Meniscus: Anatomy, Mechanisms of Injury, Surgery

Anatomy
The menisci are semilunar fibrocartilage structures between the articular surfaces of femur and tibia. In cross section, they are wedge shaped with a thicker peripheral circumference and very thin axial margins. The concave femoral surface of each meniscus receives the curved surface of the femoral condyle. The tibial surface is relatively flat. Each meniscus is anchored to the tibial plateau by cranial and caudal menisco- tibial ligaments. The cranial menisco-tibial ligaments are united by the intermeniscal ligament; an important landmark because it borders the cranial margin of the tibial insertion of the cranial cruciate ligament (CrCL). In addition, the intermeniscal ligament is often used to anchor intracapsular grafts used for CrCL stabilization. The periphery of each meniscus is attached to the joint capsule. The attachment of the lateral meniscus differs from the medial meniscus in 3 ways:

1. the caudal margin of the lateral meniscus is less firmly attached to the joint capsule,

2. the lateral meniscus is not attached to the lateral collateral ligament, but the medial meniscus is attached to the medial collateral ligament, and

3. the caudal margin of the lateral meniscus is also attached to the femur by way of the menisco-femoral ligament.

Only the peripheral 10-25% of the menisci is supplied by a vascular network and nervous innervation. The axial majority of the menisci is avascular and aneural and is nourished by diffusion of synovial fluid. The menisci have several important functions:

1. energy absorption and stress distribution across the femoro-tibial joint,

2. stabilization of the joint by deepening the articular surfaces plateau - much like a “chock” behind a tire,

3. lubrication of the joint,

4. prevention of synovial membrane impingement between the femur and tibia, and

5. joint proprioception.

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