Processed acellular nerve allograft vs. autograft in peripheral nerve gap repair: a narrative review

Abstract

Background: peripheral nerve lesions with loss of continuity require, when direct repair without tension is not possible, a material that bridges the defect; The autograft is the reference standard, but it entails morbidity of the donor area. The processed acellular nerve allograft avoids this morbidity, and its clinical use has grown despite comparative evidence that is still disputed. Objective: To synthesize evidence published between 2016 and 2026 comparing processed acellular allograft versus autograft in peripheral nerve gap reconstruction, with emphasis on functional recovery and donor site morbidity according to defect length. Methods: A narrative review structured according to the SANRA scale, with searches of PubMed/MEDLINE, Scopus, Web of Science, Embase, and the Cochrane Library (2016–2026; English and Spanish), complemented by manual search and citation tracing. Results: Seven studies (clinical synthesis, a multicenter registry, and a pre-clinical meta-analysis) were included. In short and medium gaps, especially sensitive—the allograft and autograft showed comparable recovery, both outperforming the canal. Equivalence weakens with increasing defect length and in motor or mixed nerves, where evidence is scarce and the preclinical signal favors autografting. We did not identify any randomized, independent, head-to-head trials. Conclusions: The equivalence between allograft and autograft is conditional: reasonable in short sensory defects, where the allograft avoids donor morbidity, and insufficiently supported in long, motor, or mixed defects, in which autograft remains the reference option. An independent randomized trial that resolves equivalence according to length is required.