Nerve Grafting for Axillary Nerve Injuries Following Shoulder Trauma: A Systematic Review of Surgical Outcomes

The axillary nerve is particularly susceptible to injury following shoulder trauma such as dislocation and fracture-dislocation, leading to loss of abduction, external rotation, and sensory deficits. Severe cases with loss of continuity require surgical intervention. Nerve grafting is the mainstay when direct repair is not feasible, though outcomes are influenced by timing, graft length, and patient selection. This review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. A systematic search of PubMed, Embase, Scopus, and the Cochrane Library was performed up to August 2025 using keywords including "axillary nerve injury", "nerve grafting", "shoulder trauma", and "nerve repair". Inclusion criteria were human studies of traumatic axillary nerve injuries treated with nerve grafting, with at least 12 months' follow-up and functional outcomes reported. Case reports, animal studies, and series with fewer than five patients were excluded. Two independent reviewers performed study selection, data extraction, and risk of bias assessment using the Newcastle-Ottawa Scale (NOS) and JBI checklist. A total of six studies comprising 223 patients were included. Early nerve grafting (≤4-6 months from injury) yielded the best results, with 70-85% achieving at least Medical Research Council (MRC) grade ≥3 deltoid strength, and many regaining M4-M5 with preserved long-term function. Shorter grafts (<6 cm) and younger age predicted superior recovery, while delayed repairs correlated with persistent weakness and atrophy. Comparative series showed nerve grafting and nerve transfers achieved broadly equivalent functional outcomes, though grafting demonstrated slightly higher objective strength. Nerve grafting provides reliable restoration of deltoid strength and shoulder abduction after traumatic axillary nerve injury, particularly when performed within three to six months and with shorter graft lengths. While nerve transfers remain a valid alternative in select cases, grafting preserves native neural pathways and supports durable functional recovery. Larger prospective studies with standardized metrics are required to establish evidence-based guidelines.