Targeted Muscle Reinnervation at the Time of Amputation Reduces Pain Severity in Upper Extremity Amputations
Andrew L. O'Brien, MD, MPH1, Sumanas Jordan, MD, PhD1, Jason Hehr, MD1, Julie West, PA-C1, Steven Schulz, MD1, Gregory A. Dumanian, MD, FACS2, Ian L. Valerio, MD, MS, MBA1.
1Ohio State University Wexner Medical Center Department of Plastic and Reconstructive Surgery, Columbus, OH, USA, 2Northwestern University Division of Plastic Surgery, Chicago, IL, USA.
Background: Targeted muscle reinnervation (TMR) is a technique for the management of peripheral nerves in amputees. As a pain management strategy, TMR aims to address symptomatic neuromas, which are disorganized ends of severed nerve fibers encased in scar. Neuromas are often responsible for much of the residual limb pain (RLP) experienced by people living with limb loss, limiting function and making the use of prostheses uncomfortable, or even impossible. Moreover, uncontrolled neuromas may be a driver of phantom limb pain (PLP), or the feeling of discomfort in the non-existent limb. We have employed TMR as a means to prevent such pain when performed in the index upper extremity amputation procedure setting.
Methods: A retrospective review of all patients who underwent upper extremity amputation with concurrent TMR was performed. Pain severity was assessed using the National Institutes of Health-funded Patient-Reported Outcome Measurement Information System (PROMIS) Pain Intensity Short Form 3a, which assesses the intensity of pain over a 7-day recall period. Our TMR cohort was compared to benchmarked data from an unselected population of upper extremity amputees.
Results: Fifteen patients who underwent upper extremity TMR at the time of amputation were identified and were compared to 55 patients who underwent upper extremity amputation without TMR. Median follow-up time was 13.3 months with a range of 5.3 months to 5.3 years. Among TMR patients, 26.7% underwent transradial amputation, 26.7% transhumeral amputation, and 46.7% underwent shoulder disarticulation. Mean PROMIS PLP intensity t-score for the general amputee population was 47.02 versus 37.06 in the acute TMR population (p=0.002), confirming a statistically significant reduction in PLP for the acute TMR cohort. PROMIS pain intensity for RLP trended towards benefit with TMR (44.68 versus 39.7, p=0.143). Nine patients (60%) were using a prosthetic at most recent follow-up. Average time to prosthetic use was 4.7 months.
Conclusion: In addition to the established benefit of TMR for myoelectric prosthetic control, our study demonstrates that TMR performed at the time of amputation is a promising strategy for improving phantom and residual limb pain severity in the upper extremity. TMR performed at time of index operation is cost effective, technically easier, and eliminates the need for a delayed TMR procedure. Furthermore, TMR at time of amputation permits the amputee patient earlier prosthetic rehabilitation without need for secondary delays or time without their prosthetic to permit soft tissue healing in delayed cases.
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