Factors Predicting Avascular Necrosis After Closed Reduction and Internal Fixation of Displaced Subcapital Fractures of the Hip

Background: The main complications following closed reduction and internal fixation of displaced intracapsular femur fractures (DICFF) are avascular necrosis (AVN) and nonunion. Little is known about the factors that predict these complications. The purpose of this study was to assess the clinical and radiological risk factors of failure following closed reduction and internal fixation of DICFF among non-elderly patients. Methods: We retrospectively reviewed patients under the age of 65 years who underwent closed reduction and internal fixation of DICFF in our center from January 2007 to January 2018. The extracted data included baseline characteristics and the fixation method. Postoperative radiographs were obtained during follow-up visits in order to evaluate complications, such as AVN and nonunion. Results: In total, 90 patients were included in the study, with a mean follow-up of 6.5 years. Garden III fractures were associated with significantly lower rates of AVN (odds ratio [OR] = 0.304, 95%confidence interval [CI]: 0.101-0.916) compared to Garden IV fractures. Neutral and varus reduction positions had significantly higher rates of AVN (OR = 7.182, 95%CI: 1.951- 26.446) and (OR= 5.560, 95%CI: 1.130-27.351), respectively, compared to the valgus position. Longer surgery procedures were associated with a higher risk of AVN (OR = 1.018, 95%CI: 1.006-1.031). Conclusions: Both varus and neutral reduction positions as well as Garden IV classification served as predictive factors for failure following closed reduction and internal fixation of DICFF. The type of fixation (CCS vs Targon plate) and the Pauwel angle had no significant effect on the rates of AVN or nonunion following fracture reduction.