Postoperative Imaging Characteristics of Targeted Muscle Reinnervation and Regenerative Peripheral Nerve Interfaces

Targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI) procedures can mitigate the incidence of neuroma; however, neuromas may still form. Interval soft tissue changes at the site of these nerve constructs may pose a diagnostic challenge. This review examined existing literature on ultrasound (US) and magnetic resonance imaging (MRI) characteristics of TMR and RPNI to aid in their identification.

A literature review was conducted using the PubMed, Embase, Cochrane, and Web of Science databases following the preferred reporting items for systematic reviews and meta-analyses 2020 protocol to examine studies describing imaging characteristics of TMR and RPNI in humans. Studies were screened by 2 authors. Studies that described imaging characteristics of TMR and RPNI were included.

The review yielded 623 articles. Ten articles were identified for full-text review, and 4 met the inclusion criteria. One article described the US appearance of TMR. Two articles described the US characteristics of RPNI. One article described the appearance of RPNI on MRI. A total of 44 patients, 70 RPNIs, and 6 TMRs were included.

The characterization of TMR and RPNI on US and MRI is limited, particularly regarding upper extremity TMR and RPNI. TMR and RPNI demonstrate consistent core features on US and MRI. When monitoring patients for pain postamputation, plastic surgeons should be aware of the expected changes to the nerve and surrounding soft tissues after TMR and RPNI to aid in clinical judgment of new soft tissue lesions identified on imaging after amputation.