Prevalence of Bilateral Involvement in Patients with Discoid Lateral Meniscus : a Systematic Literature Review.

We assessed the prevalence of bilateral discoid lateral meniscus (BDLM), as well as its subtypes, among patients with symptomatic DLM. Medline, Cochrane, EMBASE, and Google Scholar were searched until September 18, 2015. All studies evaluating patients with BDLM who underwent MRI, macroscopic observation, and/or arthroscopy for the diagnosis of discoid meniscus/menisci were included. Eight clinical studies with a total of 583 DLM patients examined including 103 cadavers. There was a male predominance and average age of BDLM patients ranged from 10.4 to 39.9 years. The reported prevalence was higher in East Asian countries (72.7 to 97%) than rest of the world (6.8 to 90%). Homotypes were much more common than heterotype, and ranged from 82.9 to 91.7% of all BDLM patients. The actual prevalence of BDLM is likely higher. The findings provide a glimpse of the wide spread this disorder potentially has in East Asia.