Pathognomic Discoid Medial Meniscus with a Parameniscal Cyst: A Case Report and Literature Review of Anomalous Medial Meniscus Variants

Abstract

to a discoid lateral meniscus and the age of presentation is also not defined due to rarity of such cases. The discoid medial meniscus developed a horizontal cleavage tear and consequently a parameniscal cyst which became symptomatic insidiously. Controversy exists with regards to the etiology of discoid medial meniscus wherein Kaplan in 1974 stated that congenital alteration in the attachment of posterior horn of the meniscus by the meniscofemoral ligament which becomes hypermobile and Smillie postulated that menisci exist as cartilaginous disc at an early stage in development and congenital discoid meniscus is attributable to persistence of the disc shape at varying stages of embryonic development.Various anomalies reported include anterior horn hypoplasia, anomalous posterior horn attachment to lateral femoral condyle, anomalous insertion of anterior horn to ACL, anterior transportation of the anterior medial meniscus below the anterior edge of the tibial plateau and the anterior horn contiguous with the ACL, increased tibial plateau concavity with elongated medial tibial spine and lastly bilateral occurance.