Magnetic resonance imaging of knee instability.

Patellar retinaculum and cruciate and collateral ligaments are major passive stabilizers of the knee joint. Injuries to these ligaments may alter the overall articular motion and lead to instability. Experienced as a sense of the knee "giving way," instability is a predisposing factor for recurring injuries and osteoarthritis. This section presents a practical imaging approach to knee instability based on a major injury to a specific ligament, with routine radiographic and magnetic resonance imaging findings discussed in detail. Common patterns of multiple ligamentous injuries are noted in appropriate subsections.