The role of the menisci in force transmission across the knee.

Fourteen knees were studied by a method called spatial location, to determine the contact and load-bearing areas between the femur and the upper tibia in non-loaded and loaded conditions, at various angles of flexion. Under no load, contact occurred primarily on the menisci; the lateral aspects contacted at 0 degrees flexion, moving to the posterolateral aspects at 90 degrees flexion. An area of cartilage which frequently contacted was the medial tibial spine. Under loads of up to 150 kg, the lateral meniscus appeared to carry most of the load on that side of the joint, while on the medial side, the load was shared approximately equally by the meniscus and the exposed cartilage. These findings were verified on two knees by measuring contact pressure with a miniature transducer. Two implications of these findings are that the area of load-bearing is greatly increased and that the stability of the knee joint is enhanced by the menisci.