MRI in Knee Cartilage Injury and Posttreatment MRI Assessment of Cartilage Repair

Several MR imaging techniques are available that enable detection of biochemical changes that precede the morphologic degeneration in cartilage. All of these techniques attempt to selectively demonstrate the glycosaminoglycan (GAG) components and/or the collagen fiber network of the extracellular matrix and are usually summarized as “compositional imaging” of cartilage. After cartilage repair surgeries, a regeneration of cartilage in the defect area should be visualized and quantified in the follow-up. While morphological imaging can assess the filling of the defect by repair tissue, its integration and surface, as well as structure of repair tissue and subchondral bone using the semiquantitative scoring system (MOCART), only compositional imaging can provide quantitative information of the biochemical status of the repair tissue and the “quality” of the repair tissue in the follow-up.