Risk factors for reoperation to promote union in 1,111 distal femur fractures.

Abstract

To identify modifiable and non-modifiable risk factors for reoperation to promote union after distal femur fracture. Multicenter retrospective cohort study. Ten Level-I trauma centers. Patients with OTA/AO 33A or C distal femur fractures (n = 1,111). Surgical fixation of distal femur fracture. Fixation constructs were classified as lateral plate, dual plate, nail, or nail plate combination. The outcome of interest was unplanned reoperation to promote union. There was an 11% (121/1111) rate of unplanned reoperation to promote union. In the multivariate analysis, predictive factors included BMI (odds ratio [OR] = 1.18; 95% confidence interval [CI]: 1.06 - 1.32; p < 0.01), intra-articular fracture (OR = 1.57; 95% CI: 1.01 - 2.45; p = 0.04), type III open injury (OR = 2.29; 95% CI: 1.41 - 3.72; p < 0.01), the presence of medial comminution (OR = 1.85; 95% CI: 1.14 - 3.06; p = 0.01), and medial translation on post-operative radiographs (OR = 1.23 per one tenth of condylar width; 95% CI: 1.01 - 1.48; p = 0.03). Construct type was not significantly predictive. 11% of distal femur fractures underwent unplanned reoperation to promote union. BMI, intra-articular fracture, type III open injury, medial comminution, and medial translation on postoperative radiographs were predictive factors. Construct type was not associated with unplanned reoperation, however this conclusion was limited by small numbers in the dual plate and nail plate groups. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.