The knee is a hinge joint composed of three bones, the femur, tibia and patella. These are covered with articular cartilage, the smooth surfaces that allow joint movement. Between the femur (thigh bone) and the tibia (shin bone) are the menisci, which act as load distributors or shock absorbers between the joint surfaces. The knee joint is stabilised by the anterior and posterior cruciate ligaments (ACL and PCL), the medial and lateral collateral ligaments (MCL & LCL), and the muscles and tendons around the knee.
The knee can be viewed as three separate compartments: the medial (inside) compartment, the lateral (outside) compartment, and the patello-femoral compartment.
Knee injuries can occur as a result of sport, often affecting the menisci or the ligaments. However, the articular cartilage can also be injured as a result of these injuries, exposing bare bone and resulting in pain. These injuries may require surgical treatment, and options such as arthroscopy or more extensive joint preserving surgery may be needed.
Once cartilage damage becomes more widespread, then arthritis becomes established. If your symptoms are severe enough, then surgical options usually include some form of knee replacement surgery, although alternatives such as osteotomy may be an option.