What is a Meniscus Rupture? A meniscus tear is a common knee injury, especially in athletes, but it can also occur at any age. The meniscus is a C-shaped cartilage that acts as a shock absorber between the femur and the tibia. The injury usually occurs when the knee is twisted while the foot is fixed on the ground, especially under load. Injuries can also result from repeated trauma, such as squats, and can be divided into stable and unstable.