American Society for Peripheral Nerve

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Neuroma Prevention with Prophylactic Regenerative Peripheral Nerve Interface Placement
Carrie A Kubiak, MD1; Paul S. Cederna, MD2; Stephen WP Kemp, PhD1; Theodore A Kung, MD3; (1)University of Michigan, Ann Arbor, MI, (2)Section of Plastic Surgery, University of Michigan, Ann Arbor, MI, (3)Section of Plastic & Reconstructive Surgery, University of Michigan, Ann Arbor, MI

Introduction: Regenerative Peripheral Nerve Interfaces (RPNIs) can be used to treat symptomatic end neuromas that develop after major limb amputation. Symptomatic neuromas occur in approximately 30-40% of individuals after limb loss and phantom limb pain affects 70-95% of these patients. We investigate the potential of prophylactic RPNIs to prevent neuroma formation and to mitigate the experience of phantom limb pain. Furthermore, we examine the potential complications resulting from the addition of prophylactic RPNIs to major limb amputation surgery.

Materials & Methods: At the time of amputation, RPNIs were performed by implanting transected peripheral nerves into free muscle grafts harvested from the amputated limb. Patients who underwent major limb amputation with simultaneous prophylactic RPNI implantation were identified. A retrospective chart review was performed to ascertain patient demographics, indication for amputation, level of amputation, characteristics of postamputation pain, perioperative pain management strategies, and postoperative complications. During follow up, all patients were evaluated for symptomatic neuromas and phantom limb pain through detailed history and physical exam.

Results: RPNIs were prophylactically implanted in 38 patients who underwent 44 major limb amputations. The mean patient age was 46 years (range 3-79) and mean follow up was 301 days (range 6-897). The most common indication for amputation was osteomyelitis from chronic wounds (n=11, 25%) followed by trauma (n=8, 18%). Below knee amputations comprised the majority of subjects (n=34, 77%). Major postoperative complications were defined as events that resulted in admission or surgery; one patient (2.6%) suffered residual limb infection necessitating operative washout. Minor complications included delayed wound healing (16%) and surgical site infection managed on an outpatient basis (9%). Fourteen patients (37%) reported symptoms of phantom limb pain during their postoperative course. Zero of the 142 surgical sites (0%) demonstrated any clinical evidence of symptomatic neuroma postoperatively.

Conclusions: Prophylactic RPNIs in major limb amputees resulted in a considerably lower incidence of both symptomatic neuromas and phantom limb pain as compared to published rates in the literature. Implantation of prophylactic RPNIs did not contribute to increased morbidity compared to standard amputation techniques. These findings suggest that prevention of peripheral nerve pain following major limb amputation may diminish the central pain mechanisms that lead to phantom limb pain. This pilot study supports prospective investigation of using RPNIs to significantly reduce postamputation pain.

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