Magnetic resonance imaging of articular cartilage: trauma, degeneration, and repair.

The assessment of articular cartilage using magnetic resonance imaging has seen considerable advances in recent years. Cartilage morphologic characteristics can now be evaluated with a high degree of accuracy and reproducibility using dedicated pulse sequences, which are becoming standard at many institutions. These techniques detect clinically unsuspected traumatic cartilage lesions, allowing the physician to study their natural history with longitudinal evaluation and also to assess disease status in degenerative osteoarthritis. Magnetic resonance imaging also provides a more objective assessment of cartilage repair to augment the information obtained from more subjective clinical outcome instruments. Newly developed methods that provide detail at an ultrastructural level offer an important addition to cartilage evaluation, particularly in the detection of early alterations in the extracellular matrix. These methods have created an undeniably important role for magnetic resonance imaging in the reproducible, noninvasive, and objective evaluation and monitoring of cartilage. An overview of the advances, current techniques, and impact of magnetic resonance imaging in the setting of trauma, degenerative arthritides, and surgical treatment for cartilage injury is presented.