The 2001 revised criteria for diagnosis, classification, and staging of idiopathic osteonecrosis of the femoral head

 The 2001 revised criteria for the diagnosis, classification, and staging of idiopathic osteonecrosis of the femoral head were proposed in June 2001, by the working group of the Specific Disease Investigation Committee under the auspices of the Japanese Ministry of Health, Labor and Welfare, to establish criteria for diagnosis and management of idiopathic osteonecrosis of the femoral head. Five criteria that showed high specificity were selected for diagnosis: collapse of the femoral head (including crescent sign) without joint-space narrowing or acetabular abnormality on x-ray images; demarcating sclerosis in the femoral head without joint-space narrowing or acetabular abnormality; “cold in hot” on bone scans; low-intensity band on T1-weighted MRI (bandlike pattern); and trabecular and marrow necrosis on histology. Idiopathic osteonecrosis of the femoral head is diagnosed if the patient fulfills two of these five criteria and does not have bone tumors or dysplasias. Necrotic lesions are classified into four types, based on their location on T1-weighted images or x-ray images. Type A lesions occupy the medial one-third or less of the weight-bearing portion. Type B lesions occupy the medial two-thirds or less of the weight-bearing portion. Type C1 lesions occupy more than the medial two-thirds of the weight-bearing portion but do not extend laterally to the acetabular edge. Type C2 lesions occupy more than the medial two-thirds of the weight-bearing portion and extend laterally to the acetabular edge. Staging is based on anteroposterior and lateral views of the femoral head on x-ray images. Stage 1 is defined as the period when there are no specific findings of osteonecrosis on x-ray images, although specific findings are observed on MRI, bone scintigram, or histology. Stage 2 is the period when demarcating sclerosis is observed without collapse of the femoral head. Stage 3 is the period when collapse of the femoral head, including crescent sign, is observed without joint-space narrowing. Mild osteophyte formation in the femoral head or acetabulum may be observed in stage 3. Stage 3 is divided into two substages. In stage 3A, collapse of the femoral head is less than 3 mm. In stage 3B, collapse of the femoral head is 3 mm or greater. Stage 4 is the period when osteoarthritic changes are observed. Received: April 18, 2002 / Accepted: April 21, 2002     

The 2019 Revised Version of Association Research Circulation Osseous Staging System of Osteonecrosis of the Femoral Head

BackgroundThe Association Research Circulation Osseous (ARCO) presents the 2019 revised staging system of osteonecrosis of the femoral head (ONFH) based on the 1994 ARCO classification.MethodsIn October 2018, ARCO established a task force to revise the staging system of ONFH. The task force involved 29 experts who used a web-based survey for international collaboration. Content validity ratios for each answer were calculated to identify the levels of agreement. For the rating queries, a consensus was defined when more than 70% of the panel members scored a 4 or 5 rating on a 5-point scale.ResultsResponse rates were 93.1%-100%, and through the 4-round Delphi study, the 1994 ARCO classification for ONFH was successfully revised. The final consensus resulted in the following 4-staged system: stage I—X-ray is normal, but either magnetic resonance imaging or bone scan is positive; stage II—X-ray is abnormal (subtle signs of osteosclerosis, focal osteoporosis, or cystic change in the femoral head) but without any evidence of subchondral fracture, fracture in the necrotic portion, or flattening of the femoral head; stage III—fracture in the subchondral or necrotic zone as seen on X-ray or computed tomography scans. This stage is further divided into stage IIIA (early, femoral head depression ≤2 mm) and stage IIIB (late, femoral head depression >2 mm); and stage IV—X-ray evidence of osteoarthritis with accompanying joint space narrowing, acetabular changes, and/or joint destruction. This revised staging system does not incorporate the previous subclassification or quantitation parameters, but the panels agreed on the future development of a separate grading system for predicting disease progression.ConclusionA staging system has been developed to revise the 1994 ARCO classification for ONFH by an expert panel-based Delphi survey. ARCO approved and recommends this revised system as a universal staging of ONFH.     

成人常见髋关节疾病双侧髋关节解剖参数的研究

目的探讨行全髋关节置换术中利用对侧相对正常髋关节的解剖参数作为模板重建患侧髋关节的准确性。 方法选取2019年9月至2020年12月于大连医科大学附属第一医院关节外科行首次单侧全髋关节置换术的患者作为研究对象。纳入标准：患侧诊断为髋关节骨关节炎、股骨头坏死或髋关节发育不良Crowe Ⅰ型；对侧髋关节形态不影响测量。排除标准：患侧髋关节既往手术史；畸形严重影响测量；髋关节发育不良Crowe Ⅱ型及以上。最后共纳入82例患者，其中33例男性，49例女性，年龄范围29~74岁。根据患者X线及CT影像数据，分别测量患者患侧及对侧髋臼前倾角、髋臼外展角、股骨前倾角、颈干角以及股骨偏心距，并计算其各自的联合前倾角。运用t检验、Pearson相关性分析等统计学方法分析双侧髋关节解剖参数的对称性。 结果对股骨头坏死及髋关节骨关节炎患者来说，除双侧股骨偏心距患侧小于对侧外(t＝0.523，P <0.05)，余双侧髋关节解剖参数包括髋臼前倾角、髋臼外展角、股骨前倾角、联合前倾角及颈干角的差异均无统计学意义(均为P>0.05)。Pearson相关性分析显示股骨头坏死及骨关节炎患者股骨偏心距的不对称性与颈干角有相关性(r＝-0.519，P<0.001)，颈干角的不对称性与股骨前倾角(r＝0.303，P＝0.041)以及股骨偏心距有相关性，联合前倾角的不对称性与髋臼外展角(r＝0.311，P＝0.035)、颈干角(r＝0.049，P＝0.032)有相关性。Crowe Ⅰ型髋关节发育不良患者的髋臼前倾角(t＝2.081，P＝0.045)、股骨偏心距(t＝3.934，P<0.001)患侧小于对侧，颈干角患侧大于对侧(t＝3.792，P＝0.001)；而双侧髋臼外展角、股骨前倾角、联合前倾角差异均无统计学意义(均为P>0.05)。Pearson相关性分析发现股骨偏心距的不对称性与颈干角(r＝-0.709，P<0.001)、股骨前倾角(r＝-0.349，P＝0.037)有相关性。Crowe Ⅰ型髋关节发育不良患者的股骨偏心距小于股骨头坏死患者或髋关节骨关节炎患者，而髋臼前倾角、髋臼外展角、颈干角大于后者。 结论对于股骨头坏死患者及髋关节骨关节炎患者来说利用对侧肢体作为模板重建患侧髋关节是可行的。而Crowe Ⅰ型髋关节发育不良患者双侧髋关节解剖形态差异较大，对这类患者的全髋关节置换术需个体化。     

Measurement of lesion area and volume by three-dimensional spoiled gradient-echo MR imaging in osteonecrosis of the femoral head.

The purpose of this investigation is to evaluate the diagnostic ability of three-dimensional spoiled gradient-echo (3D SPGR) magnetic resonance (MR) imaging in cases of osteonecrosis of the femoral head (ONFH), and to determine the accuracy of 3D SPGR imaging in area and volume measurement of ONFH. T1-weighted spin-echo (SE) and 3D SPGR imaging were performed on 20 femoral heads obtained from patients with ONFH. After MR imaging, the femoral heads were cut parallel to the imaging plane and were evaluated histologically. Areas and volumes of necrotic lesions were measured with a computer program and the deviation between MR images and anatomical measurements was evaluated. A low signal intensity band on 3D SPGR MR images was observed in all femoral heads and corresponded histologically to repaired marrow with viable fibrous mesenchymal tissue. The area proximate to the low band area coincided with the necrotic region. Both area and volume measurements by T1-weighted SE and 3D SPGR images showed a strong correlation to histological measurements. The discrepancies between histological and imaging results were minimal in 3D SPGR imaging, especially at the anterior and posterior portions of the femoral head. Three-dimensional SPGR imaging provides more accurate measurements of the area and volume of a necrotic lesion than T1-weighted SE imaging.     

Acetabular Anatomical Parameters in Patients With Idiopathic Osteonecrosis of the Femoral Head

BackgroundOsteonecrosis of the femoral head (ONFH) is an increasing worldwide health problem. However, about 30% of the patients are diagnosed with idiopathic ONFH, which means no underlying etiology is identified. We hypothesized that acetabular anatomical abnormalities might be related to idiopathic ONFH.MethodsThis retrospective, 1:2 matched, case-control study included 101 patients (136 hips) with idiopathic ONFH and 202 control subjects (404 hips) matched for age, gender, and body mass index who had no apparent radiographic hip pathologies. The anteroposterior pelvic X-rays of the patients and control subjects were used to measure the anatomical parameters including the center-edge angle, the sharp angle, the acetabular depth ratio (ADR), and the acetabular head index (AHI).ResultsWe found that hips with idiopathic osteonecrosis had less acetabular coverage, lower center-edge angle (28.3° vs 32.3°, P < .001), acetabular depth ratio (298.0 vs 306.4, P = .006), and acetabular head index (82.2 vs 85.8, P < .001), and higher sharp angle (39.7° vs 38.0°, P < .001), compared with the control subjects. The incidence of acetabular dysplasia was also higher in the idiopathic ONFH group than the control group.ConclusionLess acetabular coverage was found in hips with idiopathic osteonecrosis than the control subjects. Less acetabular coverage may be associated with the development of ONFH in East Asian population.     

Radiographic evaluation of linear wear of bipolar hemiarthroplasty devices in vivo

BackgroundThe indications for bipolar hemiarthroplasty (BHA) have been narrowing as those for total hip arthroplasty (THA) have been expanding in cases of femoral neck fracture and initial stages of osteonecrosis of femoral head (ONFH). It is difficult to measure wear in vivo after BHA because the equipment used has a dual bearing system with an inner head inside a metal outer cup. The present study aimed to (1) use a roentgenograph to measure linear wear in vivo after BHA with different acetabular conditions around the bipolar cup, and (2) compare the linear wear of polyethylene between integral bipolar cup (IBC) and Centrax prostheses.MethodsFrom among patients who had undergone BHA in our department after 1996, we analyzed 48 joints with osteoarthritis (OA) and without acetabular cartilage, as well as 25 joints with ONFH of stage 3 or less, in which the acetabular cartilage remains. Two types of bipolar cup prostheses were used: the IBC, which was gamma-sterilized in air using 2-Mrad irradiation, and the Centrax, which was gamma-sterilized in nitrogen using 3-Mrad irradiation. To image the inner head in vivo, we used high-pressure X-ray photography; we measured linear wear of the polyethylene with software using Martell Method 1.ResultsComparing mean annual linear wear between the OA and ONFH groups, using IBC prostheses in both groups, there was a significant difference (0.213 mm vs. 0.096 mm, respectively; P = 0.0177). There was a significant difference between the Centrax and IBC prostheses in OA patients in terms of linear wear (0.04 mm vs. 0.213 mm; P = 0.0181).ConclusionThe linear wear of polyethylene in BHA implants can be affected by the material used to manufacture the bipolar cup. Such implants should only be used for appropriate indications.     

Pathological fracture of the femoral neck as the first manifestation of osteonecrosis of the femoral head

We describe two cases of pathological fracture of the femoral neck occurring as the first manifestation of osteonecrosis of the femoral head (ONFH). No abnormal findings suggestive of ONFH were identified on the radiographs for either of the patients, and the fractures occurred like spontaneous fractures without any trauma or unusually increased activity. The patients' medical history, age, and good bone quality suggested ONFH as a possible underlying cause of the fractures. If we had not suspected ONFH as a predisposing condition, these minimally displaced fractures might have been fixed internally with multiple pins, and this would have led to nonunion or collapse of the femoral head. To avoid inappropriate treatment, ONFH should be considered as a predisposing factor in pathological fractures of the femoral neck. Received: November 20, 1999 / Accepted: July 22, 2000     

Substrain‐specific differences in bone parameters,alpha‐2‐macroglobulin circulating levels,and osteonecrosis incidence in a rat model

Osteonecrosis of the femoral head (ONFH) is a potentially devastating complication that occurs in up to 40% of young adults receiving chronic glucocorticoid (GC) therapy. Through a validated GC therapy rat model, we have previously shown that Wistar Kyoto ( WK) rats exhibit a genetic susceptibility to GC‐induced ONFH compared to Sasco Fischer (F344) rats. We have undertaken this study in order to investigate differences between these two strains for their bone parameters, alpha‐2‐macroglobulin (A2M) circulating levels and incidence of GC‐induced osteonecrosis of the femoral head. WK and F344 rats were treated either with 1.5 mg/kg/day of prednisone or placebo for 6 months. Blood was taken every month. The femoral heads were harvested for histological examination to detect ONFH and analyzed with micro‐computed tomography. After 3 months of GC‐therapy, plasma A2M was elevated in treated rats only. GC‐treated WK rats exhibited histological evidence of early ONFH through higher rates of cellular apoptosis and empty osteocyte lacunae in the subchondral bone compared to placebos and to F344 rats. Furthermore, micro‐CT analysis exhibited femoral head collapse only in GC‐treated WK rats. Interestingly, GC‐treated F344 rats exhibited significant micro‐CT changes, but such changes were less concentrated in the articular region and were accompanied histologically with increased marrow fat. These µCT and histological findings suggest that elevated A2M serum level is not predictive and suitable as an indicative biomarker for early GC‐induced ONFH in rodents. Elevated A2M levels observed during GC treatment suggests that it plays role in the host reparative response to GC‐associated effects. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1183–1194, 2017.

     

Effects of anterior boundary of the necrotic lesion on the progressive collapse after varus osteotomy for osteonecrosis of the femoral head

BackgroundAnterior 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.MethodsWe 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).ResultsAll 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.ConclusionsThis 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.     

Trochanteric rotational osteotomy for osteonecrosis of the femoral head

The rate of success of transtrochanteric rotational osteotomy for osteonecrosis of the femoral head may be improved if patients are preselected using MRI. We have used three criteria for selection for osteotomy (i) minor collapse of the infarcted area, loss of congruity or the crescent sign, without narrowing of the joint space or acetabular involvement (ii) patients younger than 55 years and with a painful hip (iii) patients with an intact area constituting an arc of more than 120 degrees between the central vertical line of the femoral head and the posterior or anterior margin of the necrotic portion as seen on a midsagittal MRI. Seventeen patients were selected, with a follow-up of more than 42 months. A bone scan four weeks after operation showed adequate perfusion of the proximal segment in all hips. The hip score of Merle d'Aubigné et al improved from 13.5 points before operation to 17.2 points at the latest follow-up. Further collapse of the femoral head did not occur. The use of MRI instead of plain radiographs for the selection of patients has improved the success rate of transtrochanteric rotational osteotomy.     

激素治疗SARS患者中期随访的髋部MRI表现

目的 对应用激素治疗的严重急性呼吸综合征(severe acute respiratory syndrome,SARS)患者进行中期髋部MRI随访,探讨早期股骨头坏死和未发生股骨头坏死即正常股骨头的MRI特征.方法 2003年6月至2004年1月对539例(1078髋)应用激素治疗的SARS患者行MR及X线榆查,诊断股骨头坏死210髋,无股骨头坏死868髋.2007年2至11月对510例(1020髋)SARS患者再行MR及X线复查.观察早期股骨头坏死和未发生股骨头坏死股骨头的MRI表现及其变化.结果 末次随访时无新发股骨头坏死病例,应用激素冲击治疗的SARS患者MRI影像上的股骨头坏死均出现在激素治疗后的6个月内.股骨头塌陷或手术后,股骨头坏死的信号类型发生改变,表现为T1加权像低信号,对应STIR序列上高信号.3髋出现坏死范围减小.正常股骨头在T1加权像上有四种MRI影像类型.24髋初次诊断无股骨头坏死者T1加权像出现异常表现,但STIR序列均无异常高信号.这些信号类型在随访的MRI上发生了改变.结论 应用激素冲击治疗的SARS患者,MRI影像上出现股骨头坏死均发生在激素治疗后的6个月内,少数早期坏死股骨头的坏死范围会减小.正常股骨头的MRI影像存在变异.T1加权像上低信号带、对应STIR序列上高信号可作为股骨头坏死的诊断标准.     

A comparison of polyethylene wear in hips with cobalt-chrome or zirconia heads. A prospective, randomised study

We have reviewed 70 patients with bilateral simultaneous total hip arthroplasties to determine the rate of failure and to compare polyethylene wear and osteolysis between an implant with a cobalt-chrome head and Hylamer liner with that of a zirconia head and Hylamer liner. The mean thickness of the polyethylene liner was 11.0 mm (8.8 to 12.2) in the hip with a zirconia head and 10.7 mm (8.8 to 12.2) in that with a cobalt-chrome head. At follow-up at 6.4 years no acetabular or femoral component had been revised for aseptic loosening and no acetabular or femoral component was loose according to radiological criteria in both the cemented and cementless groups. The mean rate of linear wear and annual wear rate were highest in the 22 mm zirconia femoral head (1.25 mm (SD 1.05) and 0.21 mm (SD 0.18), respectively) and lowest in the 22 mm cobalt-chrome femoral head (0.70 mm (SD 0.39) and 0.12 mm (SD 0.07), respectively). The mean volumetric wear was highest in the 28 mm zirconia femoral head (730.79 mm ) and lowest in the 22 mm cobalt-chrome femoral head (264.67 mm3), but if the results were compared by size of the femoral head and type of material there was no statistical difference (p > 0.05). Sequential measurements of annual wear showed that the zirconia femoral head had a relatively higher rate of penetration than the cobalt-chrome head over the first three years; thereafter the rate of wear was reduced and compared favourably with that of cobalt-chrome heads. There was a statistically significant relationship between the wear of the polyethylene liner and the age of the patient, male gender and the degree of abduction angle of the cup, but not diagnosis, weight, hip score, range of movement, or amount of anteversion. Osteolysis was identified on both sides of the acetabulum in six patients (9%). Of 12 hips with acetabular osteolysis, six had a 28 mm cobalt-chrome femoral head and the remaining six a 28 mm zirconia head. Osteolysis was observed in zones 1A and 7A of the femur in two hips (3%) with a 28 mm zirconia head (cemented hip) and in four (6%) with a 28 mm cobalt-chrome femoral head (cementless hip). Our findings suggest that although the performance of a zirconia femoral head with a Hylamer liner was not statistically different from that of a cobalt-chrome femoral head and Hylamer liner, there was a trend for the zirconia head to be worse than the cobalt-chrome femoral head.     

Screening of the COL2A1 mutation in idiopathic osteonecrosis of the femoral head

Idiopathic osteonecrosis of the femoral head (idiopathic ONFH) is an ischemic disorder resulting in necrosis of the subchondral bone of the femoral head. COL2A1 mutations, including c.3508G>A, have been reported to be involved in its etiology. However, the etiological role of COL2A1 mutations in idiopathic ONFH remains controversial, because the pathology of idiopathic ONFH is ischemic necrosis, not epiphyseal dysplasia usually seen in the diseases caused by COL2A1 mutations. The purpose of this study is to examine whether COL2A1 mutations have causal relation with idiopathic ONFH or not. We recruited 1,451 Japanese patients with idiopathic ONFH, including steroid‐, alcohol‐, and neither steroid nor alcohol‐associated (neither‐associated) ONFH. The diagnosis was based on the criteria of the Japanese Research Committee on idiopathic ONFH of the Ministry of Health, Labour and Welfare. By whole‐exome sequencing, entire COL2A1 coding regions and flanking introns were analyzed in 49 neither‐associated ONFH patients. In addition, the c.3508G>A mutation of COL2A1 was checked in all idiopathic ONFH patients using the invader assay. Whole‐exome sequencing did not detect any COL2A1 mutations in the 49 patients. The c.3508G>A mutation was not found in any of the 1,451 patients. In conclusion, COL2A1 is unlikely to cause idiopathic ONFH. Epiphyseal dysplasia of the femoral head caused by COL2A1 mutations may radiographically mimic idiopathic ONFH. COL2A1 mutations should prompt clinical re‐evaluation of the patient's phenotype. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:768–774, 2017.

     

The 2021 Association Research Circulation Osseous Classification for Early-Stage Osteonecrosis of the Femoral Head to Computed Tomography–Based Study

BackgroundThe Association Research Circulation Osseous developed a novel classification for early-stage (precollapse) osteonecrosis of the femoral head (ONFH). We hypothesized that the novel classification is more reliable and valid when compared to previous 3 classifications: Steinberg, modified Kerboul, and Japanese Investigation Committee classifications.MethodsIn the novel classification, necrotic lesions were classified into 3 types: type 1 is a small lesion, where the lateral necrotic margin is medial to the femoral head apex; type 2 is a medium-sized lesion, with the lateral necrotic margin being between the femoral head apex and the lateral acetabular edge; and type 3 is a large lesion, which extends outside the lateral acetabular edge. In a derivation cohort of 40 early-stage osteonecrotic hips based on computed tomography imaging, reliabilities were evaluated using kappa coefficients, and validities to predict future femoral head collapse by chi-squared tests and receiver operating characteristic curve analyses. The predictability for future collapse was also evaluated in a validation cohort of 104 early-stage ONFH.ResultsIn the derivation cohort, interobserver reliability (k = 0.545) and intraobserver agreement (63%-100%) of the novel method were higher than the other 3 classifications. The novel classification system was best able to predict future collapse (P < .05) and had the best discrimination between non-progressors and progressors in both the derivation cohort (area under the curve = 0.692 [0.522-0.863], P < .05) and the validation cohort (area under the curve = 0.742 [0.644-0.841], P = 2.46 × 10^?5).ConclusionThis novel classification is a highly reliable and valid method of those examined. Association Research Circulation Osseous recommends using this method as a unified classification for early-stage ONFH.Level of EvidenceLevel III, diagnostic study.     

The Role of Surgical Hip Dislocation in the Treatment of Acetabular and Femoral Head Fractures

Abstract Background and Purpose: Surgical hip dislocation by trochanteric flip osteotomy facilitates access to acetabular and femoral head fractures. Furthermore, it allows evaluation of cartilage damage and vascularity of the femoral head. In this study the potential benefits of this procedure for improved fracture management and for prognostic assessment were investigated. Patients and Methods: From July 1997 to October 1999, 20 selected patients with displaced acetabular fractures (n = 12), femoral head fractures (n = 7), or combined injuries (n = 1) were included. Inclusion criteria for acetabular fractures were either displaced posterior wall fragments with cranial extension or complex acetabular fractures involving a displaced transverse fracture line. Open reduction and fixation of either complex acetabular fractures or femoral head fractures were carried out through Kocher-Langenbeck approach, trochanteric flip osteotomy, and complete surgical hip dislocation. Additionally, the extent of cartilage destruction and femoral head perfusion were assessed. Results: Anatomic reduction ( 1 mm displacement) of acetabular fractures was achieved in 69% of patients and good reduction ( 3 mm) in 31%. In patients with acetabular fractures, severe cartilage destruction of the acetabulum was found in 38% and of the femoral head in 15%, while patients with isolated femoral head fractures revealed severe cartilage damage of the femoral head in 57%. Arterial bleeding from the femoral head, tested by drilling, was observed in all patients. Secondary dislocation of the trochanteric osteotomy occurred in one patient and made refixation necessary. Patients were reexamined at least 2 years after intervention. 77% of patients with acetabular fractures and all patients with femoral head fractures showed good or excellent results after 32.6 ± 6.1 months according to the functional score of DAubigné & Postel. Conclusion: Surgical hip dislocation allows adequate reconstruction of complex acetabular and femoral head fractures and intraoperative evaluation of local cartilage damage and femoral head perfusion.     

Arthrographic indicators for decision making about femoral varus osteotomy in Legg-Calvé-Perthes disease

Purpose  There is not always a good outcome after a femoral varus osteotomy (FVO) in those with Legg-Calvé-Perthes disease (LCPD), even when the severity warrants surgical treatment. The purpose of this study was to find arthrographic indicators for decision making regarding the likely surgical outcome of a FVO. Methods  We used an image of an abduction position during preoperative arthrography under general anesthesia that simulated the post-operative relationship between the femoral head and the acetabulum. In the image, we defined two indicators of how deeply the deformed epiphysis was contained within the acetabulum: an acetabular head index in abduction and an epiphyseal slip-in index. Finding the contact point between the top of epiphysis and acetabulum was the key for the epiphyseal slip-in index measurement. In 37 patients (38 hips) who underwent FVOs based on our inclusion criteria, these two indices were measured retrospectively and were analyzed for a correlation with surgical outcome. Surgical outcome was evaluated using a combination of three factors: sphericity of the femoral head (Stulberg’s classification), acetabular cover (acetabular head index), and the slope of acetabular roof. Results  The outcome was acceptable in 20 hips (52.6%) and unacceptable in18 hips (47.4%). There was a statistically significance difference in epiphyseal slip-in index between the acceptable group (21.9 ± 2.8%) and the unacceptable group (15.0 ± 4.4%) (P < 0.0001). An index of 20% or more determined a safe zone for predicting an acceptable outcome with 80% sensitivity, 89% specificity, and a 7.2 likelihood ratio. However, the acetabular head index in abduction showed no such statistical significance. Conclusions  In this study, we found that the epiphyseal slip-in index was a reliable indicator for predicting the effectiveness of a FVO. It is worth measuring this index when a surgeon is considering a FVO for a patient with severe LCPD. (Level of Evidence Level III.)     

A μCT analysis of the femoral bone stock in osteonecrosis of the femoral head compared to osteoarthrosis

Introduction  Long-term results of resurfacing in osteonecrosis of the femoral head (ONFH) are lacking and migration of the femoral component, necrosis of the femoral head and fracture of the femoral neck or head have been depicted. The aim of this study was to analyse the bone quality and 3-dimensional microarchitecture of the femoral head and neck in patients with ONFH compared to a group of patients with primary osteoarthritis (OA). Materials and methods  μCT was used to compare the microarchitecture of the femoral head and neck in patients with ONFH (n = 10) and a control group of patients with primary OA (n = 10). Results  No statistical significant differences were found for bone volume and the bone volume fraction, the connectivity density and the structure model index in patients with ONFH and those with OA (P > 0.05). Patients with ONFH and those with OA had a similar trabecular number, thickness and separation (P > 0.05). Conclusion  Based on our findings, we might conclude that hip resurfacing arthroplasty is a possible therapeutic option in the treatment of ONFH of the young and active patient and that an insufficient bone stock in ONFH seems not to be the deciding factor for failure. However, we just focussed on one of probably various factors. Further studies are needed to support these findings.     

Spontaneous Recurrent Dislocation After Primary Birmingham Hip Resurfacing: A Rare Complication in a 44-Year-Old Man

Dislocation is a rare complication of hip resurfacing in young people. This is thought to be due to the stability imposed by a large-diameter head [Stulberg BN, Trier KK, Naughton M, et al. Results and Lessons Learned from a United States Hip Resurfacing Investigational Device Exemption Trial. J Bone Joint Surg Am 2008;90:21]. We report an isolated case 1 week post-Birmingham hip resurfacing in a 44-year-old man without any history of trauma or infection. We note that due to massive periacetabular and femoral neck osteophyte formation and loss of normal bony anatomical landmarks, the version of the acetabular component may have been slightly retroverted. Due to marked narrowing of the femoral neck and head proximally, a cone-shaped proximal femur was found and felt to be unsuitable for direct resurfacing without prior shortening to allow fitting of the appropriate-sized Birmingham hip resurfacing femoral component. This was done successfully, but resulted in slightly reduced femoral neck offset of approximately 10 mm, compared to the native hip. We suspect this reduced offset contributed significantly to the 2 dislocations. We recommend careful preoperative planning and case selection to avoid this complication in similar patients.     

Paraoxonase 1 gene polymorphisms in patients with osteonecrosis of the femoral head with and without cerebral white matter lesions.

Cerebral white matter lesions (WML) are present in more than 50% of patients with osteonecrosis of the femoral head (ONFH). Paraoxonase 1 (PON1) gene product is a detoxifying and pesticide metabolizing enzyme. Genetic variants of the PON1 gene have been found to influence the occurrence and progression of WML. We examined whether two PON1 polymorphisms (M55L and R192Q) are associated with ONFH and influence the occurrence of WML. We studied 104 patients with ONFH and 113 healthy age- and sex-matched subjects. We used logistic regression models to examine associations and survival analyses (Cox proportional hazards models) to examine possible influence of alleles on age at onset of ONFH. We found no association of PON1 M55L alleles and genotypes with ONFH. The distribution of PON1 Q192R alleles (p = 0.001) and genotypes (QQ vs. QR/RR) (p = 0.004) were statistically different between controls and patients. Patients with QQ genotype had six times higher risk for WML at brain MRI (adjusted OR 5.95; 95% CI 1.30-27.03; p = 0.02). In Cox models, there was a significant association of allele Q with risk for ONFH indicating a possible dose effect (HR = 1.43; 95%CI = 1.04-1.97; p for trend = 0.03). We conclude that individuals with PON1 192QQ genotype may have increased risk for ONFH and WMLeOn.     

Management of femoral head osteonecrosis: Current concepts

Osteonecrosis of femoral head (ONFH) is a disabling condition of young individuals with ill-defined etiology and pathogenesis. Remains untreated, about 70-80% of the patients progress to secondary hip arthritis. Both operative and nonoperative treatments have been described with variable success rate. Early diagnosis and treatment is the key for success in preserving the hip joint. Once femoral head collapses (>2 mm) or if there is secondary degeneration, hip conservation procedures become ineffective and arthroplasty remains the only better option. We reviewed 157 studies that evaluate different treatment modalities of ONFH and then a final consensus on treatment was made.