Cartilage stiffness measurement

At present, there are no treatment to cure or attenuate the degradation of cartilage. Therefore, early detection and the ability to monitor the progression of osteoarthritis is important for developing effective therapies. In this project, we used Abaqus/Tosca in Magnetic Resonance imaging (MRI) to measure cartilage stiffness in vivo, which has never done before. Topology optimization (Tosca) is originally used to optimize material layout to achieve best mechanical performance. Moreover, it can also be used in the biomechanics simulation to calculate cartilage stiffness. With the displacement encoded MRI, we are able to measure deformation of joint cartilage under quasi-static loading. Then we built the mechanical model of cartilage in Abaqus, and used Tosca to vary the stiffness of each element to match the displacements we measured from experiments. After testing and improving this technique on gel samples, we are comfortable to move on to the intact joints right now. Recently we found that with intensive loading, cartilage got stiffer due to water depletion. The optimization capability of Tosca is a very good choice to deal with this complex problem. Other than programming by yourself, we got a huge library of tools in Abaqus to simulate the real behavior of tissue and that saved us a lot of time.