Lateral discoid meniscus is a well known disease entity with an uneventfully high incidence in Koreans and Japanese. However, the reported incidence had been obtained mainly by using arthroscopy. The purpose of this study was to determine the prevalence of discoid lateral meniscus obtained by arthroplasty, unrelated to arthroscopic surgery.

We studied the prevalence of lateral discoid meniscus in 465 cases of total knee replacement arthroplasty, after disregarding patients with any possibility of an affecting lateral meniscus. To conduct the comparison, we measured the incidence of lateral discoid meniscus in 423 arthroscopy cases, performed during study period, and in 1,364 of our arthroscopy cases.

We found 18 discoid lateral menisci during 465 total knee replacement arthroplasties, Therefore, its prevalence of lateral discoid meniscus was 3.9%. but 38 cases (9.0%) out of 423 arthroscopy cases, and 145 cases (10.6%) out of 1,364 arthroscopy cases were diagnosed as a lateral discoid meniscus. We also founded that 50% of lateral discoid meniscus cases were bilateral.

We suspect that the prevalence of lateral discoid meniscus is similar in the Korean and Western populations. However, due to different lifestyles and ethnicity, Koreans might experience in one discomfort and confront a treatment, and thus the reported prevalence of discoid lateral meniscus is higher in Koreans.