Meniscal abnormalities: Discoid meniscus

The discoid meniscus is the most common meniscal variant. The likely etiology being congenital, the condition usually affects the lateral meniscus. Poorly vascularized, thicker and unstable, the discoid lateral meniscus (DLM) is more prone to tears due to abnormal shearing forces. Watanabe et al. (1979) classified the discoid lateral meniscus into three types: Complete, incomplete and Wrisberg type; Monllau et al. (1998) added the ring type as the fourth variant. Pain and clicks/thud are the most common presentations. Plain radiograph and magnetic resonance imaging are helpful in confirming the diagnosis. Asymptomatic DLM is best left alone. For symptomatic complete and incomplete types, partial arthroscopic saucerization is the treatment of choice leaving behind a stable rim. The Wrisberg type needs peripheral stabilization with resection of excess rim, if any. Total meniscectomy should be avoided unless inevitable. Short term results after partial meniscectomy are good.