The clinical correlates of articular cartilage defects in symptomatic knee osteoarthritis: a prospective study

Objectives. To determine whether articular cartilage defects are associated with cartilage loss and joint replacement in subjects with symptomatic knee osteoarthritis (OA). Methods. One hundred and seventeen subjects with symptomatic knee OA underwent magnetic resonance imaging of their dominant knee at baseline and 2yr later. Cartilage defects were identified as prevalent (defect score ≥2) in each knee compartment. Occurrence of joint replacement by 4yr was documented. Results. Cartilage defects were present in 81% of medial, 64% of lateral tibiofemoral compartments and 55% of patellar cartilages. Annual patellar cartilage loss was highest in those with defects compared with no defects (5.5% vs 3.2%, P = 0.01). Tibial cartilage loss was not associated with defects in the medial (4.6% vs 5.8%, P = 0.42) or lateral (4.7% vs 6.5%, P = 0.21) tibial cartilages. Higher total cartilage defect scores (8-15) were associated with a 6.0-fold increased risk of joint replacement over 4yr compared with those with lower scores (2-7) (95% confidence interval 1.6, 22.3), independently of potential confounders. Conclusions. Articular cartilage defects are associated with disease severity in knee OA and predict patellar cartilage loss and knee replacement. © The Author 2005. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved.