Ultrasound in degenerative cystic meniscal disease of the knee.

Ultrasonography of the knee joint using small-parts probes was performed on 27 patients with clinical findings suggestive of meniscal cystic degeneration. Surgical or arthroscopic confirmation of sonographic findings was obtained in all cases. Sonography delineated the shape and structure of the meniscal profile and any degenerative changes. In the initial stage (6/27 patients, 22%), minor structural irregularities could be observed. Small, round, transonic cysts were found in 8 patients (30%); these lay mainly within the meniscus and were movable during stress flexion of the leg. In more advanced cases (8/27, 30%), larger cysts sometimes protruded on the skin surface. In 3 patients (12%), the soft tissue swelling was associated with a normal sonographic aspect of the menisci, but sonography could demonstrate an effusion of extra-articular origin. Ultrasound is a simple and effective method for the assessment of degenerative cysts of the menisci. It allows a reliable differential diagnosis between meniscal cysts and other causes of soft tissue swelling, and it is well suited for monitoring the course of the disease.