Early Postoperative Pain Course following Primary and Secondary Targeted Muscle Reinnervation: A Temporal Description of Pain Outcomes.

Background:  Targeted muscle reinnervation (TMR) is an effective surgical treatment of neuropathic pain for amputees. However, limited data exist regarding the early postoperative pain course for patients who undergo either primary (<14 days since amputation) or secondary (≥14 days) TMR. This study aims to outline the postoperative pain course for primary and secondary TMR during the first 6 postoperative months to aid in patient education and expectation management.

Methods:  Patients were eligible if they underwent TMR surgery between 2017 and 2023. Prospectively collected patient-reported outcome measures of pain scores, Pain Interference, and Pain Intensity were analyzed. Multilevel mixed-effects models were utilized to visualize and compare pain courses between primary and secondary TMR patients.

Results:  A total of 203 amputees were included, with 40.9% being primary and 59.1% being secondary TMR patients. Primary TMR patients reported significantly lower pain scores over the full 6-month postoperative trajectory (p < 0.001) compared with secondary TMR patients, with a difference of Δ -1.0 at the day of TMR (primary = 4.5, secondary = 5.5), and a difference of Δ -1.4 at the 6-month mark (primary = 3.6, secondary = 5.0). Primary TMR patients also reported significantly lower Pain Interference (p < 0.001) and Pain Intensity scores (p < 0.001) over the complete trajectory of their care.

Conclusion:  Primary TMR patients report lower pain during the first 6 months postoperatively compared with secondary TMR patients. This may reflect how pre-existing neuropathic pain is more challenging to mitigate through peripheral nerve surgery. The current trends may assist in both understanding the postoperative pain course and managing patient expectations following TMR.

Level of evidence:  Therapeutic - IV.