The Effect of Obesity on Functional Outcomes and Complications in Total Ankle Arthroplasty

Background: The prevalence of obesity in the United States is staggering. Currently, the effect of obesity on third-generation total ankle replacement (TAR) is unknown. Methods: We prospectively identified a consecutive series of 455 primary TARs operated between May 2007 and September 2013 who had a minimum follow-up of 2 years. We identified 266 patients with a body mass index (BMI) <30 (control), 116 with a BMI between 30 and 35 (Obese I), and 73 with a BMI >35 (Obese II). Clinical outcomes including wound issues, infection rate, complications, and failure rates were compared. Functional outcomes including American Orthopaedic Foot & Ankle Society hindfoot score, Short Form–36 (SF-36), Short Musculoskeletal Function Assessment (SMFA), Foot and Ankle Disability Index (FADI), and Foot and Ankle Outcome Score (FAOS) were compared. Average patient follow-up in the Obese I group was 44.7 ± 17.3 months, Obese II was 42.7 ± 16.4 months, and 45.2 ± 17.4 months in the control group. Results: Age, race, and smoking history in the obese group were not significantly higher than the control group; however, sex was significantly related to BMI. There was no difference in complication, infection, or failure rates between the groups. Preoperatively, the Obese II group had significantly lower SF-36 scores and higher SMFA function, FADI, and FAOS Symptoms scores. For each of the Obese I, Obese II, and control groups, all functional outcome scores 1 year postoperatively and at most recent follow-up were significantly improved. However, at most recent follow-up, Obese II patients had lower FAOS Pain and SF-36 scores and higher FADI and SMFA Functional scores. Conclusion: Total ankle arthroplasty in obese patients was a relatively safe procedure. Although obese patients after TAR had lower functional outcome scores compared to their nonobese counterpart, they did experience significant functional and pain improvements at most recent follow-up. Level of Evidence: Level III, comparative series.