Update/Refinement of Targeted Muscle Reinnervation Indication: A Scoping Review of Applications for Non-Amputees

Background: Targeted muscle reinnervation (TMR) was originally developed to enhance prosthetic control in amputees. However, it has also serendipitously demonstrated benefits in reducing phantom pain and neuromas. As a result, it has emerged as a secondary treatment for chronic neuromas in amputees and holds promise for managing neuropathic pain in non-amputee patients, particularly those with neuromas. This review synthesizes the current literature on TMR indications for non-amputee patients, highlighting its potential to address chronic peripheral nerve pain and neuromas beyond its original application in amputation. Methods: A thorough search of the PubMed and Cochrane databases up to January 2024 was conducted following the PRISMA guidelines. Inclusion criteria comprised case series, cohort studies, and randomized controlled trials reporting TMR outcomes in non-amputees. Results: Of 263 articles initially identified, 8 met the inclusion criteria after screening and full-text assessment. The articles were all case series with varied sample sizes and mainly focused on neuroma treatment (n = 6) and neuropathic pain management (n = 2) for both upper and lower extremities. Clinical studies included TMR efficacy for sural nerve neuromas in the lower extremities and hand neuromas, showing pain relief and improved function. Key findings were encouraging, showing successful pain relief, patient satisfaction, and psychosocial improvement, with only rare occurrences of complications such as motor deficits. Conclusions: In non-amputee patients, TMR appears to be a promising option for the surgical management of neuropathic pain, demonstrating favorable patient satisfaction and psychosocial outcomes along with low morbidity rates. Although functional improvements in gait recovery and range of motion are encouraging, further research will be important to confirm and expand upon these findings.