Can Processed Nerve Allografts be Used to Repair Nerve Injuries Greater than 4cm for the Return of Critical Function in the Upper Extremity?: Level 3 Evidence

Abstract

Consulting Fee: AxoGen, Inc. (Safa)Speakers Bureau: AxoGen, Inc. (Safa, Buncke)Contracted Research: Lead site for Axogen-sponsored RANGER study (Buncke) Recent animal studies suggest acellular nerve allografts may provide inadequate regeneration compared to autografts for gaps greater than 40mm in rodents. To examine whether this observation translates to clinical practice, we queried a national nerve registry on processed nerve allograft (PNA) with autograft controls for injuries between 40-70mm. Based on clinical evidence and historical controls, we hypothesized that PNA would perform similar to nerve autograft in long gap upper extremity nerve injuries in humans. The RANGER registry is an IRB-approved, active database designed to collect injury, repair, safety and outcomes data for processed nerve allografts (Avance® Nerve Graft, AxoGen, Inc). Recently active control groups for autograft and conduit repair were added to RANGER. The registry database was queried for >40mm upper extremity nerve repairs with at least 9 months of quantitative follow-up data. Subject demographics and injury information were also evaluated for observable trends. Outcomes data were incorporated into the Medical Research Council Classification (MRCC) for sensory and motor function with meaningful recovery defined as S3/M3 or higher on the MRCC scale. Outcomes were compared to registry matched controls and historical data for nerve autograft. Twenty-seven subjects with 35 injuries were included. The groups consisted of PNA (n = 23) and nerve autograft (n = 12). Subject demographics, medical history, and concomitant injuries were comparable. PNA repairs were single stranded, caliber matched epineural repairs, while autografts were multi-strand cabled repairs. The PNA group contained a higher incidence of neuroma resections of digital nerves repaired in a delayed fashion. The average gap was 46±6mm and 48±8 mm for PNA and nerve autograft respectively. Meaningful recovery was comparable between the groups at 74% for the PNA and 67% for nerve autograft. In mixed nerve repairs reporting motor function, outcomes were also comparable with 5 of 6 and 6 of 7 repairs reporting return of motor function in the PNA and autograft groups respectively. There were no reported adverse events related to the treatment groups. See Table 1 for summary. •Clinically reported levels of meaningful recovery for >40mm processed nerve allografts are comparable to nerve autografts with both sensory and motor function outcomes.•No adverse events or revisions were reported.•Outcomes compare favorably to historical literature for nerve autograft.•The registry remains ongoing and continues to collect outcomes data on processed nerve allografts in long gap nerve reconstructions.