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Patellar Tracking Disorder - Topic Overview

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What is patellar tracking disorder?

Patellar tracking disorder means that 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. In a few people, it shifts toward the inside.

Your knee joint camera.gif is a complex hinge that joins the two bones of the lower leg with the thighbone.

  • The kneecap sits in a groove at the end of the thighbone. It is held in place by tendons on the top and bottom and by ligaments on the sides.
  • A layer of cartilage lines the underside of the kneecap. This helps it glide along the groove in the thighbone.

A problem with any of these parts in or around the knee can lead to patellar tracking disorder.

What causes patellar tracking disorder?

Patellar tracking disorder is usually caused by several problems combined, such as:

  • The way your knee is formed. Things that can lead to a knee problem include having a small or flat kneecap, knock-knees, a very long patellar tendon, or a shallow groove in the end of the thighbone.
  • Muscles in the front of your thigh (quadriceps) that are weak or out of balance. Strong quadriceps help hold your kneecap in place. But your kneecap can be pulled off track if the outer quadriceps muscle is stronger or contracts more quickly than the inner muscle.
  • Ligaments, tendons, or muscles camera.gif that are too loose or too tight.
  • Damaged cartilage in your kneecap.

You are more likely to have patellar tracking disorder if you have any of the above problems and you are overweight, run, or play sports that require repeated jumping, knee bending, or squatting.

What are the symptoms?

If you have a patellar tracking problem, you may have:

  • Pain in the front of the knee, especially when you squat, jump, kneel, or use stairs (most often when going down stairs).
  • A feeling of popping, grinding, slipping, or catching in your kneecap when you bend or straighten your leg.
  • A feeling that your knee is buckling or giving way, as though all of a sudden your knee can't support your weight.

If your kneecap is completely dislocated, you may have severe pain and swelling. Your knee may look like a bone is out of place. And you may not be able to bend or straighten the knee. If you have these symptoms, be sure to see your doctor. A dislocated kneecap needs to be put back in place by a doctor right away.

How is patellar tracking disorder diagnosed?

It can be hard to tell the difference between patellar tracking disorder and some other knee problems. To find out what problem you have, your doctor will:

  • Ask questions about your past health, your activities, when the pain started, and whether it was caused by an injury, overuse, or something else.
  • Feel, move, and look at your knee as you sit, stand, and walk.

You may have an X-ray so your doctor can check the position and condition of your knee bones. If more information is needed, you may have an MRI.

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WebMD Medical Reference from Healthwise

Last Updated: January 23, 2013
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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