The kneecap is a small bone in front of the knee that is incorporated in the tendons that connect the thigh muscles to the lower leg (tibia). It sits in a groove at the end of the thigh bone (femur) and glides up and down when we bend and straighten the knee. When the kneecap comes out of its groove, or dislocates, it results in pain and difficulty walking or bearing weight. Some people have variations in the shape of the groove in the femur or alignment of the leg, that may make them more prone to dislocation of the kneecap. These include: a shallow or uneven groove at the end of the femur and a “knock-knee” alignment. A forceful blow to the knee or fall onto the kneecap can also result in popping the kneecap out of place. The kneecap usually dislocates to the outside of the knee (laterally).
The first line of treatment is reduction of the kneecap to the front of the knee. This can occur spontaneously by straightening the leg. After reduction, conservative treatments such as bracing and therapy are utilized with gradual return to normal activities in 1-3 months. If there is cartilage damage under the knee or you experience repetitive kneecap dislocations, surgical management may be recommended.