UCSF

Articular cartilage plays an important role in the knee joint, which is the largest joint in the body and carries high loads. Injury to the anterior cruciate ligament (ACL) will affect the joint stability and lead to post–traumatic osteoarthritis development. Finite element (FE) models have been used to analyze cartilage deformation and kinematic changes of human knees with osteoarthritis. However, no studies have yet used in–vivo imaging data to approximate material properties of cartilage, and no research has compared the FE output of cartilage loading patterns with in–vivo measurements of cartilage in ACL injured knees. This study developed a subject-specific FE model in knees by using in–vivo T1ρ and morphological data from high–resolution magnetic resonance imaging (MRI). The results of FE simulation demonstrated less stiffness and larger axial strains in articular cartilage with elevated T1ρ. The kinematic changes in ACL–injured knees may affect the load distribution and cause early cartilage degeneration in such joints. In conclusion, the subject-specific FE model is a powerful tool to detect strain distribution, contact area, and contact pressure within the articular cartilage. Novel imaging techniques such as T1ρ MRI coupled with FE analysis may allow for quantification of knee joint biomechanics as well as early detection of cartilage matrix degeneration.