Quantification of patellofemoral contact area using MR imaging, a validation and comparative study

Abnormal joint contact mechanics are commonly speculated to be an initiating factor in cartilage degeneration. Magnetic resonance imaging (MRI) has been used as a non-invasive measurement tool for evaluating cartilage thickness, deformation and contact area in-vivo and in-vitro. However, specific evaluation of the sources of error and their magnitude are limited. This study evaluates the use of MRI and surface modeling with thin plate splines for the determination of joint contact area in a loaded patellofemoral joint. In the absence of a gold standard, a comparative measure with staining and multistation digital photogrammetry was used to evaluate the accuracy and repeatability of the MRI, digitization and modeling procedures. The technique presented provides a successful method to obtain surface geometry and contact area of the patellofemoral joint non-invasively and in the in-vivo, loaded condition using MRI.