Lower Body Mass Index Increases Risk of Gutter Impingement after Total Ankle Arthroplasty

Research Type: Level 3 - Retrospective cohort study, Case-control study, Meta-analysis of Level 3 studies Introduction/Purpose: Gutter impingement is a common complication following total ankle arthroplasty (TAA), characterized by pain and restricted range of motion due to soft tissue or bony encroachment in the ankle joint gutters. While several risk factors have been identified, the role of body mass index (BMI) remains underexplored. Higher BMI may contribute to an increased risk of gutter impingement due to overload of the implant, lower bone density and increased risk of implant subsidence. This study investigated the association between BMI and gutter impingement in a large patient cohort. We hypothesized that higher BMI values would correlate with increased gutter impingement. Methods: A retrospective analysis was conducted on 1,322 patients who underwent primary TAA at a single institution between 2002 and 2022. Logistic regression analysis was performed to evaluate the association between BMI and impingement risk, adjusting for potential confounders, including age at surgery, gender, primary diagnosis, diabetes status, and ASA classification. Odds ratios (OR) with 95% confidence intervals (CI) and p-values were reported to determine statistical significance. Results: Lower BMI was significantly associated with an increased risk of gutter impingement (OR = 0.996, 95% CI: 0.992–0.999, p = 0.02). Younger age at surgery was also associated with a higher risk of impingement (OR = 0.997, 95% CI: 0.995–0.999, p < 0.01). Patients with a post-traumatic primary diagnosis had a significantly greater likelihood of developing impingement (OR = 1.076, 95% CI: 1.039–1.113, p < 0.01). Other factors, including gender, diabetes status, and ASA classification, were not significantly associated with impingement risk. Conclusion: Our hypothesis was not confirmed: lower BMI appears to be an independent risk factor for gutter impingement after TAA. One explanation could be that reduced soft tissue padding may increase bony prominence and mechanical irritation. Younger, leaner patients might also undergo more postoperative remodeling, contributing to persistent symptoms. Additionally, surgeons may be less vigilant in debriding gutters in lower-BMI patients, assuming impingement is more common in heavier individuals. BMI should inform surgical planning, including implant positioning, soft tissue management, and rehabilitation. Further research is needed to refine techniques and protocols to improve outcomes for leaner patients undergoing TAA.