Younger age and prior graft failure are associated with increased risk of ACL reinjury: Graft survival and contralateral ACL outcomes at a median 10.6-year follow-up after primary hamstring autograft reconstruction.

Purpose: To evaluate graft survival and contralateral anterior cruciate ligament (ACL) injury after primary hamstring autograft reconstruction and identify factors associated with these outcomes at a minimum follow-up of 7 years. Methods: This retrospective cohort study included 415 randomly selected patients who underwent primary single-bundle hamstring tendon ACL reconstruction between 2005 and 2014. Patients were followed for a median of 10.6 years (range, 7.6-17.1). Graft failure was defined as revision reconstruction, clinically or imaging-confirmed rupture or patient-reported characteristic instability in a prespecified worst-case approach. Kaplan-Meier analysis was used to estimate graft survival and contralateral ACL survival. Cox proportional hazards models were used to identify factors associated with graft failure and contralateral injury. Prior graft failure in the index knee was modelled as a time-varying covariate in the contralateral injury analysis. Results: The 10-year graft survival probability was 86.6% (95% confidence interval [CI], 82.8%-89.5%). Age 21 years or younger was associated with a higher hazard of graft failure (adjusted hazard ratio [aHR], 2.62; 95% CI, 1.49-4.61; Conclusion: At a median follow-up of 10.6 years after primary hamstring autograft ACL reconstruction, graft survival was 86.6% and contralateral ACL survival was 95.5%. Younger age was associated with a higher hazard of graft failure, whereas concomitant chondral lesions were associated with a lower hazard of graft failure. Prior graft failure in the index knee was associated with subsequent contralateral ACL injury. Level of Evidence: Level III.