Comparison of magnetic resonance imaging and x-ray imaging for the measurement of the thickness and loss of articular cartilage in osteoarthritic knees

A number of surgical and pharmacologic therapies are under development for the treatment of osteoarthritis (OA) of the knee. A bottle neck in the evaluation of these so called disease modifying OA drugs (DMOAD) is the testing of their efficacy in reducing the loss of a.rticular cartilage in the knee. The standard method for evaluating the loss of articular cartilage in the knee is through measurement of the tibial-femoral joint space in the medial compartment This measurement is difficult to perform reliably and generates indirect, limited data about the condition of the articular cartilage-the central tissue affected by OA. This project will validate a ma;:metic resonance (MR) imaqing technique for mapping the distribution of the thickness of the articular cartilaqe in the tibia, femur and patella in forty patients with mild to moderate OA. The study will also confirm the thickness maps are independent of patient position in the magnet. In this way the MR imaging technique will immediately be superior to the x-ray imaging technique which is vulnerable to errors from incorrect positioning. Using both MR imaging and x-ray imaging we will follow forty patients for 2.5 years to monitor the natural course of cartilage loss over this clinically realistic period. The two methods of measuring cartilage loss will be compared to confirm the ability of MR imaging to measure the same cartilage loss as detected on the x-ray images. During the course of the study, we will evaluate the OA patients using the WOMAC evaluation tool to determine the relationship between patient's subjective assessment of mobility and health and the objective imaging data describing the condition of their joint. This study will confirm that MR imaging is a valid, reliable technique for measuring the loss of articular cartilage in OA of the knee and that it has several advantages for monitoring the efficacy of DMOAD for treating arthritis patients.