Discoid lateral menisci in Japanese cadaver knees.

We undertook a descriptive, observational study to determine the prevalence of the discoid lateral menisci. The relation between the lateral meniscal shapes and the incidence of meniscal tears were studied, and the gender differences in discoid lateral menisci and the similarities of the lateral meniscal shapes in bilateral knees were examined. A total of 602 knees from 306 cadavers were macroscopically analyzed. Altogether, 577 lateral menisci were classified into the following three types: normal type (NM); incomplete discoid type (ICDM); and complete discoid type (CDM). Each lateral meniscus was examined for meniscal tears. The prevalence of a discoid lateral meniscus and gender differences in its prevalence were examined, as were the presence of a meniscal tear for the three types of lateral meniscus. In all, there were 21 (3. 6%) CDM cases and 171 ICDM cases (29.6%). The prevalence of discoid lateral meniscus, including ICDM and CDM, in the female cadavers was significantly higher than that in the male cadavers, but there was no significant gender difference in the prevalence of CDM. It was found that the shape of the lateral meniscus was similar bilaterally. The incidence of meniscal tears for ICDM was significantly higher than that for NM.