Symptomatic discoid medial meniscus.

man with a chief complaint of right medial knee pain for the past 4 months. The symptoms were insidious in onset, and the patient denied any history of trauma or locking of the knee. Despite physical therapist intervention for a month, which included manual physical therapy and therapeutic exercise, the patient’s right knee pain continued to progressively worsen to the point where normal activities of daily living, such as stair climbing and squatting, were difficult to perform. The patient was subsequently referred to an orthopaedic surgeon. Physical examination by the orthopaedic surgeon revealed no joint effusion, full range of motion, and normal ligamentous testing for the right knee. However, medial joint-line tenderness of the right knee was present, as well as a positive McMurray test for right medial knee pain. Due to concern for a medial meniscus tear, magnetic resonance imaging was completed, which revealed a torn discoid medial meniscus, a parameniscal cyst adjacent to the anterior horn of the medial meniscus, and cupping of the medial tibial plateau (FIGURES 1 and 2). A discoid medial meniscus is a rare abnormality in which the meniscus is characterized by a discoid rather than a semilunar shape. [ musculoskeletal imaging ]