Targeted Muscle Reinnervation for the Prevention and Treatment of Postamputation Pain and Improvement of Prosthetic Function: A Systematic Review

Abstract

PURPOSE: Targeted muscle reinnervation (TMR) is a surgical technique where transected nerves in amputated limbs are redirected to new motor targets.1 TMR was originally developed to enhance prosthetic control following amputation but has recently also become popular for managing postamputation pain.2 Standardized outcome measures and time points to evaluate pain and prosthetic function in these patients have not yet been established. We aim to identify and recommend assessment tools used to assess pain and prosthetic function following TMR, as well as to summarize early results. METHODS: A comprehensive search of literature was conducted using 5 bibliographic databases. Two independent reviewers screened abstracts and full-text articles to select studies describing postamputation pain and/or prosthetic function outcomes of TMR. Methodological quality was appraised using the Newcastle-Ottawa Scale (NOS) and Cochrane Risk of Bias tool (RoB). Studies with duplicate patient populations were identified. Data were extracted including timing of TMR with respect to amputation, location of amputation, and measured pain and/or prosthetic function outcomes. Differences between reviewers were resolved through consensus. RESULTS: A total of 476 articles were identified, of which 62 were selected for full-text screening and 16 studies were included. Studies from 8 institutions were represented, including 4 cohort studies and 1 randomized controlled trial.3 Overall, 253 unique patients underwent TMR. One hundred (39.53%) patients were male and 40 (15.81%) were female. Ten studies assessed pain outcomes and 7 described prosthetic function outcomes. Three assessment tools were used to analyze pain: Patient-Reported Outcomes Measurement Information System (PROMIS) in 3 studies, Numerical Rating Scale (n = 2), and Visual Analogue Scale (n = 3). Studies showed decreased prevalence of neuroma pain and phantom limb pain (PLP) following primary TMR compared to amputation only. Prevalence of pain following secondary TMR also decreased postoperatively, although intensity of PLP transiently increased. Primary TMR lead to a greater decrease in PROMIS pain scores compared to amputation only, although there was no significant difference in pain scores following secondary TMR compared to standard neuroma excision treatment. Nine assessment tools were used to evaluate prosthetic function, including box-and-block test (n = 5), clothespin relocation test (n = 4), and amputee mobility predictor (n = 3). Of the 5 studies using box-and-block test, 4 demonstrated improved prosthetic function following TMR. CONCLUSIONS: Early reports of TMR for the prevention and treatment of postamputation pain are convincing, although the variation in prosthetic training time and scarcity of comparative studies makes it difficult to determine comparative effectiveness for prosthetic function. We recommend that future prospective studies evaluating pain and prosthetic function deploy common assessment tools, such as PROMIS and box-and-block test, at consistent time points. REFERENCES: 1. Cheesborough JE, Smith LH, Kuiken TA, et al. Targeted muscle reinnervation and advanced prosthetic arms. Semin Plast Surg. 2015;29:62–72. 2. Souza JM, Cheesborough JE, Ko JH, et al. Targeted muscle reinnervation: a novel approach to postamputation neuroma pain. Clin Orthop Relat Res. 2014;472:2984–2990. 3. Dumanian GA, Potter BK, Mioton LM, et al. Targeted muscle reinnervation treats neuroma and phantom pain in major limb amputees: a randomized clinical trial. Ann Surg. 2019;270:238–246.