Although the lateral collateral ligament (LCL) passes in close proximity, the lateral meniscus has no attachment to this structure.The joint capsule attaches to the entire periphery of each meniscus but adheres more firmly to the medial meniscus. An interruption in the attachment of the joint capsule to the lateral meniscus, forming the popliteal hiatus, allows the popliteus tendon to pass through to its femoral attachment site. Contraction by the popliteus during knee flexion pulls the lateral meniscus posteriorly, avoiding entrapment within the joint space. The medial meniscus does not have a direct muscular connection. The medial meniscus may shift a few millimeters, while the less stable lateral meniscus may move at least 1 cm.In 1978, Shrive et al. reported that the collagen fibers of the menisci are oriented in a circumferential pattern. When a compressive force is applied in the knee joint, a tensile force is transmitted to the menisci. The femur attempts to spread the menisci anteroposteriorly in extension and mediolaterally in flexion. Shrive et al. further studied the effects of a radial cut in the peripheral rim of the menisci during loading. In joints with intact menisci, the force was applied through the menisci and articular cartilage; however, a lesion in the peripheral rim disrupted the normal mechanics of the menisci and allowed it to spread when a load was applied. The load now was distributed directly to the articular cartilage.
Males between the ages of 31 and 40 tend to tear their meniscus more frequently than younger men. Females seem to be more likely to tear their meniscus between the ages of 11 and 20. People who work in physically demanding jobs such as construction or professional sports are more at risk of a meniscal tear because of the different stresses to which their knees are subjected. According to the United States National Library of Medicine, the isolated medial meniscal tear occurs more frequently than any other tear associated with the meniscus. The prevalence of meniscus tears is the same for both knees. In a few studies the having a higher BMI puts more weight on the joints, which can cause the knee to be non-aligned, resulting in an easier tear.In 2008 the U.S Department of Health and Human Services reported a combined total of 2,295 discharges for the principal diagnosis of tear of lateral cartilage/meniscus (836.0), tear of medial cartilage/meniscus (836.1), and tear of cartilage/meniscus (836.2). Females had a total of 53.49% discharges, while males had 45.72%. Individuals between the ages of 45 and 68 had an average of 31.73% discharges followed by age group 65–84, with 28.82%. The average length of stay for a patient diagnosed with torn menisci was 2.7 days for males and 3.7 days for females. There was a report of 6,941 hospital discharges for knee repair.