Anterior Ankle Soft Tissue Thickness and Infection Risk after Total Ankle Arthroplasty

Research Type: Level 3 - Retrospective cohort study, Case-control study, Meta-analysis of Level 3 studies Introduction/Purpose: Total ankle arthroplasty (TAA) has become a widely utilized technique for managing end-stage ankle arthritis, yet complications persist. One recently identified predictor of complications is the soft tissue envelope surrounding the ankle. Our study sought to identify whether a relationship exists between the thickness of the anterior ankle soft tissues and infection rates after TAA. Methods: We performed a retrospective cohort study of 293 patients who underwent primary TAA from 2014 to 2023 at a single institution. All patients were treated by a single surgeon and with a single implant system. All patients had a preoperative computed tomography (CT) scan that was used for patient specific instrumentation (PSI). All measurements of the anterior soft tissue envelope were obtained from CT scans; these measurements were recorded in millimeters. Patient demographics including weight, body mass index (BMI), and diabetic status were recorded. A multivariable logistic regression was performed to identify significant risk factors for post-operative infection after TAA. Results: The mean age of our cohort was 68.2 years old at time of surgery (SD of 8.6 years). The median follow up was 16 months. 50.2% of patients were female. 9.6% were diabetic. Mean BMI was 30.3kg/m2 (SD of 5.3). Average anterior ankle soft tissue thickness was 16.5mm (SD of 4.0). During our logistic regression, increasing anterior ankle soft tissue thickness was found to be significantly associated with postoperative infection after TAA (OR of 1.32, 95% CI [1.17, 1.47]). This was also true of diabetic status (OR of 4.95, 95% CI [1.69, 14.8]), but not true of BMI, weight, age, or sex. Conclusion: The ankle soft tissue envelope is emerging as an important predictor of outcomes following total ankle arthroplasty. Our study demonstrates that a thicker anterior ankle soft tissue envelope was found to be a significant predictor of infection risk after TAA. This risk was independent of patient weight or BMI. Our study may help inform peri-operative care and counseling for this increasingly common procedure.