Knee Meniscal Tears

Excerpt

The lateral and medial menisci are crescent-shaped fibrocartilaginous structures that collectively cover approximately 70% of the articular surface of the tibial plateau and primarily function in load transmission and shock absorption through the tibiofemoral joint. They are wedge-shaped with thicker portions at the periphery of the joint, thereby deepening the articular surface area of the tibial plateau, which improves joint congruency and acts as a secondary stabilizing mechanism within the joint. 70% of each meniscus comprises a network of type I collagen arranged primarily in a circumferential direction. The inner 2/3 of the adult menisci is avascular and referred to as the "white zone," likely receiving nutrition through diffusion with the synovial fluid. The peripheral 1/3 of the adult menisci, or "red zone," is well-vascularized and supplied via branches of the medial and lateral genicular arteries. The peripheral 2/3 of the menisci contain nociceptive free nerve endings, while mechanoreceptors are located in the anterior and posterior horns of the menisci, suggesting a possible proprioceptive function. The outer border of the medial meniscus is firmly attached to the joint capsule and deep fibers of the medial collateral ligament (MCL), making it less mobile than the lateral meniscus, which does not connect with the lateral collateral ligament (LCL) and has looser attachments with the joint capsule. In addition to their attachments to the tibial plateau via their anterior and posterior horns, the anterior margins of the menisci are connected by the transverse intermeniscal ligament. In contrast, the posterior horn of the lateral meniscus connects to the femur via meniscofemoral ligaments and to the adjacent popliteus tendon.