Effects of intertrochanteric osteotomy plane and preoperative femoral anteversion on the postoperative morphology of the proximal femur in transtrochanteric anterior rotational osteotomy: 3D CT-based simulation study.

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 postoperative intact ratio. However, the effect of intertrochanteric osteotomy plane on postoperative femoral anteversion has not been well examined. Therefore, we performed a simulation study of ARO to determine how intertrochanteric osteotomy plane and preoperative femoral anteversion affect both femoral neck-shaft varus angle and postoperative femoral anteversion. HYPOTHESIS: Both femoral neck-shaft varus angle and postoperative femoral anteversion are predicted by intertrochanteric osteotomy plane and preoperative 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 postoperative femoral anteversion were assessed. RESULTS: With increase in the vertically-inclined degree of AP-view line, both neck-shaft varus angle and postoperative femoral anteversion increased. With increase in the posteriorly-tilted degree of lateral-view line, neck-shaft varus angle increased, whereas postoperative 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+preoperative femoral anteversion×0.7; postoperative femoral anteversion≈vertically-inclined degree of AP-view line×1.1-posteriorly-tilted degree of lateral-view line×0.8. DISCUSSION: The postoperative morphology of proximal femur was nearly defined by intertrochanteric osteotomy plane with preoperative femoral anteversion, which is useful for preoperative planning in terms of both achieving a sufficient postoperative intact ratio and maintaining femoral anteversion. LEVEL OF EVIDENCE: Level IV case series without control group.

Factors influencing progressive collapse of the transposed necrotic lesion after transtrochanteric anterior rotational osteotomy for osteonecrosis of the femoral head.

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 preoperative 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 preoperative 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), preoperative level of collapse, extent of the necrotic lesion and postoperative 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. Preoperative level of collapse in the progressive collapse group (4.4±1.4mm) was significantly larger than that in the non-progressive collapse group (2.1±1.0mm), which was independently associated with progressive collapse of the transposed necrotic lesion in multivariate analysis (P<0.0001) with cut off point of 2.98mm. In univariate analysis, lower preoperative HHS, severe extent of the necrotic lesion and the lower postoperative 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 preoperative level of collapse (cut-off point=2.98mm). LEVEL OF EVIDENCE: IV; retrospective case series.

Results of the Sugioka transtrochanteric rotational osteotomy for osteonecrosis: Frequency and role of a defect of the quadratus femoris muscle in osteonecrosis progression.

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.

Prognostic factors associated with a subchondral insufficiency fracture of the femoral head.

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.

Effect of intra-articular lesions on the outcome of periacetabular osteotomy in patients with symptomatic hip dysplasia.

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.

Morphological analysis of collapsed regions in osteonecrosis of the femoral head.

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.

Radiological outcome analysis of transtrochanteric curved varus osteotomy for osteonecrosis of the femoral head at a mean follow-up of 12.4 years.

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.

Long-term outcome of transtrochanteric anterior rotational osteotomy for osteonecrosis of the femoral head in patients with systemic lupus erythematosus.

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. Lupus (2010) 19, 860-865.

Effects of different corticosteroids on the development of osteonecrosis in rabbits.

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.