Objective: The Osteoarthritis Initiative (OAI) is a multi-center study targeted at identifying biomarkers for evaluating the progression and risk factors of symptomatic knee OA. Here we analyze cartilage loss using 3 Tesla MR imaging over one year in a subset of the OAI, and its association with various risk factors.
Methods: An age and gender stratified subsample of the OAI progression subcohort (79 women and 77 men, age 60.9±9.9 y., BMI 30.3±4.7) with both frequent symptoms and radiographic OA in at least one knee was studied. Coronal FLASHwe MR images of the right knee were acquired at 3T. Seven readers segmented tibial and femoral cartilages blinded to order of acquisition. Segmentations were quality controlled by one expert.
Results: The reduction in mean cartilage thickness (ThC) was greater (p=0.004) in the medial than in the lateral compartment, greater (p=0.001) in medial femur (-1.9%) than medial tibia (-0.5%), and greater (p=0.011) in lateral tibia (-0.7%) than lateral femur (0.1%). Multifactorial ANOVA did not reveal significant differences in the rate of change in ThC by sex, BMI, symptoms and radiographic knee OA status. Knees with Kellgren Lawrence grade 2 or 3 and with a BMI >30 tended to display greater changes.
Conclusions: In this sample of the OAI progression subcohort the greatest, but overall very modest rate of cartilage loss was observed in the weight bearing medial femoral condyle. Knees with radiographic OA in obese participants showed trends towards higher rates of change than other participants, but these trends did not reach statistical significance.