What a patellar dislocation is
MedlinePlus explains that a kneecap dislocation occurs when the round bone covering the front of the knee (the patella) moves or slides out of place, often towards the outside of the leg. NHS 111 Wales describes it as the kneecap moving out of place, usually because of a knee injury.
It should not be confused with a dislocation of the knee joint itself, which is a different injury. In a patellar dislocation, it is the kneecap that moves out of place.
How it happens
MedlinePlus explains that a kneecap dislocation often happens after a sudden change of direction with the leg planted, which puts the kneecap under stress, for example in sports such as basketball. It can also follow direct trauma to the knee.
MedlinePlus notes that some cases may not be preventable, especially when physical factors make a person more likely to dislocate the kneecap. Using proper technique in exercise and sport and keeping the knees strong and flexible can help.
Symptoms and immediate steps
MedlinePlus lists symptoms such as a knee that looks deformed, a knee that is bent and cannot be straightened, a kneecap stuck to the outside of the knee, pain, tenderness and swelling. The first few times, you will feel pain and may be unable to walk.
NHS 111 Wales advises getting medical advice as soon as possible. While waiting for help, keep the knee still and supported with padding such as rolled clothing, towels or cushions, do not raise the knee, do not try to stand or walk on the leg and do not try to put the kneecap back into place yourself. Contact a health service if the knee is very painful, swollen or bruised, you cannot stand or move it, or you think the kneecap dislocated and went back into place.
Why reduction should be done by a professional
NHS 111 Wales explains that a dislocated kneecap often moves back into place by itself. If it does not, a doctor may need to move it back, using local anaesthetic and sometimes a sedative so that you do not feel pain.
Even if the kneecap has gone back by itself, the knee still needs to be checked. Being able to walk afterwards does not rule out damage, because a dislocation can injure the cartilage or bone inside the joint.
Assessment and imaging
MedlinePlus explains that your health professional examines the knee to confirm the dislocation and may order an X-ray or MRI scan. These tests show whether the dislocation caused a broken bone or cartilage damage. NHS 111 Wales notes that you will usually need X-rays or an MRI scan.
The results guide treatment: if there is no damage, the knee is usually treated without surgery; if bone or cartilage is damaged, surgery may be discussed. For more on cartilage injuries, see our guide to knee cartilage damage.
Non-surgical treatment
MedlinePlus explains that if tests show no damage, the knee is placed in a brace (immobiliser) for about 3 weeks. NHS 111 Wales notes that you may be given a knee support to wear for 2 weeks, that you will usually be able to walk on the knee within a few days and that a crutch may help if walking is painful.
Once the knee has been treated, NHS 111 Wales advises keeping the knee and lower leg slightly raised and supported when resting to reduce swelling, taking simple painkillers if needed, staying as active as you can and not twisting the knee. Attend all follow-up appointments.
Rehabilitation and strength
NHS 111 Wales explains that your doctor or a physiotherapist will show you knee exercises to do regularly throughout the day, to stop the knee getting stiff and speed up recovery. Full recovery can take 6 to 8 weeks.
MedlinePlus explains that once the brace is off, physical therapy can help rebuild muscle strength and improve the knee’s range of motion. NHS 111 Wales advises not returning to sport until the knee has fully recovered its usual strength, and asking your doctor or physiotherapist when.
Risk of recurrence
MedlinePlus warns that people who keep having dislocations may feel less pain each time, but this is not a reason to avoid treatment. Dislocation damages the knee joint, can lead to cartilage injuries and increases the risk of osteoarthritis at a younger age. Repeat dislocations make the condition worse and harder to treat.
Contact your health professional if, during recovery, the knee feels more unstable, pain or swelling return after settling, the injury does not seem to be improving, or you injure the knee again.
Where the sources differ
The main difference is first aid. MedlinePlus (November 2024) suggests straightening the knee if you can, or splinting it if it is stuck and painful. NHS 111 Wales (October 2025) advises keeping the knee still and not trying to put the kneecap back yourself. This guide follows the more cautious NHS advice and does not describe any maneuver to relocate the kneecap. NHS 111 Wales also advises not raising the knee while waiting for help, but raising it after treatment.
For immobilisation, MedlinePlus mentions a brace for about 3 weeks and NHS 111 Wales a support for 2 weeks. Both agree that surgery is considered if there is bone or cartilage damage or if the kneecap keeps dislocating. After medical assessment, our physiotherapy practice in Bilbao can guide rehabilitation for adults (consultations are in Spanish).
In summary
A patellar dislocation is when the kneecap slips out of place, usually after a twist with the foot planted. Keep the knee still, do not try to put it back and get medical help. After X-rays or an MRI, most people are treated with a brace or support, exercises and physiotherapy; surgery is considered for damage inside the knee or repeated dislocations.
A phase table helps. Before medical care: keep the knee still and supported, do not raise it, do not walk on it. After professional reduction: wear the brace as advised, raise and support the leg at rest and walk as allowed. During rehabilitation: do the exercises daily, avoid twisting and return to sport only when strength has fully recovered.
Frequently asked questions about patellar dislocation
These answers are general information and do not replace an examination or individual medical advice.
What should I do if my kneecap dislocates?
Keep the knee still and supported, do not stand on the leg and get medical help. Go to A&E if the knee is deformed, very swollen, bleeding or bone is visible.
Should I try to put it back myself?
No. NHS advice is not to put the kneecap back yourself. It often goes back by itself; if not, a doctor does it with pain relief.
How serious is a dislocated kneecap?
It can damage cartilage or bone inside the knee, so it always needs checking, even if the kneecap went back by itself.
How long is recovery?
Most people walk within a few days. Full recovery usually takes 6 to 8 weeks, with a brace or support for about 2 to 3 weeks.
Will it happen again?
It can. Repeated dislocations damage the knee and make treatment harder, so report any new instability to your health professional.
When is surgery recommended?
When the dislocation has damaged bone or cartilage, or when the kneecap keeps dislocating. Your surgeon decides after assessment and imaging.
Sources
This guide is for general information and does not replace medical advice. How a problem is diagnosed and treated depends on your examination and medical history. If you think you have an emergency, contact your local emergency services.