Subtrochanteric fracture after free vascularised fibular grafting for osteonecrosis of the femoral head

The aim of this study was to determine the incidence and factors associated with subtrochanteric fracture after free vascularised fibular grafting for osteonecrosis of the femoral head, and to analyse clinical and radiological outcomes of open reduction and internal fixation. From April 1991 to May 2004, eight such fractures were managed by Rowe plate fixation. Factors examined included age, gender, side of operation, cause and preoperative and postoperative stage of osteonecrosis, and preoperative and postoperative functional assessment. The osteonecrosis was caused by alcohol consumption in six, steroid use in one and was idiopathic in one case. The overall incidence of fracture was 4.1% (13.9% in bilateral operations) and all occurred in men of mean age 36.3 years, were induced by low-energy injury and were attributed to defects created in the lateral femoral cortex for graft placement. Seven of the eight fractures (87.5%) developed within 12 weeks and all fractures healed at a mean of 16.6 weeks after internal fixation. No major complications occurred and no significant differences were found in clinical or radiological results between the fracture and non-fracture groups. Our findings indicate that strict education and mandatory protection from full weight bearing are required for 12 weeks after free vascularised fibular grafting for osteonecrosis of the femoral head.