Clinical outcomes and complication rates following medial collateral ligament reconstruction using Achilles tendon allograft or hamstring tendon autograft: A systematic review.

PURPOSE: The medial collateral ligament (MCL) is the most commonly injured knee ligament, yet indications for reconstruction remain debated. Although consensus statements support allograft and hamstring autograft, comparative evidence regarding graft superiority is limited. This systematic review evaluated patient-reported outcome measures (PROMs) and complication rates following MCL reconstruction using Achilles tendon (AT) allograft or hamstring autograft. METHODS: A systematic review was undertaken according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. PubMed, Cochrane, Google Scholar and Scopus were searched on 11th February 2026. Studies published within the previous 20 years that included patients aged ≥16 years undergoing MCL reconstruction with hamstring autograft or AT allograft and reporting clinical, functional and patient-reported outcomes were included. Data extraction and risk of bias assessment were performed. Due to heterogeneity, findings were narratively synthesised. RESULTS: Sixteen studies were included: six AT allograft studies (n = 107; four using a bone block) and ten hamstring autograft studies (n = 275). Mean age was 33.9 and 31.3 years, with mean follow-up of 37 and 29.1 months, respectively. Mean postoperative international knee documentation committee (IKDC) and Lysholm scores were 81.1 and 86.8 for allograft and 78.8 and 87.2, respectively, for autograft. Three allograft and six hamstring autograft studies reported preoperative and postoperative PROMs, all demonstrated significant improvement (p < 0.05). Complication rates were 11.2% for AT allograft and 4.0% for hamstring autograft. AT allograft complications included two graft failures, four cases of residual asymptomatic valgus instability, three infections and three other complications. Hamstring autograft complications included one graft failure, four cases of asymptomatic valgus instability, three manipulations, one infection and two removals of hardware. CONCLUSION: Both AT allograft and hamstring tendon autograft significantly improve PROMs following MCL reconstruction. AT allografts demonstrated a numerically higher complication rate; however, the evidence is indirect and insufficient to determine the superiority of either graft type. LEVEL OF EVIDENCE: Level III.