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Radiographic Osteoarthritis, Clinical Outcomes and Re-Injury 20 Years after ACL Reconstruction

Objective: This prospective longitudinal study compares the outcome of isolated endoscopic ACL reconstruction utilizing 4-strand hamstring tendon (HT) and patellar tendon (PT) autograft over a 20-year period. Method: Observational Series. 90 consecutive patients with isolated ACL rupture were reconstructed with a PT autograft and 90 patients received HT autograft, with an identical surgical technique. Patients were assessed at 2, 5, 7, 10, 15 and 20 years. Assessment included the IKDC Knee Ligament Evaluation including radiographic evaluation, KT1000, Lysholm Knee Score, kneeling pain, and clinical outcomes. Results: Subjects who received the PT graft had significantly worse outcomes compared to those who received the HT graft at 20 years for the variables of radiologically detectable osteoarthritis (59% v 39%, p=0.01), kneeling pain (38% v 20%, p=0.02), and incidence of contralateral ACL injury (30% v 14%, p=0.04). There was no significant difference between the HT and PT groups in overall IKDC grade (p=0.23), or IKDC subjective score (p=0.18). Subgroup gender differences were identified. The female PT group had significantly lower mean IKDC subjective scores (p=0.05), and more difficulty with kneeling (p=0.04) compared to the other subgroups. ACL graft rupture occurred in 18% of HT and 10% of the PT (p=0.13), and was associated with males (Hazard Ratio(HR)=3.9, p=0.007), age <18 years (HR=4.6, p=0.003), and non ideal radiological tunnel placement (HR=3.6, p=0.02). Contralateral ACL injury was associated with age <18 years (HR=3.4, p=0.001), and the PT graft (HR=2.2, p=0.02). Conclusion: At 20 years both HT and PT autografts continue to provide good subjective outcomes and objective stability. However, ACL reconstruction using the PT graft is associated with persisting kneeling pain and radiological osteoarthritis, compared to the HT graft. Risk factors for ACL graft rupture include males, young age, and those with tunnel malposition. This information may help in the counseling of patients undergoing this procedure and stratifying their individual risk of re-injury.