Life Course Epidemiology of Hip Osteoarthritis in Japan: A Multicenter, Cross-Sectional Study.

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.

Error of intraoperative measurement of stem anteversion is decreased by measuring in neutral hip position during total hip arthroplasty.

BACKGROUND: Intraoperative stem anteversion, which is the angle between the lower leg axis and the trial-stem axis with hip flexion and adduction, is generally evaluated by the surgeon's visual estimation during total hip arthroplasty (THA). However, the conventional approach can be influenced by knee osteoarthritis or uncertain surgeon's observation point. Therefore, we developed a new method for measuring the stem anteversion angle in the neutral hip position using an original rod attached to the trial-stem perpendicular to the long axis and parallel to the stem neck. This study aimed to assess the accuracy of our method in comparison with the conventional method of measuring intraoperative stem anteversion angle. METHODS: We measured the intraoperative stem anteversion angle in consecutive 106 hips of 106 patients who underwent cementless primary THA with a tapered wedge stem. Absolute error in the stem anteversion angle was expressed as the difference between intraoperative (common vs. neutral hip positions) and postoperative computed tomography measurements, i.e., true stem anteversion. Additionally, we investigated the factors affecting these errors. RESULTS: The absolute error of measurement was significantly smaller in the neutral hip position than in the common position (3.0° ± 2.5° vs. 8.0° ± 3.9°; p < 0.0001). The factor associated with the error was advanced knee osteoarthritis in the common position, whereas it was not statistically significant in the neutral hip position. CONCLUSIONS: This study suggests that the error in the intraoperative measurement of stem anteversion is decreased by measuring in the neutral hip position during THA.

Spherical Periacetabular Osteotomy.

Various techniques for periacetabular osteotomy have been reported to prevent the progression of osteoarthritis in dysplastic hips1-5. Bernese periacetabular osteotomy, which involves the use of an anterior approach, is widely performed throughout the world because it offers preservation of the blood supply to the bone fragment and lateral pelvic muscles. However, Bernese periacetabular osteotomy has potential complications, such as nonunion at the osteotomy site, postoperative fracture, nonunion of the pubis and ischium, and damage to the main trunk of the obturator artery. Spherical periacetabular osteotomy (SPO) has been developed to resolve some of disadvantages of Bernese periacetabular osteotomy6. Although SPO involves some technical difficulty, the procedure is safe when performed with use of appropriate preoperative 3-dimensional planning and surgical technique. Description: Preoperative 3-dimensional planning is utilized to decide the radius of the curved osteotome, locations of the reference points for the osteotomy line, and depth of the bone groove at the teardrop area. The pelvic positioning is arranged fluoroscopically to match the neutral position based on preoperative planning. A 7-cm incision is made along the medial margin of the iliac crest. An anterior iliac crest osteotomy of 4.5 cm (length) × 1 cm (medial wedge-shaped) is performed. The operative field is maintained with aluminum retractors. The osteotomy line is completed by connecting the preoperatively planned reference points on the inner cortex of the ilium. The bone groove is made along the osteotomy line with use of a high-speed burr. A blunt osteotome is inserted into the bone groove at the teardrop area until it reaches the preoperatively planned depth. The blunt osteotome makes a pathway for the curved osteotome without breaking the quadrilateral surface (QLS) or perforating the hip joint. The special curved osteotome is inserted manually until it reaches the bottom of the groove, and the posterior cortex is cut. After the top of the teardrop is divided fluoroscopically, the anterior ischial cortex is osteotomized with a sharpened spiked Cobb elevator at the infracotyloid groove. An angled curved osteotome is used for the osteotomy of the superior area of the teardrop area. The bone fragment is rotated with a spreader and an angled retractor, and fixed with 2 absorbable screws. Beta-tricalcium phosphate blocks are inserted into the bone gap. The osteotomized wedge-shaped iliac bone is repositioned and fixed. Alternatives: Alternatives include the Bernese periacetabular osteotomy, rotational acetabular osteotomy, and triple innominate osteotomy. Rationale: Bernese periacetabular osteotomy utilizes an anterior approach, cuts into the QLS, and preserves the posterior column. In contrast, SPO preserves the QLS and does not cut the pubis. These features of SPO have some advantages. The large osteotomized surface is advantageous for osseous fusion, and preserving the QLS and pubis protects the trunk of the obturator artery. Furthermore, the preservation of the connection between the ilium, ischium, and pubis in SPO maintains a more stable pelvic ring than in Bernese periacetabular osteotomy. The osteotomy line is arranged to prevent leg shortening caused by thin medial bone stock of the bone fragment. Although splitting the teardrop area in SPO is somewhat technically difficult, particularly in cases with a thin teardrop, it can be safely done with use of preoperative 3-dimensional planning and appropriate surgical technique.In addition, the use of our medial wedge-shaped osteotomy at the iliac crest has 2 advantages: protection of the lateral femoral cutaneous nerve and preservation of the attachment of the tensor fascia latae muscle. Expected Outcomes: The advantages of SPO are a stable pelvic ring postoperatively, reduced risk of nonunion at the osteotomy site, no risk to the trunk of the obturator artery, preservation of the blood supply to the bone fragment, a small incision, and early muscle recovery. Important Tips: Preoperative 3-dimensional planning of the osteotomy design is essential.The special curved osteotomes are designed so that osteotomy of the posterior cortex is completed when the handles are perpendicular to the pelvis.The special curved osteotomes are made with a radius of either 50 or 60 mm, which are the most suitable sizes for the Japanese population. Larger-diameter osteotomes may be required for different races.As the rotated bone fragment is relatively small, it is difficult to obtain rigid fixation of the osteotomy site. Hence, the fragment can move slightly in the early phase after surgery. Careful rehabilitation is needed. Acronyms and Abbreviations: AIIS = anterior inferior iliac spineASIS = anterior superior iliac spineLFCN = lateral femoral cutaneous nerveG.T. = greater trochanterK-wire = Kirschner wireBeta (ß)-TCP = beta-tricalcium phosphate.

"Anterior-shift sign": a novel MRI finding of adult hip dysplasia.

INTRODUCTION: In adult hip dysplasia, methods for direct evaluation of hip instability have not been established. The present study aimed to determine findings suggestive of hip instability on magnetic resonance imaging (MRI) and to evaluate their correlations with clinical and radiological factors. MATERIALS AND METHODS: We retrospectively reviewed 72 hips in 50 patients with hip dysplasia (45 females, 5 males; mean age: 40.0 years; age range: 15-59 years; Kellgren-Lawrence grade: ≤ 2). Hip dysplasia was defined as a lateral center-edge angle < 25°. Among the hips, 50 had pain (symptomatic dysplasia group) and 22 were asymptomatic (asymptomatic dysplasia group). As controls, 12 normal hips in 12 patients who underwent screening for asymptomatic osteonecrosis of the femoral head by MRI were evaluated. Using an oblique axial view on fat-suppressed T2-weighted images, we evaluated the presence of a gap between the posterior part of the femoral head and the corresponding acetabular surface, indicating hip instability (anterior-shift sign). The correlations of anterior-shift sign with clinical and radiographical factors were examined. RESULTS: Anterior-shift sign was observed in 92.0% in the symptomatic dysplasia group, 9.1% in the asymptomatic dysplasia group, and 0% in the control group. In adult hip dysplasia, cases with anterior-shift sign had significantly more pain and labrum tear occurrence than cases without anterior-shift sign. Anterior-shift sign was correlated with Kellgren-Lawrence grade and degree of acetabular coverage. CONCLUSIONS: This study suggested that hip instability can be observed as the anterior-shift sign on MRI. This sign is useful when considering indications for periacetabular osteotomy in adult hip dysplasia.

Distribution of Femoral Head Subchondral Fracture Site Relates to Contact Pressures, Age, and Acetabular Structure.

OBJECTIVE. Nontraumatic subchondral fracture of the femoral head (FH) is often seen in elderly patients with osteoporosis and acetabular dysplasia. Although this injury can also occur in young people, even those without osteoporosis, it remains unclear who is at risk. We examined the acetabular structure and sites of subchondral fracture of the FH in young patients compared with those in middle-aged and older patients. MATERIALS AND METHODS. Forty-eight hips with nontraumatic subchondral fracture of the FH were divided into two groups according to patient age: young (< 40 years) and middle-aged and older (≥ 40 years). Dysplasia and retroversion were defined as a lateral center-edge angle of < 20° and crossover sign on anterosuperior radiographs, respectively. Locations and extents of fracture were evaluated by measuring the edge location of low-signal-intensity bands on coronal T1-weighted MR images. Stress distribution on subchondral bone in young patients was evaluated in contralateral unaffected hips with the same acetabular structure using finite element modeling based on CT. RESULTS. Twelve hips were in young patients and 36 were in middle-aged and older patients. Hips in young patients showed retroversion in 41.7%, whereas those in middle-aged and older patients had dysplasia in 38.9%. Young patients had larger mediolateral fractures; fractures in middle-aged and older patients were laterally located. Anterosuperior fractures were seen in both groups. Contact stress in patients with retroversion was mainly distributed on the mediolateral and superior sides but was concentrated laterally and superiorly in one patient with dysplasia. CONCLUSION. Mediolateral and anterosuperior fractures and stress distribution by retroversion were commonly observed in young patients, suggesting partial involvement of retroversion in the mechanism of injury of nontraumatic subchondral fractures of the FH in young patients.

Effect of a Specific Questionnaire Sheet on Subclassification of Osteonecrosis of the Femoral Head.

BACKGROUND This study examined whether use of a specific questionnaire sheet for nontraumatic osteonecrosis of the femoral head (ONFH) could affect the subclassification of ONFH compared with a conventional medical interview. MATERIAL AND METHODS Study participants consisted of 400 patients with ONFH who visited our hospital between February 2011 and March 2015. Data on history of systemic steroid therapy and habitual alcohol intake were obtained during a conventional medical interview at the first visit and were re-evaluated using a specific questionnaire sheet at another visit. Patients were subclassified into 4 groups: steroid-associated, alcohol-associated, steroid/alcohol-associated, or idiopathic ONFH. RESULTS Use of the specific questionnaire sheet resulted in a 4.0% increase in the proportion of patients with a history of systemic steroid therapy, from 57.3% (n=229) to 61.3% (n=245), and a 14.3% increase for history of habitual alcohol intake, from 35.0% (n=140) to 49.3% (n=197). The proportion of patients with steroid/alcohol-associated ONFH increased from 2.5% (n=10) to 17.8% (n=71), while the proportion in the other 3 groups decreased: steroid-associated ONFH from 54.8% (n=219) to 43.5% (n=174); alcohol-associated ONFH from 32.5% (n=130) to 31.5% (n=126); and idiopathic ONFH from 10.2% (n=41) to 7.2% (n=29). Ninety-six patients (24.0%) were classified into a different subgroup based on the specific questionnaire sheet. CONCLUSIONS The use of a specific questionnaire sheet can change the distribution of ONFH subclassifications compared with use of a conventional medical history interview. Use of a specific questionnaire sheet can allow for more detailed self-reporting regarding potential causative factors for nontraumatic ONFH, especially habitual alcohol intake.

Effects of sclerotic changes on stress concentration in early-stage osteonecrosis: A patient-specific, 3D finite element analysis.

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. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3169-3177, 2018.

Computed tomography findings of subchondral insufficiency fractures of the femoral head.

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.

The effect of the anterior boundary of necrotic lesion on the occurrence of collapse in osteonecrosis of the femoral head.

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.

Risk factor analysis for postoperative complications requiring revision surgery after transtrochanteric rotational osteotomy for osteonecrosis of the femoral head.

BACKGROUND: This study investigated the risk factors for postoperative complications requiring revision surgery within 3 years after transtrochanteric rotational osteotomy (TRO) for osteonecrosis of the femoral head (ONFH). METHODS: We reviewed 127 patients (147 hips) who underwent TRO (anterior or posterior rotational osteotomy) for ONFH between January 2002 and December 2014. Two patients were lost to follow-up, and five patients with progression of femoral head collapse requiring a salvage procedure such as total hip arthroplasty within 3 years after TRO were excluded. The better hip in patients treated bilaterally was also excluded (n = 20) to avoid duplication of patient demographics, leaving 120 hips (120 patients) for the analysis. We reviewed the medical records of each patient to screen for postoperative complications that required revision surgery within 3 years after surgery, recording the patient's age, sex, body mass index, surgical side, condition of the contralateral hip, previous alcohol intake, previous alcohol abuse, previous corticosteroid use, perioperative corticosteroid use, smoking status, preoperative stage and type of ONFH, preoperative activity level, and preoperative and final follow-up Japanese Orthopaedic Association scores. Differences between cases with and without complications were analyzed. RESULTS: Eleven (9.2%) cases showed postoperative complications that required revision surgery. The most common complication was deep infection (n = 5), followed by nonunion of the greater trochanter (n = 3), nonunion of the intertrochanteric osteotomy site (n = 2), and femoral head fracture (n = 1). The multivariate analysis showed an independent association between previous alcohol abuse and postoperative complications (odds ratio, 13.5). CONCLUSION: A correlation might exist between alcohol abuse and complications following a TRO procedure.

Use of a long distally fixed intramedullary stem to treat a periprosthetic femoral fracture following total hip arthroplasty using a thrust plate hip prosthesis: A case report.

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.

Effect of collapse on the deformity of the femoral head-neck junction in osteonecrosis of the femoral head.

INTRODUCTION: The purpose of this study was to morphologically assess the effect of collapse on the deformity of the femoral head-neck junction in patients with nontraumatic osteonecrosis of the femoral head (ONFH). MATERIALS AND METHODS: From January 2005 through March 2016, magnetic resonance (MR) imaging including the oblique view was repeatedly performed before and after collapse in 24 hips of patients with ONFH (16 men, 8 women; mean age 43 years; range 23-68 years), that were the subjects of this study. The interval of MR imaging before and after collapse was 8.0 months (range 1-32 months). In addition, 82 asymptomatic hips in patients without ONFH as identified by MR imaging taken at the same duration were used as controls. The oblique MR image was used to measure the radiological parameters of the femoral head-neck junction, including the α-angle and head-neck offset ratio (HNOR). RESULTS: The α-angle and HNOR after collapse (58.3° ± 10.0° and 0.138 ± 0.033, respectively) indicated significantly decreased anterior femoral head-neck offset compared with those before collapse (46.2° ± 5.7° and 0.178 ± 0.018, respectively; p < 0.0001). These parameters had a positive association with the depth of femoral head collapse (p < 0.0001 and p < 0.01, respectively). However, there were no significant differences in either the α-angle or HNOR between hips with ONFH before collapse and hips without ONFH. CONCLUSIONS: This study demonstrated that the decreased femoral head-neck offset observed in patients with ONFH was a consequence of collapse.

Degeneration of articular cartilage in osteonecrosis of the femoral head begins at the necrotic region after collapse: a preliminary study using T1 rho MRI.

OBJECTIVE: The purpose of this study is to evaluate the role of collapse on the degeneration of articular cartilage in patients with osteonecrosis of the femoral head (ONFH). MATERIALS AND METHODS: Sixteen hips in 12 patients (four men, eight women; mean age, 34.8 years) with a history of systemic corticosteroid treatment were studied using T1 rho magnetic resonance imaging (MRI). Six hips had collapsed ONFH, five had non-collapsed ONFH, and five had no osteonecrosis (controls). Using oblique coronal images, we divided the articular surface of necrotic femoral heads into a region just above the necrotic bone (necrotic zone) and another above the living bone (living zone). T1 rho value was evaluated for each zone. RESULTS: The mean T1 rho value in the necrotic zone was significantly higher in the collapsed ONFH group (48.4 ± 2.7 ms) than in the non-collapsed ONFH group (41.0 ± 0.9 ms). In the collapsed ONFH group, the mean T1 rho value was significantly higher in the necrotic zone (48.4 ± 2.7 ms) than in the living zone (43.5 ± 2.5 ms). In the non-collapsed ONFH group, there was no significant difference between the mean T1 rho values of the necrotic and living zones. In the collapsed ONFH group, the mean T1 rho value of the necrotic zone and the interval from pain onset to the MRI examination were positively correlated. CONCLUSIONS: The current T1 rho MRI study suggested that the degeneration of articular cartilage in ONFH begins at the necrotic region after collapse.

Favorable Clinical and Radiographic Results of Transtrochanteric Anterior Rotational Osteotomy for Collapsed Subchondral Insufficiency Fracture of the Femoral Head in Young Adults.

BACKGROUND: Subchondral insufficiency fracture of the femoral head (SIF) occurs infrequently in young adults. As the collapsed SIF lesion is usually located at the anterior portion of the femoral head, young adults with SIF are considered to be candidates for transtrochanteric anterior rotational osteotomy, similar to patients with osteonecrosis of the femoral head (ON). In the present study, we assessed the clinical and radiographic results of anterior rotational osteotomy for the treatment of SIF as compared with ON. METHODS: We retrospectively reviewed 28 consecutive patients who underwent anterior rotational osteotomy for the treatment of unilateral SIF (7 patients) or unilateral ON (21 patients). The mean duration of follow-up was 3.7 years (range, 2.0 to 6.2 years). Clinical and radiographic assessments were performed with use of the Harris hip score (HHS), sequential radiographs, and single-photon emission computed tomography/computed tomography (SPECT/CT) with 99mTc-hydroxymethylene diphosphonate performed 5 weeks after surgery. RESULTS: The mean HHS (and standard deviation) in the SIF group improved significantly from 51.6 ± 11.7 preoperatively to 91.9 ± 7.1 at 1 year after surgery and to 96.9 ± 3.8 at the time of the latest follow-up (p = 0.0010 and 0.0002, respectively). Similarly, the mean HHS in the ON group improved significantly from 52.4 ± 13.7 preoperatively to 80.7 ± 10.0 at 1 year after surgery and to 88.2 ± 12.6 at the time of the latest follow-up (p < 0.0001 for both). The HHS was significantly higher in the SIF group than in the ON group at 1 year after surgery (p = 0.019), but there was no significant difference between the groups at the time of the latest follow-up (p = 0.10). A postoperative intact ratio (calculated as the intact area of the femoral head divided by the weight-bearing area of the acetabulum on an anteroposterior radiograph) of >80% was achieved in association with smaller femoral neck-shaft varus angles in the SIF group (10.0° ± 4.2°) as compared with the ON group (15.3° ± 8.2°). Postoperative progression of collapse at the anteriorly rotated subchondral lesion was observed in 5 patients (23.8%) in the ON group but no patients in the SIF group. SPECT/CT images showed that rate of increased tracer uptake at the collapsed lesions in the SIF group was significantly higher than that in the ON group (p < 0.0001). CONCLUSIONS: The present study suggested that the absence of progression of collapse and a sufficient postoperative intact ratio without the need for marked varus realignment may be associated with favorable results following anterior rotational osteotomy for the treatment of SIF in young adults. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Osteonecrosis of the femoral head associated with pigmented villonodular synovitis.

A 23-year-old Japanese woman with no history of corticosteroid intake or alcohol abuse presented with a 10-month history of left hip pain without any antecedent trauma. An anteroposterior radiograph performed 10 months after the onset of pain showed slight joint space narrowing and bone erosions surrounded by sclerotic lesions in both the acetabular roof and femoral neck. Magnetic resonance images of the left hip showed a feature of osteonecrosis of the femoral head and a mass with villus proliferation extending from the posterior intertrochanteric area to the anteromedial aspect of the femoral neck. In addition, the left quadratus femoris muscle, which is generally located just above the nutrient vessels of the femoral head, was not detected. Based on these findings, the patient was diagnosed with osteonecrosis of the femoral head caused by impairment of the nutrient vessels from invasion of the pigmented villonodular synovitis. She underwent radical synovectomy of the left hip 16 months after the onset of pain, and her hip pain improved after the surgery.

Patient-reported outcomes of femoral osteotomy and total hip arthroplasty for osteonecrosis of the femoral head: a prospective case series study.

BACKGROUND: Patient-reported scoring systems have recently been used after surgical procedures. The purpose of this prospective study was to evaluate the patient-reported outcomes of femoral osteotomy and total hip arthroplasty (THA) for osteonecrosis of the femoral head (ONFH). METHODS: Forty-two symptomatic ONFH patients with asymptomatic contralateral hip underwent either transtrochanteric anterior rotational osteotomy (ARO) or THA as a primary operation. Of these, 20 patients whose contralateral hips remained asymptomatic at the final follow-up (more than 1 year postoperatively) were recruited to participate in this study. Nine patients were treated with ARO (ARO group) and 11 patients were treated with THA (THA group). Both the Oxford hip score (OHS) and the short form 36 (SF-36) were evaluated preoperatively and at the final follow-up. RESULTS: The preoperative OHS was 29.1 ± 10.9 and 21.9 ± 9.6 points in the ARO and THA groups, which significantly improved to 38.4 ± 9.4 and 40.3 ± 5.1 points at the final follow-up, respectively. The preoperative physical component summary score was 30.8 ± 12.8 and 17.8 ± 14.5 points in the ARO group and THA groups, which significantly improved to 44.5 ± 10.6 and 43.3 ± 10.4 points at the final follow-up, respectively. The preoperative mental component summary score was 48.0 ± 8.5 and 48.6 ± 11.3 points in the ARO and THA groups, both of which remained unchanged at the final follow-up. CONCLUSIONS: The short-term patient-reported outcomes of this study suggested that both ARO and THA for ONFH resulted in significantly improved postoperative hip joint function.

Fat-suppressed T2-weighted MRI appearance of subchondral insufficiency fracture of the femoral head.

OBJECTIVE: Our aims were to investigate the imaging appearance of subchondral insufficiency fracture (SIF) of the femoral head based on fat-suppressed T2-weighted MRI, and evaluate its correlation with the clinical outcomes following conservative treatment. MATERIALS AND METHODS: We retrospectively evaluated 40 hips in 37 patients with SIF of the femoral head (12 males and 25 females; mean age 55.8 years, range 22-78 years). MRI examinations were performed within 3 months after the onset of hip pain. Using fat-suppressed T2-weighted imaging, we evaluated the hips for the intensity of the subchondral bone (corresponding to the area superior to the low intensity band on T1-weighted images) as well as bone marrow edema, joint effusion, and presence of the band lesion. We then correlated the intensity of the subchondral bone with clinical outcomes. RESULTS: The hips were classified into three types based on subchondral intensity on fat-suppressed T2-weighted images: type 1 (21 hips) showed high intensity, type 2 (eight hips) showed heterogeneous intensity, and type 3 (11 hips) showed low intensity. The mean period between pain onset and MRI examination was significantly longer for type 2 hips than for type 1. Healing rates were 86 % for type 1, 75 % for type 2, and 18 % for type 3. CONCLUSION: SIF cases were classified into three types based on subchondral intensity on fat-suppressed T2-weighted imaging performed within 3 months after pain onset. Type 3 SIF tended to be intractable to conservative treatment compared to type 1 and type 2.

The choice of locking plate in the treatment of peri-implant femoral fracture eight years after trans-trochanteric rotational osteotomy: A case report.

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.