The reference value of ACEA was determined by receiver operating characteristic (ROC) curve analysis. The ACEA measurement increased by 0.35° for every 1° pelvic rotation approaching the true lateral view. The pelvic rotation with the “appropriate range of positioning” was found at 5.0° (63.3–68.3°). The ACEA on the FP radiographs showed a good correlation with the VCA angle. The ROC curve revealed that an ACEA < 13.6° was associated with inadequate anterior coverage (VCA < 32°). Our findings suggest that during preoperative PAO planning, an ACEA < 13.6° on FP radiographs indicates insufficient anterior acetabular coverage. Images with the “appropriate positioning” can also have a measurement error of 1.7° due to the pelvic rotation.

DOI： 10.1038/s41598-023-35514-9

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Language：English   Publisher：Journal of Orthopaedic Science  

Background: This study aims to evaluate the accuracy of the axis connecting both anterior superior iliac spines (ASIS axis) as the absolute pelvic axis. No study has ever verified the accuracy of ASIS axis particularly on the AP pelvic radiograph, which cannot be specified on it. Methods: Sixty patients who underwent total knee arthroplasty and fifty patients with femoral neck fracture were recruited as subjects without hip deformities and their CT scan data were collected. We defined the line through both center of femoral heads as absolute reference axis of pelvis three-dimensionally. On the coronal plane, the errors between the femoral head axis and the axes through six pelvic landmarks in total, including ASIS were analyzed. On the axial plane, the errors of the lines through four landmarks were analyzed in the same way. Finally, on the coronal images, the mediolateral diameter of the obturator foramen and the mediolateral distance between the midline of the sacrum and the pelvic cavity were measured to evaluate bilateral symmetry of the pelvis. Results: The errors tended to be smaller as the axes were closer to the femoral head axis (axes connecting bilateral superior aspects of the acetabulum and the teardrops) and the ASIS axis errors were moderate. The obturator foramen based on the ASIS axis was more asymmetrical than the femoral head axis. Conclusion: Adjusting the pelvic tilt and rotation, surgeons should not always rely on the ASIS and refer to appropriate, close to the hip joint references in each case.

DOI： 10.1016/j.jos.2022.01.011

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PubMed

Language：English   Publisher：(公社)日本整形外科学会  

絶対骨盤軸として用いられる上前腸骨棘(ASIS軸)の確度について検討した。膝関節全置換術を受けた60例(A群:男性17例、女性43例、平均75.7±8.2歳)と大腿頸部骨折患者50例(B群:男性14例、女性36例、平均81.2±8.1歳)のCTスキャンデータを収集した。三次元的に両大腿骨頭を通過するラインを骨盤の絶対参照軸と定義し、冠状面では大腿骨頭軸と六つの骨盤ランドマークを介した軸との誤差を求め、軸平面では四つの骨盤ランドマークを通過するラインの誤差を測定した。A群とB群にみられる冠状面での軸誤差は同等の結果となり、A群の誤差は寛骨臼上面、ティアドロップ基部、ASIS前面、閉鎖孔上面、閉鎖孔下面、坐骨結節遠位面の順に小さく、B群の誤差は寛骨臼上面、ティアドロップ基部、閉鎖孔上面、ASIS前面、閉鎖孔下面、坐骨結節遠位面の順に小さかった。軸平面での軸誤差はA群、B群ともに寛骨臼後面、寛骨臼前面、ASIS前面、坐骨結節後面の順に小さかった。軸誤差は測定ラインが大腿骨頭軸に近づくにつれて小さくなり、ASIS軸の誤差は中等量を示していた。ASISは必ずしも信頼に足る指標になるとは限らないと考えられた。

Language：English  

DOI： 10.1093/jhps/hnac047

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PubMed

Language：Japanese   Publisher：西日本整形・災害外科学会  

【はじめに】本研究の目的は,当院で施行した寛骨臼移動術(TOA)の術後20年以上の長期成績を調査し,関節温存に関連する影響因子を明らかにすることである.【方法】1996-2005年に当院でTOAを施行した患者で追跡可能であった159例172股(平均観察期間21年)を対象とした.THA conversionをエンドポイントとしたときの累積温存率を,Kaplan-Meier生存分析を用いて調査した.関節温存に関連する影響因子は,単変量および多変量Cox回帰分析を用いて調査した.【結果】31例33股がTHA conversionとなり,術後20年の累積温存率は79.7%であった.多変量解析では,術前病期が唯一の有意な影響因子であり,リスク比は2.69(p=0.003)だった.一方,年齢は影響因子ではなかった(p=0.153).手術時年齢を考慮して術前病期別に比較したところ,前・初期では45歳未満が89.8%,45歳以上が86.2%と年齢に関わらず(p=0.62),良好な結果を示した.一方で,進行期では45歳未満が66.7%,45歳以上51.1%と年齢に関わらず(p=0.75),前・初期よりも関節温存率は低かった.【考察】寛骨臼形成不全に対するTOAにおいて,長期での良好な関節温存を得るためには,術前病期が前期・初期であることが重要であり,手術時の年齢は影響しなかった.(著者抄録)

Language：Japanese   Publisher：西日本整形・災害外科学会  

【目的】Dorr type Cに対するTHAにおけるステム沈下(Subsidence)に関してFit-and-fill stemとTaper wedge stemで比較検討すること.【方法】Dorr type Cに対してPrimary THAを行ったFit-and-fill stem群48例,Taper wedge stem群43例を対象とした.患者背景として疾患,性別,年齢,BMIを調査した.Subsidence量は術直後と術後1週,術後1週と術後6週,術直後と術後6週の3ポイントでX線を用いて評価した.【結果】両群間で患者背景に有意差は認めなかった.術直後から術後6週,術後1週から術後6週でのSubsidence量は,Fit-and-fill stem群に比べTaper wedge stem群の方が有意に小さかった.また,3mmを超えるSubsidenceは,Fit-and-fill stem群で8例,Taper wedge stem群で1例に認め有意にFit-and-fill stem群で多かった.多変量解析の結果,ステムの種類が3mmを超えるSubsidenceに影響を与える独立した因子であった.【結語】本研究結果からDorr type CにはFit-and-fill stemよりTaper wedge stemの方が適していると考えられた.(著者抄録)

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publisher：Journal of Arthroplasty  

Background: There is increasing interest in improving activity after total hip arthroplasty (THA) and periacetabular osteotomy (PAO). The present study evaluated whether there were differences in the subjective and objective activity levels of THA and PAO patients at mean 12-year follow-up (range 4-20) and what factors influence the objective activity levels. Methods: THA and PAO patients (30 patients each; mean age: 66 and 63 years, respectively), who had undergone surgery for osteoarthritis due to acetabular dysplasia, were included. Patients were retrospectively matched based on age, gender, body mass index, follow-up duration, and preoperative University of California, Los Angeles activity score (UCLA score). Patients were surveyed for the subjective activity levels using the Oxford Hip Score and UCLA score. Objective activity levels (the number of steps, upright time, and the number of sit-to-stand transitions) were made using an accelerometer. Results: There was no significant difference in subjective activity level between THA and PAO patients. The number of steps was significantly higher in PAO than in THA patients. Multivariable analyses revealed that THA and low Oxford Hip Score activities of daily living were negatively associated with the number of steps, that men and high UCLA score were negatively associated with upright time, and that high body mass index was negatively associated with sit-to-stand transitions in THA and PAO patients. Conclusion: This study suggested that although there was no difference in postoperative subjective activity level between THA and PAO patients, there was a difference in objective activity level. Providing guidance to these patients based on objective activity may lead to higher activity levels.

DOI： 10.1016/j.arth.2022.08.034

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Language：English   Publisher：Journal of Bone and Joint Surgery  

Background:Missing responses are common when Asian patients complete the Forgotten Joint Score-12 (FJS-12), which is widely used to evaluate total hip arthroplasty (THA). We aimed to provide orthopaedic researchers with a solution for handling missing values in such patient-reported outcome measures (PROMs).Methods:Patients who had undergone primary THA between 1998 and 2016 (n = 1,021) were investigated in 2020. The FJS-12 and 9 other PROMs, including questions related to Asian lifestyle activities, were administered. Risk factors for missing FJS-12 items were investigated. Partial respondents were matched with complete respondents; then, in each pair, the items not completed by the partial respondent were deleted from the responses of the complete respondent. Predictive mean matching (PMM) was performed in an attempt to recover the deleted items, using 65 sets of imputation models. After the missing values had been imputed, we explored patient characteristics that affected the FJS-12, using data from all complete and partial respondents.Results:A total of 652 patients responded to the survey (393 complete and 193 partial respondents). Partial respondents were older, more often female, and less active. Older respondents were more likely to skip items involving the bed, while those who reported a better ability to sit in the seiza style (traditional Japanese floor sitting) were more likely to skip items about chair sitting. The imputed FJS-12 value exhibited excellent reliability (intraclass correlation coefficient for agreement with the true scores, 0.985). FJS-12 values of complete respondents were significantly higher than those of respondents with 4 to 11 missing items (51.6 versus 32.8, p < 0.001). Older age was associated with higher FJS-12 values, which was revealed only via analysis of the multiply imputed data sets (p < 0.001).Conclusions:Analysis of only complete FJS-12 responses after THA resulted in a nonresponse bias, preferentially excluding older, female, and less active individuals and those with a traditional floor living style. Multiple imputation could provide a solution to scoring and analyzing PROMs with missing responses by permitting the inclusion of partial respondents.Level of Evidence:Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

DOI： 10.2106/JBJS.21.01547

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Publisher：金原出版  

DOI： 10.18888/se.0000002376

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publisher：Scientific Reports  

This study aimed to investigate the influence of bone marrow edema (BME) for the assessment of the boundaries of necrotic lesions using unenhanced and contrast-enhanced (CE) magnetic resonance (MR) images in patients with osteonecrosis of the femoral head (ONFH). We retrospectively reviewed 72 consecutive hips in 55 patients of ONFH that were Association Research Circulation Osseous (ARCO) stage III or higher and underwent both unenhanced and contrast-enhanced MR imaging between January 2005 and February 2016. The degree of extension of BMEs, and the boundaries of the necrotic lesions were compared using unenhanced and CE MR images on both mid coronal and mid oblique-axial slices. Forty-two percent of the coronal T1 images, 40% of the coronal fat-saturated T2 images, and 48% of the oblique-axial T1 images showed differences in the boundaries of necrotic lesion, by comparison with those of CET1-weighted MR images. The boundaries of necrotic lesions were clearly detected in all hips on CE coronal slices and 97% of all hips on CE oblique-axial slices. The BME grade in the difference group was significantly higher than in the non-difference group on the coronal plane (P = 0.0058). There were significant differences between the BME grade and duration from the onset of hip pain to MR imaging examination. Multivariate analyses revealed that the duration from the onset to MR imaging examination in both coronal (P = 0.0008) and oblique-axial slices (P = 0.0143) were independently associated with differences in the boundary of necrotic lesion between T1 and CET1-weighted MR images. Our findings suggest that unenhanced MR image may be insufficient for a precise assessment of the boundaries of the necrotic lesions for ONFH cases in the early phase of subchondral collapse due to the diffuse BME.

DOI： 10.1038/s41598-022-23427-y

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/s41598-022-23427-y.

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Orthopaedic Surgery  

Objective: Excessive pelvic tilt has been reported to impair the biomechanical loading of the hip joint. However, the influence of pelvic tilt in osteonecrosis of the femoral head (ONFH) remains unclear. This study aims to assess whether sagittal pelvic posture in the standing position correlates with progression of femoral head collapse in post-collapse stage ONFH. Methods: This is a single-center retrospective study. We investigated 107 patients (107 hips; 73 males and 34 females; mean age, 48 years) diagnosed with Association of Research Circulation Osseous (ARCO) stage III ONFH at the first visit and who subsequently underwent surgical treatment in our institution from July 2016 to December 2020. The sagittal pelvic posture in the standing position before surgery was quantified as the angle formed by the anterior pelvic plane and the vertical z-axis in the sagittal view (APP angle). An APP angle <0° indicated posterior pelvic tilt. Progression of femoral head collapse was calculated as collapse speed. The following factors potentially associated with collapse speed were evaluated by exploratory data analysis followed with multiple linear regression analysis: sex, age, BMI, etiology, pelvic incidence, contralateral hip condition, time interval between the first visit and surgery, size of necrotic lesion, location of necrotic lesion, and APP angle. Results: As ONFH progressed from ARCO stage IIIA to stage IV, APP angle decreased significantly and continuously (stage IIIA, −0.2° ± 5.5°; stage IIIB, −3.7° ± 5.8°; stage IV, −7.1° ± 6.4°). The factors significantly associated with collapse speed were size of necrotic lesion (p = 0.0079), location of necrotic lesion (p = 0.0190), and APP angle (p < 0.0001). APP angle showed a negative correlation with collapse speed (r = −0.40, p < 0.0001). After stratifying by size of necrotic lesion (<50% and ≥50% involvement) and location of necrotic lesion (JIC type C1 and C2), a significant negative correlation was observed between APP angle and collapse speed in each group (JIC type C1 with <50% involvement, r = −0.69, p < 0.0001; JIC type C1 with ≥50% involvement, r = −0.58, p = 0.0475; JIC type C2 with <50% involvement, r = −0.51, p = 0.0124; JIC type C2 with ≥50% involvement, r = −0.39, p = 0.0286). Conclusions: Our results suggest that posterior pelvic tilt in the standing position occurred as ONFH progressed from ARCO stage IIIA to stage IV, which might be associated with progression of femoral head collapse in ONFH.

DOI： 10.1111/os.13544

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Language：English   Publisher：Gait and Posture  

Background: In modern society, car usage is one of the most important activities of daily living. However, the three-dimensional (3D) mechanics of getting into and out of a car in total hip arthroplasty (THA) patients have not been studied. Research question: This study aimed to elucidate the hip kinematics and kinetics of unilateral THA patients while getting into and out of a car. Methods: 3D motion and ground reaction force data were collected for 40 unilateral primary THA and 30 control participants using motion capture of getting into and out of a car. Normalized joint power was used to determine the individual joint contribution and was calculated by dividing the power of each joint by the total lower-extremity power. These kinematic and kinetic data were compared between unilateral THA and control participants. Results: When getting into the car using the surgical side as the pivot limb, the peak flexion, abduction angle, and normalized power of the pivot hip were significantly lower, and the normalized power of the contralateral ankle was significantly higher. The peak flexion and abduction angle of the pivot hip were significantly lower, and normalized contralateral hip power was significantly higher when getting out of the car. In getting into and out of the car using the contralateral side as the pivot limb, there was no significant difference in the range of motion (RoM) and normalized joint power. Significance: The restoration of RoM and muscle strength in the surgical hip joint and adopting the normal side as the pivot limb may allow for a more appropriate balance in motion of getting into and out of a car, which will lead to safe mobility, assist in social participation, and improved quality of life. Level of evidence: Level III, therapeutic study.

DOI： 10.1016/j.gaitpost.2022.10.003

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Language：English   Publisher：Journal of Arthroplasty  

Background: Identifying factors associated with poor hip contact mechanics after periacetabular osteotomy (PAO) may help surgeons optimize acetabular corrections in individual patients. We performed individual-specific finite-element analyses to identify preoperative morphological and surgical correction factors for abnormal contact pressure (CP) after PAO. Methods: We performed finite-element analyses before and after PAO with reference to the standing pelvic position on individual-specific 3-dimensional hip models created from computed tomography images of 51 dysplastic hips. Nonlinear contact analyses were performed to calculate the joint CP of the acetabular cartilage during a single-leg stance. Results: The maximum CP decreased in 50 hips (98.0%) after PAO compared to preoperative values, and the resulting maximum CP was within the normal range (<4.1 MPa) in 33 hips (64.7%). Multivariate analysis identified the roundness index of the femoral head (P = .002), postoperative anterior center-edge angle (CEA; P = .004), and surgical correction of lateral CEA (Δlateral CEA; P = .003) as independent predictors for abnormal CP after PAO. A preoperative roundness index >54.3°, a postoperative anterior CEA <36.3°, and a Δlateral CEA >27.0° in the standing pelvic position predicted abnormal CP after PAO. Conclusion: PAO normalized joint CP in 64.7% of the patients but was less likely to normalize joint CP in patients with aspheric femoral heads. Successful surgical treatment depends on obtaining adequate anterior coverage and avoiding excessive lateral correction, while considering the physiological pelvic tilt in a weight-bearing position.

DOI： 10.1016/j.arth.2022.04.045

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Language：English   Publisher：Geriatric Orthopaedic Surgery and Rehabilitation  

Introduction: Lower-limb osteoarthritis (OA) in the elderly can be a risk factor for frailty, which is the preliminary of disability, but it may be reversible with appropriate interventions. We aimed to use the Kihon Check List (KCL) to assess multiple domains of frailty and to identify the characteristics of frailty in patients with hip or knee OA following total joint arthroplasty. Materials and Methods: This study included 136 ≥ 65-year-old patients (mean age: 73.0 years) who underwent total arthroplasty with end-stage hip and knee OA. We assessed frailty status, instrumental activities of daily living (IADL), and health-related quality of life (HRQoL) according to the KCL, functional ambulatory index (FAI) and EuroQol-5 Dimension (EQ5D), respectively, as well as the extent of pain preoperatively and at postoperative 6 months. Results: Using KCL, seventy-eight (57.4%) patients were frail preoperatively, but the prevalence significantly decreased to 52 patients (38.2%) at postoperative 6 months. Total arthroplasty intervention provided significant improvements in the total KCL scores, including the physical domain (P <.01), pain (P <.01), FAI scores (P <.01), and EQ5D (P <.01), but not the social domain. Multivariate logistic regression analysis identified age at surgery (OR:.93, 95% CI:.86-.99) and preoperative FAI score (OR: 1.10, 95% CI: 1.03-1.19) as independent predictors of postoperative frailty. Conclusions: Total arthroplasty procedures on patients with hip and knee OA reduced their KCL score, but social aspects were less improved than physical aspects in the shortterm. Older age and preoperative lower IADL score can be useful for accurately estimating less improvement of frailty in the early postoperative phase. Our results suggest that long term follow-up of OA is needed to provide comprehensive interventions, including in social aspects, especially for patients with lower activity.

DOI： 10.1177/21514593221126019

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Language：English   Publisher：Annals of the Rheumatic Diseases  

Objective Genome-wide association studies (GWAS) have identified >100 risk loci for systemic lupus erythematosus (SLE), but the disease genes at most loci remain unclear, hampering translation of these genetic discoveries. We aimed to prioritise genes underlying the 110 SLE loci that were identified in the latest East Asian GWAS meta-analysis. Methods We built gene expression predictive models in blood B cells, CD4 + and CD8 + T cells, monocytes, natural killer cells and peripheral blood cells of 105 Japanese individuals. We performed a transcriptome-wide association study (TWAS) using data from the latest genome-wide association meta-analysis of 208 370 East Asians and searched for candidate genes using TWAS and three data-driven computational approaches. Results TWAS identified 171 genes for SLE (p<1.0×10 -5); 114 (66.7%) showed significance only in a single cell type; 127 (74.3%) were in SLE GWAS loci. TWAS identified a strong association between CD83 and SLE (p<7.7×10 -8). Meta-analysis of genetic associations in the existing 208 370 East Asian and additional 1498 cases and 3330 controls found a novel single-variant association at rs72836542 (OR=1.11, p=4.5×10 -9) around CD83. For the 110 SLE loci, we identified 276 gene candidates, including 104 genes at recently-identified SLE novel loci. We demonstrated in vitro that putative causal variant rs61759532 exhibited an allele-specific regulatory effect on ACAP1, and that presence of the SLE risk allele decreased ACAP1 expression. Conclusions Cell-level TWAS in six types of immune cells complemented SLE gene discovery and guided the identification of novel genetic associations. The gene findings shed biological insights into SLE genetic associations.

DOI： 10.1136/annrheumdis-2022-222345

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Publisher：Orthopedics  

Periacetabular osteotomy (PAO) is an effective joint-preserving procedure for developmental dysplasia of the hip. However, some patients report dissatisfaction after PAO. Because patient satisfaction is increasingly used as a health care quality metric, it is important to gain a better understanding of factors associated with patient satisfaction after PAO. The goal of this study was to investigate patient satisfaction among a cohort of Asian patients undergoing PAO. This study included 227 Asian patients who had undergone PAO at our institution between 1998 and 2016. The study participants completed a questionnaire assessing patient satisfaction, reasons for dissatisfaction, and postoperative Oxford Hip Score (OHS) and University of California, Los Angeles (UCLA), activity scale score. Based on their satisfaction levels, the participants were divided into 4 subgroups, and their demographic characteristics and postoperative patient-reported outcomes were compared. Of the 227 patients, 190 expressed satisfaction that correlated with OHS-pain, OHD-activities of daily living, and UCLA activity scale scores. Primary reasons for dissatisfaction after PAO were persistent pain (24 of 49, 49%), functional limitations (14 of 49, 29%), stiffness around the hip (4 of 49, 8%), unmet expectations (4 of 49, 8%), conversion to total hip arthroplasty (2 of 49, 4%), and complications (1 of 49, 2%). Multivariate analysis showed that preoperative Kellgren-Lawrence grades 1 and 3 were the significant predictive factors for satisfaction and dissatisfaction, respectively. The potential for lower patient satisfaction associated with Kellgren-Lawrence grade 3 because of persistent pain and functional limitations postoperatively suggests that consideration of preoperative severity of osteoarthritis could enhance patient satisfaction after PAO.

DOI： 10.3928/01477447-20220425-02

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PubMed

Language：Japanese   Publisher：西日本整形・災害外科学会  

【はじめに】大腿骨骨切り後の人工股関節置換術(以下THA)は,通常の初回THAと比較して骨折の合併に注意が要することが報告されている.骨切り時に挿入した固定材料の抜去(抜釘)が骨折合併に影響するかを検討した報告は渉猟する限りない.骨切り後THA症例における骨折合併に影響する因子を,抜釘の有無を含めて検討することを本研究の目的とした.【対象と方法】2008年-2020年の間にPerfix HA 910を用いて施行された骨切り後THA101股を対象とした.術中骨折または術後1ヵ月以内の外傷のない骨折を骨折合併ありとした.THA時の年齢,骨切りからTHAまでの期間,同時抜釘の有無,先行骨切り術について調査し,骨折合併に影響する因子を解析した.【結果】骨折合併は7関節(6.9%)に認めた.多変量解析の結果,同時抜釘ありと骨切りからTHAまでの期間が骨折合併に有意な影響を及ぼす因子として同定された.【結語】本研究結果より,抜釘を伴う骨切り後THAは骨折を合併しやすいことが示唆された.大腿骨骨切り後症例に対しては,将来のTHAを考慮すると,事前に抜釘しておくことが薦められる.(著者抄録)

Language：Japanese   Publisher：日本股関節学会  

当院で寛骨臼移動術(TOA)を施行した発育性股関節形成不全(DDH)34例35関節(男性2関節、女性33関節、平均年齢40±12歳)を対象に、機能的骨盤傾斜がTOA後の股関節接触圧力に与える影響について検討した。その結果、TOA後は97%の症例で最大接触圧力が減少し、63%の症例で正常化していた。17%の症例では臥位から立位で10°以上骨盤が後傾しており、TOA後の最大接触圧力も臥位と立位で大きく異なっていた。以上、今回の結果から、矢状面骨盤傾斜の変化はperiacetabular osteotomy(PAO)後の股関節の力学的環境に影響を与えることから、骨形態や生体力学的な評価についてはPAO後においても荷重時の骨盤傾斜を考慮すべきであることが示唆された。

Language：Japanese   Publisher：日本股関節学会  

セメントレスステムでは、モジュラーネックの一部の機種を除いてステム前捻角が大腿骨の髄腔形状に規定されやすいが、楔形形状をしたtaper wedge型ステムは、髄腔占拠をコンセプトとするfit-and-fill型ステムに比べて前捻角の自由度が大きいと考えられる。また、同じtaper wedge型でも機種によってステムデザインは異なり、デザインが異なると前捻角の自由度も異なる可能性が考えられる。今回、当科で寛骨臼形成不全に伴う変形性股関節症に対してTHAを施行した37例37関節を対象とし、使用ステム別にInitia(taper wedge型)群、J-Taper(taper wedge型)群、PerFix910(fit and fill型)群に分け、「前捻角自由度」「後傾変化量」「外反変化量」「深度変化量」を比較検討した。結果、前捻角自由度はInitia群>J-Taper群>PerFix910群の順に大きく、各群間に有意差を認めた。後傾変化量はtaper wedge型の2群がPerFix910群に比べて有意に大きかった。外反変化量と深度変化量に有意な群間差は認められなかった。

Language：English   Publisher：Bone and Joint Journal  

Aims although periacetabular osteotomies are widely used for the treatment of symptomatic dysplastic hips, long-term surgical outcomes and patient-reported outcome measures (proMs) are still unclear. accordingly, we assessed hip survival and proMs at 20 years after transpositional osteotomy of the acetabulum (Toa). Methods a total of 172 hips in 159 patients who underwent Toa were followed up at a mean of 21.02 years (16.6 to 24.6) postoperatively. Kaplan-Meier analysis was used to assess survivorship with an endpoint of total hip arthroplasty (Tha). proMs included the visual analogue scale (VaS) Satisfaction, VaS pain, oxford hip Score (ohS), and Forgotten Joint Score-12 (FJS-12). Thresholds for favourable outcomes for OHS (≥ 42) and FJS-12 (≥ 51) were obtained using the receiver operating characteristic curve with VAS Satisfaction ≥ 50 and VaS pain < 20 as anchors. Results Tha was performed on 37 hips (21.5%) by the latest follow-up. Kaplan-Meier analysis indicated that the hip survival rate at 20 years was 79.7% (95% confidence interval (CI) 73.7 to 86.3). Multivariate analysis showed that preoperative Tönnis grade significantly influenced hip survival. Tönnis grades 0, 1, and 2 were associated with 20-year survival rates of 93.3% (95% cI 84.8 to 100), 86.7% (95% cI 79.8 to 94.3), and 54.8% (95% cI 41.5 to 72.3), respectively. More than 60% of the patients exhibited favourable proMs. an advanced Tönnis grade at the latest follow-up and a higher BMI were both significantly associated with unfavourable ohS, but not with other proMs. conclusion This study demonstrated the durability of Toa for hips with Tönnis grades 0 to 1 at 20 years. While the presence of advanced osteoarthritis and higher BMI was associated with lower hip functions (ohS), it was not necessarily associated with worse patient satisfaction and joint awareness.

DOI： 10.1302/0301-620X.104B7.BJJ-2021-1767.R1

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PubMed

Language：English   Publisher：Journal of Artificial Organs  

The impact of sports on long-term wear of highly cross-linked polyethylene (XLPE) after total hip arthroplasty (THA) is not fully understood. We investigated (1) the wear performance of the first-generation XLPE, and (2) whether sports participation influences the steady wear rate of XLPE. The femoral head penetration into the cup was measured digitally on radiographs of hips undergoing THA with XLPE. We retrospectively reviewed data that included age, gender, body mass index, follow-up period, preoperative diagnosis, types of XLPE, ball diameter, head material, inclination of the cup, physical function score, and sports participation. Statistical analyses were applied to determine whether sports affect the wear of XLPE and which factors were associated with the steady wear rate. Creep and steady wear rate were found to be 0.18 mm and 0.005 mm/year, respectively. Sports participation, regardless of impact, provided no significant difference in the steady wear rate. Multiple regression analysis demonstrated that sports did not increase the steady wear rate. Our findings showed excellent wear performance of the first-generation XLPE at a minimum of ten years after THA, without significant effect of sports participation on the liner wear.

DOI： 10.1007/s10047-021-01297-x

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PubMed

Language：English   Publisher：International Journal of Computer Assisted Radiology and Surgery  

Purpose: This prospective randomized controlled study examined whether accelerometer-based navigation resulted in more accurate or precise cup orientation than a conventional mechanical guide. We used a simulation to evaluate how cup orientation affected potential hip range of motion (RoM) and freedom from prosthetic impingement. Methods: Sixty hips were randomly allocated 1:1 to accelerometer-based portable navigation or conventional guidance. Procedures were performed through a standard posterolateral approach and combined anteversion technique. Cup inclination, cup anteversion, and stem anteversion were measured using computed tomography (CT). Using CT-based simulation, we evaluated impingement-free potential RoM and the proportion of hips with potential RoM required for daily activities. Results: Absolute cup inclination and anteversion error averaged 4.3° ± 3.2° and 4.4° ± 2.9° for the navigation cohort and 5.6° ± 3.7° and 5.7° ± 4.2° for the conventional cohort, with no significant differences. Navigation resulted in significantly less variation in anteversion error than the conventional guide (p =.0049). Flexion, internal rotation (IR) at 90° of flexion, extension, and external rotation (ER) averaged 123° ± 12°, 46° ± 13°, 50° ± 10°, and 73° ± 23°, respectively, in the navigation cohort and 127° ± 10°, 52° ± 14°, 45° ± 10°, and 63° ± 12°, respectively, in the conventional cohort (p =.15,.15,.03, and.03, respectively). Flexion > 110°, IR > 30° at 90° of flexion, extension > 30°, and ER > 30° were achieved by 93%, 90%, 100%, and 100% of hips, respectively, in the navigation cohort and 97%, 93%, 97%, and 100% of hips, respectively, in the conventional cohort, with no significant differences. Conclusions: Cup anteversion with the navigation system was more precise, but not more accurate, than with the conventional guide. The navigation cohort exhibited greater potential extension and ER than the conventional cohort, but no significant difference in impingement within the potential RoM required for daily activities. Trial registration number: 29036. Date of registration: November 14, 2017.

DOI： 10.1007/s11548-022-02592-5

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PubMed

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publisher：Journal of Orthopaedic Surgery and Research  

Background: To compare the degree of stem subsidence between two different femoral component designs and to determine the risk factors associated with stem subsidence after cementless total hip arthroplasty (THA) in Dorr type C femurs. Methods: We retrospectively reviewed 104 consecutive hips in 100 patients with Dorr type C proximal femoral morphology who underwent primary cementless THA using a fit-and-fill stem or a tapered wedge femoral stem at our institution between January 2012 and June 2021. A fit-and-fill stem was used in 55 hips and a tapered wedge stem was used in 49 hips. Radiologically, the distance between the apex of the major trochanter and the stem shoulder were measured at three different time points (immediately [0W], one week [1W], and six weeks [6W] after surgery) and the degrees of stem subsidence were assessed by comparing the distance between 0 and 1W, 1W and 6W, and 0W and 6W, respectively. Results: The mean degree of stem subsidence (0W vs. 1W) was 0.24 mm (standard deviation [SD] 0.36) in the fit-and-fill stem group, and 0.23 mm (SD 0.41) in the tapered wedge stem group. There was no significant difference between the two groups (P = 0.4862). However, the mean degrees of subsidence were significantly higher in the fit-and-fill stem group (1W vs. 6W, 0.38 mm [SD 0.68]; 0W vs. 6W, 0.65 mm [SD 0.87]) than in the tapered wedge stem group (1W vs. 6W, 0.16 mm [SD 0.32]; 0W vs. 6W, 0.24 mm [SD 0.38]) (P < 0.05 for both). In addition, the rates of > 3 mm subsidence (in which instability can be observed) were 18.2% (10 of 55 hips) and 2.0% (1 of 49 hips), respectively. There was also a significant difference between the two stems (P = 0.0091). Multivariate analysis demonstrated that fit-and-fill stem was a risk factor for > 3 mm subsidence after THA in Dorr type C femurs (P = 0.0050). Conclusion: Our findings suggest that the tapered wedge stem is more suitable for Dorr type C femurs than the fit-and-fill stem to avoid early postoperative subsidence in cementless THA.

DOI： 10.1186/s13018-022-03111-7

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PubMed

Language：English   Publisher：Human Molecular Genetics  

Osteonecrosis of the femoral head (ONFH) involves necrosis of bone and bone marrow of the femoral head caused by ischemia with unknown etiology. Previous genetic studies on ONFH failed to produce consistent results, presumably because ONFH has various causes with different genetic backgrounds and the underlying diseases confounded the associations. Steroid-associated ONFH (S-ONFH) accounts for one-half of all ONFH, and systemic lupus erythematosus (SLE) is a representative disease underlying S-ONFH. We performed a genome-wide association study (GWAS) to identify genetic risk factors for S-ONFH in patients with SLE. We conducted a two-staged GWAS on 636 SLE patients with S-ONFH and 95 588 non-SLE controls. Among the novel loci identified, we determined S-ONFH-specific loci by comparing allele frequencies between SLE patients without S-ONFH and non-SLE controls. We also used Korean datasets comprising 148 S-ONFH cases and 37 015 controls to assess overall significance. We evaluated the functional annotations of significant variants by in silico analyses. The Japanese GWAS identified 4 significant loci together with 12 known SLE susceptibility loci. The four significant variants showed comparable effect sizes on S-ONFH compared with SLE controls and non-SLE controls. Three of the four loci, MIR4293/MIR1265 [odds ratio (OR) = 1.99, P-value = 1.1 × 10-9)], TRIM49/NAALAD2 (OR = 1.65, P-value = 4.8 × 10-8) and MYO16 (OR = 3.91, P-value = 4.9 × 10-10), showed significant associations in the meta-analysis with Korean datasets. Bioinformatics analyses identified MIR4293, NAALAD2 and MYO16 as candidate causal genes. MIR4293 regulates a PPARG-related adipogenesis pathway relevant to S-ONFH. We identified three novel susceptibility loci for S-ONFH in SLE.

DOI： 10.1093/hmg/ddab306

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Scopus

PubMed

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jor.2022.02.021

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PubMed

Publisher：メジカルビュー社  

DOI： 10.18885/jjs.0000000888

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Bone and Joint Surgery  

Background: Little is known concerning differences in assessment of anteroposterior osteonecrotic lesion of the femoral head (ONFH) between the axial plane parallel to the body axis (axial) and the axial plane parallel to the femoral neck axis (oblique axial) using magnetic resonance imaging (MRI). This study aimed to compare the posterior boundary of necrotic lesions between the axial and oblique axial planes on MRI. Methods: This study retrospectively reviewed 120 consecutive hips in 71 patients (47 males and 24 females; mean age, 42 years) with ONFH, for which both axial and oblique axial MRI slices were available. The posterior boundaries of the necrotic lesions were calculated as the ratio of posterior intact circumference to anteroposterior circumference of the femoral head using mid-axial and mid-oblique axial MRI slices. The necrotic angles, calculated using the modified Kerboul method, were compared between cases with progression and nonprogression of collapse. Results: The mean posterior intact ratio in the axial slice was 49.2% (range, 8.6 to 85.1%), while that in the oblique axial slice was 33.5% (7.5 to 79.2%). The posterior intact ratio in the oblique axial slice significantly decreased compared to that in the axial slice (p < 0.0001). In cases with progression of collapse, the mean necrotic angle was significantly larger in the oblique axial slice than in the axial slice (p < 0.0001). The sensitivity and specificity of the necrotic angle with regard to the prognosis of the femoral head were both higher when using the oblique axial slice (sensitivity: 88.4%, specificity: 82.3%) than when using the axial slice (sensitivity: 85.1%, specificity: 62.0%). The posterior intact ratio at a mean of 6.8 mm superior to the mid-axial slice corresponded to that of the mid-oblique axial slice. Conclusion: Our findings suggest that the posterior boundaries of necrotic lesions differ between axial and oblique axial slices, and examination of the oblique axial MRI slice might be more suitable for predicting the prognosis of the femoral head.

DOI： 10.2106/JBJS.20.00493

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PubMed

Language：English   Publisher：(一社)理学療法科学学会  

日本人コホートにおける人工股関節全置換術(THA)後の患者満足度を判定すると共に、患者満足度に有意な影響を及ぼす因子を同定した。2012年1月～2016年1月に当施設で変形性関節症に対して初回THAを施行した患者に質問紙調査を実施し、回答が得られた285例(男性33例、女性252例、平均69.1±9.9歳)を評価した。89例で筋力、26例で日歩数を判定した。術後満足度、Oxford hip score-activities of daily living(OHS-ADL)、University of California Los Angeles activity score(UCLA AS)に関連する因子を同定した。OHS-ADLと日歩数との関連を検討した。患者の94.7%がTHAに満足したと回答した。OHS-ADLとUCLA ASは患者満足度と有意に関連していた。若年と股関節外転筋力は高OHS-ADLおよびUCLA ASと有意に関連していた。平均日歩数はOHS-ADLと有意に関連していた。

Language：English   Publisher：International Orthopaedics  

Purpose: Stem subsidence is a known cause of early failure in cementless total hip arthroplasty (THA). The aim of this study was to determine the usefulness of pneumatic femoral broaching in preventing post-operative subsidence of a proximally porous-coated, taper-wedge stem. Methods: We reviewed 169 cases of primary THA with a single taper-wedge stem. Eighty THAs performed using pneumatic broaching were compared with 89 THAs performed using manual broaching in terms of postoperative canal fill ratio (CFR) at three levels, stem subsidence at one year post-operation, and stem fixation at latest follow-up (median, 24 months). Results: The median CFRs were higher in the pneumatic group than in the manual group at all levels (p < 0.05). The median stem subsidence at one year after THA was lower in the pneumatic group than in the manual group (0.2 mm vs. 0.6 mm, p = 0.007). A multivariate analysis determined a decreased CFR at 60 mm below the lesser trochanter and the manual broaching as independent factors affecting post-operative stem subsidence. At the latest follow-up, all stems showed stable fixation by bone ingrowth in both groups. Conclusion: Our results showed that the pneumatic broaching device was useful in maximizing the mediolateral canal filling and initial stability and minimizing the subsidence of taper-wedge stems.

DOI： 10.1007/s00264-021-05196-x

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PubMed

Language：English   Publisher：Clinical Biomechanics  

Background: Dislocation after total hip arthroplasty is a frequent cause of revision surgery. This study was performed to determine the optimal implant alignment in total hip arthroplasty by simulating the postoperative range of motion. Methods: All operations were performed via posterolateral approach using combined anteversion of the stem and cup technique. Maximum range of motion without implant impingement was simulated in 79 replaced hips using postoperative computed tomography and the achievement of the required range of motion defined by previous studies was assessed. Optimal cup and stem alignment for impingement-free range of motion were statistically determined using the receiver operator coefficient curve. Findings: Cup inclination and anteversion, stem anteversion, and combined anteversion were 37.6°, 20.1°, 26.2°, and 46.3°, respectively. Maximum range of motion in flexion, extension, internal rotation at 90° of flexion, and external rotation were 131.8°, 42.3°, 56.4°, and 64.5°, respectively. Flexion >110°, extension >30°, internal rotation >30° at 90° of flexion, and external rotation >30° were fulfilled by 96%, 86%, 92%, and 96% of all replaced hips, respectively. Optimal implant alignment for impingement-free range of motion was 34°–43° of cup inclination, 18°–26° of cup anteversion, 17°–29° of stem anteversion, and 35°–56° of combined anteversion. Both cup and stem anteversion showed significant relationship with postoperative range of motion. Interpretation: Surgeons could gain valuable insights into optimal cup and stem alignment to perform postoperative range of motion simulations.

DOI： 10.1016/j.clinbiomech.2021.105555

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PubMed

Language：English   Publisher：BMC Musculoskeletal Disorders  

Background: The ideal acetabular position for optimizing hip joint biomechanics in periacetabular osteotomy (PAO) remains unclear. We aimed to determine the relationship between acetabular correction in the coronal plane and joint contact pressure (CP) and identify morphological factors associated with residual abnormal CP after correction. Methods: Using CT images from 44 patients with hip dysplasia, we performed three patterns of virtual PAOs on patient-specific 3D hip models; the acetabulum was rotated laterally to the lateral center-edge angles (LCEA) of 30°, 35°, and 40°. Finite-element analysis was used to calculate the CP of the acetabular cartilage during a single-leg stance. Results: Coronal correction to the LCEA of 30° decreased the median maximum CP 0.5-fold compared to preoperatively (p < 0.001). Additional correction to the LCEA of 40° further decreased CP in 15 hips (34%) but conversely increased CP in 29 hips (66%). The increase in CP was associated with greater preoperative extrusion index (p = 0.030) and roundness index (p = 0.038). Overall, virtual PAO failed to normalize CP in 11 hips (25%), and a small anterior wall index (p = 0.049) and a large roundness index (p = 0.003) were associated with residual abnormal CP. Conclusions: The degree of acetabular correction in the coronal plane where CP is minimized varied among patients. Coronal plane correction alone failed to normalize CP in 25% of patients in this study. In patients with an anterior acetabular deficiency (anterior wall index < 0.21) and an aspherical femoral head (roundness index > 53.2%), coronal plane correction alone may not normalize CP. Further studies are needed to clarify the effectiveness of multiplanar correction, including in the sagittal and axial planes, in optimizing the hip joint’s contact mechanics.

DOI： 10.1186/s12891-022-05005-5

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PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Scientific Reports  

Periprosthetic bone loss due to adaptive bone remodeling is an important unresolved issue in cementless total hip arthroplasty (THA). The use of porous tantalum on the proximal surface of the femoral stem is expected to decrease postoperative bone loss around the prosthesis through early fixation. We conducted a multicenter randomized controlled study to determine if porous tantalum could reduce periprosthetic bone loss after THA. From October 2012 to September 2014, 118 patients (mean age, 61.5 years; 107 females and 11 males) were prospectively enrolled and were randomly allocated at a ratio of 1:1 to either a metaphyseal filling stem with a proximal porous tantalum coating (Trabecular Metal) or a conventional metaphyseal filling stem with fiber mesh coating (VerSys). Patients underwent dual-energy x-ray absorptiometry scans within 1 week after surgery (baseline) and at 6, 12, and 24 months after surgery to assess periprosthetic bone mineral density (BMD) in the 7 Gruen zones. In addition, the Japanese Orthopaedic Association hip score was assessed before surgery and at 6, 12, and 24 months after surgery. In the proximal periprosthetic region (zones 1 and 7), the Trabecular Metal group had significantly smaller reductions in BMD than the VerSys group throughout the study period. In the VerSys group, significant reductions in BMD compared to baseline were seen at each measurement point in all regions, except in zone 6 at 24 months. In the Trabecular Metal group, no significant reductions in BMD relative to baseline were seen in zones 1, 5, or 6 throughout the study period. Both groups demonstrated similar improvement in Japanese Orthopaedic Association hip scores over the study period. This study demonstrated that a proximally coated stem with porous tantalum has superior results over a conventional stem with titanium fiber mesh in terms of periprosthetic bone remodeling.

DOI： 10.1038/s41598-022-04936-2

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PubMed

Language：English   Publisher：Clinical Orthopaedics and Related Research  

Background Inappropriate sagittal plane correction can result in an increased risk of osteoarthritis progression after periacetabular osteotomy (PAO). Individual and postural variations in sagittal pelvic tilt, along with acetabular deformity, affect joint contact mechanics in dysplastic hips and may impact the direction and degree of acetabular correction. Finite-element analyses that account for physiologic pelvic tilt may provide valuable insight into the effect of PAO on the contact mechanics of dysplastic hips, which may lead to improved acetabular correction during PAO.

DOI： 10.1097/CORR.0000000000001893

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PubMed

Language：English   Publisher：The Society of Physical Therapy Science  

<p> [Purpose] To determine patient satisfaction after total hip arthroplasty in a Japanese cohort and to identify factors that significantly influence patient satisfaction. [Participants and Methods] This study included 285 patients who underwent primary total hip arthroplasty for osteoarthritis. Postoperative satisfaction, Oxford hip score, short form-12 mental component summary score, and University of California Los Angeles activity score were investigated. Muscle strength and daily step counts were determined using a hand-held dynamometer (μ-Tas F1) and activity monitor (ActivPAL) in 89 and 26 patients, respectively. Factors associated with postoperative satisfaction, Oxford hip score-activities of daily living, and University of California Los Angeles activity score were identified. The relationship between the Oxford hip score-activities of daily living and daily step counts was examined. [Results] Overall, 94.7% of the patients reported satisfaction with total hip arthroplasty. The Oxford hip score-activities of daily living and University of California Los Angeles activity score were significantly associated with patient satisfaction. Younger age and hip abductor strength were significantly associated with a higher Oxford hip score-activities of daily living and University of California Los Angeles activity score. The average daily step count was significantly correlated with the Oxford hip score-activities of daily living. [Conclusion] Self-reported physical activity levels significantly influenced patient satisfaction and were correlated with objective muscle strength and daily step count measurements. These findings can guide total hip arthroplasty patient counseling on the importance of muscle strength and activity levels.</p>

DOI： 10.1589/jpts.34.76

PubMed

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Background: Perceiving replaced joints as natural is one of the best scenario after total hip arthroplasty (THA). We investigated the distribution of and influencing factors for patient's joint perception after THA in Asian cohort, which is not well known. Methods: We mailed a questionnaire to Asian patients who had undergone THA in our institution between 2012 and 2016, and this study included 318 Asian patients. The questionnaire assessed patient's joint perception, Oxford Hip Score (OHS), Short Form-12 Health Survey (SF-12) physical, mental, and role component summaries, and satisfaction score. Leg length discrepancy and global femoral offset before and after THA were measured using radiographs. The patients were divided into 2 groups with patient's joint perception: natural and artificial perception groups. OHS, SF-12, satisfaction, leg length discrepancy, and global femoral offset were compared between natural and artificial perception groups, and which factors significantly influenced joint perception were determined. Results: Of the 318 patients, 165 patients (51.8%) perceived their replaced joint as a natural joint. OHS, SF-12 physical and role component summaries, and satisfaction score in natural perception group were significantly higher than those in artificial perception group, without significant difference in SF-12 mental component summary. Multivariate analysis showed that less of usual pain, easier to get in or out of a car, and osteoarthritis in the contralateral hip were positively associated with natural joint perception after THA. Conclusion: This study indicated to surgeons that pain relief and improvement in getting in or out of a car after THA could lead to even better patient's joint perception.

DOI： 10.1016/j.arth.2019.12.039

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Background: Although lateralized head sign (LHS) is considered indicative of structural instability, it lacks reproducibility, and its usefulness in diagnosing adult hip dysplasia is unknown. In this study, we proposed a modified LHS and aimed to determine its reliability and accuracy in diagnosing adult hip dysplasia. Methods: We reviewed anteroposterior pelvic radiographs of 94 patients (134 hips) with hip dysplasia. As controls, 133 normal hips were evaluated. We defined the modified lateralization distance (LD) as the horizontal distance between the medial aspect of the femoral head to the acetabular fossa. The sensitivity, specificity, and cutoff value of modified LD in diagnosing hip dysplasia were calculated using receiver operating characteristic curve analysis. Results: The sensitivity and specificity of the modified LD (79% and 87%, respectively) were higher than those of the conventional LD (63% and 80%, respectively). Diagnostic accuracy was further improved when patients were divided on the basis of sex. The sensitivity and specificity of the modified LD in men were 89% and 97%, respectively, with a cutoff value of 12 mm, while in women, they were 80% and 96%, respectively, with a cutoff value of 9.7 mm. Therefore, we defined the modified LHS as presentation with a modified LD ≥ 12 mm in men and ≥10 mm in women. Between three observers, the kappa value for intraobserver reliability was ≥0.9, while that for interobserver reliability was >0.8. The mean sensitivity and specificity of the modified LHS in diagnosing hip dysplasia were 85% and 99%, respectively. Conclusions: Modified LHS—a horizontal distance between the medial aspect of the femoral head and the acetabular fossa ≥12 mm in men and ≥10 mm in women—is a clinically useful marker in detecting lateral femoral head subluxation indicative of hip dysplasia or structural hip instability.

DOI： 10.1016/j.jos.2019.05.015

Language：English   Publishing type：Research paper (scientific journal)  

Background: Physiologic pelvic tilt can change acetabular orientation and coverage in patients with hip dysplasia. In this study, we aimed to clarify the impact of change in sagittal pelvic tilt on joint stress distribution in dysplastic hips. Methods: We developed patient-specific finite element models of 21 dysplastic hips and 21 normal hips. The joint contact area, contact pressure, and equivalent stress of the acetabular cartilage were assessed at three pelvic tilt positions relative to the functional pelvic plane: 10° anterior tilt, no tilt, and 10° posterior tilt. Findings: The mean contact area was 0.6–0.7 times smaller, the mean maximum contact pressure was 1.8–1.9 times higher, and the mean maximum equivalent stress was 1.3–2.8 times higher in dysplastic hips than in normal hips at all three pelvic positions. As the pelvis tilted from 10° anterior to 10° posterior, the mean contact area decreased, and the mean maximum contact pressure and median maximum equivalent stress increased. The latter two changes were more significant in dysplastic hips than in normal hips (total increment was 1.3 MPa vs. 0.4 MPa, P = 0.001, and 3.6 MPa vs. 0.4 MPa, P < 0.001, respectively). The mean equivalent stress increased in the anterosuperior acetabulum during posterior pelvic tilt in dysplastic and normal hips, while the change was not significant in the superior and posterosuperior acetabulum in both groups. Interpretation: Sagittal pelvic tilt alters the loading environment and joint stress distribution of the hip joint and may impact the degeneration process in dysplastic hips.

DOI： 10.1016/j.clinbiomech.2020.02.011

Language：English   Publishing type：Research paper (scientific journal)  

The purpose of this study was to clarify whether bone mineral density (BMD) of the necrotic lesion in precollapse osteonecrosis of the femoral head (ONFH) is reduced according to Hounsfield unit (HU) values on computed tomography (CT). The superior one-third of the femoral head in the coronal section was set as the region of interest (ROI) for the measurement of HU values. First, HU values of 101 control participants were assessed to identify relevant confounding factors. Next, the relationship between HU values and BMD on dual-energy X-ray absorptiometry (DXA) was verified. Then the mean HU value of the ROI in patients with pre-collapse ONFH was compared with that in propensity score-matched control participants. Finally, the HU values of the lateral boundary in the patients with and without subsequent collapse were compared. Multivariable analysis showed that both age and BMI were significantly correlated with the HU value, which showed a strong correlation with the BMD of the femoral neck on DXA (r = 0.92). In 25 ONFH patients and 25 propensity-matched control participants, no significant difference was found in the HU value of the ROI (p =.54). The mean HU value of the lateral boundary in patients with subsequent collapse was found to be significantly higher than that in patients without subsequent collapse (p <.01). The assessment of HU values on CT was useful for the evaluation of BMD of the femoral head. The current assessment did not demonstrate reduced bone mineral density of the necrotic lesion in pre-collapse ONFH.

DOI： 10.1002/jor.24674

Language：English   Publishing type：Research paper (scientific journal)  

Objectives To quantify the volume of bone-resorptive lesions in post-collapse osteonecrosis of the femoral head (ONFH) using micro-computed tomography (micro-CT) and assess their characteristics in post-collapse ONFH. Methods We investigated 35 femoral heads resected from 35 patients with ONFH (20 men and 15 women; mean age, 47.2 years). On each of seven coronal high-resolution micro-CT slices of the femoral head, the bone-resorptive areas were extracted using bone microstructure measurement software. Next, the total bone-resorptive volume ratio, defined as the ratio of all bone-resorptive cross-sectional areas to all femoral head cross-sectional areas in all seven slices, was calculated. Associations between total bone-resorptive volume ratio and sex, age, ONFH-associated factors, patient workload levels, ONFH stage, ONFH type, necrotic volume on magnetic resonance imaging, and duration from the onset of pain to surgery were analyzed. Lesion location and the association between bone-resorptive lesion and collapse were also evaluated. Results The mean total bone-resorptive volume ratio was 7.0 ± 6.0%, which varied significantly by ONFH stage (ARCO collapse quantitation 3A, 3.5 ± 2.1%; 3B, 6.8 ± 3.0%; and 3 C, 13.6 ± 8.8%). ONFH stage was independently associated with total bone-resorptive volume ratio (P < 0.05). Furthermore, high bone-resorptive volume ratios were found in the anterior femoral head and were associated with collapse. Conclusions This study demonstrated that bone-resorptive volume in post-collapse ONFH was significantly associated with the disease stage, which was more widespread in the anterior portion of the femoral head than in the posterior portion.

DOI： 10.1016/j.jbspin.2019.09.004

Language：English   Publishing type：Research paper (scientific journal)  

Objectives: This retrospective study aimed to assess long-term hip survival after transtrochanteric anterior rotational osteotomy (ARO) for osteonecrosis of the femoral head (ONFH) and identify factors influencing patient-reported outcome measures (PROMs) in patients with preserved joints. Methods: Altogether, 95 consecutive hips in 85 ONFH patients who underwent ARO during 2000–2007 (86.7% follow-up) were studied. Controls were 35 patients with 41 hips with ONFH managed conservatively for >1 year after collapse. We analyzed hip survival using the Kaplan–Meier method, with the endpoint defined as any therapeutic surgery related to ONFH. We also evaluated PROMs for both groups in patients with surviving hips and available radiographs at the final follow-up. Results: The 10-year hip survival rate after ARO was 85.4%, which was significantly higher than the 5-year rate in the control group (50.4%). Multiple regression analyses showed that the presence of osteoarthritic change after ARO was significantly associated with poor scores for both the Oxford Hip Score and the Short Form-12 Health Survey Physical Component Summary. Conclusions: ARO could effectively preserve hip joints with post-collapse ONFH, although the presence of osteoarthritic change could lead to lower satisfaction even among patients with long-term hip survival after ARO.

DOI： 10.1080/14397595.2018.1558917

Language：English   Publishing type：Research paper (scientific journal)  

Introduction: Avascular necrosis of the femoral capital epiphysis is the most serious complication after traumatic dislocation of the hip in children. This case report discusses the localization and revascularization of the necrotic femoral head following rarely experienced traumatic open anterior hip dislocation in children. Case presentation: Our patient was an 11-year-old Japanese boy who had open anterior hip dislocation sustained in a traffic accident. Reduction of the hip joint was performed in an emergency operation, and he was evaluated using serial gadolinium-enhanced magnetic resonance imaging. T1-weighted magnetic resonance images showed two bands with low signal intensity in the femoral capital epiphysis on coronal and oblique axial planes, indicating the existence of avascular osteonecrosis of the femoral head. We observed gadolinium enhancement in the central region of the epiphysis, where the area between the two bands with low signal intensity was located. Serial assessment with enhanced magnetic resonance images during a non-weight-bearing period of 1.5 years after injury showed revascularization starting from the central region and converging toward the peripheral region. Although the patient had leg-length discrepancy due to the early epiphyseal closure, non-weight-bearing treatment for the avascular osteonecrosis of the femoral head achieved a favorable outcome without any hip joint dysfunction, pain, or sign of secondary osteoarthritic change within 4.5 years after injury. Conclusion: We confirmed the revascularization process of the necrotic lesion in the femoral capital epiphysis in an 11-year-old boy using serial gadolinium-enhanced magnetic resonance imaging. Conservative non-weight-bearing treatment achieved a favorable outcome.

DOI： 10.1186/s13256-019-2192-7

Language：English   Publishing type：Research paper (scientific journal)  

Purpose: The purpose of this study was to assess the differences in magnetic resonance (MR) findings between the symptomatic and asymptomatic pre-collapse stage of osteonecrosis of the femoral head (ONFH). Materials and methods: This study reviewed 123 consecutive hips in 91 patients in the pre-collapse stage of ONFH based on plain radiographic findings. These 123 hips were divided into symptomatic and asymptomatic groups according to the pain domain score in the Harris hip score system. Bone marrow edema (BME), synovial fluid effusion, and subchondral fracture were evaluated using MR imaging. Odds ratios (ORs) were calculated between these three parameters and symptoms. The subsequent clinical course after MR examination was also assessed for each hip that could be followed more than 1 year. Results: Forty-six hips (37.4%) were categorized as symptomatic and 77 hips (62.6%) as asymptomatic. The prevalence of BME, synovial fluid effusion, and subchondral fracture were 87.0% (40/46), 80.4% (37/46), and 34.8% (16/46), respectively, in the symptomatic group, and 0%, 28.6% (22/77), and 0%, respectively, in the asymptomatic group, indicating significant differences between the two groups (p < 0.0001). Among these parameters, BME showed the highest OR with regard to the presence or absence of symptoms (BME, 965.8; joint effusion, 10.3; subchondral fracture, 83.9). Due to persistent pain and subsequent collapse, 30 of 35 (85.7%) symptomatic hips with BME subsequently underwent surgical treatment at a mean interval of 3.47 months after MR examination, while 25 of 66 (37.9%) asymptomatic hips without BME underwent surgical treatment at a mean interval of 20.7 months after MR examination. Conclusions: This study demonstrated that symptomatic pre-collapse ONFH diagnosed based on plain radiographic findings could be distinguished from asymptomatic pre-collapse ONFH by the presence of BME on MR imaging, and thus BME may be a sign of occult fracture.

DOI： 10.1016/j.ejrad.2019.01.002

Language：English   Publishing type：Research paper (scientific journal)  

Background: Anterior localization of the necrotic lesion was recently proposed as an important factor for the occurrence of collapse even in medially located osteonecrosis of the femoral head (ONFH). We examined the effects of the anterior boundary of the necrotic lesion on progressive collapse after varus osteotomy for ONFH. Methods: We reviewed the outcomes of 31 hips in 27 patients with ONFH treated by transtrochanteric curved varus osteotomy (CVO) from 2000 to 2012 with a mean follow-up of 10.5 years. The occurrence of progressive collapse of the anterior necrotic lesion was defined as the presence of ≥2 mm collapse using follow-up lateral radiographs. Postoperative osteoarthritic change was defined as ≥1 mm progression of joint space narrowing on follow-up radiographs. The location of the anterior boundary of the necrotic lesion was assessed using the anterior necrotic angle (the angle between the midline of the femoral neck shaft and the line passing from the femoral head center to the anterior boundary of the necrotic lesion on a mid-slice oblique magnetic resonance image). Results: All hips had a postoperative intact ratio of ≥34% (percentage of the transposed intact articular surface of the femoral head to the weight-bearing area of the acetabulum after femoral osteotomy). Progressive collapse of the anterior necrotic lesion was seen in five hips (16%) during a mean of 2.2 years after CVO. Of these, four hips (80%) proceeded to develop osteoarthritic change at an average of 4.3 years after the collapse. Multivariate analysis revealed that the anterior necrotic angle was independently associated with progressive collapse of the anterior necrotic lesion as well as the postoperative intact ratio. Conclusions: This study suggests that hips with anterior localization of the necrotic lesion have a possible risk of progressive collapse of the anterior necrotic lesion after CVO, which can frequently lead to subsequent osteoarthritic change.

DOI： 10.1016/j.jos.2019.02.014

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Orthopaedic Science  

DOI： 10.1016/j.jos.2019.05.016

Web of Science

Scopus

PubMed

Language：English   Publishing type：Research paper (scientific journal)  

Objective: To evaluate the relationship between the volume of hip synovitis detected on contrast-enhanced magnetic resonance imaging (MRI) and the disease stage of osteonecrosis of the femoral head (ONFH). Materials and methods: Sixty-three consecutive hips in 40 ONFH patients were reviewed using contrast-enhanced MRI. Ten unaffected hips in 10 patients with unilateral ONFH were used as controls. Based on the Japanese Investigation Committee system, these hips were classified according to stage and type. The volume and location of hip synovitis were semi-quantitatively measured on contrast-enhanced MRI. Clinicoradiological factors were statistically analyzed to determine the relationship with the volume of hip synovitis. Results: The mean synovial volume was significantly larger in ONFH hips (8,020 ± 6,900 mm³) than in controls (910 ± 1,320 mm³; p = 0.001). The area of synovitis in the anterior portion of the hip joint was double (mean: 2.17 ± 1.77) that in the posterior portion. The volume of synovitis was small in pre-collapse-stage hips (stage 1: 680 ± 690 mm³, stage 2: 1,460 ± 1,200 mm³), but significantly larger in post-collapse-stage hips (stage 3A: 7,820 ± 4,490 mm³, stage 3B: 13,850 ± 7,110 mm³; p < 0.001). Multiple regression analysis showed that disease stage was the only factor related to hip synovitis. Conclusions: Our study suggests that hip synovitis in ONFH might occur after femoral head collapse and worsen with collapse progression, mainly in the anterior portion.

DOI： 10.1007/s00256-019-3158-y

Language：English   Publishing type：Research paper (scientific journal)  

Background: In total hip arthroplasty (THA), placing the cup in an anatomic position is not always possible in case of deformities related to developmental dysplasia of the hip (DDH). Thus far, the influence of a hip center on the abductor moment after THA has not been clearly elucidated. Therefore, we performed a retrospective study to assess (1) how abductor muscle moment recovers postoperatively in THA and (2) whether acetabular cup position affects the recovery of abductor moment. Hypothesis: A high hip center affects the recovery of abductor moment of a dysplastic hip after THA. Patients and Methods: We evaluated 100 patients, who underwent unilateral primary THA, at 12 months postoperatively. The study included 86 women and 14 men, with a mean age of 65.5 ± 9.9 years (range, 40 to 86 years). Patients with secondary osteoarthritis due to DDH were included (Crowe 1: 76; Crowe 2: 15, Crowe 3:9, and Crowe 4: none). A cementless straight stem was implanted in all hips. Hip abductor moment was measured using a belt-stabilized hand-held dynamometer. The ratio of moment of the affected side to that of the contralateral side was calculated as moment ratio. The horizontal and vertical centers of rotation (H-COR and V-COR) (with respect to the inter teardrop line) and vertical shift (V-shift) (difference in V-COR between the affected hip and the contralateral normal hip) were determined. Results: At 6 and 12 months postoperatively, the abductor moment ratios were 95.1 and 94.7%, respectively. Significant negative correlation was observed between the postoperative abductor moment ratio and V-COR at 6 months postoperatively (r = −0.2436, p = 0.0238). Significant delay in the recovery of abductor moment ratio was observed in the groups with higher hip center (V-shift > 15 mm) (odds ratio = 12.7; 95% CI: 2.11–232.1, p = 0.0034) at 6 months postoperatively, which was fully recovered at 12 months postoperatively. Discussion: Superior placement of a hip center, more than 15 mm above the true hip center, delayed the recovery of abductor muscle moment after THA. Level of evidence: III, retrospective comparative study.

DOI： 10.1016/j.otsr.2018.06.022

Language：Others   Publishing type：Research paper (scientific journal)  

Background: In total hip arthroplasty (THA), placing the cup in an anatomic position is not always possible in case of deformities related to developmental dysplasia of the hip (DDH). Thus far, the influence of a hip center on the abductor moment after THA has not been clearly elucidated. Therefore, we performed a retrospective study to assess 1) how abductor muscle moment recovers postoperatively in THA and 2) whether acetabular cup position affects the recovery of abductor moment. Hypothesis: A high hip center affects the recovery of abductor moment of a dysplastic hip after THA. Patients and methods: We evaluated 100 patients, who underwent unilateral primary THA, at 12 months postoperatively. The study included 86 women and 14 men, with a mean age of 65.5 ± 9.9 years (range, 40 to 86 years). Patients with secondary osteoarthritis due to DDH were included (Crowe 1: 76; Crowe 2: 15, Crowe 3: 9, and Crowe 4: none). A cementless straight stem was implanted in all hips. Hip abductor moment was measured using a belt-stabilized handheld dynamometer. The ratio of moment of the affected side to that of the contralateral side was calculated as moment ratio. The horizontal and vertical centers of rotation (H-COR and V-COR) (with respect to the inter teardrop line) and vertical shift (V-shift) (difference in V-COR between the affected hip and the contralateral normal hip) were determined. Results: At 6 and 12 months postoperatively, the abductor moment ratios were 95.1 and 94.7%, respectively. Significant negative correlation was observed between the postoperative abductor moment ratio and V-COR at 6 months postoperatively (r = −0.2436, p = 0.0238). Significant delay in the recovery of abductor moment ratio was observed in the groups with higher hip center (V-shift > 15 mm) (odds ratio = 12.7; 95% CI, 2.11–232.1, p = 0.0034) at 6 months postoperatively, which was fully recovered at 12 months postoperatively. Discussion: Superior placement of a hip center, more than 15 mm above the true hip center, delayed the recovery of abductor muscle moment after THA. Level of evidence: III, retrospective comparative study.

DOI： 10.1016/j.rcot.2018.09.138

Language：English   Publishing type：Research paper (scientific journal)  

Stress distribution remains unclear in early-stage osteonecrosis of the femoral head (ONFH). To clarify this issue, we generated patient-specific finite element models (FEMs) from 51 patients with ONFH. Patients’ hips were classified into three groups: ONFH without a sclerotic boundary (Stage 1, n = 6), ONFH with a sclerotic boundary (Stage 2, n = 10), and ONFH with both a sclerotic boundary and <2 mm collapse (Stage 3, n = 35). Four hips without ONFH were used as controls. Stress distribution in each FEM was compared with magnetic resonance imaging (MRI) and computed tomography (CT) results. Fifteen wholly resected femoral heads in Stage 3 hips were assessed by micro-CT. Furthermore, we histologically examined three Stage 2 femoral heads that subsequently developed subchondral fractures after FEM analyses. In all FEMs of both control and Stage 1 hip, stress was equally distributed on the femoral head surface. However, in all FEMs of both Stages 2 and 3 hips, stress was concentrated at the lateral boundary of the femoral head surface, corresponding to both a low-intensity band on T1-weighted MRI images and sclerotic changes on CT. On micro-CT, subchondral fractures consistently began at the lateral boundary with sclerotic changes, in which bone volume fraction was increased. Histology showed breakage of subchondral plates at the junction between necrotic and reparative zones. In early-stage ONFH, sclerotic changes caused stress concentration, which can trigger subchondral fractures at the lateral boundary. Clinical Significance: Our results will clarify the pathogenic mechanism of collapse in ONFH.

DOI： 10.1002/jor.24124

Language：English   Publishing type：Research paper (scientific journal)  

Similar to the radiological findings in rapidly destructive arthrosis of the hip joint (RDA), subchondral insufficiency fracture of the femoral head (SIF) can result in progressive femoral head collapse of unknown etiology. We thus examined the osteoclast activity of hip joint fluid in SIF with progressive collapse in comparison with that in RDA. Twenty-nine hip joint fluid samples were obtained intraoperatively with whole femoral heads from 12 SIF patients and 17 RDA patients. SIF cases were classified into subgroups based on the presence of ≥2 mm collapse on preoperative radiographs: SIF with progressive collapse (n = 5) and SIF without progressive collapse (n = 7). The levels of tartrate-resistant acid phosphatase (TRACP)-5b, interleukin-8, vascular endothelial growth factor (VEGF), and matrix metalloproteinase (MMP)-9 were measured. The number of multinuclear giant cells at the subchondral region was histopathologically assessed using mid-coronal slice of each femoral head specimen. The median levels of all markers and the median number of multinuclear giant cells in SIF with progressive collapse were significantly higher than those in SIF without progressive collapse, while there were no significant differences in SIF with progressive collapse versus RDA. Regression analysis showed that the number of multinuclear giant cells was positively correlated with the level of TRACP-5b in joint fluid. The present study demonstrated the possible association of increased osteoclast activity with the existing condition of progressive collapse in SIF, which was quite similar to the findings in RDA, indicating that increased osteoclast activity may reflect the condition of progressive collapse in SIF as well as RDA.

DOI： 10.1002/jor.24066

Language：English   Publishing type：Research paper (scientific journal)  

The purpose of this study was to examine the minimum 10-year clinical outcomes, including patient-reported and functional outcomes, of periacetabular osteotomy in patients with advanced osteoarthritis. A total of 46 hips in 44 patients with advanced osteoarthritis who underwent periacetabular osteotomy between 1992 and 2006 were retrospectively reviewed. Mean age at surgery was 47.5 years, and mean follow-up was 16.9±4.7 years. Survivorship was determined using the Kaplan-Meier method, and the associated risk factors for the endpoint-conversion to total hip arthroplasty less than 15 years after surgery-were evaluated. The Oxford Hip Score and the University of California, Los Angeles activity score were evaluated at final follow-up. The survival rates at 15 and 20 years after surgery were 80% and 59%, respectively. Multivariate analysis indicated that body mass index greater than 24 kg/m² (P=.034; odds ratio, 1.72) was significantly associated with the endpoint as an independent risk factor. For 32 hips of 31 patients with preserved native joints at final follow-up, the Oxford Hip Score and the University of California, Los Angeles score averaged 41±5 and 5.2±1.8, respectively, equivalent (P=.28 and P=.215, respectively) to the scores of 14 hips of 13 patients with conversion to total hip arthroplasty (38±8.7 and 5.8±1.4, respectively). The results of this mid-term study may be useful for surgical decision-making among patients with advanced osteoarthritis who want to preserve native hip joints.

DOI： 10.3928/01477447-20180806-04

Language：English   Publishing type：Research paper (scientific journal)  

Purpose: Quality-of-life (QOL) assessments in patients with osteonecrosis of the femoral head (ONFH) have rarely been reported. This multicentre study aimed to elucidate the relationship between disease severity, including necrotic lesion type and radiological staging, and QOL, as well as between patients’ characteristics and QOL. Methods: Two hundred seventy-four patients with ONFH (108 females, 166 males; median age, 46 years) were asked to complete self-assessment QOL questionnaires including the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire, Oxford Hip Score, and SF-12v2. Results: Patients with large necrotic lesion type or collapsed ONFH had low QOL scores. Among patients with non-collapsed lesions, patients with alcohol-associated ONFH had lower QOL scores than those with steroid-associated ONFH, those with bilateral ONFH had lower mental scores, and male patients had worse social condition scores. Among patients with collapsed lesions, middle-aged patients exhibited lower mental QOL, and a strong correlation was observed between social activity and mental health. Conclusion: Collapsed ONFH was associated with low QOL scores. Among patients with non-collapsed lesions, alcohol-associated ONFH, bilateral disease, and male sex were linked to low QOL scores.

DOI： 10.1007/s00264-018-3897-8

Language：English   Publishing type：Research paper (scientific journal)  

Purpose: The location of the necrotic lesion is one of the important factors for collapse in osteonecrosis of the femoral head (ONFH). The significance of anterior localization has been little studied. This study evaluated the effects of anterior boundary of a necrotic lesion on collapse. Methods: We reviewed the outcomes of 113 consecutive non-collapsed asymptomatic hips in 98 ONFH patients with mean follow-up of 4.7 years (2.0–11.8) after the initial magnetic resonance (MR) imaging. The presence or absence of collapse was investigated using follow-up radiographs. The location of the anterior boundary of a necrotic lesion was assessed using the anterior necrotic angle between the midline of the femoral neck shaft and the line passing from the femoral head centre to the anterior boundary on mid-oblique MR imaging. Multivariate analysis was performed to identify risk factors for collapse, and further analyses were executed according to the lateral boundary of the necrotic lesion. Results: During the follow-up period, collapse was confirmed in 61 hips (54.0%). Multivariate analysis revealed that the anterior necrotic angle was independently associated with collapse as well as the lateral boundary of the necrotic lesion. When the lateral boundary was located at the middle third of weight-bearing portion (32 hips), that was generally categorized as a low risk of collapse, all five cases with anterior necrotic angle ≥ 79° developed collapse, whereas only one of 27 cases (3.7%) with an anterior necrotic angle < 79° developed collapse (p < 0.0001). Conclusions: This study indicates that ONFH patients with anterior localization of a necrotic lesion can develop collapse even if the necrotic lesion is medially located.

DOI： 10.1007/s00264-018-3836-8

Language：English   Publishing type：Research paper (scientific journal)  

Objectives: The objective of this study was to describe the appearance of Subchondral insufficiency fracture (SIF) by computed tomography (CT). Methods: Images of 52 consecutive patients diagnosed with SIF were retrospectively reviewed. CT was available for five patients (7 cases). Results: Corresponding to a low-intensity band on MR images, a radiolucent or sclerotic band was observed on CT images. Conclusion: The present study is the first to report CT findings of SIF. A radiolucent or sclerotic band was observed on CT images. The results of the present study provide useful information for diagnosis of SIF.

DOI： 10.1016/j.jor.2018.01.044

Language：English   Publishing type：Research paper (scientific journal)  

Background: No studies have compared sports participation between total hip arthroplasty (THA) and periacetabular osteotomy (PAO) in matched Asian cohorts. We investigated sports participation and activity levels in Asian THA cohort, and compared them between THA and PAO cohorts. Methods: Multivariate analyses were applied to determine which factors were associated with postoperative sports participation and University of California-Los Angeles (UCLA) activity score in (1) 524 THA patients and (2) 487 acetabular dysplasia patients (295 THA patients and 192 PAO patients). In addition, postoperative sports participation and UCLA score were compared between 62 THA and 62 PAO patients after adjusting for baseline characteristics with propensity score matching. Results: Sports participation and UCLA score significantly increased after THA (P <.001 in both analyses). Preoperative sports participation was the factor most associated with both postoperative sports participation and UCLA score in both 524 THA patients and 487 acetabular dysplasia patients (P <.001 in all analyses). Multivariate analysis in 487 acetabular dysplasia patients demonstrated that THA, compared with PAO, was negatively associated with postoperative sports participation (P <.001), but not postoperative UCLA score (P =.22). THA patients showed significantly lower rate of postoperative sports participation (32.3% and 51.6%, respectively, P =.046), but not postoperative UCLA score (5.0 ± 1.6 and 5.2 ± 1.9, respectively, P =.47) compared with matched PAO patients. Conclusion: THA significantly increased both sports participation and activity levels. Both multivariate and propensity score-matched analyses showed that postoperative activity levels were comparable between THA and PAO cohorts.

DOI： 10.1016/j.arth.2017.08.035

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1186/s13018-018-0714-4

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jos.2018.02.001

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jos.2017.09.009

Language：English   Publishing type：Research paper (scientific journal)  

Background: To achieve sufficient socket coverage by the native bone, high placement of cementless acetabular cup is often required. We previously reported, using computer simulation, that higher hip centre improved the bone coverage but decreased the range of motion in total hip arthroplasty (THA) for patients with hip dysplasia. However, in a clinical setting, the correlation between the hip centre height and dislocation after primary THA is still unclear. We examined whether a high hip centre affects dislocation after THA. Methods: A total of 910 patients, with 1079 dysplastic hips, who underwent primary THA were retrospectively reviewed. The age at THA averaged 63.0 years and mean follow-up was 74.3 months. Vertical centre of rotation (V-COR) was defined as the distance from the head centre to the interteardrop line. Uni- and multivariate logistic regression models were applied to identify significant factors affecting dislocation. Results: Ten hips in nine patients (0.9%) had dislocation after THA. In univariate analysis, age at surgery and V-COR were significant risk factors for dislocation. Multivariate analysis identified advanced age at operation (odds ratio [OR] 1.8/5 years), Crowe classification (OR 15.6), V-COR (OR 3.1/5 mm), and femoral head size (OR 11.6) as independent risk factors for dislocation. Receiver operating characteristic curve analysis revealed the cutoff value of the V-COR for dislocation as 23.9 mm. Conclusions: A higher hip centre with the V-COR > 23.9 mm affected dislocation after THA for DDH. Our results would be useful for reconstruction of the hip centre, particularly with cementless acetabular cups.

DOI： 10.1007/s00264-018-4154-x

Language：English   Publishing type：Research paper (scientific journal)  

Idiopathic osteonecrosis of the femoral head (IONFH) is an ischemic disorder that causes bone necrosis of the femoral head, resulting in hip joint dysfunction. IONFH is a polygenic disease and steroid and alcohol have already known to increase its risk; however, the mechanism of IONFH remains to be elucidated. We performed a genome-wide association study using ~60,000 subjects and found two novel loci on chromosome 20q12 and 12q24. Big data analyses identified LINC01370 as a candidate susceptibility gene in the 20q12 locus. Stratified analysis by IONFH risk factors suggested that the 12q24 locus was associated with IONFH through drinking capacity. Our findings would shed new light on pathophysiology of IONFH.

DOI： 10.1038/s41598-017-14778-y

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.otsr.2017.06.012

Language：English   Publishing type：Research paper (scientific journal)  

Background: Periacetabular osteotomy (PAO) is an effective treatment for symptomatic acetabular dysplasia. However, whether postoperative participation in sports leads to progression of the Kellgren-Lawrence (KL) grade of osteoarthritis (OA) in these patients is unclear. Purpose: To investigate (1) participation in sports before and after PAO and (2) whether postoperative participation in sports leads to progression of the KL grade. Study Design: Case-control study; Level of evidence, 3. Methods: The authors retrospectively reviewed data on 161 patients (183 hips) who underwent PAO for symptomatic acetabular dysplasia with preoperative KL grade 1 or 2 between 1998 and 2011. The mean age at the time of surgery was 42.0 ± 10.9 years (range, 12-64 years), and the mean follow-up duration was 100 months (range, 13-180 months). Data included participation in sports, the University of California, Los Angeles (UCLA) activity scale score, age at the time of surgery, body mass index, follow-up duration, history of treatment for developmental hip dislocations, Merle d'Aubigné-Postel score, Oxford Hip Score, center-edge angle, and KL grade. Univariate and multivariate analyses were applied to determine which factors were associated with progression to KL grade 3 or 4 after PAO. Results: The number of patients who participated in sports significantly increased from 50 (31.1%) preoperatively to 89 (55.3%) postoperatively. The mean UCLA score significantly increased from 4.7 ± 2.1 preoperatively to 5.5 ± 2.0 postoperatively. The KL grade progressed to grade 3 or 4 in 16 hips, including 4 hips that underwent conversion to total hip arthroplasty. No significant differences were found in postoperative participation in sports (89 hips [53.3%] vs 11 hips [68.8%], respectively; P =.24) and the UCLA score (5.6 ± 2.0 vs 5.1 ± 2.0, respectively; P =.30) between hips with KL grade 1 or 2 and KL grade 3 or 4. A multivariate analysis revealed that no factors, including postoperative participation in sports, were significantly associated with progression to KL grade 3 or 4. Conclusion: Postoperative participation in sports after PAO did not significantly and negatively influence progression of the KL grade at midterm follow-up.

DOI： 10.1177/0363546517707942

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.arth.2017.04.034

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s00402-017-2720-0

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jos.2017.02.009

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s00296-016-3624-y

Language：English   Publishing type：Research paper (scientific journal)  

Objective: The purpose of this study was to clarify the minimum joint space width (MJSW) that leads to subchondral bone exposure (SBE) in patients with hip dysplasia. Methods: We included 82 subjects (86 hips) who had hip dysplasia with center-edge angle less than 20° and who underwent periacetabular osteotomy combined with hip arthroscopy. The acetabular and femoral cartilages were divided into three regions: anterosuperior, superior, and posterosuperior; for each region, we analyzed the correlation between the incidence of SBE and the MJSW measured on plain radiographs. The disease stage was defined according to the Kellgren and Lawrence grades (KL grade). Results: SBE was found in 51 hips (59.3%) in total, involved the acetabulum in 49 hips (57.0%), and involved the femoral head in 26 hips (30.2%). SBE was more frequent in the acetabulum, with the highest incidence in the anterosuperior region, followed by the superior region. SBE was present in six hips (22.2%), 17 hips (56.7%), and 28 hips (96.5%), at KL-1, KL-2, and KL-3, respectively. MJSW of hips with SBE was significantly smaller than those without SBE (2.3 vs 4.0 mm, p < 0.001), and the cut-off value for MJSW that led to SBE was 3.7 mm (sensitivity: 0.902, 1–specificity: 0.343). SBE was present in 23.3% in patients with MJSW ≥3.7 mm, whereas 76.7% in those <3.7 mm. Conclusions: Cartilage degeneration is more advanced than would be predicted on plain radiographs. The cut-off value of MJSW for SBE was 3.7 mm in patients with symptomatic hip dysplasia.

DOI： 10.1080/14397595.2016.1222663

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.otsr.2016.10.019

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s00256-017-2567-z

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2106/JBJS.OA.16.00013

Language：English   Publishing type：Research paper (scientific journal)  

Introduction The thrust plate hip prosthesis (TPP; Zimmer, Winterthur, Switzerland) is a hip prosthesis that is no longer in production. Few reports have focused on periprosthetic fractures following total hip arthroplasty (THA) with the use of a TPP. Presentation of case We report a 57-year-old woman with a periprosthetic femoral fracture 13 years after THA with the use of a TPP. A plain radiograph showed a displaced subtrochanteric fracture of the right femur just below the distal tip of the lateral plate without implant loosening. She underwent revision surgery with a long distally fixed intramedullary stem in conjunction with a plate and cable system. Three months after surgery, bone union was confirmed using radiography and the patient was clinically asymptomatic. Discussion We encountered three major problems while planning surgical treatment, these being, discontinuation of the TPP system, loss of proximal femoral cancellous bone, and difficulties with the type of subtrochanteric fracture. After considering these problems, we planned revision surgery using a long distally fixed intramedullary stem in conjunction with a plate and cable system. Conclusion This case shows that sufficient implant preparation based on precise preoperative planning is necessary to obtain good clinical results for the surgical treatment of periprosthetic femoral fractures following THA with the use of a TPP.

DOI： 10.1016/j.ijscr.2017.06.010

Language：Others   Publishing type：Research paper (scientific journal)  

Background: Transtrochanteric anterior rotational osteotomy (ARO) is joint-preserving surgery for patients with osteonecrosis of the femoral head (ONFH). During ARO, femoral neck-shaft varus angulation by changing intertrochanteric osteotomy plane is often designed to obtain a sufficient post-operative intact ratio. However, the effect of intertrochanteric osteotomy plane on post-operative femoral anteversion has not been well examined. Therefore we performed a simulation study of ARO to determine how intertrochanteric osteotomy plane and pre-operative femoral anteversion affect both femoral neck-shaft varus angle and post-operative femoral anteversion. Hypothesis: Both femoral neck-shaft varus angle and post-operative femoral anteversionare predicted by intertrochanteric osteotomy plane and pre-operative femoral anteversion in ARO. Materials and methods: Using CT-data obtained from 10 hips in 10 patients with ONFH, ARO was simulated. On anteroposterior view, basic intertrochanteric osteotomy line (AP-view line) was defined as the perpendicular line to the femoral neck axis. On lateral view, basic intertrochanteric osteotomy line (lateral-view line) made through the cut surface of greater trochanter was defined as the perpendicular line to the lateral axis of the femur. By changing either AP-view or lateral-view line, 49 ARO models/hip were produced, in which femoral neck-shaft varus angle and post-operative femoral anteversion were assessed. Results: With increase in the vertically-inclined degree of AP-view line, both neck-shaft varus angle and post-operative femoral anteversion increased. With increase in the posteriorly-tilted degree of lateral-view line, neck-shaft varus angle increased, whereas post-operative femoral anteversion decreased. The approximation equations based on the multiple regression analyses were as follows: neck-shaft varus angle. ≈. vertically-inclined degree of AP-view line. ×. 0.9 + posteriorly-tilted degree of lateral-view line. ×. 0.8 + pre-operative femoral anteversion. ×. 0.7; post-operative femoral anteversion. ≈. vertically-inclined degree of AP-view line. ×. 1.1-posteriorly-tilted degree of lateral-view line. ×. 0.8. Discussion: The post-operative morphology of proximal femur was nearly defined by intertrochanteric osteotomy plane with pre-operative femoral anteversion, which is useful for pre-operative planning in terms of both achieving asufficient post-operative intact ratio and maintaining femoral anteversion. Level of evidence: Level IV case series without control group.

DOI： 10.1016/j.rcot.2017.07.014

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s00256-016-2462-z

Language：English   Publishing type：Research paper (scientific journal)  

Background Avascular necrosis of the femoral head (AVN) is the most serious complication after unstable slipped capital femoral epiphysis (SCFE), and is often unsalvageable. We report a minimum 10 years of clinical results for transtrochanteric rotational osteotomy of the femoral head (TRO) for AVN. Methods This study included 7 patients (7 hips) with a mean age at surgery of 13.3 years, and the follow-up period was 15.8 years. All patients had prior treatment via closed reduction and pinning of the unstable SCFE, and showed severely collapsed femoral heads. The direction of rotation was anterior in 3 hips and posterior in 4. The Merle d'Aubigné–Postel score (MDPS) was used for clinical assessment, and joint degeneration was assessed with the Kellgren and Lawrence classification (KL-grade). Results The spherical intact area of the femoral head was moved to the weight-bearing portion, and subluxation was corrected via rotation combined with intentional varus positioning. The mean MDPS improved from 10.3 points to 15.6 points at 5 years, and it was maintained at 15.0 points by 10 years; 3 hips were excellent, 1 was good, 2 were fair, and 1 showed poor outcomes. No patient experienced re-collapse after TRO or required conversion to hip replacement or arthrodesis. After 10 years, degenerative changes became evident over time, and 2 hips progressed to KL-4 with a decreased MDPS. Conclusions Although some joint degeneration is inevitable in the long-term, TRO is an effective salvage procedure for treating AVN after unstable SCFE.

DOI： 10.1016/j.jos.2016.06.014

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1186/s40064-016-3576-4

Language：English   Publishing type：Research paper (scientific journal)  

There are few reports describing the clinicopathologic characteristics of subchondral insufficiency fractures of the femoral head (SIF) in men over 50 years of age. A 59-year-old man experienced a sudden onset of the left hip pain without any antecedent trauma. The hip pain did not improve despite conservative treatments, and he underwent a total hip arthroplasty. The mid-coronal cut section of the resected femoral head revealed a fracture line paralleling the subchondral bone endplate beneath the articular cartilage. In addition, the subchondral fracture broadly underlaid the weight bearing area of the femoral head. Histopathologically, reparative tissue including fracture callus and granulation tissue, as well as thin disconnected bone trabeculae were observed. These clinicopathological findings were similar to those of previously described SIF in women. It is therefore important to consider SIF in cases of acute hip pain, even in middle-aged men.

DOI： 10.1007/s00256-016-2443-2

Language：English   Publishing type：Research paper (scientific journal)  

Purpose: Femur deformities can make stem fixation difficult in total hip arthroplasty (THA). We report the clinical results of cementless THA using a press-fit stem in patients who had previously undergone femoral osteotomy for hip dysplasia. Methods: The subjects included 66 hips in 64 patients, with the mean follow-up period of 7.3 years. THA was performed at a mean period of 17.1 years after intertrochanteric femoral osteotomy. Valgus osteotomy was performed in 42 hips, and varus osteotomy in 24. Clinical results were evaluated by using the Merle d’Aubigne-Postel score. Implant survival was determined with revision as the end point, and any related complications were investigated. Results: The Merle d’Aubigne-Postel score improved from 9.4 to 16.1 at the final follow-up, without any implant loosening. However, periprosthetic femoral fractures were observed in four hips (6.0 %), one intra-operatively and three within three weeks after THA. Among these cases, three hips previously had varus osteotomy (12.5 %) and one hip had valgus osteotomy (2.3 %). Two hips were revised with full porous stems and circumferential wiring. The five and ten year cumulative survivorship rates were 97 % (range, 88.8–99.3 %) and 97 % (88.8–99.3 %), respectively. Conclusions: Although the use of a press-fit cementless stem yielded acceptable results in most of the patients, perioperative femoral fracture was a major complication especially in the patients previously treated with intertrochanteric varus osteotomy. Careful planning and implant selection could be emphasized for these cases.

DOI： 10.1007/s00264-015-2992-3

Language：English   Publishing type：Research paper (scientific journal)  

Purpose To identify demographic and morphologic factors associated with the severity of intra-articular lesions in patients with severe hip dysplasia. Methods One hundred twenty-one patients (134 hips) with symptomatic hip dysplasia were retrospectively reviewed. The cartilage and labral lesions were scored according to the Outerbridge and the original classification systems, respectively. The association of the cartilage and labrum scores with patient demographics (age, gender, body mass index, bilateral hip dysplasia, and treatment history for developmental hip dislocation) and morphologic factors (the lateral center-edge angle, Sharp angle, acetabular index, acetabular head index, acetabular depth ratio, Shenton line disruption, roundness index of the femoral head, and femoral neck shaft angle) were determined using a multiple linear regression analysis. Results The cartilage and labral scores were significantly associated with radiographic osteoarthritis; however, these scores showed wide distribution among hips with equivalent degrees of radiographic osteoarthritis. Age (38.4 ± 12.8 years) (P <.001), lateral center-edge angle (0.2 ± 9.0°) (P =.014), acetabular head index (54.4 ± 9.1%) (P =.001), and the roundness index of the femoral head (55.6 ± 4.6%) (P =.022) were identified as independent factors associated with the cartilage score. Age (P <.001), having a medical history of developmental hip dislocation (P =.002), acetabular index (27.8 ± 6.8°) (P =.011), and the roundness index of the femoral head (P =.022) were identified as independent factors associated with the labral score. Conclusions Our findings suggest that the morphologic factors responsible for severe intra-articular lesions differ for cartilage degeneration and labral tears in patients with severe hip dysplasia. Decreased acetabular coverage of the femoral head was responsible for cartilage degeneration severity, whereas an increased acetabular index was responsible for labral tear severity. Level of Evidence Level III, diagnostic study.

DOI： 10.1016/j.arthro.2016.01.060

Language：English   Publishing type：Research paper (scientific journal)  

Purpose: Dislocation is a leading cause of failure after revision total hip arthroplasty (THA). This study was conducted to examine the risk factors for dislocation as well as their recurrence after revision THA. Methods: We retrospectively reviewed 178 revision THAs in 162 patients between 1998 and 2013. The mean patient age was 65.2 years at operation and the mean follow-up period was 6.7 years. Multivariate logistic regression was performed to identify risk factors for dislocation, and further comparison was made between patients with single and recurrent dislocations. Results: Sixteen hips in 15 patients (9.0 %) dislocated at a mean of 9.1 months (range, 0–83 months) after revision THA. Multivariate analysis identified advanced age (odds ratio [OR] = 2.94/10 years) and osteonecrosis of the femoral head (OR = 7.71) as the independent risk factors for any dislocations. Risk factors for recurrent dislocations, which were observed in eight hips (50 %), were later dislocations (≥4 months) and lower BMI. Conclusion: Dislocation is a serious problem after revision THA with multiple risk factors. Although our findings were limited to revision THAs done through posterolateral approach, recognition of these factors is helpful in patient education and surgical planning.

DOI： 10.1007/s00264-015-3020-3

Language：English   Publishing type：Research paper (scientific journal)  

No previous studies comparing the clinical wear rates of the two different kinds of cross-linked ultra-high-molecular-weight polyethylene (XLPE), annealed and remelted, are available. We compared the creep and steady wear rates of 36 matched pairs (72 hips in total) adjusting for baseline characteristics with propensity score matching techniques. Zirconia femoral heads with 26-mm diameter were used in all cases. The femoral-head cup penetration was measured digitally on radiographs. Significantly greater creep ( p=0.006) was detected in the remelted (0.234 mm) than annealed (0.159 mm) XLPE. However, no significant difference ( p=0.19) was found between the steady wear rates (0.003 and 0.008 mm/year, respectively) of the annealed and remelted XLPE. Multiple regression analyses showed that remelted XLPE is significant independent variable ( p<0.001) that is positively associated with creep. However, the patient age and body weight, cup size, the liner thickness, cup inclination, follow-up periods, and postoperative Merle d'Aubigné hip score had no significant effects ( p>0.05) on the steady wear rates. No patients exhibited above the osteolysis threshold of 0.1 mm/year, progressive radiolucencies, osteolysis, or polyethylene fracture. This[U+3000]propensity-matched cohort study document no significant difference in wear resistant performances of annealed and remelted XLPE over an average period of 10 years.

DOI： 10.1016/j.jmbbm.2015.12.022

Language：English   Publishing type：Research paper (scientific journal)  

Background: Hydroxyapatite (HA) has been applied to joint prostheses as a bioactive coating to prolong their durability. However, HA benefits for cup survival in total hip arthroplasty (THA) remain controversial. In this study, we compared the survival of cups with and without HA coating during a minimum follow-up of 18 years. Methods: In total, 183 THA cases in 163 patients were analyzed, including 73 cups with HA coating (HA⁺ group) and 110 without HA coating (HA^- group); otherwise, the cups had identical titanium-sprayed rough surfaces and were fixed with screws. In both groups, the same conventional polyethylene liners were applied. Zirconia and alumina ceramic heads were used in the HA⁺ and HA^- groups, respectively. We retrospectively analyzed cup survival based on cup revision for any reason or aseptic loosening as end points. Results: In total, 7 and 8 revisions were performed in the HA^- and HA⁺ groups with survival rates of 86.3% and 90.1%, respectively. Among them, 3 cups in the HA^- group and 1 cup in the HA⁺ group were revised for aseptic loosening in 20 years (survival rates 94.1% and 98.7%, respectively). No significant difference was detected in cup survival rates between the groups based on both end points. There were no stem revisions during the observation period. Conclusion: The results suggested that HA coating did not have either beneficial or adverse effects on the long-term cup survival in primary cementless THA.

DOI： 10.1016/j.arth.2015.11.034

Language：Others   Publishing type：Research paper (scientific journal)  

Background: Transtrochanteric anterior rotational osteotomy (ARO) for osteonecrosis of the femoral head (ONFH) can preserve for a long-time collapsed femoral head. Progressive collapse of anteriorly-transposed necrotic lesion leads to secondary arthritic changes and clinical failure. Critical factors influencing collapse of the transposed necrotic lesion after ARO remain largely unknown. Therefore, we performed a retrospective study of ARO to determine: 1) if pre-operative collapse influences collapse of the transposed necrotic area, 2) if any other factor may influence collapse of the transposed necrotic area. Hypothesis: We hypothesized the degree of pre-operative femoral head collapse influences progressive collapse of the transposed necrotic lesion after ARO. Materials and methods: We reviewed 47 hips in 42 patients with ONFH treated with ARO between 2000 and 2005 with a mean follow-up of 11.4. years (10-14. years). The occurrence of progressive collapse of the transposed necrotic lesion after ARO was examined using lateral radiographs taken at least once every year after ARO. The following factors were statistically analyzed: age, sex, body mass index, Harris Hip Score (HHS), pre-operative level of collapse, extent of the necrotic lesion and post-operative intact ratio (ratio of the transposed intact articular surface of the femoral head). Results: Progressive collapse of the transposed necrotic lesion (progressive collapse group) was seen in 17 hips (36 %) during a mean period of 1.8 years (0.5-3.7 years) after ARO, which has developed within 4 years in all cases. Pre-operative level of collapse in the progressive collapse group (4.4. ±. 1.4. mm) was significantly larger than that in the non-progressive collapse group (2.1. ±. 1.0. mm), which was independently associated with progressive collapse of the transposed necrotic lesion in multivariate analysis (P <. 0.0001) with cutoff point of 2.98. mm. In univariate analysis, lower pre-operative HHS, severe extent of the necrotic lesion and the lower post-operative intact ratio were also associated with progressive collapse of the transposed necrotic lesion, but were not associated as independent factors in multivariate analysis. Discussion: The current study suggests that progressive collapse of the transposed necrotic lesion after ARO depends mainly on the pre-operative level of collapse (cutoff point = 2.98. mm). Level of evidence: IV; retrospective case series.

DOI： 10.1016/j.rcot.2016.12.011

Language：English   Publishing type：Research paper (scientific journal)  

We histopathologically examined a surgically resected full specimen obtained from an early-stage spontaneous osteonecrosis of the knee (SPONK). On a mid-coronal cut section of the resected medial femoral condyle, a linear fracture line paralleling the subchondral bone endplate was found. Histopathologically, prominent callus formation was seen comprising of reactive woven bone and granulation tissue on both sides of the fracture. Fracture-related bone debris was focally observed at the osteochondral side of the fracture. Definitive features of antecedent bone infarction such as creeping substitution and bone marrow necrosis were not detected. These findings suggested that SPONK was the result of a subchondral fracture rather than primary osteonecrosis.

DOI： 10.1007/s00256-016-2328-4

Language：Others   Publishing type：Research paper (scientific journal)  

Background: During transtrochanteric rotational osteotomy (RO), it is important to preserve the posterior column artery (PCA), which is generally located in the adipose tissue underneath the quadratus femoris muscle (QF). If there is a defect in the QF, the risk of injuring the PCA, subsequently resulting in total necrosis of the femoral head, may increase. Therefore we investigated (1) the frequency of defects of the QF at the time of RO, (2) clinical outcome of RO based upon a defect of the QF. Hypothesis: The presence of defects of the QF at the time of RO could be detected pre-operatively by magnetic resonance imaging. Methods: RO was performed in 124 hips between 2001 and 2010. In all, 95 of the hips were in male patients and 29 in female patients. The mean age was 45.4 years (range: 11-61 years) at the time of surgery and MRI was performed before RO in all cases. We retrospectively evaluated the progression of a collapse through 3 years after RO. Results: MRI showed a defect in the QF in four hips (3.2 %) (two males, two females), all of which were confirmed intraoperatively. Among the four patients, one (25 %) underwent total hip arthroplasty because of varus deformity of the osteotomy site due to total necrosis of the femoral head 1 year after RO. The 120 hips with a normal QF showed no evidence of total necrosis or progression of necrosis of the femoral head, indicating that the presence of defects of the QF may increase the risk of poor survivorship of this procedure. Conclusions: Defects of the QF have been reported to occur in 1-2 % of all patients, whereas in our study the incidence in ON was approximately 3 %. In ON patients with QF defects, pre-operative MRI evaluation of the QF appears to be important when planning RO, followed by a carefully performed surgical procedure. Level of evidence: IV retrospective case series without control group.

DOI： 10.1016/j.rcot.2016.02.016

Language：English   Publishing type：Research paper (scientific journal)  

Background: During transtrochanteric rotational osteotomy (RO), it is important to preserve the posterior column artery (PCA), which is generally located in the adipose tissue underneath the quadratus femoris muscle (QF). If there is a defect in the QF, the risk of injuring the PCA, subsequently resulting in total necrosis of the femoral head, may increase. Therefore, we investigated: (1) the frequency of defects of the QF at the time of RO, and (2) clinical outcome of RO based upon a defect of the QF. Hypothesis: The presence of defects of the QF at the time of RO could be detected pre-operatively by magnetic resonance imaging. Methods: RO was performed in 124 hips between 2001 and 2010. In all, 95 of the hips were in male patients and 29 in female patients. The mean age was 45.4 years (range: 11-61 years) at the time of surgery and MRI was performed before RO in all cases. We retrospectively evaluated the progression of a collapse through 3 years after RO. Results: MRI showed a defect in the QF in four hips (3.2%) (2 males, 2 females), all of which were confirmed intra-operatively. Among the four patients, one (25%) underwent total hip arthroplasty because of varus deformity of the osteotomy site due to total necrosis of the femoral head 1 year after RO. The 120 hips with a normal QF showed no evidence of total necrosis or progression of necrosis of the femoral head, indicating that the presence of defects of the QF may increase the risk of poor survivorship of this procedure. Conclusions: Defects of the QF have been reported to occur in 1-2% of all patients, whereas in our study the incidence in ON was approximately 3%. In ON patients with QF defects, pre-operative MRI evaluation of the QF appears to be important when planning RO, followed by a carefully performed surgical procedure. Level of evidence: IV; retrospective case series without control group.

DOI： 10.1016/j.otsr.2016.01.017

Language：English   Publishing type：Research paper (scientific journal)  

Objectives: Total hip arthroplasty (THA) is often performed in the lateral decubitus (lateral) position. In this position, the pelvis may have various degrees of tilt leading to implant malposition. We sought to quantify the pelvic tilt in lateral position and further pelvic movement during surgery.Methods: In 95 cases with primary THA, three-dimensional pelvic tilts were quantified by superimposing images reconstructed from CT data onto antero-posterior radiographs taken in lateral position at set-up and after cup placement. Pelvises were fixed with a device compressing anterior superior iliac spines and sacrum.Results: Various degrees of pelvic tilt occurred compared to the supine position; sagittal: -3.1° (-25.5° to 10.2°), axial: 3.9° (-8.4° to 17°), coronal: 0.9° (-11.9° to 13.2°). Absolute changes more than 5° were observed 43%, 47%, and 12% in the sagittal, axial, and coronal planes, respectively. The more preoperative posterior pelvic tilt resulted in the more change in the sagittal plane. Further pelvic movement of about 3° in three planes were observed ranging from -11° to 20° after cup placement.Conclusion: This study showed various pelvic tilt and movement during THA. As pelvic tilt directly alters the cup orientation, its changes should be well understood. Improved tools for positioning and holding the pelvis are required.

DOI： 10.3109/14397595.2015.1092914

Language：English   Publishing type：Research paper (scientific journal)  

Exposure to dioxin-related compounds results in many adverse health effects. Several studies have examined the effects of dioxin-related compounds on human bone metabolism with inconsistent results. In Japan in 1968, accidental human exposure to rice oil contaminated with dioxin-related compounds led to the development of Yusho oil disease. The aim of this study was to determine whether exposure to dioxin-related compounds was associated with bone mineral density in Yusho patients. In 2010, 262 women and 227 men underwent dual-energy X-ray absorptiometry bone scans as part of the nationwide Yusho health examination. Serum levels of polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofurans, and non-ortho polychlorinated biphenyls were measured using high-resolution gas chromatography and high-resolution mass spectrometry. When adjusted for prefecture, 1,2,3,4,7,8-HxCDD and 2,3,7,8-TCDF were significantly positively associated with Z-scores in men. No congeners were positively associated with Z-scores in women. After adjustment for prefecture and body mass index, one congener, 1,2,3,4,6,7,8-HpCDD, was negatively associated with Z-scores in women. In contrast, no congeners remained significant in men after adjusting for body mass index. This may suggest that 1,2,3,4,6,7,8-HpCDD has a negative effect on bone mineral density in women; however, the findings should be interpreted carefully, because no increase in the serum level of this congener was observed in patients with Yusho disease.

DOI： 10.1016/j.chemosphere.2015.11.091

Language：English   Publishing type：Research paper (scientific journal)  

Objectives: The objective of this study was to investigate the common sites of subchondral insufficiency fractures of the femoral head (SIF) based on three-dimensional (3-D) reconstruction of MR images. Materials and methods: In 33 hips of 31 consecutive patients diagnosed with SIF, 3-D reconstruction of the bone, fracture, and acetabular edge was performed using MR images. These 3-D images were used to measure the fractured areas and clarify the positional relationship between the fracture and degree of acetabular coverage. Results: The fractured area in the anterior portion was significantly larger than in the posterior area. In 11 cases, the fractures contacted the acetabular edge and were distributed on the lateral portion. The indices of acetabular coverage (center-edge angle and acetabular head index) in these cases were less than the normal range. In the remaining 22 cases, the fractures were apart from the acetabular edge and distributed on the mediolateral centerline of the femoral head. The majority of these cases had normal acetabular coverage. Conclusions: The common site of SIF is the anterior portion. In addition, two types of SIF are proposed: (1) Lateral type: the contact stress between the acetabular edge and lateral portion of the femoral head causes SIF based on the insufficient acetabular coverage, and (2) Central type: the contact stress between the acetabular surface and the mediolateral center of the femoral head causes SIF independent from the insufficiency of acetabular coverage. These findings may be useful for considering the treatment and prevention of SIF.

DOI： 10.1007/s00256-015-2258-6

Language：English   Publishing type：Research paper (scientific journal)  

Introduction We experienced a rare case in which magnetic resonance imaging (MRI) showed a transient epiphyseal lesion of the femoral head four months after traumatic hip dislocation. To our knowledge, there have been no previously published reports on the development of such transient lesions after traumatic hip dislocation involving no abnormalities just after dislocation. Presentation of case We report a 22-year-old man who showed a transient epiphyseal lesion of the femoral head after traumatic hip dislocation. On MRI performed two days after dislocation, no bony injuries were observed around the hip joint. Four months after dislocation, the patient suddenly experienced right hip pain without any new trauma or injury. A low-intensity band convex to the articular surface was apparent above the epiphyseal scar on T1-weighted imaging, and bone marrow edema was observed around the band lesion on short-tau inversion recovery imaging. Following a two-month period of non-surgical conservative therapy, the patient's hip pain resolved and the low-intensity band was no longer observed on follow-up MRI. Discussion Although the detailed pathogenesis of this transient changes was unclear, we speculate that prolonged rest after traumatic hip dislocation may contribute to bone insufficiency, resulting in an insufficiency fracture of the femoral head. Conclusion This study suggests that transient epiphyseal lesions of the femoral head may occur in patients with a history of traumatic hip dislocation associated with an adapted long-term rest.

DOI： 10.1016/j.ijscr.2016.05.009

Language：English   Publishing type：Research paper (scientific journal)  

Introduction Transtrochanteric anterior rotational osteotomy of the femoral head (TRO) was developed as a joint preserving surgery for osteonecrosis of the femoral head. To the best of our knowledge, peri-implant fractures after femoral osteotomy have rarely been reported. Presentation of case We report a 58-year-old female who suffered a peri-implant femoral shaft fracture following a fall from a stepladder eight years after TRO. Fracture union was achieved six months after a preferred proximal femoral locking plate. Discussion The entry point of the ante-grade femoral nail would have been very close to the new position of the nutrient artery of the femoral head occasioned by the TRO and to avoid injury, we chose proximal femoral locking plate. Conclusion It is important to consider the new position of the nutrient artery of the femoral head in the surgical planning of peri-implant fracture after TRO.

DOI： 10.1016/j.ijscr.2016.07.020

Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Excessive pelvic tilt may be one of the factors leading to instability in total hip arthroplasty (THA), even when the acetabular cup is placed properly. To our knowledge, only a few studies have described late anterior dislocation due to posterior pelvic tilt. We present 3 cases with late anterior dislocations possibly due to posterior pelvic tilt.
CASES PRESENTATIONS: Case-1: An 84-years-old woman fell and presented with an anterior dislocation 12-years after THA. Her pelvis had tilted to approximately 30° posteriorly in a supine position. After conservative treatment, she presented with 10 recurrent anterior dislocations. She had thoracolumbar kyphosis due to multiple compression fractures. Revision with anterior placement of an elevated liner and a 32-mm head corrected the dislocation, and no further dislocations occurred. Case-2: A 78-years-old woman fell and presented with an anterior dislocation 4-years after THA. Her posterior pelvic tilt had increased 23° due to a lumbar compression fracture. Revision by decreasing the cup anteversion was performed, but recurrent posterior dislocations occurred. Owing to her worsened general condition, further treatment was abandoned. Case-3: A 79-years-old woman twisted her body and presented an anterior dislocation 3-years after THA. After manual reduction and conservative treatment, the dislocation recurred. Her posterior pelvic tilt had increased 16°.
CONCLUSION: Although minor trauma triggered the anterior instability in these patients, the underlying pathomechanism existed in the progressive pelvic posterior tilt due to thoracolumbar kyphosis. As longer life expectancy as well as implant survivorship is predicted, attention must be paid to the change of pelvic tilt in elderly patients.

DOI： 10.2174/1874325001610010206

Language：English   Publishing type：Research paper (scientific journal)  

Introduction: Corticosteroid-induced osteonecrosis of the femoral head (ONFH) often affects both femoral heads. Such bilateral ONFH cases are generally detected concurrently on magnetic resonance imaging (MRI). On the other hand, in unilateral cases, it is rare that contralateral ONFH is subsequently detected. We herein report a case in which bilateral ONFH was detected in both femoral heads by repeated MRI examination at an interval of 6 weeks. Case description: A 34-year-old man with purpura nephritis was started on corticosteroid therapy with prednisolone at 30 mg/day. Eight months after the initiation of corticosteroid therapy, he complained of left hip pain with no antecedent triggering activity. MRI obtained 8.5 months after the initiation of corticosteroid therapy showed the findings of osteonecrosis of the left femoral head, while no abnormalities were detected in the right femoral head. On the second MRI obtained 10 months after the initiation of corticosteroid treatment, however, osteonecrosis of the right femoral head was newly detected without an increase of the corticosteroid dose. Conclusions: This case may indicate that corticosteroid-induced bilateral ONFH do not always develop at the same time.

DOI： 10.1186/s40064-015-1458-9

Language：English   Publishing type：Research paper (scientific journal)  

Purpose: To assess the distributions of stress, strain, and fractured areas using a finite element model (FEM), and examine the osteoclastic activity histopathologically in osteonecrosis of the femoral head. Methods: Three femoral heads were obtained during hip arthroplasty for femoral head osteonecrosis. One sample with a normal area, two samples with a non-sclerotic boundary without collapse (Type 1), two samples with a non-collapsed sclerotic boundary (Type 2), and two samples with a collapsed sclerotic boundary (Type 3) were collected from each femoral head for the FEM and histopathological analyses. FEM was performed using CT data, and the distributions of von Mises equivalent stress, octahedral shear stress, octahedral shear strain, and simulated fractured area were evaluated. Furthermore, the osteoclast count at the boundary was compared for each type. Results: In normal and Type 1 samples, the distributions of von Mises equivalent stress, octahedral shear stress, octahedral shear strain, and the fractured area were equally concentrated along the whole analytical range; however, in the Type 2 and 3 samples, they were concentrated along the thickened bone trabeculae at the boundary, which corresponded to the fractured area. Histopathologically, a significantly increased osteoclast number was observed only at the collapsed sclerotic boundary. Conclusion: These results demonstrated that both shear stress and shear strain tend to be concentrated on thickened bone trabeculae at the boundary. Fracture analyses revealed that the boundary of sclerotic changes, which results from the repair process, may be the starting point of the fracture. Additionally, the osteoclastic activity increases after collapse.

DOI： 10.1016/j.bone.2015.09.009

Language：English   Publishing type：Research paper (scientific journal)  

Osteonecrosis of the femoral head is considered to occur early during the course of corticosteroid treatment. However, it remains unclear exactly how early it can develop after initiation of corticosteroid treatment. We report a case of osteonecrosis of the femoral head in which abnormal findings were observed on short-tau inversion recovery (STIR) sequence image performed 2 weeks and 4 days after initiation of high-dose corticosteroid therapy. A 45-year-old man with hemophagocytic syndrome was started on prednisolone, with a maximum dose of 40 mg/day. On day 13 after initiation of this corticosteroid therapy, he transiently experienced left hip pain with no apparent cause. STIR sequence image 5 days after the onset of pain revealed high-intensity bone marrow lesions at the femoral neck of both hips. At 3 months after initiation of corticosteroid therapy, T1-weighted magnetic resonance imaging revealed concave-shaped low-intensity bands, which corresponded to the preceding high-intensity lesions on both hips. Because of the subsequent progression to collapse of the left femoral head, he underwent prosthetic replacement surgery. The high-intensity lesions on STIR sequence image indicate the possibility that osteonecrosis can occur within 3 weeks after initiation of high-dose corticosteroid therapy.

DOI： 10.1007/s00296-015-3346-6

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s00296-015-3304-3.

Language：English   Publishing type：Research paper (scientific journal)  

A 37-year-old female had been treated with corticosteroids for systemic lupus erythematosus clinically diagnosed at age 10. She suddenly had right hip pain without any antecedent trauma. Four months after the onset of pain, she visited her primary care physician. On magnetic resonance imaging, joint space narrowing at the weight-bearing area was already seen with bone marrow edematous lesions in both the femoral head and acetabulum. She was treated non-operatively; however, her pain continued to worsen in severity. Thirteen months after the onset of pain, she was referred to our hospital. A plain radiograph showed subluxation of the collapsed femoral head accompanied by destruction of the acetabular rim. Because of her severe intractable pain, she underwent total hip arthroplasty 1 month after her first visit. Histological examination of the resected femoral head revealed pseudogranulomatous lesions along with prominent callus formation, suggesting rapid destruction of the femoral head.

DOI： 10.1007/s00296-015-3304-3

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1097/RLU.0000000000000886

Language：English   Publishing type：Research paper (scientific journal)  

Introduction: This study examined the outcomes of applying transtrochanteric rotational osteotomy (TRO) for posttraumatic osteonecrosis of the femoral head (ON). Patients and Methods: We retrospectively reviewed 28 hips in 28 patients (male, n = 17; female n = 11) with a mean age of 34.8 years (12–61 years) at the time of TRO. Transtrochanteric anterior rotational osteotomy (ARO) was used when the lesion was localized on the anterior aspect of the femoral head, and transtrochanteric posterior rotational osteotomy (PRO) was indicated in patients with lesions limited to the posterior aspect of the femoral head. The mean follow-up period was 12.3 years (5.0–21.3 years). We investigated the patients’ clinical and radiological factors, including age, sex, body mass index, preoperative Harris Hip Score (HHS), type of antecedent trauma, preoperative stage, and postoperative intact ratio (the ratio of the intact articular surface of the femoral head to the weight-bearing surface of the acetabulum). We divided the patients into a hip-survival group and a conversion-to-total hip arthroplasty (THA) group and then compared these factors between the two groups. Results: At the final follow-up, 22 hips had survived with a mean HHS of 85.8. The remaining six hips underwent THA at a mean of 10.2 years after TRO. The preoperative stage was correlated with hip survival. Furthermore, the postoperative intact ratio was significantly lower in the conversion-to-THA group. Based on the receiver operating characteristic curve, a ratio of less than 33.6 % was found to be associated with the need to convert to THA. Conclusions: TRO to correct posttraumatic ON resulted in favorable midterm results. The possible risk factors for conversion to THA were an advanced preoperative stage and a postoperative intact ratio of less than 33.6 %.

DOI： 10.1007/s00402-015-2282-y

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s00776-014-0541-3

Language：English   Publishing type：Research paper (scientific journal)  

Background: Nontraumatic osteonecrosis of the femoral head (ONFH) is a rare disorder caused by ischemic necrosis of unknown etiology. A few studies have demonstrated trends in the number of patients with ONFH. However, there are no data on temporal trends in characteristics such as age, gender, and causative factors. To investigate this, we examined data from a multicenter hospital-based sentinel monitoring system in Japan. Methods: A total of 3041 newly-diagnosed ONFH patients from 34 participating hospitals who were reported to the system from 1997-2011 were analyzed. We examined age at diagnosis, potential causative factors, and underlying diseases for which patients received systemic steroid administration. Their temporal trends were assessed according to date of diagnosis in 5-year intervals (1997-2001, 2002-2006, and 2007-2011). Results: The gender ratio and distribution of potential causative factors did not change. Regarding underlying diseases requiring steroid administration, the proportion of patients with systemic lupus erythematosus decreased in males (10% to 6.4%) and in females (37% to 29%). Proportion of patients with renal transplantation fell consistently across the study period in both males (3.8% to 1.2%) and females (3.2% to 0.8%). In contrast, the proportion of patients receiving steroids for pulmonary disease (except asthma) significantly increased in both males (0.5% to 5.5%) and females (0.5% to 3.6%). Conclusions: This large descriptive study is the first to investigate temporal trends in the characteristics of ONFH, which provide useful information for future studies.

DOI： 10.2188/jea.JE20140162

Language：English   Publishing type：Research paper (scientific journal)  

OBJECTIVE: The aim of this study was to compare the levels of bone and cartilage metabolism markers in the synovial fluid of the hip joint between patients with secondary OA due to osteonecrosis of the femoral head (ONFH), rapidly destructive arthrosis (RDA) and developmental dysplasia of the hip (DDH).
METHODS: We studied 70 synovial fluid samples obtained from 57 patients with ONFH (mean age 46 years, 34 males, 23 females), 21 samples obtained from 21 patients with RDA (mean age 70 years, 2 males, 19 females) and 20 samples obtained from 20 patients with DDH (mean age 56 years, 2 males, 18 females). The levels of bone alkaline phosphatase (BAP) and tartrate-resistant acid phosphatase 5b (TRACP-5b), as bone metabolism markers, and matrix metalloproteinase 3 (MMP-3) and keratan sulphate (KS), as cartilage metabolism markers, were analysed.
RESULTS: The levels of BAP, MMP-3 and KS were significantly higher in the ONFH group than in the RDA and DDH groups. The levels of TRACP-5b were highest in the RDA group. The levels of BAP in the ONFH group after the development of osteoarthritic changes were significantly lower than those observed in earlier stages. In comparisons between the samples obtained from each group with a terminal condition, the ONFH samples exhibited significantly higher MMP-3 and KS levels, while the TRACP-5 levels were highest in the RDA group.
CONCLUSION: The ONFH patients showed a relatively bone formative condition before the osteoarthritic stage and maintained a higher rate of cartilage turnover throughout several stages compared with the RDA and DDH patients. RDA patients were characterized by a significantly high osteoclast activity.

DOI： 10.1093/rheumatology/keu253

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

A 60-year-old female experienced the gradual onset of left hip pain without any triggering event. Radiographs showed vertical sclerosis in the center of the femoral head and the lesion inside the boundary demonstrated diffuse bony sclerosis. No collapse was observed at the weight-bearing portion on radiograph. However, computed tomography showed a subchondral collapse at the medial lesion. On T2-weighted magnetic resonance imaging, the necrotic lesion showed diffuse high-intensity signals that indicated a prominent repair process. Bone biopsy diagnosed osteonecrosis with associated prominent appositional bone and vascular granulation tissue.

DOI： 10.4137/CCRep.S18171

Language：English   Publishing type：Research paper (scientific journal)  

Summary: The aim of this study was to investigate cytochrome P4503A activity and its correlation with the development of osternecrosis (ON) among male and female steroid-treated rabbits. Forty adult rabbits (male, n = 20; female, n = 20) were injected once with 20 mg/kg of methylprednisolone intramuscularly. Haematologically, cytochrome P4503A activity was measured by plasma 1′-hydroxymidazolam-to-midazolam (1′-OH-MDZ/MDZ) ratio just before and 48 h after the steroid injection. We also measured the levels of oestradiol every week. Both femora and humeri were histopathologically examined for the presence of ON. Fifteen of 20 male rabbits (75%) developed ON, while 6 of 20 female rabbits (30%) did so. There was a significant difference in the rate of incidence of ON between male and female rabbits (P = 0.010). The 1′-OH-MDZ/MDZ ratio in female rabbits just before, as well as 48 h after the steroid injection was significantly higher than that in male rabbits (P = 0.039 and P = 0.001 respectively). In addition, 1′-OH-MDZ/MDZ ratio in female rabbits significantly increased in 48 h after the steroid injection (P = 0.044), while that in male rabbits did not so (P = 0.978). The levels of oestradiol in female rabbits were significantly higher than those in male rabbits during the experimental period (P = 0.008). In conclusion, this study indicates that the gender difference in cytochrome P4503A activity may be one of the important factors for the development of steroid-induced ON, possibly due to the effects of oestradiol.

DOI： 10.1111/iep.12060

Language：English  

In nontraumatic osteonecrosis (ON) of the femoral head, several abnormalities in the coagulation-fi brinolysis system have been reported, including increase of plasminogen activator inhibitor-1 level [ 1 ], the presence of antiphospholipid antibodies [ 2 ], familial heterozygous protein S defi ciency [ 3 ], and antithrombin III defi ciency [ 4 ]. These abnormalities are thought to induce hypercoagulability in the blood vessels.

DOI： 10.1007/978-3-642-35767-1_33

Language：English   Publishing type：Research paper (scientific journal)  

Purpose: This study was conducted to assess the posterior inclination of the contralateral femoral epiphysis in patients with unilateral slipped capital femoral epiphysis (SCFE). Methods: The posterior sloping angle (PSA) was measured using lateral radiographs in 67 patients with a unilateral SCFE and in 41 age-matched normal controls. A symptomatic epiphyseal slip was defined as the development of SCFE. Results: The contralateral PSA in SCFE patients was more widely distributed and significantly larger compared to controls (15.0°vs. 9.0°, p < 0.0001). Forty-seven hips (70.1 %) had a PSA of greater than 12.8°, which was +2SD of the control hips. Of the 65 hips excluding the two cases with prophylactic pinning, 11 hips (16.9 %) eventually developed a contralateral SCFE during adolescence and their PSA at the initial visit was significantly larger compared to patients without a contralateral SCFE (18.0°vs. 14.3°, p < 0.005) with a cutoff value of 19°. Conclusions: These findings suggested the possibility of bilateral hip involvement in SCFE patients. Hips with greater degrees of PSA (> 19°) are likely to become symptomatic.

DOI： 10.1007/s00264-013-2131-y

Language：English   Publishing type：Research paper (scientific journal)  

Late segmental collapse after internal fixation for femoral neck fracture is the phenomenon observed in post-traumatic osteonecrosis of the femoral head (ON), which has generally been reported to occur over a year or more after internal fixation. Subchondral insufficiency fracture of the femoral head (SIF) has also been recognized to cause femoral head collapse, however, only two cases of SIF after internal fixation for femoral neck fracture have been reported. We report a case with femoral head collapse observed 5 months after internal fixation for femoral neck fracture, which was histopathologically diagnosed as SIF. Clinically, differentiating SIF from ON is important because some cases of SIF have been reported to heal without surgical treatments. The timing of femoral head collapse after femoral neck fracture may be different between SIF and post-traumatic ON.

DOI： 10.1007/s00256-014-1835-4

Language：English   Publishing type：Research paper (scientific journal)  

Introduction: Preventing post-traumatic osteoarthritis is a challenging problem following acetabular fracture. Progressive osteoarthritis is considered to be caused by an irregular articular surface of the acetabular roof or cartilage injury, but little is known about the pathogenesis of collapse of the femoral head after acetabular fracture. We report a case of post-traumatic osteoarthritis after acetabular fracture in which subchondral fracture of the femoral head contributed to the progressive collapse of the femoral head and osteoarthritis. To the best of our knowledge, there has been no previous report of subchondral fracture of the femoral head after acetabular fracture. Case presentation: A 58-year-old Japanese man fell from a ladder. He was diagnosed with a left acetabular fracture, which was managed conservatively. He developed left coxalgia six months after injury and was seen at our institution one year after the onset of pain. The left acetabular fracture had fused, but his left femoral head had collapsed. The images at the time of injury showed a fracture of the acetabular roof, and an approximately 2mm step-off existed in the articular surface. Retrospective evaluation of the plain radiographs and computed tomography images showed that his femoral head had progressively collapsed. Our patient underwent total hip arthroplasty. Histopathologic findings demonstrated that the collapse of his femoral head was caused by a subchondral fracture of his femoral head. Conclusion: Our experience with this case indicates that in addition to post-traumatic osteonecrosis, subchondral fracture may need to be considered in cases with progressive collapse of the femoral head after acetabular fracture.

DOI： 10.1186/1752-1947-8-447

Language：English   Publishing type：Research paper (scientific journal)  

OBJECTIVE: The aim of the study was to assess the degree and location of the reparative process in early osteonecrosis of the femoral head on the basis of single-photon emission computed tomography/computed tomography (SPECT/CT) with technetium-99m hydroxymethylene diphosphonate. MATERIALS AND METHODS: This study was approved by the institutional review board. We retrospectively evaluated SPECT/CT scans of 23 consecutive hips. On the basis of the classification system used, 12 hips were classified as stage 1 (no radiographic abnormality), six hips as stage 2 (demarcating sclerosis without femoral head collapse), and five hips as stage 3A (<3mm femoral head collapse). In each femoral head, the area with the maximum uptake count was defined as the region of maximum uptake. The degree of maximum uptake was assessed by the count ratio, which was defined as the maximum count within the femoral head divided by the mean uptake count of the cross-sectional region of the ipsilateral femur at the level of the distal end of the lesser trochanter. RESULTS: In stage 1, the maximum uptake count tended to occur in the anterior region of the femoral head. Meanwhile, in both stage 2 and stage 3A, the maximum uptake count was more likely to be observed in the lateral region. The mean count ratio of stage 2 was significantly higher than that of stage 1. CONCLUSION: We speculate that osteoblastic activity in the precollapsed stage may gradually increase around the necrotic lesion, with a tendency to advance toward the lateral region of the femoral head.

DOI： 10.1097/MNM.0000000000000166

Language：English   Publishing type：Research paper (scientific journal)  

Methods: A total of 296 hips in 275 patients who underwent transposition osteotomy of the acetabulum between 2001 and 2012 were retrospectively reviewed. Patient characteristics and radiographic parameters were compared between patients with and without fracture.
Results: Fourteen ipsilateral hips (4.7 %) in 14 female patients had fracture of the inferior pubic ramus (11 hips) or the ischial ramus (three hips) on the same side as the surgery at an average of 4.6 weeks after PAO. Multivariate analysis indicated that younger age at operation (odds ratio of 1.43 per five years, p = 0.0169) and greater degree of correction (odds ratio of 1.98 per five degrees, p = 0.0005) were significantly associated with ischio-pubic fracture as independent risk factors. All fractures healed conservatively with partial weight-bearing.
Conclusions: Younger female patients and greater deformity corrections increased the risk of ischio-pubic stress fracture after PAO.
Purpose: Ischio-pubic stress fracture is one of the potential complications after peri-acetabular osteotomy (PAO) in patients with hip dysplasia. The purpose of this study was to examine the prevalence of and risk factors for ischio-pubic fractures following PAO.

DOI： 10.1007/s00264-014-2375-1

Language：English   Publishing type：Research paper (scientific journal)  

Purpose: The combined anteversion (CA) technique is a method in which the cup is placed according to the stem anteversion in total hip arthroplasty (THA). We examined whether the CA technique reduced the dislocation rate, and the distribution of CA with the manual placement of the cup. Methods: We retrospectively reviewed 634 hips in 579 patients with primary cementless THA. In 230 hips using the CA technique [CA(+)], a CA of 50 ± 10 was the aim. In the remaining 404 hips [CA(-)], the cup was first placed targeting 20 of anteversion. The post-operative CA was measured using the computed tomography (CT) images in 111 hips. Results: One hip (0.4 %) had a dislocation in the CA(+) group, whereas ten hips (2.5 %) had a dislocation in the CA(-) group. A multivariate analysis showed that primary diagnosis, head size and CA technique significantly influenced the dislocation rate. Patients in the CA(-) group were 5.8 times more likely to have a dislocation compared to the CA(+) group. In the 111 hips with CT images, 81 hips (73.0 %) achieved the intended CA. Conclusions: Although the manual placement of the cup resulted in 27 % of outliers from the intended CA, the CA technique significantly reduced the dislocation after primary THA.

DOI： 10.1007/s00264-013-2091-2

Language：English   Publishing type：Research paper (scientific journal)  

Background and purpose It remains controversial how hypercholesterolemia influences the development of steroid-induced osteonecrosis (ON). We investigated the role of hypercholesterolemia induced by a cholesterol-rich diet on the development of ON in rabbits. Methods 40 adult male Japanese white rabbits were randomly divided into 2 groups. 20 rabbits were maintained on a cholesterol-rich diet for 2 weeks before receiving steroid treatment (the CHOL group). The other 20 rabbits were maintained on a standard diet (the control (CTR) group). 2 weeks after the start of the study, all 40 rabbits were injected with methylprednisolone acetate (MPSL) into the right gluteus medius muscle (20 mg/kg body weight). 2 weeks after the steroid injection, both the femora and humeri were examined histopathologically for the presence of ON. Hematological analysis of the serum lipid levels was performed every week. Based on the same protocol, we also investigated the effects of lanolin, a primary component of a cholesterol-rich diet, in another group (the LA group). Results The incidence of ON in the CHOL group (3/20) was lower than that observed in the CTR group (15/20) (p < 0.001). During the whole experiment, the levels of total cholesterol and the ratio of low-density lipoprotein to high-density lipoprotein in the CHOL group were higher than those observed in the CTR group (p < 0.001). The LA group also had a lower incidence of ON (2/20), and the lipid levels in the LA group showed similar changes to those observed in the CHOL group. Interpretation Our findings suggest that preexisting hypercholesterolemia itself induced by a cholesterol-rich diet does not increase the risk of developing steroid-induced ON, but rather seems to diminish it. Lanolin may be the active anti-ON component of the cholesterol diet.

DOI： 10.3109/17453674.2013.859421

Language：English   Publishing type：Research paper (scientific journal)  

Purpose: Subchondral insufficiency fractures of the femoral head (SIF) need to be differentiated from osteonecrosis of the femoral head (ON), since these two conditions have several overlapping characteristics especially in their radiological findings. The purpose of this study was to determine the useful clinical features for differentiating SIF from ON. Methods: This study reviewed 44 consecutive patients, aged 60 years or older with a radiological evidence of subchondral collapse of the femoral head. According to the histopathological diagnosis, 22 patients were grouped as SIF and 22 patients as ON. A 2 × 2 contingency table analysis was used to obtain the odd ratios (ORs) for SIF compared to ON. Results: The age, proportion of females, the rate of a history of either corticosteroid intake or alcohol abuse, and the presence of vertebral compression fracture in subchondral insufficiency fracture were significantly higher than those with osteonecrosis (p = 0.0001, 0.0212, 0.0001, and 0.0040, respectively). ORs for SIF were 12.01 [95 % confidence intervals (CI) 1.35-106.80] and 7.29 (95 % CI 1.91-27.86), if the patient were female and 70 years of age or older, respectively. In addition, OR for SIF was extremely high (OR 56.01, 95 % CI 6.12-512.87) compared to ON, if the patients have a history of either corticosteroid intake or alcohol abuse. Conclusion: The results of this study indicate that osteoporotic elderly women without any history of corticosteroid intake or alcohol abuse need to first be considered to have subchondral insufficiency fracture when radiographs show a collapse of the femoral head.

DOI： 10.1007/s00402-013-1847-x

Language：English   Publishing type：Research paper (scientific journal)  

Purpose: We examined the remodelling of the femoral head-neck junction in patients with slipped capital femoral epiphysis (SCFE) and the frequency of residual cam deformities. Methods: We reviewed 69 hips in 56 patients with stable SCFE who had undergone in situ pinning. Mean age at slip was 11.7 years and the follow-up period 63.4 months. Cam deformity was evaluated using the anterior offset alpha (α) angle and head-neck offset ratio (HNOR). Results: The average α angle and HNOR significantly improved from 76.2 to 51.3 and 0.086 to 0.135, respectively; 25 hips (36.2 %) still had an α angle greater than 50, and 32 hips (46.4 %) had an HNOR of under 0.145. A multivariate analysis selected age at onset and slip angle as risk factors for cam deformity, with cutoff values 11.1 years and 21.0, respectively. Conclusions: Although most hips had remodelling of the head-neck junction, 29.4 % had residual cam deformities that may be susceptible to femoroacetabular impingement.

DOI： 10.1007/s00264-013-2047-6

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s00402-013-1863-x

Language：English   Publishing type：Research paper (scientific journal)  

Purpose: This study was conducted to examine the risk factors for recurrent dislocation after total hip arthroplasty (THA) and test the hypothesis that late dislocations are associated with recurrence. Methods: A total of 1,250 hips in 1,017 patients were retrospectively reviewed. All operations were performed through the posterolateral approach with posterior soft tissue repair. An early or late dislocation was defined as a dislocation occurring before or after one year postoperatively, respectively. Results: Dislocation occurred in 36 hips (2.9 %) and 20 of them experienced recurrence. Recurrent dislocations were observed in ten out of 25 hips (40.0 %) with early dislocation; however, ten out of 11 hips (90.9 %) with late dislocation experienced recurrence (p = 0.0046). Multivariate analysis revealed that late dislocation was significantly associated with recurrence with odds ratio of 5.94 per year. Seven in 20 hips with recurrent dislocation required surgical treatment. Conclusion: Late dislocation significantly contributed to the development of recurrent dislocations.

DOI： 10.1007/s00264-013-1921-6

Language：Japanese  

Language：English   Publishing type：Research paper (scientific journal)  

OBJECTIVE. The objective of this study was to identify the risk factors associated with the prognosis and need for surgery of patients with subchondral insufficiency fractures of the femoral head. MATERIALS AND METHODS. Twenty-nine consecutively registered patients with subchondral insufficiency fractures of the femoral head were divided into the two groups: a nonprogression of collapse group, which included patients who had no collapse or 2 mm or less of collapse of the femoral head and whose symptoms resolved (14 patients), and a progression of collapse group, which included patients who had more than 2 mm of collapse, for which surgery was indicated (15 patients). Both groups received the same conservative therapy. The following radiographic measurements were obtained: Sharp angle, center edge angle, acetabular roof angle, and acetabular head index. On MR images, band length, defined as the length of a lowsignal-intensity band in the coronal plane, and band length ratio, defined as the proportion of the band length relative to the weight bearing portion, were assessed for each patient. Bone mineral density measurements (T score) were available for 17 patients. RESULTS. In the univariate analyses, T score, Sharp angle, center edge angle, acetabular roof angle, acetabular head index, band length, and band length ratio were found to be significant prognostic factors. Multivariate analyses of T score, acetabular head index, and band length ratio showed that both acetabular head index and band length ratio were significant predictors. CONCLUSION. Both acetabular head index and band length ratio are important prognostic factors in the care of patients with subchondral insufficiency fractures of the femoral head.

DOI： 10.2214/AJR.12.9615

Language：English   Publishing type：Research paper (scientific journal)  

A number of studies have suggested that ischemia is the principal pathomechanism of osteonecrosis, however, the detailed mechanism responsible for ischemia remains unclear. We examined the effects of fasudil, an anti-vasospasm agent, on the development of steroid-induced osteonecrosis in rabbits. One group of rabbits received 15mg/kg of fasudil intravenously, which were then injected once intramuscularly with 20mg/kg of methylprednisolone (n=33), and one received methylprednisolone alone as a control (n=28). Eight rabbits from each group were sacrificed 24h after methylprednisolone injection to analyze them by the expression of endothelin_A-receptor and eNOS. Two weeks after the steroid injection, the femora and humeri were examined histopathologically for the incidence of osteonecrosis. In addition, plasma from each of four osteonecrosis-positive or -negative rabbits was used for the proteomic analysis in the fasudil group. The incidence of osteonecrosis was significantly lower in the fasudil group (32%) than that in the control group (75%) (P<0.01). Immunohistochemically, endothelin_A-receptor expressions levels were decreased in the smooth muscle of the bone marrow in the fasudil group in comparison to that in the control group. The eNOS expressions levels in both serum and bone marrow in the MF group were significantly higher than those in the M group (P<0.05). Based on the proteomic analysis, several proteins related to vasospasm, such as fibrinogen, thrombin, and apolipoprotein E, were identified in rabbits with osteonecrosis soon after steroid administration. This study indicates that vasospasm is one of the important factors involved in the pathogenesis of steroid-induced osteonecrosis and that the anti-vasospasm agents seem to decrease the incidence of steroid-induced osteonecrosis.

DOI： 10.1016/j.bone.2012.12.050

Language：English   Publishing type：Research paper (scientific journal)  

Osteonecrosis of the femoral head (ONFH) is an ischemic disorder that can lead to femoral head collapse and secondary osteoarthritis. Although the condition is usually limited to the femoral head, we report a rare case of biopsy-proven ONFH extending into the femoral neck, which required hip replacement surgery. We emphasize the imaging features of this condition and briefly discuss its potential relevance.

DOI： 10.1007/s00256-012-1525-z

Language：English   Publishing type：Research paper (scientific journal)  

Objectives: Porous tantalum is a biomaterial newly applied for artificial joints. We present here 5-years follow-up report of a multicenter clinical trial of total hip arthroplasties (THA) with porous tantalum modular acetabular component (modular PTC). Methods: Study participants received 82 hips in 79 cases, with 61.2 months follow-up on average. Age at operation was 60.9 years. Clinical results were evaluated using Merle d'Aubigne Postel score. Presence of implant loosening, periacetabular radiolucency, osteolysis, and gap filling were examined for radiographic results. Results: Merle d'Aubigne Postel score improved from 10.0 to 16.4 points. All PTC were radiographically stable, with no evidence of progressive radiolucencies. Average polyethylene wear rate was 0.004 mm/year, with no periacetabular osteolysis. Fifteen hips (18.3%) showed a gap >1 mm; however, all showed bone filling within 12 months. PTC with oversized reaming was significantly less likely to have a gap. No implant failure was noted related to modularity. Resulting survival rate of modular PTC was 100% at 5 years. Conclusions: Modular PTC showed excellent results at 5-years of follow-up. Some hips showed periacetabular gaps, which were filled with bone within 1 year. Further follow-up was needed to determine long-term efficacy.

DOI： 10.1007/s10165-012-0618-9

Language：English   Publishing type：Research paper (scientific journal)  

Purpose: The purpose of this study was to report results at a minimum of 10 years for hydroxyapatite (HA) coating on the titanium arc-sprayed cementless total hip arthroplasty (THA) and to evaluate the impact of cross-linked polyethylene (XLPE) on implant longevity. Methods: A total of 131 consecutive primary THAs in 123 patients using an AMS acetabular cup and a PerFix HA stem were retrospectively reviewed. Conventional PE was used for 62 hips (CPE group) and cross-linked PE for 69 hips (XLPE group), with mean follow-up periods of 13 and 11.5 years, respectively. These patients were reviewed using the Japanese Orthopaedic Association (JOA) Hip Score and evaluated in terms of PE wear, osteolysis, and implant survival. Results: The JOA score improved from 42.6 to 83.9 points at the final follow-up. The mean wear rate of 0.12 mm/year in the CPE group was significantly greater than that of XLPE at 0.007 mm/year. In the CPE group, ten (16.1 %) and two (3.2 %) hips, respectively, underwent PE exchange due to severe wear and acetabular revision due to loosening associated with osteolysis. Three patients had revision in the XLPE group: one cup for aseptic loosening, one PE for recurrent dislocation, and one stem for neck fracture. No evident osteolysis was seen in the XLPE group. Kaplan-Meier survivorship with any revision as the end point shows that the 12-year survival rate was 97.7 % for cups, 93.8 % for PE liners, and 99.2 % for stems. Multivariate analysis revealed that the use of XLPE significantly reduced the risk of revision, with the odds ratio (OR) of 4.3. Conclusions: AMS and PerFix HA components in this series show excellent implant fixation; however, high rates of PE wear and subsequent osteolysis were limiting factors in long-term success. Low wear rates with XLPE suggest improved implant longevity.

DOI： 10.1007/s00776-013-0456-4

Language：English   Publishing type：Research paper (scientific journal)  

Background: This study investigated the radiological factors that correlated with progression of collapse and joint space narrowing after transtrochanteric posterior rotational osteotomy (PRO) for osteonecrosis of the femoral head. Methods: This study reviewed 51 hips in 47 patients with a mean follow-up of 11 years (5-20). The subjects included 29 males and 18 females with a mean age of 34 years (12-54) at the time of surgery. The 51 hips were divided into two groups based on the radiological outcome (group I: evidence of progression of collapse and/or joint space narrowing, group II: no evidence of either progression of collapse or joint space narrowing). Both clinical and radiological factors were analyzed by both univariate and multivariable analyses. Results: Six hips were categorized as group I and 45 hips were categorized as group II. The postoperative intact ratio and preoperative stage were significantly correlated with the radiological outcome in both univariate (P < 0.0001, P = 0.006) and multivariate (P = 0.0014, P = 0.0039) analysis. The cutoff point for the postoperative intact ratio (the minimum ratio required to prevent both progression of collapse and joint space narrowing) was 36.8 %. Conclusions: The results of this study indicate that the postoperative intact ratio is one of the main influences on progression of collapse and/or joint space narrowing after PRO, and should be at least 36.8 %. An increased awareness of this critical ratio would be useful for planning the optimal use of this procedure.

DOI： 10.1007/s00776-012-0347-0

Language：English   Publishing type：Research paper (other academic)  

The purpose of this study was to examine the effects of ceramic femoral head material on the wear of annealed, crosslinked ultra-high molecular weight polyethylene (UHMWPE) (XLPE) in total hip arthroplasty compared to non-crosslinked conventional UHMWPE (CPE). XLPE was fabricated by crosslinking with 60 kGy irradiation and annealing. Femoral heads made from zirconia and alumina ceramics, and cobalt-chrome (CoCr) of 22 mm or 26 mm diameter were used. In this study, the femoral head penetration into the cup was measured digitally on radiographs of 70 hips with XLPE and 50 hips with CPE. The average follow-up periods were 6.1 and 12.7 years, respectively. The steady wear rate of XLPE was significantly lower than those of CPE (0.002 versus 0.08 mm/year, respectively). Zirconia displayed increased wear rates compared to alumina in CPE; however, there was no difference among head materials in XLPE (0.0028, 0.011 and 0.009 mm/year for zirconia, alumina and CoCr, respectively). Neither head size or implantation period impacted XLPE wear. In contrast to CPE, XLPE displayed low wear rates surpassing the effects of varying femoral head material, size, implantation period and patient demographics.

DOI： 10.4028/www.scientific.net/KEM.529-530.279

Language：English   Publishing type：Research paper (scientific journal)  

The purpose of this study was to examine the effects of ceramic femoral head material, size, and implantation periods on the wear of annealed, cross-linked ultra-high molecular weight polyethylene (UHMWPE) (XLPE) in total hip arthroplasty compared to non-cross-linked conventional UHMWPE (CPE). XLPE was fabricated by cross-linking with 60 kGy irradiation and annealing. Femoral heads made from zirconia and alumina ceramics and cobalt-chrome (CoCr) of 22 or 26 mm diameter were used. In this retrospective cohort study, the femoral head penetration into the cup was measured digitally on radiographs of 367 hips with XLPE and 64 hips with CPE. The average follow-up periods were 6.3 and 11.9 years, respectively. Both XLPE creep and wear rates were significantly lower than those of CPE (0.19 mm vs. 0.44 mm, 0.0001 mm/year vs. 0.09 mm/year, respectively). Zirconia displayed increased wear rates compared to alumina in CPE; however, there was no difference among head materials in XLPE (0.0008, 0.00007, and -0.009 mm/year for zirconia, alumina, and CoCr, respectively). Neither head size or implantation period impacted XLPE wear. In contrast to CPE, XLPE displayed low wear rates surpassing the effects of varying femoral head material, size, implantation period, and patient demographics. Further follow-up is required to determine the long-term clinical performance of the annealed XLPE.

DOI： 10.1002/jor.22148

Language：English   Publishing type：Research paper (scientific journal)  

Objective: Morphological correlation between the acetabulum and femur at the hip joint is still controversial. We tested the hypothesis that femoral anteversion correlates with acetabular version and coverage in patientswith developmental dysplasia of the hip (DDH). Materials and methods: Using pelvic computed tomography (CT) images of 79 hips in 49 Asian women with DDH and 49 normal hips, we measured femoral anteversion, the axial and vertical acetabular version and the acetabular sector angle (ASA) to demarcate femoral head coverage. Depending on the location of the acetabular bone defect, dysplastic hips were divided into three subgroups: the anterior, global and posterior deficiency groups. We performed a comparative analysis between dysplastic and normal hips using the Wilcoxon rank sum test, and a relative analysis between femoral anteversion and acetabular measurements in dysplastic hips using Pearson's correlation coefficient. Results: The amount of femoral anteversion in dysplastic hips was greater and more variable than in normal hips (p<0.0001, p00.0277 respectively). Femoral anteversion in dysplastic hips correlated significantly with acetabular anteversion in the groups with anterior and global deficiency subgroups (p<0.05, r00.2990, p<0.05, r00.451 respectively), but not with the posterior deficiency subgroup. Femoral anteversion also correlated with vertical acetabular version. When acetabular coverage was examined, significant correlations were noted between femoral anteversion and anterior and superior coverage, but not with posterior coverage. These correlations were not observed in normal hips. Conclusions: Our results showed significantly greater and more variable femoral anteversion in DDH, and a significant correlation between femoral anteversion and acetabular version and coverage in DDH with anterior and global acetabular bone deficiency.

DOI： 10.1007/s00256-012-1368-7

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Objective: To investigate the effects of an anti-platelet drug (clopidogrel) on the prevention of steroid-induced osteonecrosis (ON) in rabbits. Methods: Adult male Japanese white rabbits were divided into two groups and treated as follows: one group received daily clopidogrel mixed in normal saline (AP; n = 35), the other received only normal saline (NS; n = 30). One week after the administration, all rabbits were injected once intramuscularly with 20 mg/kg of methylprednisolone acetate into the right gluteus medius muscle. Three weeks after, both the femora and humeri were examined histopathologically for the presence of ON. The platelet aggregation assay and hematological examinations were performed before and after the steroid injection. Results: The incidence of ON in the AP group (48.5%) was significantly lower than that observed in the NS group (73.3%). The platelet aggregations in the AP group were significantly inhibited by the administration of clopidogrel. The levels of total cholesterol and triglycerides showed no significant differences between the AP and NS group. Conclusion: The present experimental study demonstrated that the administration of an anti-platelet drug prevented steroid-induced ON in rabbits and that platelet aggregation seems to be one of the possible factors involved in the pathogenesis of steroid-induced ON.

DOI： 10.1093/rheumatology/ker197

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Objective: The aim of this study was to identify the risk factors associated with the prognosis of a subchondral insufficiency fracture of the femoral head (SIF). Methods: Between June 2002 and July 2009, 25 patients diagnosed with SIF were included in this study. Sequential radiographs were evaluated for the progression of collapse. Clinical profiles, including age, body mass index, follow-up period and Singh's index, were documented. The morphological characteristics of the low-intensity band on T ₁ weighted MRI were also examined with regards to four factors: band length, band thickness, the length of the weight-bearing portion and the band length ratio (defined as the proportion of the band length to the weight-bearing portion of the femoral head in the slice through the femoral head centre). Results: Radiographically, a progression of collapse was observed in 15 of 25 (60.0%) patients. The band length in patients with progression of collapse [22.5 mm; 95% confidence interval (CI) 17.7, 27.3] was significantly larger than in patients without a progression of collapse (13.4 mm; 95% CI 7.6, 19.3; p<0.05). The band length ratio in patients with progression of collapse (59.8%; 95% CI 50.8, 68.9) was also significantly higher than in patients without a progression of collapse (40.9%; 95% CI 29.8, 52.0; p<0.05). No significant differences were present in the other values. Conclusion: These results indicate that the band length and the band length ratio might be predictive for the progression of collapse in SIF.

DOI： 10.1259/bjr/44936440

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1111/j.1365-2613.2011.00798_2.x

Language：English   Publishing type：Research paper (scientific journal)  

Purpose The purpose of this study was to investigate the factors that affect the joint space narrowing after transtrochanteric anterior rotational osteotomy (ARO) for osteonecrosis of the femoral head (ONFH). Methods We reviewed 39 cases (43 hips) of ONFH in patients who underwent ARO between 2000 and 2004. Their mean age was 42 years (23-61) at the time of surgery. The mean follow-up period was 7.3 years (3-10). The following clinical and radiological factors were investigated: the preoperative stage, localization and extent of the necrotic lesion, and the postoperative intact ratio (transposed intact articular surface of the femoral head to the weight-bearing surface of the acetabulum). The 43 hips were divided into two groups: a joint space narrowing (JSN) group and a non-joint space narrowing (non-JSN) group. Results Thirty-seven hips (86 %) were categorized as non-JSN and six (14 %) as having JSN. The preoperative Japanese Orthopaedic Association score was significantly higher in the non-JSN group than in the JSN group (P = 0.01). In the non-JSN group, the rate of early stage disease was significantly higher than in the JSN group (P = 0.03). The postoperative intact ratio was significantly higher in the non-JSN group than in the JSN group (P = 0.002). A multivariate analysis revealed that the postoperative intact ratio was an independent predictor of the progression of joint space narrowing after ARO, and the cutoff point was 39.2 %. Conclusion The results of this study suggest that the postoperative intact ratio is one of factors determining the progression of joint space narrowing after ARO and that an approximately 40 % or higher postoperative intact ratio is recommended to prevent joint space narrowing.

DOI： 10.1007/s00776-012-0238-4

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Background Transtrochanteric anterior rotational osteotomy for osteonecrosis of the femoral head should be performed to obtain [34% of the ratio of transposed intact posterior articular surface to the acetabular weight-bearing area. Therefore, the presence of acetabular dysplasia is unfavorable in obtaining this ratio. Between 1999 and 2005, we performed the modified Spitzy shelf acetabuloplasty combined with anterior rotational osteotomy for three patients (four hips) with acetabular dysplasia. In this study, we retrospectively evaluated the midterm results of this combined surgery. Methods and results Patients comprised one man and two women with a mean age of 29 years at the time of surgery. Mean follow-up was 7.5 years. The average preoperative Harris hip score of 65.5 points increased to an average of 79.3 points at the latest follow-up. None of the hips required conversion to total hip arthroplasty during the follow-up periods. The average postoperative intact ratio without a shelf procedure was 23%, and with a shelf procedure, this ratio increased to be 58%. As a result, collapse progression was not observed in any of the four hips. Conclusions Our results suggest that anterior rotational osteotomy combined with shelf acetabuloplasty may be a surgical option for osteonecrosis of the femoral head with acetabular dysplasia. Further studies with a larger patient population are necessary to clarify appropriate indications and limitations of this combined surgery.

DOI： 10.1007/s00776-012-0205-0

Language：English   Publishing type：Research paper (scientific journal)  

Background Acetabular retroversion is observed in hips after various pediatric hip diseases. This study sought to examine the frequency of acetabular retroversion in both affected and unaffected hips after Legg-Calvé- Perthes disease and its correlation with the prominence of the ischial spine. Methods We retrospectively investigated the version and morphological features of the acetabulum using pelvic radiographs after Legg-Calvé-Perthes disease (107 affected hips treated non-operatively and 72 unaffected hips from the contralateral side). The diagnosis of acetabular retroversion was made based on the presence of a positive cross-over sign on anteroposterior pelvic radiographs. The correlation between the presence of a positive cross-over sign and modified Stulberg classes, the onset age of Legg-Calvé-Perthes disease, radiographic parameters for acetabular dysplasia and the prominence of the ischial spine were examined. Results The prevalence of a positive cross-over sign was 49.5 % (45 of 91 hips) in affected hips and 45.8 % (33 of 72 hips) in unaffected hips. Hips with a positive cross-over sign were significantly coexistent bilaterally. The prevalence of prominence of the ischial spine in the positive cross-over sign group was 71.4 % in the affected side and 81.8 % in the unaffected side, indicating a significant correlation between the cross-over sign and the prominence of the ischial spine in both affected and unaffected hips. The positive cross-over sign did not have any correlation with the parameters for acetabular dysplasia and the onset age, however, had a significant correlation with the severity of the femoral head deformity. Conclusions High prevalence of acetabular retroversion in both affected and unaffected hips after Legg-Calvé-Perthes disease was demonstrated. Symmetric acetabular deformity and the coexistence of prominence of the ischial spine suggested the effects of the Legg-Calvé-Perthes disease lesions on the skeletal development of the whole pelvis. Further follow-up is needed to clarify the pathological significance of acetabular retroversion after Legg-Calvé-Perthes disease.

DOI： 10.1007/s00776-012-0213-0

Language：English   Publishing type：Research paper (scientific journal)  

In order to clarify how intra-articular lesions influence the survival of a periacetabular osteotomy in patients with dysplasia of the hip, we performed an observational study of 121 patients (121 hips) who underwent a transposition osteotomy of the acetabulum combined with an arthroscopy. Their mean age was 40.2 years (13 to 64) and the mean follow-up was 9.9 years (2 to 18). Labral and cartilage degeneration tended to originate from the anterosuperior part of the acetabulum, followed by the femoral side. In all, eight hips (6.6%) had post-operative progression to Kellgren-Lawrence grade 4 changes, and these hips were associated with the following factors: moderate osteoarthritis, decreased width of the joint space, joint incongruity, and advanced intra-articular lesions (subchondral bone exposure in the cartilage and a full-thickness labral tear). Multivariate analysis indicated subchondral bone exposure on the femoral head as an independent risk factor for progression of osteoarthritis (p = 0.003). In hips with early stage osteoarthritis, femoral subchondral bone exposure was a risk factor for progression of the grade of osteoarthritis. Although the outcome of transposition osteotomy of the acetabulum was satisfactory, post-operative progression of osteoarthritis occurred at a high rate in hips with advanced intra-articular lesions, particularly in those where the degenerative process had reached the point of femoral subchondral bone exposure.

DOI： 10.1302/0301-620X.93B11.27314

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Objective To estimate the incidence rate of nontraumatic osteonecrosis of the femoral head (ONFH) in the Japanese population. Methods A survey was conducted to ascertain newly identified patients with nontraumatic ONFH in the Specified Disease Treatment Research Program of Fukuoka Prefecture (population 5 million) between 1999 and 2008. Distributions of age and sex in this population were investigated. Crude incidence rates of nontraumatic ONFH were calculated, and age-adjusted incidence rates were estimated by adjusting the crude values against those for the Japanese standard population in each year. Results In Fukuoka Prefecture, 1,244 newly identified patients with nontraumatic ONFH were recruited into the Japanese subsidy program over the span of 10 years. The ratio of men to women was 1.6, comprising 758 men (61%; mean age 48 years) and 486 women (39%; mean age 56 years). The crude incidence rate of nontraumatic ONFH in the 10-year period was 2.58 cases per 100,000 person-years (range 1.54-3.66). The mean age-adjusted incidence rate was 2.51 cases per 100,000 person-years. Conclusion This study showed that the incidence rate of nontraumatic ONFH was 2.51 cases per 100,000 person-years in the Japanese population.

DOI： 10.1002/art.30484

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Background: The pathology of late-onset Legg-Calve-Perthes disease (LCPD) is similar to that of avascular necrosis of the femoral head in adult and is associated with poorer prognosis of the hip. The optimal treatment for this condition is still controversial. The purpose of this study was to evaluate the long-term clinical results of the transtrochanteric rotational osteotomy for the patients with LCPD onset at more than 9 years of age. Methods: Individuals included 14 hips in 13 cases with the mean age at onset of the disease and operation of 10 years 9 months and 12 years. Average follow-up periods were 12 years. All cases were resistant to the conservative treatments and did not have our indications for varus osteotomy. Clinical results were evaluated using Merle d'Aubigne Postel score and the modified Stulberg criteria. Results: Average Merle d'Aubigne Postel score at the final follow-up was 16.2 points ranging from 12 to 18 points. All patients did not have additional treatment except nail removal. Stulberg class II, III, and IV were obtained in 5, 2, and 7 hips, respectively. More spherical femoral head was obtained in patients with less head involvement and more bone preservation or new bone formation at posterior pillar. Three hips showed slight narrowing of joint space without severe osteoarthritic changes. Conclusions: Transtrochanteric rotational osteotomy is an effective procedure to salvage the hips of the late-onset LCPD. Amount of head involvement, posterior and lateral pillar had influences on the surgical outcomes.

DOI： 10.1097/BPO.0b013e318223b4f3

Language：English   Publishing type：Research paper (scientific journal)  

The pathogenesis of alcohol-induced osteonecrosis remains unclear. The purpose of the present study was to evaluate the morphological changes in bone marrow fat cells and the changes in the serum lipid levels in alcohol-treated rabbits. Fifteen rabbits were randomly assigned into three groups: Four rabbits intragastrically received low-dose alcohol (LDA) (15ml/kg per day) containing 15% ethanol for 4weeks, five rabbits received high-dose alcohol (HDA) (30ml/kg per day) for 4weeks and six rabbits received physiologic saline for 4weeks as a control group. Six weeks after the initial alcohol administration, all rabbits were sacrificed. The mean size of the bone marrow fat cells in rabbits treated with HDA was significantly larger than that in the control group (P=0.0001). Haematologically, the levels of triglycerides and free fatty acids in the rabbits treated with both low-dose and HDA were significantly higher than those in the control group (P=0.001 for both comparisons). The results of this study are that there are lipid metabolism abnormalities, both morphologically and haematologically, after alcohol administration. Also these findings were more apparent in rabbits treated with HDA than those treated with LDA.

DOI： 10.1111/j.1365-2613.2011.00773.x

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

A subchondral insufficiency fracture of the femoral head (SIF) is generally observed in elderly women. In addition, SIF has been reported to occur in young military trainees, which are considered to be due to a fatigue stress fracture. This report reviewed five cases of SIF in young adults without any history of overexertion or antecedent trauma. The clinical findings, time to the initial radiograph, time to the initial magnetic resonance imaging (MRI), and follow-up period were investigated. Radiographs and MRI were obtained in both hips. Bone mineral density and bone scintigram were performed. Measurements of a bone mineral density indicated presence of osteopenia in three patients. MRI disclosed a discontinuous irregular-shaped low-intensity band surrounded by bone marrow edema in all cases. After conservative treatments, one patient's condition resolved, while four patients underwent femoral head collapse resulting in surgical treatment. In these four patients, the diagnosis of SIF was histologically confirmed. In addition, the histological findings showed thin disconnected bone trabeculae, thus indicating the presence of some degree of osteopenia. These patients were considered to demonstrate an insufficiency fracture rather than a fatigue stress fracture based on both clinical findings and histological findings. SIF needs to be considered in patients presenting with hip pain even in young cases.

DOI： 10.1016/j.clinimag.2010.05.005

Language：Japanese  

Language：Japanese  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

In order to investigate the mechanisms of collapse in osteonecrosis of the femoral head, we examined which part of the femoral head was the key point of a collapse and whether a collapsed region was associated with the size of the necrotic lesion. Using 30 consecutive surgically removed femoral heads we retrospectively analysed whole serial cut sections, specimen photographs, specimen radiographs and histological sections. In all of the femoral heads, collapse consistently involved a fracture at the lateral boundary of the necrotic lesion. Histologically, the fractures occurred at the junction between the thickened trabeculae of the reparative zone and the necrotic bone trabeculae. When the medial boundary of the necrotic lesion was located lateral to the fovea of the femoral head, 18 of 19 femoral heads collapsed in the subchondral region. By contrast, when the medial boundary was located medial to the fovea, collapse in the subchondral region was observed in four of 11 femoral heads (p = 0.0011). We found that collapse began at the lateral boundary of the necrotic lesion and that the size of the necrotic lesion seemed to contribute to its distribution.

DOI： 10.1302/0301-620X.93B225476

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s00776-011-0059-x

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

OBJECTIVE. The purpose of this article is to verify the hypothesis that osteonecrosis and subchondral insufficiency fracture of the femoral head can be differentiated on the basis of their appearance on MRI. SUBJECTS AND METHODS. Between May 1998 and February 2009, we reviewed 30 consecutive hips in 30 patients, 60 years old or older at the time of onset of hip pain, with radiologic evidence of subchondral collapse of the femoral head and with both MR images and histologic results available. Both clinical and radiologic appearances were investigated. The patients were divided into two groups according to the shape of low-intensity bands on T1-weighted images. The first group showed concavity of the articular surface, which is characteristic of osteonecrosis, and the second group showed an irregular convexity of the articular surface, which is characteristic of subchondral insufficiency fracture. RESULTS. Sixteen hips (53.3%) showed evidence of osteonecrosis, and 14 (46.7%) showed evidence of subchondral insufficiency fracture, which was consistent with the corresponding histopathologic diagnoses. In all cases of osteonecrosis, the patient had a history of either corticosteroid intake or alcohol abuse. Among patients with subchondral insufficiency fracture, the proportion of women was significantly higher than that among patients with osteonecrosis. A crescent sign (subchondral fracture) was present radiographically in about half of all cases in both groups. CONCLUSION. The results of the present study suggest that the shape of the low-intensity band on MRI is useful for the differentiating subchondral insufficiency fracture from osteonecrosis. In addition, among osteoporotic elderly women without any history of corticosteroid intake or alcohol abuse, a diagnosis of subchondral insufficiency fracture should be considered.

DOI： 10.2214/AJR.09.3271

Language：English   Publishing type：Research paper (scientific journal)  

This study sought to examine the long-term outcomes of transtrochanteric anterior rotational osteotomy (ARO) as treatment for osteonecrosis of the femoral head (ONFH) in patients with systemic lupus erythematosus (SLE). Twenty-one patients (33 hips), aged 20-40 years, underwent ARO between 1980 and 1988. We examined 16 patients (25 hips), a 76% follow-up rate. A Kaplan-Meier curve was used for survivorship analysis. Patients with surviving hips were evaluated by the modified Oxford hip score and Short Form 36 (SF-36). Twelve hips in eight patients had survived at the final follow-up. The average length of hip survival was 24.6 years (range: 20.1-27.2 years). Three patients (six hips) had died of unrelated causes without any subsequent operation. Based on Kaplan-Meier analysis with the endpoint defined as the need for a subsequent operation, the hip survival rate at 25 years was 73.7% (95% confidence interval, ±19.8%). Based on classification by the modified Oxford hip score, five hips were classified as excellent, two hips were good, and the remaining five hips were fair. The average SF-36 summary score for the physical and mental components was 38.7 and 47.2 points, respectively. The physical component summary scores for three patients exceeded the normal level of the Japanese population.

DOI： 10.1177/0961203310361896

Language：English   Publishing type：Research paper (scientific journal)  

We investigated the factors related to the radiological outcome of a transtrochanteric curved varus osteotomy in patients with osteonecrosis of the hip. We reviewed 73 hips in 62 patients with a mean follow-up of 12.4 years (5 to 31.1). There were 28 men and 34 women, with a mean age of 33.3 years (15 to 68) at the time of surgery. The 73 hips were divided into two groups according to their radiological findings: group 1 showed progression of collapse and/or joint-space narrowing; group 2 had neither progressive collapse nor joint-space narrowing. Both of these factors and the radiological outcomes were analysed by a stepwise discriminant analysis. A total of 12 hips were categorised as group 1 and 61 as group 2. Both the post-operative intact ratio and the localisation of the necrotic lesion correlated with the radiological outcome. The cut-off point of the postoperative intact ratio to prevent the progression of collapse was 33.6%, and the cut-off point to prevent both the progression of collapse and joint-space narrowing was 41.9%. The results of this study indicate that a post-operative intact ratio of 33.0% is necessary if a satisfactory outcome is to be achieved after this varus osteotomy.

DOI： 10.1302/0301-620X.92B6.23621

Language：English   Publishing type：Research paper (scientific journal)  

Background: Patients with developmental dysplasia of the hip are prone to the development of degenerative changes in the affected hip. The aim of this study was to evaluate the prevalence, morphological features, and clinical relevance of acetabular retroversion in these patients. Methods: We investigated the version and morphological features of the acetabulum using pelvic radiographs and computed tomography images of ninety-six hips in fifty-nine patients with developmental dysplasia of the hip. A diagnosis of acetabular retroversion was based on the presence of a positive cross-over sign on the pelvic radiograph. Using computed tomography images, we determined the acetabular anteversion angle at various levels in the axial plane. The acetabular sector angle served as an indicator of acetabular coverage of the femoral head. We evaluated the association between acetabular version and the patient's age at the onset of pain. Fifty normal hips were examined as controls. Results: Weobserved acetabular retroversion in 18% (seventeen) of the ninety-six hips in the patients with developmental dysplasia of the hip. The mean acetabular anteversion angle in the hips with acetabular retroversion was significantly smaller, at all levels, than that in the hips with acetabular anteversion; this tendency was more evident at proximal levels. There was significantly less posterior and posterosuperior coverage in the hips with acetabular retroversion than in those with acetabular anteversion, but superior acetabular coverage did not differ between the groups. Multivariate analysis showed that the onset of pain occurred at a significantly earlier age in patients with acetabular retroversion (27.9 years) than in those with acetabular anteversion (40.5 years), regardless of the severity of the dysplasia (p = 0.003). Conclusions: In patients with developmental dysplasia of the hip, acetabular retroversion results from relatively deficient coverage by the posterior portion of the acetabulum. Developmental dysplasia with acetabular retroversion is associated with an earlier onset of pain than is developmental dysplasia with anteversion, suggesting a correlation between deficiency of the posterior acetabular wall and the earlier onset of pain. Level of Evidence: Prognostic Level IV. See Instructions to Authors for a complete description of levels of evidence.

DOI： 10.2106/JBJS.I.00046

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Objective: To investigate the incidence of steroid-induced osteonecrosis (ON) among male and female rabbits. Methods: Forty-seven adult rabbits (male, n = 24; female, n = 23) were injected once intramuscularly into the right gluteus medius muscle with 20 mg/kg of methylprednisolone acetate. Haematological examinations were performed just before and at 1 and 2 weeks after the steroid injection. Two weeks after the injection, both femora and humeri were histopathologically examined for the presence of ON, and the bone marrow fat cells were examined morphologically. Results: Sixteen of 24 male rabbits (66.7%) and 5 of 23 female rabbits (21.7%) developed ON. There was a significant difference in the rate of incidence of ON between male and female rabbits (P = 0.0032). Haematologically, at 1 week after the steroid injection, both the mean low-density lipoprotein (LDL) and the ratio of LDL cholesterol to high-density lipoprotein cholesterol in the male rabbits were significantly higher than those in the female rabbits (P = 0.0001 for both comparisons). The bone marrow fat cells of the male rabbits [61.5 (5.6) μm] were significantly larger than those of the female rabbits [58.9 (3.7) μm; P = 0.0102]. Conclusion: This study indicates that gender may be an important factor in considering the pathogenesis of steroid-induced ON.

DOI： 10.1093/rheumatology/keq044

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A 73-year-old female suffered from right hip pain without any history of antecedent trauma. The initial radiograph showed a slight narrowing of the joint space in the right hip. The patient was treated by non-weight bearing for 5 weeks. Radiographs obtained 3 months after the onset of pain showed the progression of both the joint-space narrowing and subchondral collapse at the superior portion. T1-weighted MR (magnetic resonance) images obtained 3 months after the onset revealed an irregular-shaped lowintensity area just beneath the articular cartilage as well as a low-intensity band, which was concave to the articular surface. A total hip replacement was performed. A histopathological examination revealed fracture callus and granulation tissue in the subchondral area. This subchondral fractured area was surrounded by vascular rich granulation tissue and fibrous tissue, which corresponded to the concave-shaped low-intensity band observed on the T1- weighted image.

DOI： 10.1007/s00256-009-0750-6

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A 53-year-old woman developed a subchondral insufficiency fracture of the right femoral head after undergoing a liver transplantation. Radiographs obtained at her first visit demonstrated a slight subchondral collapse in the superolateral portion of the femoral head. Magnetic resonance imaging (MRI) disclosed an irregular, discontinuous, low-intensity band on the T1-weighted image. After 7 months of conservative treatment, the hip pain and the radiograph abnormalities had both disappeared. On the follow-up T1-weighted MR image obtained 17 months after the onset, the band of low signal intensity was not obvious. A subchondral insufficiency fracture is one of the diagnoses to be considered in patients presenting with hip pain after a liver transplantation.

DOI： 10.1007/s00256-009-0706-x

Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND:: For young patients with osteonecrosis of the femoral head, especially those younger than 20 years, a joint-preserving operation may be one of the surgical treatment options to be considered. We investigated the clinical and radiological results of transtrochanteric anterior rotational osteotomy for the treatment of osteonecrosis of the femoral head in patients 20 years or younger. METHODS:: Between 1976 and 2001, a transtrochanteric anterior rotational osteotomy was performed in 28 hips of 23 patients aged 20years or younger with osteonecrosis of the femoral head. Among them, 27 hips of 22 patients with a minimum follow-up duration of 2years were investigated (follow-up rate, 96.4%). They included 7males and 15 females with a mean age of 16 years at the time of surgery. The mean follow-up period was 14.7 years (range, 2.0-31.7 years). The clinical assessment was made based on the Merle d'Aubigné-Postel score. The postoperative intact ratio, joint-space narrowing, and progression of collapse were all investigated radiographically. RESULTS:: Two (7.4%) of the 27 hips required total hip arthroplasty because of restrictions in the range of motion, whereas the original hip joints in 25 (92.6%) of the 27 hips were preserved at the time of final follow-up. The mean preoperative Merle d'Aubigné-Postel score was 10.4 points, which improved to 15.9 points at the final follow-up (P < 0.0001). The mean postoperative intact ratio was 49.8% (range, 30-100). Five (18.5%) of the 27 hips had a progressive joint-space narrowing, but progression of the collapse was not observed in anyhips. CONCLUSIONS:: Transtrochanteric anterior rotational osteotomy appears to be a useful joint-preserving operation for patients younger than 20years.

DOI： 10.1097/BPO.0b013e31819bc746

Language：English   Publishing type：Research paper (scientific journal)  

Objective. The relationship between dose of corticosteroids and the prevalence of osteonecrosis (ON) has not been established. We examined the dose effects of corticosteroids on the development of ON in a rabbit model. Methods. Rabbits were injected once intramuscularly with 1 (12 rabbits), 5 (12 rabbits), 20 (20 rabbits), and 40 (25 rabbits) mg/kg of methylprednisolone acetate (MPSL) into the right gluteus medius muscle. Four weeks after the MPSL injection, the proximal and distal parts of both the femora and humeri were histopathologically examined for the presence of ON. Hematological examinations were performed before and after the corticosteroid injection. Results. In rabbits with 1, 5, 20, and 40 mg/kg MPSL, the incidence of ON was 0, 42%, 70%, and 96%, respectively. The dose of MPSL showed a significant association with the incidence of ON. Histologically, reparative tissues around the ON sites were observed in the rabbits with 5 mg/kg MPSL, but not observed in rabbits with 20 and 40 mg/kg MPSL. On hematological examination, hyperlipidemia and thrombocytopenia were most apparent in the rabbits receiving 40 mg/kg MPSL. Conclusion. The study suggested that the dose of corticosteroids plays an important role in the development of ON in rabbits. The repair process was also found to be influenced by the dose of corticosteroids. Corticosteroid-induced hyperlipidemia and thrombocytopenia seemed to be associated with the incidence of ON.

DOI： 10.3899/jrheum.080324

Language：English   Publishing type：Research paper (scientific journal)  

Objective. Both abnormal lipid metabolisms and coagulopathy have been suggested to be associated with the development of steroid-induced osteonecrosis (ON). We examined plasma risk factors for development of steroid-induced ON in rabbits after prophylaxis with a lipid-lowering agent and/or an anticoagulant. Methods. Seventy adult male rabbits were injected intramuscularly once with 20 mg/kg methylprednisolone acetate. Fifty-five rabbits received prophylaxis with probucol (a lipid-lowering agent; n = 20) or warfarin (an anticoagulant; n = 14) or both (n = 21). Probucol and warfarin were administered beginning 1 to 2 weeks prior to steroid injection. Two weeks after steroid injection, the bilateral femora and humeri were examined histopathologically for the presence of ON. Based on a logistic regression model, laboratory variables before steroid injection were assessed to determine whether they demonstrated any association with the risk of ON. Results. Twenty-one rabbits developed ON. In the univariate analyses, significant positive associations were observed between plasma concentrations of triglyceride and low-density lipoprotein and the risk of development of ON. In the multivariate model, only the plasma triglyceride level suggested a positive association. Even after adjusting for probucol and warfarin use, the plasma triglyceride level was still suggested to be a predictor for development of ON. Rabbits with higher baseline triglyceride levels had a more pronounced triglyceride increase in their response to steroids. Conclusion. Our study suggests that, after prophylaxis with probucol and/or warfarin, plasma triglyceride level is associated with the development of steroid-induced ON in rabbits.

DOI： 10.3899/jrheum.080416

Language：English   Publishing type：Research paper (scientific journal)  

The present study examined the effects of tacrolimus (FK506) on the development of osteonecrosis in rabbits. In Experiment A, rabbits were given FK506, and also given a single dose of steroid. Control rabbits were given the same dose of steroid only. In Experiment B, rabbits were given FK506 and a reduced dose of steroid. The results showed that addition of FK506 did not change the number of rabbits with osteonecrosis when an identical steroid dose was given. When the steroid dose was reduced, the osteonecrosis incidence significantly decreased (p < 0.01). These results suggest that the clinically reported decrease in the osteonecrosis incidence following the introduction of FK506 is most likely attributable to the lower doses of steroids.

DOI： 10.1080/08923970701812647

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Several animal and human studies suggest pharmacological approaches may prevent steroid-induced osteonecrosis (ON). We asked whether the newly developed 3-hydroxymethyl-3-glutaryl-CoA (HMG-CoA) reductase inhibitor, pitavastatin, could prevent steroid-induced ON in rabbits. We injected 65 adult male Japanese white rabbits once with 20 mg/kg of methylprednisolone acetate into the right gluteus medius muscle. The rabbits were divided into two groups; one group of 35 rabbits received pitavastatins (PS), and the other group of 30 rabbits received no prophylaxis (CTR). Hematological examinations were performed just before the steroid injection (0 weeks) and at 1 and 2 weeks after steroid injection; both the femora and the humeri were histologically examined 2 weeks postinjection. The incidence of histologic changes consistent with early ON in the PS group (13 of 35; 37%) was lower in comparison to the CTR group (21 of 30; 70%). The size of the bone marrow fat cells in the PS group (56.6 ± 10 μm) was smaller than those in the CTR group (60 ± 4 μm). The data suggest pitavastatin has the potential to lower the incidence of steroid-induced ON in rabbits.

DOI： 10.1007/s11999-008-0189-4

Language：English   Publishing type：Research paper (scientific journal)  

We describe that high-dose methylprednisolone (20 mg/kg) can induce multifocal osteonecrosis (ON) in conjunction with thrombocytopenia, hypofibrinogenemia, and hyperlipemia. Detailed clinical and laboratory evaluations of coagulation system are recommended in those patients who develop manifestations of an abnormal lipid metabolism shortly after high-dose corticosteroid therapy. Moreover, we investigated the effects of the combination treatment with an anticoagulant (warfarin) plus a lipid-lowering agent (probucol) on prevention of steroid-induced osteonecrosis (ON) in this animal model. The incidence of ON in warfarin plus probucol (5%) was significantly lower than that observed in the control group (70%) (p <0.0001). Our results experimentally showed that the combined use of an anticoagulant and a lipid-lowering agent helps prevent steroid-induced ON in rabbits.

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Background: Osteonecrosis (ON) of the femoral head is a serious complication in patients who have undergone organ transplantation. Introduction of cyclosporin A has resulted in lower-dosage steroid treatment and a decrease in the occurrence of ON. We examined the effect of cyclosporin A on the development of ON in rabbits. Methods: In experiment A, rabbits were given cyclosporin A and 20 mg/kg methylprednisolone acetate. The control group was given 20 mg/kg methylprednisolone acetate only. Experiment B was then performed to mimic the clinical situation in which the use of cyclosporin A and lower steroid doses resulted in a decrease in occurrence of ON. In Experiment C, the effects of treatment with cyclosporin A only on development of ON were examined. 4 weeks after injection, bilateral femora and humeri were examined histopathologically for ON. Results: Cyclosporin A increased the incidence of ON in rabbits when given in combination with steroid (p = 0.04). No ON lesions were observed in rabbits treated with cyclosporin A alone. Interpretation: Our findings suggest that the clinically reported reduction in occurrence of ON following the use of cyclosporin A is probably attributable to the lower steroid doses used. Copyright

DOI： 10.1080/17453670610013042

Language：English   Publishing type：Research paper (scientific journal)  

We investigated the outcome of the contralateral hip in patients with rapidly destructive arthrosis of the hip after total hip arthroplasty. Twenty-four patients were included, and the mean duration of radiographic follow-up was 7.0 years (range, 3.8-17.8 years). To assess the capable parameters for predicting the development of osteoarthritis, we evaluated the receiver operating characteristic curves. Three (12.5%) of 24 patients developed osteoarthritis and underwent total hip arthroplasty within 3.8 to 6.5 years. In these 3 patients, both the acetabular-head index and the center-edge angle were significantly lower than those in patients without osteoarthritis (P < .005). Based on the receiver operating characteristic curves, both an acetabular-head index of less than 72% and a center-edge angle of less than 16° were considered to be associated with the development of osteoarthritis.

DOI： 10.1016/j.arth.2005.08.007

Language：English   Publishing type：Research paper (scientific journal)  

We documented a case of rapidly destructive arthrosis of the hip joint (RDA), in whom abnormal findings were observed not only in the femoral head but also in the acetabulum on magnetic resonance images (MRI) in the early stage. Radiographs made 1 month after the onset of pain showed a slight narrowing of the joint space. MRI obtained 2 months after the onset detected small foci of low signal intensity in the subchondral area of the femoral head on the T1-weighted images, and a linear pattern of high signal intensity in the lateral side of the acetabulum on the T2-weighted images. During the 17-month follow-up period, this case eventually underwent massive destruction of the femoral head as well as the acetabulum.

DOI： 10.1007/s00402-005-0053-x

Language：English   Publishing type：Research paper (scientific journal)  

Objectives. Osteonecrosis (ON) of the femoral head is a devastating complication occurring in patients receiving corticosteroid treatment. This study examined the effect of three corticosteroids on the development of ON in rabbits. Methods. Thirty-nine rabbits were injected once intramuscularly with either 25 mg/kg prednisolone sodium succinate (PSL; 13 rabbits), 20 mg/kg methylprednisolone acetate (MPSL; 13 rabbits) or 20 mg/kg triamcinolone acetonide (TR; 13 rabbits). Four weeks after corticosteroid injection, the bilateral femora and humeri were examined histopathologically for the presence of ON. Haematological examinations were performed before and after corticosteroid injection. Results. MPSL treatment (17/26 proximal femora, 65%) significantly increased ON incidence in the proximal femora compared with the levels seen after TR (4/26, 15%) or PSL (3/26, 12%) treatment (P < 0.01). Although not significantly increased in comparison with rabbits receiving PSL treatment (1/26 proximal humeri, 4%), ON incidence within the proximal humeri was significantly increased in MPSL-treated rabbits (6/26, 23%) in comparison with those seen in rabbits receiving TR (0/26, 0%) treatment (P < 0.05). Serum levels of cholesterol, triglyceride and free fatty acid were significantly higher 1, 2 and 4 weeks after corticosteroid treatment in rabbits treated with MPSL relative to rabbits receiving TR and rabbits with PSL treatment (P < 0.05). Conclusions. MPSL treatment significantly increased ON incidence in rabbits over levels seen after TR or PSL treatment.

DOI： 10.1093/rheumatology/keh505

Language：English   Publishing type：Research paper (scientific journal)  

Some animal studies and magnetic resonance imaging studies suggest that there may exist a relationship between abnormal lipid metabolisms and osteonecrosis. The purpose of this study was to examine the size of bone marrow fat cells in the early osteonecrosis femoral head using autopsy specimens. We compared the size of bone marrow fat cells in the viable areas in the following three autopsy groups: the early osteonecrosis group (4 femoral heads); the steroid-administered group (without osteonecrosis) (n = 10), and the normal group (n = 19). In addition, after adjusting for age and sex, the size of bone marrow fat cells was compared using multiple regression analysis. The size of bone marrow fat cells was significantly larger in the early osteonecrosis group (84.7±5.5 μm) than in both the steroid-administered group (75.3±4.3 μm) and the normal group (76.3±4.9 μm) (p < 0.01 and p < 0.05, respectively). After adjusting for age and sex, the size of bone marrow fat cells in the early osteonecrosis group was significantly larger as compared with the other groups. This study suggests that in steroid-induced osteonecrosis, the size of bone marrow fat cells increases significantly at an early stage.

DOI： 10.1016/j.prp.2004.10.003

Language：English   Publishing type：Research paper (scientific journal)  

Objective. To investigate the effects of combination treatment with an anticoagulant (warfarin) plus a lipid-lowering agent (probucol) on the prevention of steroid-induced osteonecrosis (ON) in rabbits. Methods. Adult male Japanese white rabbits were injected once intramuscularly with 20 mg/kg of methylprednisolone acetate into the right gluteus medius muscle. The rabbits were then divided into 4 groups and treated as follows: one group received warfarin plus probucol (WP; n = 25), one received probucol alone (PA; n = 30), one received warfarin alone (WA; n = 26), and one received no treatment (nonprophylactic [NP]; n = 20). Two weeks after the steroid injection, the femora anil humeri were examined hisiopathologically for the presence of ON. The sizes of the bone marrow fat cells were examined morphologically. Hmatologic examinations were performed before and after the steroid injection. Results. The incidence of ON in the WP group (5%) was significantly lower than that observed in the NP group (70%). While the incidence rates of ON in the PA (38%) and WA (33%) groups were also significantly lower than that in the NP group, they were significantly higher than that observed in the WP group. The sizes of the bone marrow fat cells in both the WP (53.5 ± 4.1 μm) and the PA (52.0 ± 5.0 μm) groups were significantly smaller than those in the NP group (60.0 ± 4.0 μm). We also observed a prolongation of the prothrombin time and a reduction in the plasma lipid levels in the WP group during the study. Conclusion. This study experimentally confirmed that the combined use of an anticoagulant and a lipid-lowering agent helps prevent steroid-induced ON in rabbits.

DOI： 10.1002/art.20517

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2106/00004623-200303000-00036

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2106/00004623-200207000-00018

Event date： 2023.10

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：福岡   Country：Japan  

Event date： 2023.10

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：福岡   Country：Japan  

Event date： 2023.10

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：つくば   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：web   Country：Japan  

Event date： 2022.10

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：山形   Country：Japan  

Event date： 2022.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：web   Country：Japan  

Event date： 2022.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡   Country：Japan  

Event date： 2022.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡   Country：Japan  

Event date： 2021.11

Language：Japanese  

Venue：web   Country：Japan  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：web   Country：Japan  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：web   Country：Japan  

Event date： 2020.10

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：三重   Country：Japan  

Event date： 2019.10

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：宮崎   Country：Japan  

Event date： 2019.10

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：横浜   Country：Japan  

Event date： 2018.5

Language：Japanese  

Country：Japan  

Event date： 2018.5

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Country：Japan  

Event date： 2018.3

Language：Japanese  

Country：United States  

Event date： 2018.3

Language：English  

Country：United States  

Event date： 2018.3

Language：English  

Country：United States  

Event date： 2018.3

Language：Japanese  

Country：United States  

Event date： 2018.3

Language：English  

Country：United States  

Event date： 2018.2

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：北九州   Country：Japan  

Event date： 2017.10 - 2018.10

Language：English  

Country：Germany  

Event date： 2017.10

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：東京   Country：Japan  

Event date： 2017.3

Language：English   Presentation type：Oral presentation (general)  

Venue：San Diego   Country：United States  

Event date： 2017.3

Language：English   Presentation type：Oral presentation (general)  

Venue：San Diego   Country：United States  

Event date： 2017.3

Language：English   Presentation type：Oral presentation (general)  

Venue：San Diego   Country：United States  

Event date： 2017.3

Language：English   Presentation type：Oral presentation (general)  

Venue：San Diego   Country：United States  

Event date： 2017.3

Language：English   Presentation type：Oral presentation (general)  

Venue：San Diego   Country：United States  

Event date： 2016.11

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：大分   Country：Japan  

Event date： 2016.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：北九州市   Country：Japan  

Event date： 2015.5

Language：Japanese  

Venue：神戸   Country：Japan  

Event date： 2015.4

Language：English  

Venue：Chiayi, Taiwan   Country：Taiwan, Province of China  

Event date： 2014.10 - 2014.11

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：東京   Country：Japan  

Event date： 2014.6

Language：Japanese  

Venue：福岡   Country：Japan  

Event date： 2014.5

Language：Japanese  

Venue：神戸   Country：Japan  

Event date： 2013.11

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：広島   Country：Japan  

Event date： 2013.5

Language：Japanese  

Venue：広島市   Country：Japan  

Event date： 2013.3

Language：English  

Venue：Chicago   Country：United States  

Event date： 2012.12

Language：Japanese  

Venue：新潟   Country：Japan  

Event date： 2012.5

Venue：京都市   Country：Japan  

Event date： 2012.1

Venue：Brussels   Country：Belgium  

Event date： 2011.12

Venue：福岡   Country：Japan  

Event date： 2011.10

Presentation type：Symposium, workshop panel (public)  

Venue：鹿児島   Country：Japan  

Event date： 2011.10

Venue：鹿児島   Country：Japan  

Event date： 2011.5

Venue：横浜   Country：Japan  

Event date： 2011.1

Venue：Long Beach   Country：United States  

Event date： 2011.1

Venue：福岡   Country：Japan  

Event date： 2010.10

Venue：京都   Country：Japan  

Dose effects of corticosteroidson the development of osteonecrosis in rabbits

Event date： 2010.10

Venue：福岡   Country：Japan  

Morphological Analysis of Collapsed Regions in Osteonecrosis of the Femoral Head

Event date： 2010.7

Venue：福岡   Country：Japan  

Event date： 2010.5

Country：Japan  

Event date： 2010.4

Venue：神戸   Country：Japan  

Long-term Outcome of Transtrochanteric Anterior Rotational Osteotomy
for Osteonecrosis of the Femoral Head in Patients with Systemic Lupus Erythematosus

Language：Japanese  

Language：Japanese  

Language：Japanese  

Language：Japanese  

Language：Japanese  

Language：Japanese  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publisher：(株)メジカルビュー社  

＜文献概要＞大腿骨頭回転骨切り術後の大腿骨近位部は,解剖学的形態が通常とはまったく異なっており,骨切り既往のない人工股関節全置換術(total hip arthroplasty;THA)と比べると手術の難易度が高くなる。手術では骨切り後の特徴を考慮して処置を行うことが肝要であり,ステムの設置位置不良の原因となる骨癒合部の硬化骨を切除すること,屈曲内旋時にインピンジメントの原因となる転子部前方に張り出した骨や肥厚変性した前方関節包を切除すること,および意図的内反による脚短縮に対する脚長補正を適切に行うこと,が重要である。以上の点を踏まえて施行されたTHAの成績は,手術時間の延長や術中出血量の増加はあるものの,通常のTHAと変わらぬ成績が得られることが報告されている。

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Internal/External technical report, pre-print, etc.  

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：5

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：2

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：3

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：3