Predictors of femoral head avascular necrosis after internal fixation of femoral neck fractures

Objective To identify the independent prognostic factors for femoral head avascular necrosis after internal fixation of femoral neck fractures. Methods A retrospective analysis was made on 246 patients (246 hips) with femoral neck fractures treated by internal fixation between January 2002 and January 2010. There were 111 male and 135 female patients aged 19-59 years. A total of 101 patients were injured in traffic accidents, 79 patients in falls from the height and 66 patients in ground-level falls. Eight parameters were identified as the prognostic factors of femoral head avascular necrosis, including gender, fracture type, preoperative traction, interval from injury to surgery, reduction methods, quality of fracture reduction, time of weight bearing, and fixation removal. Multivariate Logistic regression analysis was used to explore the risk factors of postoperative femoral head avascular necrosis. Results Period of follow-up was 1-13 years (mean, 7.5 years). There were 38 patients (15.4%) with avascular necrosis of the femoral head. Multivariate analysis identified fracture type (95%CI-3.41--2.43, P<0.01), preoperative traction (95%CI-3.77--0.6, P<0.05) and quality of fracture reduction (95%CI-3.33--0.94, P<0.01) as the independent predictors of avascular necrosis of the femoral head. Conclusion Fracture type, preoperative traction and quality of fracture reduction are the independent risk factors for avascular necrosis of the femoral head after internal fixation of femoral neck fractures. Key words: Femoral neck fractures; Fracture fixation, internal; Femur head necrosis; Risk factors