TMRpni Decreases Long-term Narcotic Use in Amputees: A Case Control Study

Abstract

PURPOSE: “TMRpni” is a novel management strategy combining the well-described technique of targeted muscle reinnervation (TMR), which coapts a sensory or mixed nerve to a motor nerve, with the more recently described regenerative peripheral nerve interface (RPNI) technique, in which the coaptation is insulated with an autologous free muscle graft.1 The goal of this combined procedure is to optimally reduce neuroma and phantom limb pain in amputees. The purpose of this study was to evaluate the effect of TMRpni on opioid consumption after amputation. We hypothesized that TMRpni decreases chronic opioid consumption. METHODS: We performed a retrospective case control study evaluating opioid refills within 30 days of surgery, after 30 days, and after 90 days. The cases comprised all patients who underwent amputation at a single center from April 2019 to February 2021 with immediate or delayed TMRpni. These were then age matched 1:1 with patients who underwent same level amputation without TMR or RPNI between January 2015 and December 2020. Data collected included patient demographics, comorbidities, operative details, and pre- and postoperative opioid use. IBM SPSS Version 25 was used to perform the statistical analysis with the Fisher T test. RESULTS: 32 patients underwent TMRpni during the study period and were matched to 32 controls. Two controls were eliminated due to incomplete data. There were 13 TMRpni patients (43%) and 15 control patients (50%) who refilled narcotics within 30 days (P = 0.79), and 9 TMRpni patients (30%) and 11 control patients (37%) still using narcotics after 30 days (P = 0.78). However, at the 90-day interval following surgery, there were significantly fewer TMRpni patients requiring opioid pain medication than the control group (7% versus 33%, P = 0.02). CONCLUSIONS: This study demonstrates that the combination technique of TMRpni may decrease chronic opioid use in amputees. Continued study is indicated to further elucidate the potential benefits of TMRpni in amputees and to optimize patient selection and technique. The long-term efficacy and how it compares with TMR versus RPNI alone remain unknown. REFERENCE: 1. Kurlander DE, Wee C, Chepla KJ, et al. TMRpni: combining two peripheral nerve management techniques. Plast Reconstr Surg Glob Open. 2020;8(10):e3132.