What is a Meniscus?

There are medial and lateral meniscus-shaped bones on the articular surface of the tibia, called meniscus, whose edges are thicker, are tightly connected to the joint capsule, and the center is thin and free. Except that the edge part can be repaired by itself, the meniscus cannot be repaired by itself. After the meniscus is removed, a thin, narrow meniscal with fibrocartilage can be regenerated by the synovium. Normal meniscus has the function of increasing the tibial condyle depression and lining the inner and outer femoral condyles, in order to increase the stability of the joint and cushion the shock.

There are medial and lateral meniscus-shaped bones on the articular surface of the tibia, called meniscus, whose edges are thicker, are tightly connected to the joint capsule, and the center is thin and free. Except that the edge part can be repaired by itself, the meniscus cannot be repaired by itself. After the meniscus is removed, a thin, narrow meniscal with fibrocartilage can be regenerated by the synovium. Normal meniscus has the function of increasing the tibial condyle depression and lining the inner and outer femoral condyles, in order to increase the stability of the joint and cushion the shock.

Western Medicine Name

Meniscus

Chinese Medicine Name

Osteoporosis

English name

meniscus [m'nsks]

Other name

Knee cartilage

Affiliated Department

Surgery-Orthopedics

Disease site

Knee joint

The main symptoms

Pain can not be flexed and stretched, swelling

Main cause

Excessive exercise, physical exertion or exercise

Multiple groups

Large leg exercise group

Contagious

Non-contagious

Treatment

Chinese ointment

Meniscus anatomy

The meniscus is composed of fibrocartilage, one inside and one outside, and is located in the joint space of the knee joint. The anterior part of the medial and lateral meniscus is connected to the transverse knee ligament. The structure of the meniscus is semi-circular, with a thicker outer periphery, a thin inner edge, and a depression on the upper side, adapted to the femoral condyle, and flat on the lower side, adapted to the tibial plateau. Because of the presence of the meniscus, the knee joint is divided into two groups: femoral-meniscus, meniscus-tibia. The meniscus is mainly attached to the tibia, but it can move with the femur to a certain extent. Combined with its morphological characteristics, it can compensate the mismatch between the tibial condyle and femoral condyle, increase the stability of the joint, and prevent the surrounding soft tissue from being squeezed into the joint . The meniscus is grayish white, smooth and shiny, tough and has some elasticity. It can cushion the impact of the two bone surfaces, absorb shocks, spread synovial fluid, increase lubrication, reduce friction, and protect the joints.

Meniscus meniscus blood supply

The meniscus' blood supply comes from the branches of the internal and external knee arteries, which form a network of blood vessels in the joint capsule. These arterial meshes from the articular capsule and synovium provide only 10% to 30% of the blood flow around the periphery of the meniscus. This part is called red area under arthroscopy and can be healed after repair. The central part has no blood flow, so it is called white area. It is nourished by the penetration of joint fluid, so it lacks the ability to repair and regenerate after injury. When the knee joint is straight, the meniscus is pushed forward by the femoral condyle, and when the knee joint is flexed, it moves backward. When the knee joint rotates, the two menisci are forward and one backward. When the knee flexes and stretches, the femoral medial and lateral condyles move above the meniscus, and when the knee rotates, the meniscus is fixed below the medial and lateral ankles, and its rotation occurs between the lower meniscus and the tibial plateau. Therefore, the rupture of the meniscus occurs mostly under the plate, and the rotation is the main cause of the rupture of the meniscus.

Meniscus classification

Inner meniscus

The inner meniscus has a "C" shape with a large circumference, a narrow front end and a wide rear part. The anterior horn attaches to the anterior cruciate ligament attachment point and lies between the two condyles of the tibia. However, according to autopsy, the Third Affiliated Hospital of Peking University believes that the anterior corner stop of the medial meniscus is more forward, lower than the front of the platform. This is of great significance during meniscus transplantation. Some fibers in the anterior horn pass through the front of the joint and are connected to the anterior horn of the lateral meniscus. The posterior horn is attached to the tibial intercondylar fossa, just before the posterior cruciate ligament and below the posterior horn fibers of the lateral meniscus. The medial meniscus is closely connected to the posterior medial collateral ligament and the medial joint capsule, thus limiting the mobility of the medial meniscus. At the junction of the slack front half and the fixed rear half, a horizontal fracture is liable to occur due to torsional external forces.

2. Outer meniscus

The outer meniscus has a smaller diameter and a wider area than the inner meniscus, and it has a ring shape and is approximately "O" shaped. It is slightly wider in the middle and slightly narrower in the front and rear, but the overall length is wider than the inner meniscus. The anterior horn is attached behind the anterior cruciate ligament and mixed with the anterior cruciate ligament; the posterior horn is attached to the rear of the intersacral bulge and the front of the posterior horn attachment point of the medial meniscus. The ligaments are not connected. In most cases, a small ligament emanates from the posterior horn and ends on the lateral side of the femoral condyle. This ligament passes before or after the posterior cruciate ligament. The anterior side is called the Humphrey ligament, while the latter is called the Wrisberg ligament. These ligaments help control the meniscus as the knee moves. The ligament is taut during flexion and pulls the posterior angle of the meniscus forward and inward to fit the tibiofemoral space and increase its adaptability. Because the anterior and posterior angular attachment points are close and not connected to the lateral collateral ligament, the lateral meniscus has a relatively large degree of activity. Part of the outer meniscus is discoid and prone to damage. According to the meniscus shape, it can be divided into primitive type, intermediate type and infant type, among which primitive type is more common, accounting for about 60%.

Meniscus inspection

Rotary extrusion test:

The conical extrusion test is also called the Mc Murray test, the meniscus popping test, and the conical grinding test. This test uses the rotation of the knee joint surface and mutual grinding action to check whether the meniscus is damaged. This method has 2 actions, each of which includes 3 powers.

Operation method: Ask the patient to lie supine, first make the knee joint maximally flexed, fix the knee joint with the left hand, hold the finer part of the foot and ankle with the right hand, and try to force the long axis of the tibia to rotate outwards. While the valgus force continues to work, slowly straighten the knee joint. If there is sound and pain on the medial side, the medial meniscus is ruptured. Act in the opposite direction according to the above principle, straighten the knee joint while turning the varus of the knee joint. If there is sound and pain, it is proved that the lateral meniscus is ruptured. The above is the description mentioned in the relevant books. The actual clinical experience is not exactly the same as this description. Sometimes the pain and sound position are opposite to the above. When the calf is turned inward and straight, it is often the medial pain and the lateral meniscus pain. But sometimes, no matter inward or outward, as long as the joint surface is abraded and rotated, the pain is always fixed in the knee joint space.