Patellar SubluxationThe kneecap slides up and down a groove on the end of the thigh bone as the knee bends. This groove is called the trochlea. The kneecap is designed to fit in the center of this groove, and slide evenly within the groove. In some people, the kneecap is pulled towards the outside of the knee. As this happens, the kneecap does not slide centrally within its groove.
Also called patellar subluxation, patients who experience an unstable kneecap have a kneecap that does not slide centrally within its groove. Depending on the severity of the patellar subluxation, this improper tracking may not cause the patient any problems, or it may lead to dislocation of the patella (where the kneecap fully comes out of the groove). Most commonly, the tracking problem causes discomfort with activity, and pain around the sides of the kneecap. Patellar subluxation is a condition that usually affects adolescent, and sometimes younger children.
Causes of Patellar SubluxationThere are dozens of factors implicated in the cause of patellar subluxation. The bottom line is that it is probably the contribution of several factors that lead to instablitiy of the kneecap. Possible factors include:
- A wider pelvis
- A shallow groove for the kneecap
- Abnormalaties in gait
What else may be causing kneecap pain?
The most common cause of kneecap pain is chondromalacia, or an irritation of the cartilage on the undersurface of the kneecap. Patellar subluxation and chondromalacia can go hand in hand, but they should be considered separate entities. That said, if chondromalacia is being caused by subluxation, then the instability of the kneecap must be addressed for treatment to be successful. Other causes of kneecap pain include osteoarthritis, patellar tendonitis (Jumper's knee), and plica syndrome.
Treatment of Patellar SubluxationTreatment of the unstable patella is first to ensure that the patella is not dislocated. Your doctor can determine by examining your knee and obtaining x-rays, to see if the kneecap is outside of its groove. In patients with a kneecap dislocation, the kneecap may need to be repositioned, or "reduced." Treatment of patellar subluxation includes:
- Physical Therapy
Traditionally, patients were sent to physical therapy to strengthen their VMO (part of the quadriceps muscle) to realign the pull on the kneecap. More recent research has shown that this is probably not the critical factor in eliminating kneecap problems. Focusing instead on strengthening of the hip abductors and hip flexors (so-called pelvic stabilization exercises) offers better control of the kneecap.
- Bracing and Taping
Bracing and taping of the kneecap are also a conroversial topic in the rehabilitation of kneecap problems. These often provide symptomatic relief, but are certainly not a long-term solution. Caertianly if symptomatic relief is found with a brace or tape, it is certainly appropriate to continue with this as a treatment.
- Better Footwear
Footwear contributes to the gait cycle. Motion control running shoes may help control your gait while running and decrease the pressure on the kneecap.