Regenerative Peripheral Nerve Interface Surgery to Treat Chronic Postamputation Pain: A Prospective Study in Major Lower Limb Amputation Patients.

Objective: The objective was to assess the postsurgical outcomes of regenerative peripheral nerve interface (RPNI) surgery in a prospective cohort of major lower extremity amputation patients with chronic postamputation pain.

Background: Chronic pain in lower limb amputation patients is commonly the result of neuroma formation after traumatic peripheral nerve injury. By implanting more proximal transected nerve ends into autologous free muscle grafts, RPNI surgery can treat postamputation pain by diminishing the development of neuromas. RPNI surgery in prior retrospective studies has been shown to mitigate postamputation pain.

Methods: Twenty-two lower limb amputation patients with established chronic postamputation pain were recruited from 2 studies in this prospective study. All patients underwent RPNI surgery to treat identified symptomatic neuromas within the residual limb. Patient-reported outcome instruments were administered preoperatively and postoperatively at 1 week, 4 months, and 12 months to examine residual limb pain (McGill Pain Questionnaire, PROMIS Pain Intensity, and PROMIS Pain Interference), phantom limb pain (modified PROMIS Pain Intensity and Phantom Limb sensation questionnaire), psychosocial status (PHQ-9, GAD-7, and PCS), and functional (OPUS) outcomes.

Results: RPNI surgery significantly improved residual limb pain. While phantom limb sensation improved significantly, phantom limb pain demonstrated a modest decrease. Psychosocial outcomes also improved significantly after RPNI surgery. Prosthetic use slightly increased, and patients did not experience loss of function.

Conclusions: RPNI surgery leverages the processes of reinnervation to successfully treat residual limb pain and improve psychosocial outcomes in patients with chronic postamputation pain. Phantom limb pain may be more difficult to treat in chronic pain patients who have central sensitization at the time of surgery.