Skip to Content

Patellar Dislocation


What is a patellar dislocation?

A patellar dislocation occurs when your patella (kneecap) is forced out of place. It can be caused by a fall or a direct blow to your knee. It can also happen if your knee twists or rotates. It is most likely to happen during physical activity, such as sports, military training, or dance.

What increases my risk for a patellar dislocation?

  • Being tall
  • Being overweight
  • A kneecap that sits high or is not lined up straight in your knee joint
  • Weak or imbalanced leg muscles
  • Previous knee injury or patellar dislocation, or a family history of knee problems

What are the signs and symptoms of a patellar dislocation?

  • Pain and swelling in your knee
  • Not being able to bend your knee or put weight on your leg
  • A kneecap that feels out of place or a knee that gives out

How is a patellar dislocation diagnosed?

Your caregiver will examine you. He will feel your kneecap and bend your knee, moving it in different positions. Tell him if you have had your kneecap dislocate or a knee injury in the past. Tell him if you have a family history of knee problems. Tell him if you have other health conditions. You may need the following tests:

  • X-rays are pictures of your knee. They are used to see if your patella is dislocated and if you have other injuries.
  • An MRI scan uses powerful magnets and a computer to take pictures of your knee. You may be given dye to help the pictures show up better. Tell the caregiver if you have ever had an allergic reaction to contrast dye. Do not enter the MRI room with anything metal. Metal can cause serious injury. Tell the caregiver if you have any metal in or on your body.
  • A CT scan is also called a CAT scan. An x-ray machine uses a computer to take pictures of your knee. You may be given dye before the pictures are taken to help caregivers see the pictures better. Tell your caregiver if you have ever had an allergic reaction to contrast dye.

How is a patellar dislocation treated?

Your kneecap may move back into place on its own. You may need the following:

  • Reduction is a procedure to move your kneecap back into place. Caregivers will move your knee and leg in different positions until your kneecap is where it belongs. After reduction, you will have another x-ray or CT scan.
  • Pain medicine may include acetaminophen, NSAIDs, and prescription pain medicine. These are given to decrease swelling and pain.
  • Aspiration is when a needle is used to remove blood and fluid from your knee. This reduces swelling and pain.
  • Surgery is done when caregivers cannot move your kneecap back into place. Surgery may also be done if your kneecap dislocates more than once. Surgery will usually be arthroscopic. This means a small incision is made and a scope is used to help your caregiver repair your knee joint.

What are the risks of patellar dislocation?

With or without treatment, your kneecap may not be as stable as it was before dislocation. You may develop arthritis in your knee. Your kneecap may dislocate again. There is a risk of infection if you have surgery.

How can I manage my symptoms?

  • Ice helps decrease swelling and pain. Ice may also help prevent tissue damage. Use an ice pack, or put crushed ice in a plastic bag. Cover it with a towel and place it on your knee for 15 to 20 minutes every hour or as directed.
  • Raise your knee above the level of your heart as often as you can. This will help decrease swelling and pain. Prop your knee on pillows or blankets to keep it elevated comfortably.
    Ice and Elevation
  • Immobilize your knee for 3 to 6 weeks or as directed. Your caregiver may give you a brace, cast, or splint. He may tell you to wrap your knee with athletic tape. This is done to decrease pain and hold your knee joint still to help it heal. This may also help prevent your kneecap from dislocating again.
  • Use crutches if your caregiver tells you not to put weight on your injured knee. Your caregiver will show you how to use crutches. You may need them for 4 to 6 weeks.
  • Physical therapy teaches you exercises to increase the range of motion in your knee. Exercises make your knee stronger, increase balance, and decrease pain. You may also need to strengthen your stomach, back, hip, and leg muscles. You must continue these exercises after physical therapy ends to help prevent another dislocation.

When should I contact my caregiver?

  • You have more knee pain.
  • Your knee feels like it is going to give out.
  • You have questions or concerns about your condition or care.

When should I seek immediate care?

  • Your kneecap dislocates again.
  • You have severe pain and swelling in your knee.

Care Agreement

You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your caregivers to decide what care you want to receive. You always have the right to refuse treatment. The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

© 2015 Truven Health Analytics Inc. Information is for End User's use only and may not be sold, redistributed or otherwise used for commercial purposes. All illustrations and images included in CareNotes® are the copyrighted property of A.D.A.M., Inc. or Truven Health Analytics.