Patellar tracking disorder occurs when the kneecap (patella) shifts out of place as the leg bends or straightens. In most cases, the kneecap shifts too far toward the outside of the leg, although in a few people it shifts toward the inside.
Your knee joint is a complex hinge that joins the lower leg bones (tibia and fibula) with the thighbone (femur). The kneecap is held in place in the front of the knee joint by tendons on the top and bottom and by ligaments on the sides. A layer of cartilage lines the underside of the kneecap, helping it glide along the groove at the end of your thighbone.
The kneecap can shift or rotate off track if the groove is too shallow or if the cartilage is damaged. Ligaments, tendons, or muscles that are too loose or too tight may also lead to a misaligned kneecap.
