Imaging of the knee

Multiple traumatic, degenerative, inflammatory, infectious, and neoplastic conditions occur in and around the knee joint. Radiographs, ultrasound, CT, MR, and arthrography each play a role in the imaging evaluation of these conditions. Imaging is important not only to detect or exclude disease, but also to stage, guide therapy, follow up, and prognosticate knee disorders. Knee injury is the most frequent cause of sports-related disability. Because common traumatic mechanisms produce predictable patterns of knee injury, a biomechanical approach has several advantages in the interpretation of MR images. Locations of meniscal tear, capsulo-ligamentous sprain, and osseous injury all provide clues about the mechanism of injury. By understanding traumatic patterns, the identification of one abnormality may lead to a directed search for subtle abnormalities involving anatomically or functionally related structures, thus improving diagnostic confidence.