Analysis of related factors and evaluation of quality of life of osteonecrosis of femoral head after internal fixation of femoral neck fracture

OBJECTIVE To explore the risk factors of osteonecrosis of femoral head after internal fixation of femoral neck fracture in young patients, to describe the quality of life of patients with surviving femoral head, and to quantify the predictive factors. METHODS From January 2013 to December 2016, 172 patients (174 hips) with femoral neck fracture treated by closed reduction and cannulated screw internal fixation were selected for retrospective analysis. The general data of the patients were summarized, including age, gender, body mass index, trauma mechanism, trauma operation interval, trauma season and whether the internal fixation was removed. The imaging data included the Garden classification and Pauwel classification of fractures, femoral head retroversion angle, postoperative fracture reduction, screw distribution. Single factor analysis and multi-factor Logistic regression analysis were carried out to explore the risk factors of femoral head necrosis and internal fixation failure. The patients who survived the internal fixation were followed up. The quality of life of the patients was evaluated by the health survey of SF-36. The Harris score of hip joint function was used to evaluate the hip joint function. The predictors of the quality of life of the patients after the operation of femoral neck fracture were analyzed by multiple linear regression analysis. RESULTS Total 172 patients(174 hips) were included in the study, 29 patients(16.67%) had necrosis of the femoral head. In multivariate Logistic regression analysis, the significant differences were reduction quality (OR=0.126, P=0.027) and posterior inclination angle (OR=4.380, P=0.010). One hundred and thirty six patients (137 hips) who survived the femoral head were included in the quality of life survey. Harris score was 90.14±7.92, including excellent 96 hips (70.07%), good 28 hips (20.44%), medium 13 hips (9.49%) and poor 0 hip. In SF-36 score, physical health summary (PCS) was 46.12±9.12, mental health summary(MCS) was 50.21±3.97, there was no linear correlation between them (P>0.05). In multiple linear regression analysis, the variables with significant difference in PCS were reduction quality and retroversion angle, and the variables with significant difference in MCS were fracture displacement and trauma mechanism. CONCLUSION Poor reduction quality and posterior inclination angle>15° are the risk factors of femoral head necrosis. The function of hip joint and MCS of patients with femoral neck fracture recovered well, but PCS could not recover to the average level of normal people. The reduction quality and retroversion angle could be used as the predictors of PCS, and the displacement and trauma mechanism of fracture could be used as the predictors of MCS.