The four bones that meet at the knee joint are the femur, the tibia, the fibula and the patella (kneecap).
The femur is the thighbone or the bone of the upper leg.
The tibia is the shinbone and is the larger bone of the lower leg.
The fibula is the smaller bone of the lower leg.
The kneecap, or patella, is approximately 2-3 inches in width and 3-4 inches in length. Its position in the front of the knee joint allows it to slide when the leg moves, as well as protect the knee and give leverage to the muscles.