Magnetic resonance imaging in the diagnostic management of diseases of the knee.

Magnetic resonance imaging (MRI) of the knee is fast assuming a major role in evaluating disorders of the knee. The major advantage of MRI is that it is a totally non-invasive procedure with superior soft tissue contrast resolution and multi-planar capabilities. In contrast to arthrography, intra-articular as well as extra-articular structures in the knee can be evaluated by MRI. Indications include studying abnormalities of the menisci, ligament, patella and quadriceps mechanisms, articular cartilage, bone, bursa and other soft tissue. A review of the literature comparing MRI to arthrography and arthroscopy of the knee, especially in relation to meniscal injuries and anterior cruciate ligament tears, shows wide ranges in the accuracy rates of MRI. There are pitfalls in the interpretation of meniscal tears on MRI like normal variants, tears at the free edge and healed or previously repaired tears. Arthrography remains a useful diagnostic modality in some of these settings.