To understand the function of the meniscus, we must first know the morphological characteristics of the meniscus, a question I answered in the previous lecture “What is the meniscus? I have already answered this question in the previous lecture “What is the meniscus? Then you need to know what type of joint it is located in, what are the main bony structures that make up this type of joint, and what are the characteristics of this type of joint. The meniscus is located in the knee joint, which is a complex hinge joint. The femoral condyle and tibial plateau are the main bony structures that make up the knee joint. The main structures that maintain the stability of the knee joint are the anterior and posterior cruciate ligaments and the medial and lateral collateral ligaments on both sides of the joint, which are called the primary stability structures. Due to the morphological characteristics of the femoral condyles and tibial plateau surfaces of the knee, the direct contact area between the femoral condyles and the tibial plateau surfaces is small, and the pressure on the tibial plateau surfaces is greater when the lower extremity is walking with weight. In addition, the depression of the tibial plateau articular surface is shallow, and the stability of the knee joint is poor if it relies solely on the primary ligament to stabilize the structure. The direct contact area between the femoral condyles and the tibial plateau is small, which can lead to uneven distribution of synovial fluid. The meniscus is a solution to these problems. The femoral surface of the meniscus is smooth and concave, coinciding with the femoral condyles and in close contact with the femoral condyles, while the tibial surface is located on the tibial plateau, smooth and flat. This structure increases the contact area between the femoral condyles and the joint surface of the tibial plateau, and with this increase in contact area, the pressure on the joint surface of the tibial plateau is reduced, which at the same time ensures the stability of the knee joint and provides the basis for the uniform diffusion and distribution of synovial fluid. Therefore, the main functions of the meniscus are to increase the contact area of the articular cartilage, to distribute the weight and pressure on the articular surface, to increase the stability of the joint, and to assist in lubricating the joint and nourishing the cartilage.