The discoid lateral-meniscus syndrome.

Discoid lateral meniscus has been described as a morphologically variable anomaly, and several classifications have been proposed. We have seen twelve patients with the so-called complete type of discoid lateral meniscus, with intact ligament attachments as an incidental finding at the time of arthroscopy. Ten of the twelve patients were without significant symptoms attributable to the meniscus; that is, they had no meniscal tears or laxity. We also have seen six patients with the Wrisberg-ligament type of discoid lateral meniscus, in which there is abnormal meniscal mobility. All six patients were symptomatic and had the so-called snapping-knee syndrome, for which they had arthroscopic lateral meniscectomy. During arthroscopy, care should be taken not to confuse the asymptomatic complete type of discoid lateral meniscus with the Wrisberg-ligament type.