37 Knee osteoarthritis on MRI in symptomatic young adults after ACL reconstruction: prevalence and association with early-stage clinical osteoarthritis criteria

Introduction Early osteoarthritis features on magnetic resonance imaging (MRI) can develop within 1–2 years after anterior cruciate ligament reconstruction (ACLR) and increase the risk of future radiographic and symptomatic osteoarthritis. This study describes the prevalence of MRI-defined osteoarthritis in young adults with ongoing symptoms 9–36 months post-ACLR and explores the association between MRI-defined osteoarthritis and early-stage osteoarthritis clinical criteria.Materials and Methods Baseline knee MRIs from 184 SUPER-Knee trial participants (68 female, mean age 30±6 years) with a symptomatic knee 9–36 months post-ACLR were assessed for osteoarthritis features using the MRI Osteoarthritis Knee Score. The prevalence of MRI-defined osteoarthritis was described based on published criteria (encompassing cartilage loss, osteophytes, bone marrow lesions, and meniscal pathology). Logistic regression explored the association between MRI-defined osteoarthritis and early-stage clinical osteoarthritis criteria (i.e. a ‘positive’ score [≤85%] on two of four possible Knee injury and Osteoarthritis Outcome Score [KOOS] subscales and joint line tenderness or knee crepitus on physical examination).Results Seventy-one (39%) participants were characterised with MRI-defined osteoarthritis (tibiofemoral, n=58 [32%]; patellofemoral, n=34 [18%]). Cartilage loss was the most prevalent MRI osteoarthritis feature in both tibiofemoral (61%) and patellofemoral (51%) joints of participants. No association was observed between MRI-defined osteoarthritis and early-stage osteoarthritis clinical criteria.Conclusion Over one-third of symptomatic young adults 9–36 months post-ACLR met MRI-defined osteoarthritis criteria, with the tibiofemoral joint more commonly affected than the patellofemoral joint. A lack of association between MRI-defined osteoarthritis and early-stage osteoarthritis clinical criteria suggests a symptom-structure discordance in the early-stages of post-traumatic osteoarthritis.