Clinical, radiologic, and arthroscopic assessment of discoid lateral meniscus

PURPOSE: To establish the common clinical and radiologic features of discoid lateral meniscus in a setting where magnetic resonance imaging was not routinely possible because of cost and access. Arthroscopy was used to confirm the diagnosis. Type of Study: Retrospective study of group of patients with discoid lateral meniscus as the diagnosis. METHODS: Of 1,643 arthroscopies of the knee performed between January 1993 and January 1999, 87 patients (95 knees) with discoid lateral meniscus were studied with regard to their clinical presentation and radiologic features. Arthroscopy was used for confirmation of diagnosis, classification of types of discoid lateral meniscus and pattern of tears, and for treatment. RESULTS: Of all the knee arthroscopies, 5.8% involved patients with discoid lateral meniscus. The average age of patients at presentation (24.7 years), contributed to a 67.3% incidence of associated tears. Tears were more frequently associated with patients older than 15 years, which was statistically significant (P =.0005). The most common clinical features were pain and joint-line tenderness. In this series, the incidence of radiologic findings was high (53.9%). CONCLUSIONS: The high incidence of tears is attributable to the late presentation. The incidence of radiologic findings in this series is high.