Impact of Obesity on Short- and Mid-Term Complications Following Total Ankle Replacement

Category: Ankle, Ankle Keywords: Ankle Arthritis, Ankle Arthroplasty, Ankle Replacement Introduction/Purpose: Total ankle replacement (TAR) is increasingly used to treat end-stage ankle osteoarthritis, but failure and complication rates remain significant. These are often attributed to implant and patient factors, including obesity, which affects 42.4% of U.S. adults (BMI ≥30 kg/m²). While obesity is well established as a risk factor for higher complication, infection, and revision rates in total knee and hip replacement, there is a limited literature investigating the impact of obesity on TAR outcomes. This study evaluates complication, infection, and revision rates of primary TAR in patients across BMI cohorts. We hypothesized that TAR patients with BMI 35-39.9 kg/m2 and BMI >40.0kg/m2 would have higher short-term complications and long-term infection and revision rates compared to those without obesity. Methods: This is a retrospective database cohort study using the TriNetX research database. Patients ≥18 years who underwent primary TAR from database inception to 2025 with minimum 2-years of follow-up were included. Patients were stratified by BMI: non-obese (BMI0.05 for all). Kaplan-Meier analysis showed no significant differences in survival rates between cohorts (5-year survival: BMI<30: 90.0%, BMI 30.0-34.9: 90.3% (p=0.949), BMI 35.0-39.9: 91.6% (p=0.364), and BMI≥40: 86.4% (p=0.106)). Conclusion: TAR demonstrates good 5-year survivorship across BMI groups. However, at 90-days, patients with BMI ≥35 face increased risk of periprosthetic fractures and those with BMI ≥40 have increased medical complications. These findings suggest that while obesity does not appear to compromise overall 5-year implant survivorship, careful preoperative patient optimization and patient selection is needed to reduce early postoperative risks in patients with elevated BMI. In addition, patients with BMI ≥35 are at a higher risk for periprosthetic fracture and may benefit from prophylactic malleolar fixation.