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

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. 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. 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). MPSL treatment significantly increased ON incidence in rabbits over levels seen after TR or PSL treatment.