Clinical effect of 7.5 mm QWIX screw fixation of femoral neck fracture

Objective To evaluate the clinical effect of femoral neck fracture fixed with 7.5mm QWIX screws and to find out risk factors for avascular necrosis of the femoral head postoperatively. Methods From January 2009 and March 2013, 53 patients underwent closed or open reduction of femoral neck fracture with 7.5mm QWIX screws. Healing process of fracture, complications of internal fixation, Harris hip score and avascular necrosis of the femoral head were followed up. The data reviewed were age, gender, injury patterns, fracture type, preoperative waiting time, reduction ways, reduction condition, and others. Unilateral and multivariate Logistic analysis were applied to identify factors for avascular necrosis of the femoral head. Results All patients were followed up for 2-5 years (mean, 3.4 years). There was no non-union at follow-up, and all the screws were in the original site without loosening, cut-out or penetration. Mean Harris score was 91.2 points (range, 68 to 100 points) 2 years after operation, including 42 excellent, 6 good, 1 fair and 4 poor results with the excellent-good rate of 91%. Four patients (8%) had avascular necrosis 12 to 15 months after operation. With Logistic regression analysis, fracture anatomic type was identified as the only factor for avascular necrosis of the femoral head. Conclusions The 7.5 mm QWIX fixation screw provides rigid fixation, high healing rate and low incidence of avascular necrosis of the femoral head, appearing to be a good hardware to repair femoral neck fracture. Avascular necrosis of the femoral head is associated with the anatomic type of femoral neck fracture after operation. Key words: Femoral neck fractures; Internal fixators; Femur head necrosis; 7.5 mm QWIX screws