The knee is a hinged joint formed by the meeting of the thigh bone (femur) and the shin bone (tibia). This is called the tibiofemoral joint. It also has an additional joint on the front where the knee cap (patella) moves on the end of the femur called the patellofemoral joint. They are both contained within the same lining (capsule) and lubricated by a special fluid called synovial fluid. Thus any injury to one of the joints in the knee can cause a build up of fluid that can harm the function of the other.
