A thorough knowledge of the anatomy and function of the knee joint is essential for understanding the mechanism of meniscal injuries. It is also useful for diagnostic evaluation of any type of knee injury.
The knee joint is the largest articulation in the body. It is composed of the distal end of the femur and the proximal epiphysis of the tibia. The stability of the knee joint is provided by the anterior cruciate ligament (ACL), the posterior cruciate ligament (PCL), the medial and lateral collateral ligaments (MCL & LCL), the menisci, and by the surrounding capsule and muscles. These soft tissue structures are arranged in such a way as to provide minimal rotational movements while allowing for extension and flexion. .
The menisci are the remnants of an embryonic septum between the tibia and fibula (Ricklin, 1983). The menisci are two semilunar shaped wedges which act to deepen the articular surfaces between the flat tibial plateau and the rounded femoral condyles. As a result, their superior surfaces are concave and the inferior surface is flat.
The menisci are mobile buffers which help to distribute the pressure of the femur over a larger area of the tibia and act to increase the elasticity of the joint. The peripheral, convex borders of the menisci are thick and attach to the tibia via the coronary ligaments; the inner border narrows to a free edge centrally. The medial and lateral menisci each have distinct and individual anatomic characteristics.
The medial meniscus is semicircular or C-shaped with an average width of 10 mm. It is asymmetric with its posterior horn usually wider than the middle and anterior portions. Peripherally, the medial meniscus is continuously attached to the joint capsule with the middle horn firmly to the MCL . It is anchored to the tibia by the meniscotibial ligaments. The posterior horn inserts in the posterior intercondylar fossa directly anterior to the PCL.