Illustration of an injury to the meniscus of the knee joint. The menisci are two crescent-shaped pads of cartilage attached to the top of the tibia (shin bone), which articulate with the base of the femur (thigh bone). They reduce friction and cushion the joint. They are a common site of injury amongst athletes due to knee trauma or repeated high-impact activity. They can also suffer chronic injury through normal wear and tear over time. Surgery can repair or remove a damaged meniscus, or a prosthetic meniscus can be implanted. Physiotherapy is required to strengthen the knee after surgery.