Tear Pattern of Normal and Discoid Lateral Meniscus

Kim, Jung Man; Han, Chang Whan; Yeon, Gun; Chung, Jin Hwa

Abstract

Discoid lateral meniscus is wider and thicker than normal lateral meniscus. The tear pattern and vulnerability to injury of discoid lateral meniscus may be different from that of normal shaped meniscus. Seven hundred and seventy one meniscal tears which were treated arthroscopically between the period of 1982 and 1995 were reviewed retrospectively. Of those cases, tear of normal shaped lateral menisci occupied 327 knees (42.4 %) and discoid lateral menisci 132 knees (17.1 %) representing the higher incidence of tear in normal shaped lateral meniscus. In normal shaped menisci there were no tear in the age of below 10 and there were 37 knees of teens. In discoid lateral menisci, there were 3 knees (2.3 %) of below 10 and 42 knees of teens (31.8 %) that represent higher incidence of younger age group (P<0.05). Tears without trauma history in 31 knees (9.5 %) of normal shaped lateral meniscus and in 70 knees (53.0 %) of discoid menisci represent vulnerability of the discoid lateral meniscus to tear without injury (P<0.05). Symptomatic menisci without tear were noted only in 16 knees (12.1 %) of the discoid lateral menisci. In normal shaped menisci, longitudinal tear within the substance was most common (119 knees, 36.4 %) whereas peripheral tear was most common (57 knees, 43.2 %) in the discoid lateral meniscus, Concealed horizontal tear (11 knees, 8.3 %) and Wrisberg type discoid lateral menisci (2 knees, 1.5 %) was noted only in the discoid lateral meniscus. In summary, discoid lateral meniscus revealed different tear pattern and vulnerability to injury and different age incidence from that of normal shaped lateral meniscus.