The application of targeted muscle reinnervation in lower extremity amputations: A systematic review

Targeted muscle reinnervation (TMR) is a promising surgical modality for reducing post-amputation pain. We sought to provide a succinct overview of TMR specific to the lower extremity (LE) amputation population. A systematic review was performed per PRISMA guidelines. Ovid MEDLINE, PubMed, and Web of Science were queried for records using various combinations of Medical Subject Heading (MeSH) terms such as "LE "amputation," "below-knee amputation" (BKA), "above-knee amputation" (AKA), and "TMR." Primary outcomes included (1) operative techniques, (2) changes in neuroma, phantom limb pain (PLP), or residual limb pain (RLP), and (3) postoperative complications. Studies were only included if outcomes data were discretely provided for LE patients. Eleven articles examining 318 patients were identified. Average patient age was 47.5 ± 9.3 years, and most patients were male (n = 246, 77.4%). Eight manuscripts (72.7%) described TMR at the index amputation. The average number of nerve transfers performed per TMR case was 2.1 ± 0.8, and the most commonly employed nerve was the tibial (178/498; 35.7%). Nine (81.8%) articles incorporated patient-reported outcomes after TMR, with common methods including the Numerical Rating Scale (NRS) and questionnaires. Four studies (33.3%) reported functional outcomes such as ambulation ability and prosthesis tolerance. Complications were described in seven manuscripts (58.3%), with postoperative neuroma development being the most common (21/371; 7.2%). The application of TMR to LE amputations is effective in reducing PLP and RLP with limited complications. Continued investigations are warranted to better understand patient outcomes specific to anatomic location using validated patient-reported outcome measures (PROM).