Predictors of Time to Clinical Union in Ankle Fractures

Abstract

Category: Ankle Introduction/Purpose: Ankle fractures are an increasingly common musculoskeletal injury and represent a substantial source of societal economic loss due to missed days of work and utilization of healthcare resources. While common protocols exist for postoperative management of these fractures, predictors of time to union have not been analyzed. We aim to evaluate patient characteristics, injury features and perioperative factors that predict time to union and may allow for optimized postoperative protocols and improved patient counseling. Methods: A cohort of consecutive patients with isolated, closed operative ankle fractures treated by multiple surgeons at a tertiary care academic medical center from 2008-2012 was retrospectively reviewed for time to clinical union. Clinical union was defined as plain film radiographic evidence of bony healing and minimal to no pain clinically. Patients with pilon fractures, open injuries, additional fractures and incomplete outcomes data were excluded from analysis. Means and standard deviations were calculated and multivariate linear regression modeling was utilized to identify predictors of time to clinical union. Results: A total of 108 isolated, closed operative ankle fractures met inclusion criteria. Of these, 99.1% achieved clinical union in less than 6 months and the remaining one patient completed union in a delayed fashion with the use of non-operative adjuncts. Mean time to union was 14.1 weeks (SD 5.3 weeks). Statistically significant negative predictors of time to union were BMI, dislocation of the tibiotalar joint, external fixation for initial stabilization and delay of definitive management (all p < 0.05). Sex, age, diabetes mellitus, tobacco usage and high-energy mechanism were not significant after adjustment (Table 1). Fracture pattern and definitive operative fixation technique did not contribute to a parsimonious regression model and were excluded from final analysis. Conclusion: Time to clinical union after ankle fracture is significantly correlated with BMI, tibiotalar dislocation, external fixation for initial stabilization and delay of definitive management. In these instances, it is important to counsel patients about the potential for nonunion and consideration should be given to healing adjuncts such as prolonged non-weightbearing immobilization, bone stimulation and vitamin D.