A multiple correlation factors analysis of avascular necrosis after closed reduction and cannulated compression screws fixation of intra-capsular femoral neck fracture.A multi-center retrospective study

Objective To determine the incidence of avascular necrosis after closed reduction and cannulated compression screws fixation of intra-capsular femoral neck fracture and to investigate the multiple factors correlated to avascular femoral head necrosis.Methods All the patients of intra-capsular femoral neck fracture who accepted closed reduction and cannulated compression screws fixation between 2001 and 2010 in Jiangsu Province were reviewed in multi-centers retrospectively.The multiple factors were analyzed including age,gender,affected side,mechanism of injury,fracture classification,procedure delay,quality of reduction,time of full-weight-bearing,configuration of the screws and removal of the screws.Multiple correlation factors were analyzed with SPSS 13.0 statistic system.Results Complete case records were documented in 1849 cases who were followed up for an average 6.5±2.7 years (range,2-10 years).Avascular necrosis occurred in 246 cases (13.3％).The average time of diagnosis of avascular necrosis was 17±4.6months (range,8-72 months) after injury.The average Harris score of the hips which didn't develop to avascular necrosis was 93.8±8.9 (range,78～100) at the last follow up.Multiple correlation factors analysis indicated that displacement degrees of fracture and the quality of reduction were significantly correlated to the incidence of avascular necrosis (OR=2.078,3.423).Conclusion Closed reduction and cannulated compression screws fixation after the intra-capsular femoral neck fracture can get satisfactory results.Displacement degrees of fracture and the quality of reduction are significantly correlated to the incidence of avascular femoral head necrosis. Key words: Femoral neck fractures;  Femoral head necrosis;  Logistic models;  Multicenter studies