Factors affecting avascular necrosis of femoral head after internal fixation with cannulated screws in femoral neck fractures

Objective:To investigate the factors influencing the avascular necrosis of femoral head after internal fixation of femoral neck fracture.Methods:A total of 99 patients with femoral neck fracture,who were treated with internal fixation between May 1999 and April 2004,were followed up in outpatient Department and by telephone.The data was set up and analyzed by SPSS 14.0 software.Results:Until January 2006,avascular necrosis of the femoral head was found in 15 cases(15.2%).Age×internal fixation,gender×the time of reduction were found interactive in two factors interactive analysis.Age,the displacement of fractures,the quality of reduction,and internal fixation were found to be significant factors in single factor logistic regression analysis.Age,age×internal fixation,and the quality of reduction were found to be significant factors in multivariate logistic regression analysis.In fine analysis of interactive after multivariate logistic regression analysis,the removal of internal fixation was the most important risk factor for femoral head necrosis in 56-85yrs group,with the risk ratio being 26.00(95%CI=3.076-219.747).Conclusion:Elder patients have less chance for avascular necrosis of femoral head.The extraction of cannulated screws might lead to more avascular necrosis of femoral head and collapse in old patients.Dissection reduction can help to reduce avascular necrosis.