Outcomes of Targeted Muscle Reinnervation and Regenerative Peripheral Nerve Interfaces for Chronic Pain Control in the Oncologic Amputee Population

BACKGROUND: Outcomes of targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI) in the oncologic population are limited. We sought to examine the safety and effectiveness of TMR and RPNI in controlling postamputation pain in the oncologic population. STUDY DESIGN: A retrospective cohort study of consecutive patients who underwent oncologic amputation followed by immediate TMR or RPNI was conducted from November 2018 to May 2022. The primary study outcome was postamputation pain, assessed using the Numeric Pain Scale and Patient-Reported Outcomes Measurement Information System (PROMIS) for residual limb pain (RLP) and phantom limb pain (PLP). Secondary outcomes included postoperative complications, tumor recurrence, and opioid use. RESULTS: Sixty-three patients were evaluated for a mean follow-up period of 11.3 months. The majority of patients (65.1%) had a history of previous limb salvage. At final follow-up, patients had an average Numeric Pain Scale score for RLP of 1.3 ± 2.2 and for PLP, 1.9 ± 2.6. The final average raw PROMIS measures were pain intensity 6.2 ± 2.9 (T-score 43.5), pain interference 14.6 ± 8.3 (T-score 55.0), and pain behavior 39.0 ± 22.1 (T-score 53.4). Patient opioid use decreased from 85.7% preoperatively to 37.7% postoperatively and morphine milligram equivalents decreased from a mean of 52.4 ± 53.0 preoperatively to 20.2 ± 38.4 postoperatively. CONCLUSIONS: In the oncologic population TMR and RPNI are safe surgical techniques associated with significant reductions in RLP, PLP, and improvements in patient-reported outcomes. This study provides evidence for the routine incorporation of TMR and RPNI in the multidisciplinary care of oncologic amputees.