Restricting Access to Care by Using Body Mass Index as Eligibility Criteria for Total Ankle Arthroplasty: A Retrospective Cohort Study.

BACKGROUND: Body mass index (BMI) is associated with increased risk of complications in total hip and knee arthroplasty and is commonly used to screen for surgical eligibility. BMI's role in total ankle arthroplasty (TAA), however, is less defined, with limited evidence connecting obesity to poor outcomes. This study evaluates the potential trade-off between reducing complications and restricting access to care when applying BMI-based eligibility criteria for TAA.

METHODS: We conducted a retrospective cohort study of 3019 patients who underwent primary TAA between January 1, 2007, and December 31, 2023, using the American College of Surgeons National Surgical Quality Improvement Program database, which restricts data collection to 30 days postoperatively. We assessed the number of complications potentially avoided, and the number of complication-free surgeries potentially denied under various BMI eligibility thresholds and random selection. For each cutoff, we calculated the positive predictive value (PPV).

RESULTS: Among the 3019 patients analyzed (mean age 65 years; 45.3% female), with a BMI cutoff of ≥30 kg/m2, 1527 patients would have been denied a complication free surgery, and 58 patients would have avoided complications. Using a BMI cutoff of ≥40 kg/m2, 237 patients would have been denied a complication-free surgery, and 9 patients would have avoided complications. Both cutoffs had a PPV of 3.7% (95% CI of 2.7%-4.6% and 1.3%-6.0%, respectively). For each patient with a complication avoided with a BMI cutoff of either ≥30 or ≥40 kg/m2, 27.3 patients would have been denied a complication-free surgery. Random selection performed the same with a PPV of 3.6%, and 26 patients denied complication-free surgery for each patient, with a complication avoided.

CONCLUSION: With a BMI cutoff of ≥30 or ≥40 kg/m2, the number of patients denied a complication-free surgery is approximately 27 times larger than those spared complications, and BMI criteria demonstrated a similar PPV for complications compared to random selection. Based on this analysis of 30-day postoperative complications, BMI-based cutoffs alone may not be sufficient to determine TAA eligibility.

LEVEL OF EVIDENCE: Level III, retrospective cohort study.