Patellar Tracking Disorder

Topic Overview

Picture of the knee joint

What is patellar tracking disorder?

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.

See a picture of the knee joint.

What causes patellar tracking disorder?

A patellar tracking disorder is usually caused by several problems combined. The shape of the patella; too tight or too loose muscles and tendons in the leg, foot, or hip areas; damage to cartilage; and overuse may lead to patellar tracking disorder. See a picture of the muscles and tendons related to patellar tracking disorder.

Also, a severe blow to the inside of a healthy knee can knock a kneecap out of alignment or, in extreme cases, dislocate it. Symptoms of a dislocated kneecap include the knee looking misshapen like a bone is out of place, not being able to bend or straighten the knee, knee swelling, and severe pain.

Sometimes patellar tracking problems run in the family. If you have a family member with knee pain, you may want to take preventive measures, such as strengthening your thigh muscles.

What are the symptoms?

If your kneecap is out of alignment, you may have discomfort or pain, especially when you go down stairs, sit for a long time, stand up from sitting, or squat. This kind of pain, also known as patellofemoral pain, may be caused by patellar tracking disorder.

You also may feel a popping, grinding, slipping, or catching of the kneecap when you bend or straighten your leg. Or you may feel that your knee is buckling or giving way, as though the knee suddenly cannot support your body weight.

How is patellar tracking disorder diagnosed?

Some knee problems can be hard to tell apart. Your doctor will ask questions about your past health and carefully examine you to rule out other conditions. Some of the questions might be: When and how did the pain start? Did it start on its own with no direct cause? Or was the pain caused by injury, overuse, or some other problem with the knee? The doctor will also feel and move your knee as part of the physical exam.

You may also have imaging tests such as X-ray, CT scan, and MRI.

How is it treated?

You can try home treatment if your knee is not swollen, dislocated, giving way, or causing you severe pain. Take a break from activities that cause knee pain, like squatting, kneeling, running, and jumping. Put ice on your knee, and use pain medicines you can buy without a prescription.

As your knee pain starts to decrease, begin stretching and strengthening your leg. Strengthening your thigh muscles can help keep the kneecap stable. Your doctor or physical therapist can help you plan an exercise program specifically for your condition. You will probably start with one or two exercises and add others over time. It is important to closely follow the instructions from your doctor or physical therapist.

Knee pain can be a slow and frustrating condition to heal. But most people with pain from patellar tracking disorder gain relief with a few months of treatment and without surgery. As a rule, the longer you have had this problem, the longer it will take to get better.

Most people can gradually return to their previous activity level if they:

  • Avoid movements that make symptoms worse.
  • Do specific stretches and muscle-conditioning exercises.
  • Lose excess weight.
  • Tape or brace the knee, in some cases.
  • Learn the best way to perform a sport, and wear the right shoes or equipment.

Surgery is usually not needed for patellar tracking disorder. It is most often used when dislocation happens many times and other treatments have not worked. There are many types of surgery that can realign the kneecap and correct the tracking problem in some people. You and your doctor can decide which surgery is best for you.

How can patellar tracking disorder be prevented?

You may be able to prevent patellar tracking disorder and related knee pain. Avoid activity that overloads and overuses the knee. Stretch your legs and hips well, both before and after activity. Cycling and swimming are especially good activities. Stay at a healthy weight to reduce stress on your knee joints.

Frequently Asked Questions

Learning about patellar tracking disorder:

Being diagnosed:

Getting treatment:

Ongoing concerns:

Living with patellar tracking disorder:

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  Patellar tracking disorder: Exercises

Cause

A combination of factors is usually responsible for patellar tracking disorder. These factors can include:

  • How your body is formed. The patellar tendon connects the bottom edge of the patella to the front of the shinbone. When the patellar tendon is very long, the patella can slide too high on the knee joint. Other physical traits that increase your risk of having knee problems include a patellar shape that is unusually small or flat, flat feet, hips set more to the outside of the knees than usual, a shallow femoral groove for the patella to glide along, or a knock-knee position.
  • Weak thigh muscles. Strong thigh muscles (quadriceps) anchor the kneecap (patella) in place. Weak quadriceps allow the patella to move off track. See a picture of the muscles and tendons related to patellar tracking disorder.
  • An imbalance in the contraction of the thigh muscles. Your quadriceps are a group of four muscles. If the outer muscle is stronger than the inner muscle, or if it tends to contract quicker than the inner muscle, your kneecap can be pulled toward the outside as your leg straightens.
  • Tendons and muscles in the leg, foot, or hip areas that are too tight or too loose. For example, weak quadriceps combined with tight hamstrings and a tight iliotibial (IT) band can pull the patella toward the outside of the knee.
  • A blow to the kneecap, causing it to shift (partially dislocate or sublux) or dislocate. Dislocation can also be caused by twisting the thigh inward while the foot is firmly planted, pointing outward. After an initial dislocation, the patella is at increased risk of dislocating more easily.
  • A previous injury that has healed improperly, causing an imbalance in how the leg functions.
  • Generalized ligamentous laxity, or "loose-jointedness." Joint instability results from ligaments that are not as tight as they should be.

Symptoms

Symptoms of patellar tracking disorder can include:

  • A dull ache under, around, and/or at the outer edges of the kneecap, sometimes called patellofemoral pain syndrome. This is often made worse by using the stairs (especially going down stairs), sitting for long periods, and squatting.
  • A popping, grinding, slipping, or catching of the kneecap as the knee bends or extends. A grinding or popping sensation may develop before painful symptoms start or may not occur at all. If you have kneecap popping or grinding without pain, see the Prevention section of this topic for stretching and strengthening exercises.
  • Swelling of the knee, in some cases.
  • The knee buckling or "giving way," as though the knee suddenly won't support your weight.

Knee pain has many causes. If you have knee pain when you are squatting, standing up from a sitting position, going down stairs, or sitting, you may have patellar tracking disorder. But other conditions cause symptoms similar to those of patellar tracking disorder. For more information on other causes of knee symptoms, see the topic Knee Problems and Injuries.

What Happens

Patellar tracking disorder is a condition that disrupts the normal function of the knee.

Normal kneecap function

As your knee straightens and bends, the kneecap (patella) glides up and down the femoral groove at the front end of the thighbone (femur). At the same time, the patella tilts and rotates slightly, held in check by ligaments on the sides and tendons on the top and bottom.

See a picture of the knee joint.

Kneecap instability

If the femoral groove is shallow, the patellar tendon is too long, or the stabilizing ligaments, tendons, or muscles are too tight or loose, the kneecap can shift, tilt, or rotate off track (sublux). As you bend your knee to a 90-degree angle, a misaligned kneecap will have increasing abnormal contact with the thighbone, creating painful pressure.

In extreme cases, the kneecap can dislocate. After a kneecap has been dislocated once, it may dislocate more easily in the future. Any resulting damage to the kneecap or supportive tissue can lead to ongoing patellar tracking problems.

Untreated patellar tracking disorder can lead to:

A blow to the middle or inside of a structurally sound kneecap can also dislocate the kneecap.

What Increases Your Risk

Some risk factors for patellar tracking disorder are beyond your control. Others, such as having weak quadriceps, you can change.

Risk factors that you cannot change

  • Family history of knee problems.
  • Knee abnormalities, such as knock-knees or an excessively long patellar tendon that allows the patella to slide too high on the knee joint (patella alta).
  • A poorly healed injury of the hip, leg, knee, or foot.
  • Previous kneecap dislocation.
  • Previous knee surgery.
  • Generalized ligamentous laxity, or "loose-jointedness."
  • Damage to cartilage.

Risk factors that you can avoid or change

  • Weak thigh muscles (quadriceps).
  • The outer part of your thigh muscle is stronger or contracts quicker than the inner thigh muscle.
  • Tight ligaments, tendons, and muscles.
  • Excessive body weight.
  • Running, particularly on hills.
  • Playing sports that require repeated jumping, knee bending, or squatting.
  • Improper footwear.
  • Improper athletic training or technique.

When To Call a Doctor

Call your doctor immediately if you have severe knee pain or your kneecap has dislocated.

If your doctor hasn't determined that you have patellar tracking disorder but you have knee pain or dysfunction, see the topic Knee Problems and Injuries to evaluate your symptoms.

Watchful Waiting

If your knee aches or your kneecap shifts or catches, first try the stretching and strengthening exercises and other tips in the Home Treatment section of this topic. If your symptoms continue longer than 1 to 2 weeks or if your knee is swollen, talk to your doctor.

Who To See

The following health professionals can perform initial diagnosis and treatment for patellar tracking disorder or dislocation of the kneecap:

For instruction in strengthening, stretching, bracing, and taping techniques, see a physical therapist.

For evaluation of whether a dislocated kneecap could benefit from surgery, see an orthopedic surgeon (orthopedist) or sports medicine specialist. For more information, see the Surgery section of this topic.

To prepare for your appointment, see the topic Making the Most of Your Appointment.

Exams and Tests

Patellar tracking disorder can be hard to distinguish from other knee problems. If your knee still has pain after 2 weeks of stretching, strengthening, and rest from aggravating activity, your doctor will:

  • Review your health history, including the history of your knee problem, your current physical activities, previous injuries, and family history of knee problems.
  • Do a physical exam of your knee and the muscles, ligaments, and tendons that support it.

Tests that are done as needed

If your diagnosis is unclear, one or more of the following imaging tests may be used to gather more information about your knee:

  • X-ray, which is the standard imaging technique for assessing the position and condition of the knee bones
  • CT scan, which is sometimes used for imaging the joint in more detail
  • MRI, for evaluating cartilage or ligament damage, and to confirm the results of a physical exam

Treatment Overview

Knee pain can be a slow and frustrating condition to heal. But most people with patella-related knee pain gain relief with a few months of nonsurgical treatment. In general, the longer you have had a patellar tracking disorder, the longer you can expect to be in treatment.

Self-care

Unless your knee is swollen, dislocated, giving way, or causing you severe pain, try the measures described in the Home Treatment section for a week or two before deciding whether to see your doctor. With rest from aggravating activity, ice, and nonsteroidal anti-inflammatory drugs (NSAIDs), you can expect your pain to decrease. Do not give aspirin to anyone younger than 20 because of the risk of Reye's syndrome, a rare but serious disease.

As your pain starts to subside, begin stretching and strengthening exercises. These will loosen tight connective tissue that can pull the patella off track. Also, the exercises will help stabilize the patella in the femoral groove as you bend and straighten your knee.

Click here to view an Actionset. Patellar tracking disorder: Exercises

Medical treatment

If home treatment isn't enough to reduce your knee problems, or if your knee is swollen, dislocated, giving way, or causing you severe pain, see your doctor for evaluation. Knee problems are often hard to distinguish from one another. So a thorough exam and accurate diagnosis are essential for you to receive proper treatment.

After confirming that you have a patellar problem, your doctor will review your home treatment measures and make further recommendations. You may be advised to have physical therapy, use a custom brace or shoe inserts (orthotics), stabilize your knee with tape or a neoprene brace, or lose excess weight.

Surgery is not commonly done for patellar tracking disorders. But surgery is recommended in cases of repeated patellar dislocation, displaced or damaged cartilage following a dislocation, loose bodies (such as small pieces of bone or cartilage) in the knee following a dislocation, repeated subluxations caused by a structural deformity, or failed nonsurgical therapy.

What To Think About

Nonsurgical treatment—including stretching and strengthening exercises, temporary use of nonsteroidal anti-inflammatory drugs, and sometimes bracing or orthotics—usually eases the pain of a patellar tracking disorder and makes surgery unnecessary. Keeping your knee strong and flexible will help to prevent further problems. Staying at a healthy weight to decrease stress around your knees may also help. For more information, see the topic Weight Management.

Prevention

To prevent patellar tracking disorder and related knee pain, try to:

  • Avoid activity that overloads and overuses the knee.
  • Keep your thigh muscles strong.
  • Engage in other activities or exercises that work different parts of the legs (cross train), especially if you are a runner. Cycling and swimming are especially good activities for building other muscle groups and reducing the stress on your knee.
  • Stretch your legs and your hips well, both before and after activity.
  • Stay at a healthy weight to reduce stress on your knee joints.
  • Use proper footwear, technique, and training for your sport or activity.

Home Treatment

If you have achy knee pain on or around your kneecap and have not yet been diagnosed with a patellar tracking disorder, first try the following home treatment:

  • Take a break from activities that cause knee pain, particularly squatting, kneeling, running, and jumping. Swimming and cycling are good aerobic choices.
  • Ice your knee regularly, particularly before and after activity.
  • Use nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce pain and swelling.

You may also want to try:

  • Wearing a neoprene brace with a patellar cutout, if you feel that your kneecap is shifting enough to need stabilizing.
  • Using supportive shoe inserts (orthotics). You can buy good-quality inserts from a shoe store or drugstore.

As your knee pain starts to go away, begin stretching and strengthening your leg. Stretching can loosen tight muscle and connective tissue that have been pulling the patella off track. Strengthening your thigh muscles can help stabilize the patella in the femoral groove as you bend and straighten your knee.1

  • Stretch your thigh muscles (quadriceps), hamstrings, iliotibial (IT) band, and Achilles tendon daily, particularly before and after activity.
  • Begin thigh strengthening with isometric exercise and straight leg raises only. Progress to exercises such as quarter squats and leg presses, in which your feet are pushing against something (closed-chain exercises). Avoid knee-extension exercises in which you are raising and lowering your foot, which may further damage your unstable knee.
Click here to view an Actionset. Patellar tracking disorder: Exercises

Medications

To reduce knee pain and swelling related to patellar tracking disorder, you can take nonsteroidal anti-inflammatory drugs (NSAIDs). Do not give aspirin to anyone younger than 20 because of the risk of Reye syndrome, a rare but serious disease.

The dietary supplements glucosamine and chondroitin sulfate may also relieve pain that is caused by cartilage damage.

Surgery

Surgery is considered appropriate only for chronic and severe cases of patellar dislocation and select cases of chronic patellar tracking disorder. Surgery can be used to realign the kneecap and restore normal patellar tracking and to repair knee damage.

Surgery Choices

The type of surgery that is appropriate for you depends on the type of tracking disorder you have and its cause. Surgeries for patellar tracking disorder include:

What To Think About

Surgeons use different procedures for repairing knee problems. The procedure used depends on the cause of your knee problem and your surgeon's experience.

Having knee surgery for patellar tracking problems increases your risk for osteoarthritis.2

Some surgeons think it best in some cases to repair knee damage immediately after a first patellar dislocation. Other surgeons will wait until they see a recurrent problem.

Although surgery for dislocation offers a good chance that the patella will no longer dislocate, many people continue to have pain after surgery.3 There is no proof that surgery to make the knee joint more stable will prevent long-term joint changes such as osteoarthritis.2

Other Treatment

Other treatments are often used for patellar tracking disorder. Before using other treatments, first try home treatment to reduce pain and inflammation.

Other Treatment Choices

Try physical therapy to:

  • Receive personal instruction for the stretching and strengthening exercises that are important for treating your knee.
  • Learn a specialized taping technique for holding an unstable kneecap in place. Ask your physical therapist about the McConnell taping technique.
  • If recommended by your doctor, be fitted for a nonprescription or prescription (custom) knee brace or shoe inserts (orthotics) for extra knee support or to improve your stride.

In addition to stretching and strengthening, you can also try massage to improve circulation and healing.

What To Think About

Before investing in a custom brace or orthotics, try over-the-counter versions from a sporting goods supply or drugstore.

Other Places To Get Help

Organization

American Academy of Orthopaedic Surgeons (AAOS)
6300 North River Road
Rosemont, IL  60018-4262
Phone: 1-800-346-AAOS (1-800-346-2267)
(847) 823-7186
Fax: (847) 823-8125
E-mail: orthoinfo@aaos.org
Web Address: www.aaos.org
 

The American Academy of Orthopaedic Surgeons (AAOS) provides information and education to raise the public's awareness of musculoskeletal conditions, with an emphasis on preventive measures. The AAOS Web site contains information on orthopedic conditions and treatments, injury prevention, and wellness and exercise.


References

Citations

  1. Hertling D, Kessler RM (2006). Patellar tracking dysfunction (chondromalacia patellae) section of Knee. In D Hertling, RM Kessler, Management of Common Musculoskeletal Disorders: Physical Therapy Principles and Methods, 4th ed., pp. 524–532. Philadelphia: Lippincott Williams and Wilkins.
  2. Mulford JS, et al. (2007). Assessment and management of chronic patellofemoral instability. Journal of Bone and Joint Surgery, British Volume, 89-B(6): 709–716.
  3. Harner CD, et al., eds. (2005). Patellofemoral instability and malalignment section of Knee and lower leg. In LY Griffin, ed., Essentials of Musculoskeletal Care, 3rd ed., pp. 541–545. Rosemont, IL: American Academy of Orthopaedic Surgeons.

Other Works Consulted

  • American Academy of Family Physicians (2007). Patellofemoral Pain Syndrome. Available online: http://familydoctor.org/online/famdocen/home/healthy/physical/injuries/479.
  • American Academy of Podiatric Sports Medicine (2004). Patellofemoral Dysfunction. Available online: http://www.aapsm.org/patellofemoraldys.html.
  • Earl JE, Vetter CS (2007). Patellofemoral pain. Physical Medicine and Rehabilitation Clinics of North America, 18(2007): 439–458.
  • Grudziak JS, Musahl V (2007). Patella instability and dislocation in adolescents section of The youth athlete. In PJ McMahon, ed., Current Diagnosis and Treatment in Sports Medicine, p. 230. New York: McGraw-Hill.
  • Hudgins T (2008). Patellofemoral syndrome. In WR Frontera et al., eds., Essentials of Physical Medicine and Rehabilitation: Musculoskeletal Disorders, Pain, and Rehabilitation, 2nd ed., pp. 371–374. Philadelphia: Saunders Elsevier.

Credits

Author Judy Dundas
Editor Maria Essig
Associate Editor Pat Truman, MATC
Primary Medical Reviewer William H. Blahd, Jr., MD, FACEP - Emergency Medicine
Specialist Medical Reviewer Patrick J. McMahon, MD - Orthopedics
Last Updated January 19, 2010

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