Lesions of the menisci. Autopsy incidence in adults less than fifty-five years old.

The menisci were removed from the knees of seventy autopsy subjects less than fifty-five years old and 18.6% exhibited at least one horizontal cleavage lesion. Seven per cent of 200 autopsy subjects showed at least one discoid lateral meniscus, and it is suggested that neither these nor the horizontal cleavage lesions had caused symptoms during the lifetime of each subject. Microscopic signs of degeneration were seen in 76% of the grossly normal medial menisci examined. Medial menisci not only have a larger surface area than lateral menisci but are broader and thicker posteriorly. It may be that the greater thickness of the medial meniscus posteriorly renders it more vulnerable because there is less nutritional diffuse of synovial fluid.