Allograft vs. autograft for chronic acromioclavicular joint instability: a systematic review and meta-analysis of outcomes and complications.

Background: Chronic acromioclavicular joint (ACJ) instability is commonly treated with surgical reconstruction of the coracoclavicular ligament using tendon grafts. Both autografts and allografts are widely utilized, with no clear consensus on the superior option. Autografts, such as hamstring tendons, provide favorable outcomes but are associated with donor-site morbidity, whereas allografts offer an alternative without harvesting morbidity but may introduce complications such as osteolysis and immune-mediated tissue rejection. The choice between these grafts remains a topic of debate. This systematic review and meta-analysis aim to compare the clinical and radiological outcomes, complication rates, and donor-site morbidity of autograft vs. allograft tendon augmentation in chronic ACJ instability. Methods: A comprehensive search was conducted in PubMed, Embase, Cochrane, SportDiscus, and Web of Science until July 3, 2024. Studies were screened independently by two reviewers, with inclusion limited to English, Dutch, French, and German publications. Studies involving adults (≥18 years) with chronic ACJ dislocation (Rockwood type ≥ III) undergoing autograft or allograft reconstruction were included. Exclusion criteria encompassed biomechanical, cadaveric studies, and studies lacking separate outcome reporting for graft types. Data extraction was performed using standardized templates and analyzed with RStudio. Functional, radiological, and complication outcomes were pooled using random-effects models. Study quality was assessed using the Methodological Index for Non-Randomized Studies criteria and Cochrane Risk of Bias Tool. Results: A total of 42 studies (827 patients) met the inclusion criteria, with 26 included in the meta-analysis. No significant differences were observed in American Shoulder and Elbow Surgeons, Constant-Murley Score, Visual Analog Scale, or Disabilities of the Arm, Hand and Shoulder scores between autografts and allografts (P > .05, except for higher Simple Shoulder Test scores in autografts (P = .009). Autografts showed higher donor-site morbidity and infection rates, while allografts were more frequently associated with osteolysis and acromioclavicular arthritis. Conclusion: Both autograft and allograft tendon augmentation provide comparable functional outcomes for chronic ACJ instability. During graft selection, one should consider patient-specific factors, weighing donor-site morbidity against potential allograft-related complications. Further standardized, high-quality research is required to guide optimal treatment selection.