Association Between Obesity and Short- and Midterm Complications Following Total Ankle Replacement

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Public health

Background:

• Total ankle replacement (TAR) is a growing treatment for end-stage ankle osteoarthritis.
• The impact of obesity on TAR complications and implant failure requires further investigation.
• This study assesses short- and midterm outcomes of TAR based on body mass index (BMI) categories.

Purpose of the Study:

• To evaluate the association between obesity (BMI categories) and complications following total ankle replacement.
• To assess the midterm implant failure rates in patients undergoing total ankle replacement across different BMI categories.
• To compare early postoperative complications and implant survival rates between nonobese and obese patients undergoing TAR.

Main Methods:

• Retrospective cohort study utilizing the TriNetX Research Database (over 100 healthcare organizations).
• Included patients (≥18 years) who underwent primary TAR from 2014-2025 with a minimum 2-year follow-up.
• Patients stratified by BMI (<30, 30.0-34.9, 35.0-39.9, ≥40); propensity-score matching (PSM) used for BMI <30 vs. ≥35 comparison.
• Primary outcome: 5-year implant failure rate. Secondary outcomes: 90-day complications, surgical site infections, and periprosthetic joint infection (PJI) rates.

Main Results:

• Analyzed 3533 patients; 1511 nonobese, 1118 BMI 30.0-34.9, 608 BMI 35.0-39.9, 296 BMI ≥40.
• Patients with BMI ≥40 had higher 90-day major medical complication rates (OR 2.45, P=.005).
• Elevated 90-day periprosthetic fracture risk observed in BMI 35.0-39.9 (OR 1.78, P=.025) and ≥40 (OR 1.98, P=.030).
• PSM showed only 90-day medical complication risk remained elevated for BMI ≥35.
• No significant differences in 5-year implant failure observed (nonobese: 90.0%, BMI 30.0-34.9: 90.3%, BMI 35.0-39.9: 91.6%, BMI ≥40: 86.4%).
• Study underpowered to exclude clinically meaningful differences in long-term failure.

Conclusions:

• While 5-year implant survivorship appeared comparable, patients with BMI ≥40 faced significantly higher early postoperative medical complication risks.
• The study lacked statistical power to definitively rule out clinically significant long-term failure differences.
• A trend towards lower survivorship in morbidly obese patients warrants further investigation.