Assessing the Risk of Perioperative Complications after Targeted Muscle Reinnervation and below Knee Amputation: A Multi-institutional, Propensity Score-matched Analysis

Abstract

PURPOSE: Targeted muscle reinnervation (TMR) has emerged as a technique to reduce neuroma and phantom limb pain after below knee amputation (BKA). While the benefits of TMR on postamputation pain continue to be reported, the addition of a separate procedure increases operative time and often introduces a second surgical team, both of which may increase the risk for postoperative complications such as surgical site infection and delayed wound healing. This multi-institutional study assessed the risk of postoperative complications among patients who underwent TMR at the time of BKA (BKA+TMR) as compared with BKA only. METHODS AND MATERIALS: Patients at Duke University and the University of Pennsylvania (2018–2020) who underwent BKA+TMR were propensity score-matched to patients who underwent BKA only. The primary outcome of this study was the incidence of major complications within 60 days among patients who underwent a BKA versus BKA with TMR. Major complications were defined as those that required a readmission, transfer to the intensive care unit (ICU), reoperation, or a cause of death related to the amputation procedure. Minor complications were classified as those which occurred that were managed as an outpatient. Regression models were utilized to estimate the relative risk (RR) of major and minor complications. RESULTS: Overall, 96 patients were matched, including 31 BKA+TMR and 65 BKA only. In the matched sample, a slightly higher incidence of major complications (29% versus 24.6%) and minor complications (25.8% versus 20.0%) was seen after BKA+TMR. Furthermore, patients who underwent BKA+TMR displayed a longer operative time [mean (standard deviation) 188.5 (63.6) versus 88 (28.2) minutes]. When evaluating the risk of experiencing major or minor complications, there was no statistically significant difference in the risk of major (RR: 1.20, 90% confidence interval: 0.68, 2.11) or minor (RR: 1.21, 90% confidence interval: 0.61, 2.41) complications between the two cohorts. CONCLUSIONS: This propensity-matched study assessed the risk of perioperative complications among patients who undergo a BKA+TMR. Our study suggests that patients who undergo a TMR at the time of BKA display no statistically significant increased risk of major or minor complications relative to a matched cohort. In patients with multiple medical comorbidities or those who are anticipated to have a prolonged operative time, a “delayed” or “secondary” approach to TMR may be considered to reduce the incidence of adverse postoperative outcomes in a high-risk patient population. Future studies are needed to further elucidate the impact of TMR on postoperative complications to better delineate patient selection criteria when assessing the suitability of primary TMR at the time of major limb amputation.