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Analysis of Quantitative Endpoints from a Multicenter Retrospective Registry Study on the Use of Acellular Nerve Grafts for Sensory, Mixed, and Motor Nerve Reconstructions
Darrell Brooks, MD1, Renata V. Weber, MD2, Jerome J. Chao, MD3, Brian D. Rinker, MD4, Jozef Zoldos, MD5, Michael R. Robichaux, MD6, Sebastian B. Ruggeri, MD7, Kurt A. Anderson, MD8, Ekkehard Bonatz, MD9, Scott M. Wisotsky, MD10, Mickey S. Cho, MD11, John V. Ingari, MD12, Brian M. Parrett, MD1, Bauback Safa, MD1, Gregory M. Buncke, MD1.
1California Pacific Medical Center, San Francisco, CA, USA, 2Montefiore Medical Center, Bronx, NY, USA, 3Albany Medical Center, Albany, NY, USA, 4University of Kentucky, Lexington, KY, USA, 5Arizona Center for Hand Surgery, Phoenix, AZ, USA, 6Baton Rouge Orthopaedic Clinic, Baton Rouge, LA, USA, 7Affiliated Arm, Shoulder and Hand Clinic, Phoenix, AZ, USA, 8Orthopaedic Specialty Clinic of Spokane, Spokane, WA, USA, 9Southlake Orthopaedics, Birmingham, AL, USA, 10Tampa Bay Orthopaedic Specialist, Pinellas Park, FL, USA, 11Brooke Army Medical Center, San Antonio, TX, USA, 12The San Antonio Hand Center, San Antonio, TX, USA.
PURPOSE: To report the outcomes data collected from an ongoing multi-center retrospective study on the use of processed nerve allograft (Avance® Nerve Graft, AxoGen, Inc) for sensory, mixed and motor nerve reconstruction.
METHODS: Twelve centers encompassing 25 surgeons have reported their experiences with the Avance® Nerve Graft between 2007-2010 resulting in a database of 108 subjects with 132 repairs. Subjects who have provided sufficient follow-up assessments (SFU) to evaluate functional outcomes were placed into the Outcomes Population (OP). To qualify for this population, subjects had to have reported follow-up assessments at a time-point commiserate with the approximated distance for re-innervation, based on estimated 2 mm/day regeneration. The OP currently consists of 59 subjects with 76 nerve repairs. Chart reviews were completed in a retrospective fashion to collect subject, injury and repair demographics. Follow-up data points for safety and functional outcomes were collected in an observational manner. Data points for quantitative assessments included 2-point discrimination, Semmes-Weinstein monofilament testing, electromyography, range of motion, grip/pinch strength and Medical Research Council Classification of recovery following nerve injury (MRCC). Qualitative assessments include surgeon, subject or physical therapy descriptions of function. All data points were collected on standardized study case report forms and organized into a centralized study database for analysis. SAS/STAT® software was utilized for the data analysis (Statistical Analysis Systems, 2011). Data was segregated to perform population analysis for utilization, safety, and efficacy outcomes. Chi-square analysis was performed to determine whether there were statistical differences between populations.
RESULTS: Our study contained 49 Sensory, 18 Mixed and 9 Motor nerves treated with processed nerve allograft. Nerve graft lengths ranged from 5 mm to 50mm with a mean of 22 ± 11 mm. Subject age ranged from 18 to 86 years with a mean of 41 ± 16 years. Meaningful levels of functional recovery were achieved in 89% of Sensory, 77% of Mixed and 86% of Motor nerve injuries. Meaningful recovery was observed regardless of type of nerve, time-to-repair (TTR), nerve gap up to 50mm, and age. (Fig. 1) No graft related adverse experiences were reported and a 5% revision rate was observed.
CONCLUSIONS: Avance® Nerve Graft was shown to be safe and effective for nerve gaps between 5 mm and 50 mm. These outcomes compare favorably with those reported in the literature for nerve autograft and nerve conduit. This study challenges the current outcome expectations for nerve reconstructions across large gaps, increased patient age, unfavorable mechanism of injury, and nerve type (motor, mixed) and establishes a foundational understanding for this alternative nerve repair method. Continuation of this study will allow for construction of an increasingly robust database to provide additional recovery data after nerve repair with processed nerve allografts.
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