The menisci (plural for meniscus) are C-shaped strong cartilage that sit between the femur (thigh bone) and the tibia (lower leg bone). The menisci are sometimes referred to as the cartilage of the knee, but they are separate from the articular cartilage that covers the surface of the joint.
There are two parts to the meniscus: medial and lateral. Medial refers to the side of the knee closest to the other leg. Lateral is the side away from the other leg. The medial and lateral menisci of the knee work like a gasket to spread the force from the weight of the body over a larger area help the ligaments with stability of the knee. Without the menisci, any weight on the femur will be concentrated to one point on the tibia. But with the menisci, weight is spread out across the tibial surface.
The front portion of the meniscus is referred to as the anterior horn, the back portion is the posterior horn, and the middle section is the body. The posterior horn is an important anatomical feature. Without it, stress on the meniscus is enough to cause significant load on the joint. That’s when the degenerative processes speed up. A complete tear or rupture of the posterior horn is called an avulsion.
How often does it happen that someone ends up with a posterior horn avulsion of the medial meniscus? It was once thought that this was a relatively uncommon injury. But with the availability of MRIs, doctors have documented a much higher incidence than previously thought. Up to 28 per cent of all medial meniscal tears involve the posterior horn.