Knee Joint Anatomy
The knee joint is the largest joint in the body, and one of the most easily injured. It is made up of the lower end of the thighbone (femur), which rotates on the upper end of the shinbone (tibia), and the knee cap (patella), which slides in a groove on the end of the femur. The knee also contains large ligaments, which help control motion by connecting bones and by bracing the joint against abnormal types of motion.
Cartilage is the smooth lining on the surface of bone that plays a role in joint lubrication and shock absorption. As we get older, the water content in cartilage decreases and other changes in it makes it vulnerable to injury. It can get worn out from traumatic sports injuries or a gradual “wear and tear” from years of impact loading of the knee joint, needing cartilage repair. Another important structure, the meniscus, is a wedge shape piece of “rubber” between the femur and tibia that serves to cushion the knee and helps it absorb shock during motion.