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Determination of human articular cartilage condition using magnetic resonance imaging, creep indentation testing and biochemistry [electronic resource]

Human articular cartilage can degrade, losing functional quality and eventually exposing bone surfaces; when significantly advanced, this cartilage degradation can be diagnosed as osteoarthritis (OA). Currently, knee OA can be diagnosed only when the disease is advanced and the patient is suffering from pain. There is no cure for knee OA, nor are there prevent preventative therapies; current treatment strategies relieve the pain of OA or completely replace the knee joint. To evaluate potential therapies and treatments, we need a method that can identify and measure changes to cartilage prior to the onset of degradation. Magnetic resonance imaging (MRI) is a potentially powerful tool to non-invasively evaluate the progression of knee OA by mapping MR image parameters to molecular and material properties that are known to change with disease. The goal of this dissertation was to determine MR image parameters that can be used to evaluate the progression of OA. We examined the biphasic and viscoelastic models of cartilage to determine cartilage material properties from indentation creep tests. We compared initial elastic modulus and cartilage macromolecules to MRI parameters, specifically T2 and T1rho relaxation times and T1rho dispersion. We determined that a predictive model based on T1rho relaxation time maps, which accounts for T2 relaxation time and the effects of age, may estimate longitudinal trends in GAG content in the same person. In addition, a simple T1rho dispersion estimate has the potential for substantial clinical impact by measuring changes in cartilage initial elastic modulus and macromolecules non-invasively. This work is an important step toward developing clinical methods for evaluating cartilage functional condition, and in turn, to advance work towards preventing and treating knee OA.