Patella (kneecap) dislocation

You have received a diagnosis of a kneecap (patella) dislocation. This leaflet will explain the following.

• What a kneecap dislocation is.

• What the symptoms and causes are.

• How the dislocation is diagnosed.

• What treatments are available.

• How to manage the pain and swelling.

• How to carry out the rehabilitation exercises given to you by physiotherapy.

We hope this leaflet answers some of the questions you may have. If you have any further questions or concerns, please speak to a member of your healthcare team.

What is a kneecap dislocation?

The kneecap (patella) is at the front of the knee. When the knee bends and straightens, the patella moves in a groove on the thigh bone (femur).

A kneecap dislocation is where the kneecap moves out of the groove, usually to the outside of the knee. This may cause injury to the muscles and ligaments in the area. It is usually caused by a twisting injury or trauma to the knee.

A dislocated kneecap often goes back into place on its own. If it doesn't, a paramedic or healthcare professional needs to put it back in as soon as possible.

How common is a kneecap dislocation?

Kneecap dislocations are common, and can happen at any age. On average, 5 to 7 people out of every 100,000 will have a first-time kneecap dislocation each year. However, first-time dislocations most often happen in young people. Approximately 29 out of every 100,000 10 to 17 year-olds will have a first-time kneecap dislocation each year. [1] 

What are the symptoms?

• You may be able to see your kneecap has moved out of place. If this happens only for a moment before the kneecap returns to its normal position, you might not see it.

• It is normal to have pain and swelling around the joint or front of your knee. This may make it hard to put weight on your leg, and bend or straighten your knee. The pain and swelling should improve within a few days.

What causes kneecap dislocation?

Kneecap dislocation can happen after a twisting movement or an injury to the knee. Some people are more likely to have this injury due to the shape of their knee bones.

If your knee is not recovering as expected, we may check the shape of your knee bones. This could help us find out if their shape is impacting your recovery from the injury.

It is important to follow advice and complete your knee rehabilitation.

How is kneecap dislocation diagnosed?

A full history of your injury is important for making a diagnosis.

When you arrive at the hospital, you will have x-rays taken. This will check your injury and confirm the position of your kneecap. Your doctor may recommend more tests, such as an MRI scan, based on the x-ray results. If this is needed, they will make a referral and these tests will be completed at a later date. You may return to the hospital or receive a telephone call to confirm this.

If you have other injuries as well as your kneecap dislocation, your treatment may differ from what is in this booklet.

What treatments are available?

Most people recover well from a kneecap dislocation within 6 to 8 weeks. The injury can be managed without surgery. Management would usually be as follows.

1 to 3 days after your dislocation

• To allow your knee to recover, it is important to protect your knee from too much activity.

• If this is a first-time dislocation, you might be given a knee support for pain relief. These supports will allow you to fully bend and straighten your knee. It is important to keep your joint moving and your muscles working.

• If needed, you will be given crutches and taught how to use them. With a simple kneecap dislocation there is no restriction as to how much weight you can put on your leg. You may need crutches for pain relief. You should gently increase the weight over the first couple of days, as your pain allows.

• We will contact you to decide on your ongoing management and refer you for physiotherapy.

If you have previously had the same injury, the management of your injury will differ. You will not be given a knee support, but you may be offered crutches for support. The hospital will let you go and refer you to physiotherapy.

Your GP can refer you to the Soft Tissue Knee clinic if there are any concerns about your recovery.

How can I manage the swelling and pain?

• After the first few days, it is important to start moving your knee again. This helps you return to normal movement and function as your symptoms get better. It also helps repair the injured structures.

• Some pain is normal to begin with; it will get better in time.

• Make physical activity part of your recovery, as it boosts blood flow to the injured area. Low-impact activities include cycling on a static bike, or walking in water in the swimming pool. It is important to exercise the muscles around your knee. This helps keep your strength. The stronger your thigh muscles are, the more stable your kneecap will be.

If you are following the above advice and your symptoms get worse, please contact the Virtual Fracture Clinic. Their phone numbers are at the bottom of this leaflet.

Early rehabilitation exercises (as soon your pain allows)

Aim to perform the following exercises:

• 5 days a week

• Do 2 to 3 sets of 8 to 12 repetitions (reps). Rest for 60 to 120 seconds between each set.

Ankle pumps

Static quads

1. 
   1. Sit with your legs straight. Keep your knee still.
2. 
   2. Gently tense and relax your thigh muscle.

Inner range quads

Straight leg raises

1. 
   1. Sit with your legs straight. You can do this exercise lying flat or sitting upright.
2. 
   2. Tighten your thigh muscle and lift your leg up about 5cm. Lower back down slowly.

Heel slides

1. 
   1. Lie down.
2. 
   2. Slide your heel up and down. Let your knee bend and straighten as much as you can.

Single leg balance

How successful are these treatments?

Most people recover well after a kneecap dislocation.

Some people who have had a kneecap dislocation may go on to have another dislocation in their lives. People who are more likely to have another kneecap dislocation are:

• people who are a younger age when they have their first dislocation

• females

• people with a previous dislocation of the other knee

• people who have a family history of kneecap dislocation

• people with different shapes or positions of the leg bones.

If you dislocate your kneecap again, physiotherapy can help. Sometimes surgery is needed to stabilise it.

Further information

If you have any questions or concerns about your condition or your treatment options, please discuss these with your doctor or physiotherapist at your next appointment.

• Physiotherapy Central Booking Office
  Telephone: 01227 783065

• Virtual Fracture Clinic

  • Kent and Canterbury (K&C) Hospital, Canterbury
    Telephone: 01227 783075

  • Queen Elizabeth the Queen Mother (QEQM) Hospital, Margate
    Telephone: 01843 235056

  • William Harvey Hospital (WHH), Ashford
    Telephone: 01233 616849

References

1. Tsai CH, Hsu CJ, Hung CH, et al. Primary traumatic patellar dislocation. J Orthop Surg Res. 2012; 7(21).

[Website last accessed 24th September 2025]

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We have used the term ‘female’ in this leaflet. When we use this term we also mean people with female reproductive organs who do not identify as a female. East Kent Hospitals is committed to supporting people of all gender identities. Please tell your midwife or doctor how you would like them to address you, so we can be sure to get this right.