Soft Tissue Thickness as a Predictor of Wound Complications after Total Ankle Arthroplasty: A Retrospective Study

Abstract

Category: Ankle Arthritis; Ankle Introduction/Purpose: Periprosthetic joint infection following total ankle arthroplasty (TAA) is a serious complication often related to the surrounding soft tissue envelope which can lead to poor patient outcomes. The purpose of this study was to determine the relationship between wound complications following TAA and the overlying soft tissue envelope thickness using standardized radiographic soft tissue measurements. We hypothesized that a smaller soft tissue thickness would correlate with an increase in complications. Methods: 197 patients who underwent primary TAA between October 2014 and December 2018 at a single institution with preoperative radiographs and 6 months of follow up were analyzed. We measured the horizontal distance from the posterior tibia to the overlying anterior skin surface and tibial width 2 cm above the tibiotalar joint on lateral ankle films. The ratio of the soft tissue thickness to the tibial width was calculated and named the ankle soft tissue thickness ratio (ASTR). The patients were divided into 2 groups based upon their ASTR. There were 102 patients in the low ASTR group (ASTR 1.38). Minor complications involved office-based treatment and/or oral antibiotics. Major complications involved surgical intervention. A chi-squared test determined complication incidence variance amongst patients in each ASTR group and an independent t-test determined mean ASTR difference. Results: Twenty-nine wound complications (14.7%) were identified among 197 patients, 24 (82.8%) minor and 5 (17.2%) major. There were 19 wound complications in the low ASTR group (17 minor and 2 major) and 10 wound complications in the high ASTR group (7 minor and 3 major). Complications were more frequent in the low ASTR group compared to high ASTR group, though not statistically significant (18.6% vs. 10.5%, P=0.158). There was no difference in the mean ASTR measurement between patients with and without wound complications (1.36 vs. 1.40, P=0.093). Conclusion: This study does not demonstrate a statistically significant difference in post-operative TAA wound complications based on standardized radiographic soft tissue thickness measurements. Though not statistically significant, complications were more frequent in patients with a lower ASTR. Lower surgical site soft tissue thickness may be a predictor of increased risk for wound complications following TAA however further research including studies with larger patient populations is needed to make this determination.