High resolution Magnetic Resonance Imaging (MRI) may provide an important new tool in the diagnosis of the functional state of articular cartilage. We are presently engaged in a project where we measure the thickness of the tibial plateau articular cartilage in patients with malleolar fractures. The patients will be non-weight bearing on the leg in which the fracture occurs but mobility at the knee joint will be retained. By making serial measurements of cartilage thickness using high-resolution MRI techniques we are following the change in thickness of the cartilage in response to the decreased stress placed on the cartilage when the patient is non-weight bearing.