Regional dGEMRIC analysis in patients at risk of osteoarthritis provides additional information about activity related changes in cartilage structure

Abstract

Background Previously, a positive effect of exercise on cartilage structure was indicated with delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC). However, in that study only one full-thickness region of interest (ROI) in the medial femoral condyle was analyzed. Purpose To improve the knowledge about exercise effects on cartilage structure by re-analyzing previous images with regional dGEMRIC analysis. Material and Methods Thirty patients (age range, 38–50 years) with a previous medial meniscus resection were divided into three groups according to self-reported change in physical activity (PA) level in a 4-month exercise intervention study: Group I ( n = 11), increased PA level; Group II ( n = 13), no change in PA level; and Group III ( n = 6), reduced PA level. dGEMRIC index was analyzed at inclusion and after 4 months. Anterior (less load) and posterior (more load) ROIs of medial and lateral femoral condyles were analyzed, as well as superficial and deep cartilage regions. Results Group I increased the dGEMRIC index in the posterior cartilage ( P = 0.004). The increase was larger in the lateral ( P = 0.005) than the medial compartment in both superficial and deep cartilage regions. The dGEMRIC index did not change in Group II. In Group III, the dGEMRIC index decreased in the medial posterior cartilage ( P = 0.03). Conclusion In patients with a previous medial meniscectomy, the beneficial effect of exercise varies between different locations within the joint, the largest improvement being observed in lateral posterior cartilage, i.e. the load-bearing cartilage in the compartment without a meniscus lesion. The effects of exercise do not seem to vary with cartilage depth.