What are Patellar Dislocation and patellar subluxation

Patellar dislocation and patellar subluxation are injuries that happen when the patella slips out of its normal position.

Patellar dislocation occurs when your kneecap (patella) slips all the way out of the groove. The kneecap (patella) is located in a groove in front of the lower end of your thighbone (femur). This groove is called the patellofemoral groove.

It usually occurs toward the outside of the leg. If the patella slips partly out of the groove, it is called a patellar subluxation.

What are the causes?

This condition is caused by:

• Force – A hit to the knee.
• Sports injuries.
• Twisting the knee when the foot is planted.

What increases the risk?

This condition is more likely to occur in:

• Women.
• People who play certain types of sports, including:
  • Sports that include quick turns or changes in direction, or where there is contact, like soccer.
  • Sports that require jumping, such as basketball or volleyball.
  • Sports in which cleats are worn.
• People who have had this condition before.

• Athletes in their teens or 20s.

What are the signs or symptoms?

Symptoms of this condition include:

• Sudden, severe knee pain.
• Swelling of the knee.
• Not being able to straighten or bend the knee.
• Numbness and tingling or skin that is cool or pale below the injured knee.
• A popping sensation, followed by a feeling that something is out of place.
• A misshapen knee.
• Being able to move the kneecap too much from left to right.

How is this diagnosed?

This condition may be diagnosed with:

• A physical exam.
• An X-ray or MRI. These may be done to see:
  • The position of the patella.
  • If a bone is broken.
  • The alignment of the knee.
  • The ligaments that hold the patella in place.
  • Any cartilage damage.

In some cases, your health care provider may look inside your knee joint with a pencil-sized surgical instrument called an arthroscope. This may be done to make sure you have no loose cartilage in your joint.

How is this treated?

Your patella may move back into place on its own when you straighten your knee. If your patella does not move back into place on its own, your health care provider will move it back into place. After your patella is back in its normal position, treatment may involve:

• Wearing a knee brace to keep your knee from moving (immobilized) while it heals.
• Doing exercises that help improve strength and movement in your knee. Your health care provider may recommend that you see a physical therapist.
• Taking medicine to help with pain and inflammation.
• Applying ice to the knee to help with pain and inflammation.
• Having surgery to prevent the patella from slipping out of place or to clean out any loose cartilage in your joint. This may be needed if other treatments do not help or if the condition keeps happening.

Follow these instructions at home:

If you have a brace:

• Wear it as told by your health care provider. Remove it only as told by your health care provider.
• Loosen the brace if your toes tingle, become numb, or turn cold and blue.
• Do not let your brace get wet if it is not waterproof.
• Keep the brace clean.
• If your brace is not waterproof, cover it with a watertight covering when you take a bath or a shower.

Managing pain, stiffness, and swelling

• If directed, apply ice to the injured area.
  • If you have a removable brace, remove it as told by your health care provider.
  • Put ice in a plastic bag.
  • Place a towel between your skin and the bag.
  • Leave the ice on for 20 minutes, 2–3 times a day.
• Move your toes often to avoid stiffness and to lessen swelling.

Activity

• Return to your normal activities as told by your health care provider. Ask your health care provider what activities are safe for you.
• Do exercises as told by your health care provider.

General instructions

• Do not use the injured limb to support your body weight until your health care provider says that you can. Use crutches as told by your health care provider.
• Take over-the-counter and prescription medicines only as told by your health care provider.
• Keep all follow-up visits as told by your health care provider. This is important.

How is this prevented?

• Warm up and stretch before being active.
• Cool down and stretch after being active.
• Give your body time to rest between periods of activity.
• Make sure you use equipment that fits you.
• Protect yourself against falls and injuries by doing activities in a safe way.

Contact a health care provider if:

• Your pain or swelling does not get better.

Get help right away if:

• The pain in your knee gets worse and is not relieved by medicine.
• You have more warmth or redness (inflammation) in the knee.
• Your knee catches or locks.
• You are unable to bend your knee.
• You have new swelling, pain, or tenderness in any area of your affected leg.

Summary

• Patellar dislocation occurs when your kneecap (patella) slips all the way out of the groove.
• If your patella does not move back into place on its own, your health care provider will move it back into place.
• Treatment may involve icing, medicine, knee brace, and exercises as told by your health care provider.
• In some cases, surgery may be done to prevent the patella from slipping out of place or to clean out any loose cartilage in your joint.