American Society for Peripheral Nerve

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Use of Processed Nerve Allografts to Repair Nerve Gap Injuries Greater than 25mm in the Hand
Brian Rinker, MD1; Jozef Zoldos, MD2; Renata V. Weber, MD3, Jason H Ko, MD4, Wesley Thayer, MD, PhD5, Jeffrey Greenberg, MD6; Fraser J. Leversedge, MD7; Bauback Safa, MD, MBA, FACS8; Gregory M Buncke, MD8
1Division of Plastic Surgery, University of Kentucky, Lexington, KY, 2Arizona Center for Hand Surgery, Phoenix, AZ, 3Institute for Nerve, Hand and Reconstructive Surgery, Rutherford, NJ, 4Division of Plastic and Reconstructive Surgery, University of Washington, Seattle, WA, 5Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN, 6Indiana Hand to Shoulder Center, Indianapolis, IN, 7Department of Orthopaedic Surgery, Duke University, Durham, NC, 8The Buncke Clinic, San Francisco, CA

Introduction: Recent research has shown that processed nerve allografts (PNA) have improved clinical results compared to hollow conduits for reconstruction of digital nerve gaps less than 25 mm. However, the utility of PNAs as a nerve autograft alternative in injuries involving longer gaps warrants further clinical investigation. Long nerve gaps have been traditionally hard to study due to low incidence. We queried a large national registry to examine the efficacy of PNA in the reconstruction of long gaps.

Materials & Methods: The RANGER registry is an IRB approved, active database for PNA (Avance® Nerve Graft, AxoGen, Inc). The database was queried for digital nerve repairs ≥ 25 mm. Demographics, injury, treatment, and functional outcomes were recorded on standardized forms. Patients younger than 18, and those lacking quantitative follow-up data were excluded. Recovery was graded according to the Medical Research Council Classification (MRCC) for sensory function, with meaningful recovery defined as ≥ S3. Outcomes were compared to historical data for nerve autograft reconstructions.

Results: Fifty digital nerve injuries in 28 subjects were included. There were 22 males and 6 females, and the mean age was 45. Three patients gave a prior history of diabetes, and there were six active smokers. The most commonly reported mechanisms of injury were saw injuries (n=13), crushing injuries (n=9), resection of neuroma (n=9), amputation/avulsions (n=8), sharp lacerations (n=7), and blast/gunshots (n=4). The average gap length was 35 ± 8 mm (range 25-50 mm). Recovery to the S3 or greater level was reported in 86% of repairs. Static two point discrimination (s2PD) and Semmes-Weinstein monofilament (SMF) were the most common completed assessments. Mean s2PD in 24 repairs reporting 2PD data was 9 ± 4 mm. For the 38 repairs with SWF data, protective sensation was reported in 33 repairs, deep pressure in 2, and no recovery in 3. These data compared favorably to historical data for nerve autograft repairs, with reported levels of meaningful recovery of 60-88%. There were no reported adverse effects.

Conclusions: Processed nerve allograft can be used to reconstruct long gap nerve defects in the hand with consistently high rates of meaningful recovery. Results for PNA repairs of digital nerve injuries with gaps longer than 25 mm compare favorably to historical reports for nerve autograft repair, but without donor site morbidity.

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