Postoperative Outcomes Following Acute and Delayed Targeted Muscle Reinnervation and Regenerative Peripheral Nerve Interface in Upper-Extremity Amputees

BACKGROUND: Chronic postamputation pain is frequently caused by symptomatic neuroma formation. Advanced nerve interface procedures, including targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI), were developed to enhance prosthetic control and have been shown to reduce phantom and residual limb pain. However, data regarding how surgical timing relates to postoperative complications and reoperations remain limited. This study evaluated postoperative outcomes after acute and delayed TMR/RPNI in upper-extremity amputees. METHODS: We retrospectively analyzed 48 upper-extremity amputations in 42 patients who underwent TMR and/or RPNI. Procedures were classified as acute (prophylactic) or delayed (symptomatic). Baseline and operative variables were analyzed using Mann-Whitney U and chi-square tests. Multivariable logistic regression was used to evaluate the association between surgical timing and postoperative complications after adjustment. RESULTS: Of 48 limbs, 25 (52.1%) underwent acute and 23 (47.9%) delayed procedures. Baseline characteristics differed in smoking history, amputation etiology, and number of nerves treated. Complication rates were 20.0% and 21.7%, respectively. Wound-related complications occurred predominantly after acute procedures, whereas recurrent neuroma reoperations occurred predominantly after delayed procedures. Unexpected reoperation rates at 1 year were 12.0% and 21.7%, respectively. Mean 1-year pain scores were lower after acute than delayed procedures (2.09 vs 3.70). CONCLUSIONS: Acute and delayed TMR/RPNI had similar complication and reoperation rates, with differing event patterns. Surgical timing was not significantly associated with complications after adjustment, though meaningful differences cannot be excluded due to heterogeneity and limited power. These findings support individualized timing and the need for larger prospective studies including patient-reported outcomes.