Predictors of Patient-Reported Function and Pain Outcomes in Operative Ankle Fractures

Background: Risk factors associated with short-term functional outcomes in patients with operative ankle fractures have been established. However, no previous studies have reported the association between these risk factors and functional outcomes outside of the first postoperative year. We identified predictors of functional and pain outcomes in patients with operative ankle fractures using the Patient Reported Outcomes Measurement System (PROMIS) physical function (PF) and pain interference (PI) measures. Methods: We retrospectively reviewed a multicenter cohort of patients ≥18 years old who underwent operative management of closed ankle fractures from 2001 to 2013 with a minimum of a 2-year follow-up. Patients with pilon variants, Maisonneuve fractures, Charcot arthropathy, prior ankle surgery, and chronic ankle fractures were excluded. Patients meeting inclusion criteria were contacted and evaluated using the PROMIS PF and PI computerized adaptive tests. Patient demographic and injury characteristics were obtained through a retrospective chart review. Univariate and multivariate regression models were developed to determine independent predictors of physical function and pain at follow-up. Included in this study were 142 patients (64 women, 78 men) with a mean age of 52.7 years (SD = 14.7) averaging 6.3 years of follow-up (range 2-14). Results: Patients had a mean PF of 51.9 (SD = 10.0) and a mean PI of 47.8 (SD = 8.45). Multivariate analysis demonstrated that independent predictors of decreased PF included higher age (B = 0.16, P =.03), higher American Society of Anesthesiologists (ASA) class (B = 10.3, P <.01), and higher body mass index (BMI; B = 0.44, P <.01). Predictors of increased PI included higher ASA class (B = 11.5, P <.01) and lower BMI (B = 0.41, P <.01). Conclusion: At follow-up, increased ASA class, increased BMI, and higher age at time of surgery were independently predictive of decreased physical function. Factors that were associated with increased pain at follow-up include lower BMI and higher ASA class. ASA class had the strongest effect on both physical function and pain. Level of Evidence: Level IV, case series.