Patellofemoral joint geometry and motion measured using magnetic resonance imaging

The biomechanics of the knee must be understood to uncover the basic mechanism of patellofemoral pain and to design more effective treatments for this disorder. The mechanics of the joint have been evaluated extensively under static conditions or with minimal joint loading; however, the joint mechanics have not been thoroughly investigated during the highly loaded motions that often result in pain. The goal of this dissertation was to measure patellofemoral joint geometry and motion during weight-bearing conditions to improve the diagnosis and treatment of patellofemoral pain.; We measured cartilage thickness in load-bearing regions of the patellofemoral joint in 16 pain-free subjects and 34 individuals with patellofemoral pain using MRI. Males had thicker cartilage than females and males with patellofemoral pain had lower peak cartilage thickness on the patella than pain-free males. These data indicate that decreased peak cartilage thickness may be one mechanism of pain in males, but it is likely that other factors contribute to pain in females.; We established the accuracy of using real-time MRI to measure joint motion using an MRI-compatible motion phantom. We could track the motion of the phantom with real-time MRI to within 2mm in a 1.5T closed-bore MRI scanner and a 0.5T open-bore MRI scanner. We used these results to design a protocol for measuring patellofemoral joint kinematics in vivo using real-time MRI.; We measured patellofemoral joint kinematics during weight-bearing knee extension using real-time MRI in 13 pain-free females and 22 females with patellofemoral pain. Subjects with patellofemoral pain exhibited increased lateral translation of the patella, compared to pain-free subjects, for knee flexion angles between full extension and 44°. Application of a knee brace reduced the lateral translation of the patella near full extension. The implication of these results is that abnormal patellofemoral joint motion may be a cause of patellofemoral pain in some subjects and could be addressed with treatments, such as a brace.; This dissertation evaluates two potential mechanisms of patellofemoral pain and establishes the need to differentiate the underlying abnormalities present in each patient to achieve more successful treatments.