Demystifying Targeted Muscle Reinnervation: A Systematic Review of Nerve Transfers for the Lower Extremity.

Targeted muscle reinnervation (TMR) outcome studies reveal the benefit amputees experience and the potential functional improvement by optimizing neurocutaneous signaling for myoelectric prosthesis control. However, there are still many settings where these techniques are not offered to patients requiring lower extremity amputations or neuroma reconstruction. With growing consistency in the literature, it is helpful to systematize the nerve transfers described for lower extremity TMR and to simplify its integration into reconstructive care. Methods: A systematic literature review was performed and contained the following inclusion criteria: original cases of primary or secondary lower extremity amputation defects or nerve-related pain that underwent TMR with clearly described target muscles for each nerve transfer. Studies were excluded if the cases had been previously described or contained incomplete data. The primary outcomes were nerves transferred and muscles targeted. Target muscle options were presented in tables specific to anatomic region, and cross-sectional schematics were created for intraoperative assistance. Results: Seventeen studies presenting original cases with clearly described nerve transfers and target muscles in the lower extremity were included in the review. Target muscle selection for all nerve transfers at the transfemoral and transtibial levels were presented in separate tables. Conclusions: Reports of early experience at multiple institutions identify trends in the selection of certain target muscles for nerve transfers in transfemoral and transtibial TMR. Familiarity with these common target muscles and nerve transfers can simplify intraoperative decision-making and enhance integration of lower extremity TMR in amputation care and in the treatment of nerve-related pain.