To analyze the possible involvement of a change in the lipid metabolism and PPARgamma2 level in the occurrence of ON of the femoral head.

The lipid profiles (Cholesterol, Triglyceride, LDL, HDL and Free fatty acid) of 130 patients with ON of the femoral head and 30 control persons were evaluated. The level of PPARgamma2 mRNA expression was examined by performing, RT-PCR using the bone marrow stromal cells obtained from 17 patients during THA.

Among the 130 patients, the free fatty acid level in the alcohol (676.9±264.7 mg/dl,) and steroid (666.0±163.4 mg/dl) induced ON groups was higher than the control (453.5±169.3 mg/dl) and idiopathic (468.5±194.1 mg/dl) groups. The triglyceride level in the alcohol (223.7±70.9 mg/dl) and steroid (183.6±58.4 mg/dl) induced groups was higher than the control (93.1±79.0 mg/dl) and idiopathic groups (130.9±63.1 mg/dl). The level of PPARgamma2 mRNA expression in the ON patients was significantly higher than the other groups (P <0.05).

These results are significant and suggest hyperlipidemia as a risk factor for ON of the femoral head. Higher expression of PPARgamma2 mRNA was found in ON. However, functional studies of PPARgamma2 mRNA in vivo would be needed to reveal the pathogenesis of ON of the femoral head.