54. one year outcomes after regenerative peripheral nerve interface surgery for postamputation pain: results of a prospective clinical trial

PURPOSE: Postamputation pain decreases quality of life, prosthetic use, and functional status. Regenerative peripheral nerve interface (RPNI) surgery can treat and prevent postamputation pain. This prospective clinical trial examines the effects of RPNI surgery on postamputation pain, psychosocial wellbeing, and prosthetic use. METHODS: Arm 1 included patients undergoing RPNI surgery to treat existing postamputation pain (pre- versus post-comparison). Arm 2 compared patients undergoing prophylactic RPNI surgery at the time of initial lower limb amputation to those undergoing standard of care amputation (control). The primary endpoint was 1-year after RPNI surgery. Measures included the McGill Pain Questionnaire (MPQ), Amputation Pain, Phantom Pain, Patient-Reported Outcomes Measurement Information System instruments, Orthotics and Prosthetics Users’ Survey (OPUS), Patient Health Questionnaire-9, and Generalized Anxiety Disorder-7 (GAD). Analysis included calculation of standardized mean difference (effect size, d) and t-tests. RESULTS: To date, 86 patients have been enrolled (Arm 1=21; Arm 2=65). In both Arms, RPNIs were associated with favorable 1-year outcomes. In Arm 1, RPNIs had the greatest effect size in improving outcomes on the MPQ (d=-0.86; p=0.186) and GAD (d=-1.27; p=0.009). In Arm 2, compared to controls, RPNI patients had the greatest effect size in improving Amputation Pain (d=-1.19; p=0.003), Phantom Pain (d=-1.15; p=0.005), and MPQ (d=-1.13; p=0.064). CONCLUSION: This clinical trial supports the use of RPNI surgery to treat and prevent postamputation pain. Prophylactic RPNI surgery has significant effects in improving postamputation pain. RPNI surgery also showed improved anxiety and pain in patients with existing postamputation pain.