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.

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.

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Background and purposeIt 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.Methods40 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).ResultsThe 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.InterpretationOur 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.

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