Evaluating Criteria for Symptoms Suggestive of Early Osteoarthritis Over Two Years Post-ACL Reconstruction: Data from the New Zealand ACL Registry.

Objectives: The objectives were to determine the prevalence of meeting criteria for symptoms suggestive of early osteoarthritis (OA) following anterior cruciate ligament reconstruction (ACLR) and to characterize the longitudinal changes in these symptoms during the first two years post-ACLR.

Methods: We analyzed data from 10231 patients aged 14-40 years in the New Zealand ACL Registry who completed the Knee injury and Osteoarthritis Outcome Score (KOOS) at 6, 12, and 24 months post-ACLR. Symptoms suggestive of early OA were defined as scoring ≤85% on at least 2 of 4 KOOS subscales. Longitudinal patterns of change were categorized as persistent, resolution, new, inconsistent, or no symptoms across the three visits. Prevalence and odds ratios (ORs) of symptoms were compared across visits, sex, and age groups using generalized estimating equations, and longitudinal patterns of symptom change were analyzed using multinomial logistic regression.

Results: Prevalence of meeting criteria of symptoms suggestive of early OA was 68% at 6 months, 54% at 12 months, and 46% at 24 months post-ACLR. Longitudinally, 33% had persistent symptoms, 23% had no symptoms, 29% showed symptom resolution, 6% developed new symptoms, and 9% had inconsistent symptoms. Females consistently showed higher odds of symptoms (OR range:1.17-1.52). Older age groups demonstrated higher odds of symptoms, particularly at 6 months (OR range:1.64-2.45).

Conclusion: Symptoms suggestive of early OA are highly prevalent within two years post-ACLR, with one-third of patients experiencing persistent symptoms. These findings indicate that symptoms are more likely to persist rather than newly develop, emphasizing the importance of early identification and targeted interventions.