Osteoarthritis Progression after ACL Reconstruction Was Significantly Higher Than That of the Healthy Contralateral Knees: Long-Term Follow Up Study of Mean 16.4 Years

Background: This study aimed to assess long-term progression of osteoarthritis (OA) after isolated anterior cruciate ligament (ACL) reconstruction in athletes compared to the healthy contralateral side. Methods: The study included 15 patients and 30 knees with a mean age of 40 years (range, 35-46) years, none of whom had had revision surgery or an injury to the contralateral side. The mean follow-up period was 16.4 years (range, 13-22). Clinical and radiographic assessment included the Tegner activity scale (TAS), International Knee Documentation Committee (IKDC) score, Knee injury and Osteoarthritis Outcome Score (KOOS), and Kellgren and Lawrence (KL) grade. The long-term results of the injured knees were compared with the status of the healthy contralateral side and compared with previously published mid-term results of the same cohort of patients. Results: Patients generally remained clinically asymptomatic or mildly symptomatic at final follow-up, which is reflected by a KOOS pain score of 33 points (maximum 36 points) and an IKDC total subjective score of 87% (maximum 100%). There was a significant difference between mid-term and final follow-up in terms of the function score of the IKDC subjective questionnaire (p = 0.031), compartment findings and donor site morbidity of the IKDC functional examination (both p = 0.034), and the total KOOS score (p = 0.047). The KL score indicated significant progression of OA from mid-term to final follow-up in the injured knees (p = 0.004) and healthy contralateral knees (p = 0.014). Mean OA grades of the injured knees were significantly higher compared with the healthy contralateral side (p = 0.006) at final follow-up, and two patients showed moderate to severe signs of OA in the injured knee. Conclusions: Although most patients remained clinically asymptomatic or mildly symptomatic, long-term progression of OA after isolated ACL reconstruction in athletes was significantly higher compared with the healthy contralateral knee.