Discoid lateral menisci: a report of 29 cases.

Of 7,056 knee arthroscopies performed during the period September 1979-November 1986, 30 patients had discoid menisci, one medially and 29 laterally. The frequency of discoid lateral menisci appears to be lower in Sweden than in North America, Scotland, and Japan. Our policy, to do a meniscectomy only when the discoid meniscus is thought to play a role in the symptoms, but leave it intact when an incidental finding, seems to give good results. Nine of the 29 patients studied had trauma as an initiating factor, but of those 10 patients whose discoid lateral menisci were thought to cause the symptoms, only one had trauma as an initiating factor. Theories of the cause of discoid menisci are discussed, as well as recommended treatment.