The purpose of our project is to determine if incorporating preventative surgical techniques such as regenerative peripheral nerve interfaces (RPNI) into sural nerve biopsy can reduce the incidence of symptomatic neuroma formation. Findings from this study will inform best practice guidelines and can dramatically impact patient care, improve patient quality of life, and reduce the number of required repeat operations.

Neuromas are a known complication from traumatic injury or surgery, including nerve biopsies. Neuromas are formed by non-neoplastic aberrant proliferation of injured nerves that cannot innervate an end target resulting in a neuroma bulb made of free nerve ends, fibrotic tissue, and blood vessels. Neuromas can cause significant, debilitating pain resulting in decreased quality of life for patients and potential repeat operative interventions. The incidence rate of neuroma formation following injury is not well described but previous literature reports rates up to 30% with 14% of patients requiring repeat operation. In order to address this problem, numerous preventative and therapeutic measures have been explored. Nonsurgical management options such as desensitization, anesthetic and/or steroid injections, analgesia, and nerve stimulation have yielded mixed results.10 Therefore there is a need for reproducible and reliable prevention and treatment strategies for painful neuroma. Currently, the main surgical interventions consist of targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI). In TMR, free nerve ends are transferred onto recipient motor nerves, whereas in RPNI, free nerve ends are wrapped in a free muscle graft. Both methods provide denervated muscle targets for nerve ends. Compared to TMR, and other microsurgical measures such as primary repair or nerve grafting, RPNI is a much simpler operation that can easily be performed in the minor procedures or ward setting where nerve biopsies are usually completed. Given the functional impact from painful neuromas and subsequent burden on operative resources, efforts should be taken to prevent neuroma formation with RPNI at time of biopsy. Our project could directly improve patient care by substantiating the need for preventative measures for neuroma formation during for sural nerve biopsy thereby changing the standard of care. Given the significant pain, decreased quality of life, and need for repeat interventions, incorporating RPNI could have dramatic impacts on patient care and reduce operative and resources burdens.

Inclusion Criteria:

• Patient 18 years old and older who are referred for sural nerve and muscle biopsy to the University of British Columbia Division of Plastic Surgery from January 2025 onwards for diagnostic or prognostic clarification of a medical condition.

Exclusion Criteria:

• Patients with previous nerve trauma (traumatic injury, surgery, or repeat biopsy) of biopsied nerve.

Patients will be unaware whether they undergo sural nerve and muscle biopsy alone vs sural nerve, muscle biopsy, and RPNI