Can Baseline MRI Findings Identify Who Responds Better to Early Surgery Versus Exercise and Education in Young Patients With Meniscal Tears? A Subgroup Analysis From the DREAM Trial

OBJECTIVE: To investigate whether magnetic resonance imaging (MRI) findings modified the outcomes of early surgery compared to exercise and education in young patients with meniscal tears. DESIGN: A secondary effect modifier analysis of a randomized controlled trial. METHODS: The primary outcome was change from baseline to 12 months in the mean score of 4 Knee injury and Osteoarthritis Outcome Score subscales (KOOS₄). Three potential MRI-defined effect modifiers were predefined: (1) the type of meniscal tear (simple vs bucket handle or complex), (2) the meniscus affected (medial vs lateral), and (3) the presence of knee effusion/synovitis (yes/no). We used a linear mixed model to investigate the difference in mean change between the treatment groups, stratified by each of the 3 potential effect modifiers, and estimated the interactions. An adjusted effect difference ≥ 10 points (0-100 scale) was considered clinically relevant. RESULTS: Data from all participants (60 in the surgery group and 61 in the exercise group) were analyzed. The mean (SD) age was 29.7 (6.6) years, and 28% were female. A potential effect modification was observed for knee effusion/synovitis, with its presence implying an increase of the effect of early surgery by 11 points on the KOOS₄ (P = .07). CONCLUSION: Knee effusion/synovitis on MRI potentially modified the treatment effect with a clinically relevant difference in change of the KOOS₄ in patients with effusion/synovitis, favoring early surgery. We found no indication that patients with bucket handle or complex versus simple tears or medial versus lateral tears benefited more from early surgery.