The diagnostic value and limitation of magnetic resonance imaging on chondral lesions in the knee joint.

Chondral lesions of the knee joint, which have been detected via arthrotomy or arthroscopy, were examined prospectively and retrospectively through a review of previously obtained magnetic resonance images (MRIs). The study group was composed of 34 men and 29 women whose average age was 24.6 years. Of these 63 patients, there were 72 articular cartilage lesions in 65 knees. On retrospective analysis, the sensitivity of MRI, which was defined as a true positive reading for softening, fragmentation, erosion, and/or a full-thickness loss of cartilage, was 14.3%, 57.3%, 75.0%, and 100%, respectively. Although the sensitivity to early changes of chondral lesions was low, indicating the limitation of MRI at the present stage, it has been demonstrated that MRI can delineate intracartilaginous changes associated with softening and thickening of cartilage that cannot be detected even with arthroscopy. Therefore, it may be worthwhile to perform an MRI as well as arthroscopy to clarify the pathogenesis of internal derangement of the knee.