D59. The Long-term Postoperative Pain Course Following Primary and Secondary Targeted Muscle Reinnervation in Amputees

PURPOSE: Targeted muscle reinnervation (TMR) is effective in the surgical treatment of neuropathic pain for amputees. However, the long-term postoperative pain course for patients that undergo primary or secondary TMR surgery is not clearly known. This study aims to describe the long-term postoperative pain course to aid in managing postoperative expectations. METHODS: Chart review was performed for amputees who underwent primary or secondary TMR and were prospectively enrolled between 2018 and 2023 (minimum follow-up: 12 months). Pain scores (Numerical Rating Scale 0-10) were collected. Mean NRS pain levels were compared between primary and secondary TMR cohorts. Multilevel mixed-effects models were utilized to analyze pain courses. RESULTS: Forty-nine amputees (62% secondary TMR patients) were included. The median follow-up was 2.3 years (IQR: 1.6-2.9). Primary TMR patients achieved average mild pain levels at 12 months (2.8, versus 4.0 for secondary TMR patients (p=0.013)) before stabilizing. Secondary TMR patients reached an average mild pain level after 36 months (NRS=2.9, versus 2.2 for primary TMR patients (p=0.233)). The difference in pain between primary and secondary TMR patients is significantly different from the 6-month through the 30-month post-operative period (p<0.050). CONCLUSION: Primary TMR reached low levels of pain at 12 months before stabilizing. Secondary TMR patients demonstrate slower but consistent decline in pain levels. These trends may assist in understanding the long-term postoperative pain course and counseling patients in pain expectations following TMR.