Factors Associated With Amputation Following Ankle Fracture Surgery

Abstract

Patients with diabetes mellitus (DM) are at increased risk of complications following ankle fracture surgery. Previous research suggests that patients of low socioeconomic status are at increased risk of amputation following orthopaedic complications. The purpose of this research was to determine if low socioeconomic status increases risk of below knee amputation (BKA) following ankle fractures among patients with DM. The National Inpatient Sample (NIS) was queried from 2010 to 2014 to identify 125 diabetic patients who underwent ankle fracture surgical fixation followed by BKA. Two cohorts (BKA vs. no BKA) and a multivariate logistic regression model were created to compare the effects of independent variables, including age, sex, race, primary payer, median household income by ZIP code, hospital location/teaching status, and comorbidities. The most predictive variables for BKA were concomitant peripheral vascular disease (odds ratio [OR] 5.35, 95% confidence interval [CI] 3.51-8.15), history of chronic diabetes-related medical complications (OR 3.29, CI 2.16-5.01), age in the youngest quartile (OR 2.54, CI 1.38-4.67), and male sex (OR 2.28, CI 1.54-3.36). Patient race and median household income were not significantly associated with BKA; however, risk of BKA was greater among patients with Medicaid (OR 2.23, CI 1.09-4.53) or Medicare (OR 1.85, CI 1.03-3.32) compared to privately insured patients. Diabetic inpatients with Medicaid insurance are at over twice the odds of BKA compared to privately insured patients following ankle fracture. Furthermore, peripheral vascular diseases, uncontrolled diabetes, younger age, and male sex each independently increase risk of BKA.