Knee Osteoarthritis on MRI in Symptomatic Young Adults After ACL Reconstruction From the SUPER-Knee Trial: Feature Prevalence and Association With Early-Stage Clinical Osteoarthritis Criteria.

Background: One of the most common long-term consequences of a traumatic knee injury is the development of knee osteoarthritis (OA), yet the characteristics of OA structural change and their relationship to early-stage OA clinical criteria in those with persistent knee symptoms following traumatic knee injury has not been described. Purpose: To describe the prevalence of OA features on magnetic resonance imaging (MRI) and explore the association between MRI-defined OA and early-stage knee OA clinical criteria in young adults with a symptomatic knee at short- to medium-term follow-up after anterior cruciate ligament reconstruction (ACLR). Study Design: Cross-sectional study; Level of evidence, 3. Methods: Knee MRIs from 184 SUPER-Knee trial participants with a symptomatic knee at 9 to 36 months post-ACLR (68 female; mean ± SD age, 30 ± 6 years; months post-ACLR, 27.6 ± 8.4) were assessed for tibiofemoral and patellofemoral OA features using the MRI Osteoarthritis Knee Score. The prevalence of MRI-defined OA was described based on published criteria by Hunter and colleagues. Logistic regression was used to explore the association between MRI-defined OA and the Luyten classification criteria for early-stage clinical knee OA. Results: Across participants, cartilage loss was the most prevalent MRI-defined OA feature in both the tibiofemoral (61%) and the patellofemoral (51%) joint. Osteophytes were more common in the tibiofemoral (52%) than patellofemoral (28%) joint of participants. Bone marrow lesions (tibiofemoral, 26%; patellofemoral, 13%), meniscal tears (42%), and meniscal extrusion (18%) were also observed. Based on MRI-defined criteria, 71 (39%) participants were characterized with OA (tibiofemoral, n = 58 [32%]; patellofemoral, n = 34 [18%]). No association was observed between MRI-defined OA and the Luyten classification criteria for early-stage clinical knee OA. Conclusion: Over half of symptomatic young adults 9 to 36 months post-ACLR demonstrated OA features on MRI, with the tibiofemoral joint more commonly affected than the patellofemoral joint. More than one-third of participants met the criteria for MRI-defined OA. A lack of association between MRI and clinical definitions of early-stage knee OA suggests a possible symptom-structure discordance in the early stages of post-traumatic OA disease.