Decellularized Peripheral Nerve Allografts for Nerve Gap Reconstruction in Humans: A Systematic Review of Clinical Outcomes

Title: Decellularized Peripheral Nerve Allografts for Nerve Gap Reconstruction in Humans: A Systematic Review of Clinical OutcomesBackground: Peripheral nerve injuries resulting in significant gaps require grafting to restore function. While autologous nerve grafts (ANG) remain the clinical gold standard due to the presence of viable Schwann cells, they are associated with donor-site morbidity and limited availability. Decellularized or processed nerve allografts (PNA) have emerged as a significant alternative to bridge these gaps without the need for a secondary donor site. Objective: The primary goal of this systematic review is to evaluate the clinical efficacy and safety of human implantation of decellularized/processed peripheral nerve allografts. The review focuses on motor and sensory recovery rates, functional outcomes (e.g., MRC grades, DASH scores), and reported complications.Methods: This study follows the PRISMA guidelines. A systematic search was conducted across PubMed, Embase, and Scopus to identify clinical studies involving human subjects. Inclusion criteria focus on original studies (RCTs, cohorts, and case series) reporting on nerve-level outcomes. Data extraction includes patient demographics, gap length, nerve type, and recovery scores (Motor MRC and Sensory S0-S4). Risk of bias is assessed using validated tools (Newcastle-Ottawa Scale and JBI).Registration Note: This protocol is archived post-hoc on Zenodo to ensure transparency and prevent publication bias. Formal registration with PROSPERO was not possible as the study had progressed past the initial data extraction phase at the time of submission.