American Society for Peripheral Nerve
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Outcomes of Peripheral Nerve Operations combined with Regenerative Peripheral Nerve Interfaces in the Treatment of Chronic Neuropathic Knee Pain
Gabriela Cinotto, MD1; Katherine L Burke, MD1; Erin Guy, BS1; Jennifer B. Hamill, MPH1; Paul S Cederna, MD2; Stephen WP Kemp, PhD1; David L Brown, MD1
1University of Michigan, Ann Arbor, MI; 2Plastic Surgery, University of Michigan, Ann Arbor, MI

Background: Chronic neuropathic knee pain can result from an injury or operation. Previous estimates suggest that up to 40% of patients experience neuropathic pain following total knee arthroplasty. Previous reports of the treatment of neuroma pain and phantom pain associated with amputation with the combination of neurectomy and nerve end wrapping with Regenerative Peripheral Nerve Interfaces (RPNI, free muscle grafts) and/or Dermal Sensory Regenerative Peripheral Nerve Interfaces (DS-RPNI, free dermal grafts) have shown promise in effecting pain relief. In this study, we investigated the benefits of both interfaces on the reduction of chronic neuropathic knee pain.
Methods: A retrospective chart review was conducted on patients with chronic neuropathic knee pain who were treated between June 2017 and January 2022 with neurectomy and RPNI/DS-RPNI and/or nerve decompression (Fig.1). All patients were diagnosed with peripheral neuropathy with a history, physical exam (focal tenderness, paresthesias, and/or Tinel sign), and greater than 50% reduction in pain score following local anesthetic nerve block.
Results: Post-operative outcomes were evaluated in 13 patients (Table1). Three patients (23%) underwent RPNI creation, and seven patients (54%) underwent DSRPNI creation (Table.1). A total of 22 RPNIs and DSRPNIs were constructed with an average of 1.37 per limb (Table.2). All patients treated with RPNI or DS-RPNIs reported a significant reduction of neuropathic knee pain, ranging from 7.46 2.0 preoperatively to 0.460.96 at 3 months or greater (average 27 months) post-operative evaluation (P = 0.0002) (Fig.2).
Conclusions: By providing free muscle and dermal grafts as physiologic target tissues for peripheral nerve reinnervation, both RPNIs and DS-RPNIs take advantage of the process of nerve sprouting, reinnervation, and prevention of neuroma formation. Both surgical procedures were associated with a significant reduction in pain scores, and limited complications were reported.




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