A patella dislocation occurs when the kneecap is forced out of its normal position at the front of the knee joint. This can result from a fall, a blow to the knee, or a sudden twisting or pivoting motion. It's a common injury among athletes and dancers who have to make quick turns. But some people are simply prone to the problem because they were born with a misaligned kneecap or because the ligaments and tendons supporting the knee are weak.
Whatever the cause, the dislocation is painful and requires immediate medical attention. Sometimes the patella will pop back into place on its own, but the knee may still be swollen and sore from the trauma. Repeated dislocations can make it harder to treat. If the problem persists, it can damage the knee joint and cartilage, increasing the risk of osteoarthritis.
Our approach to patella dislocation
We have a world-class team of sports medicine doctors, orthopedic surgeons, physical therapists and athletic trainers to expertly diagnose and treat problems affecting the knees. We will work with you to relieve the pain and restore your mobility so you can get back to regular life and your favorite activities.
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Signs & symptoms
Symptoms of a patella dislocation may include sudden pain, swelling, and buckling or instability of the knee joint. You may hear an audible pop when it occurs or be able to see that the kneecap is out of place. It may feel as if your knee is locked or as if you can't bend or straighten your leg.
A physical exam is usually all we need to diagnose a dislocated kneecap. But if the dislocation has corrected itself or there's concern about damage inside the knee, the doctor may order X-rays.
X-ray imaging can show whether the kneecap is outside of the joint and reveal any fractures or bone fragments. X-rays also can be used to confirm a dislocation after the fact – if your kneecap popped back into place on its own – and indicate whether you're at risk for it to happen again.
In some cases, the doctor may also order an MRI scan, which can show whether there's damage to ligaments, cartilage or nerves.
Your treatment plan will depend on the severity of your injury.
Unless the kneecap pops back into place on its own, the patella will have to be manually relocated. You may be able to do it yourself. Otherwise, you'll need to go to an emergency room where a doctor can ease it back into place and assess the degree of injury.
Once your kneecap is situated correctly, you'll be advised to rest, ice the knee, and take an anti-inflammatory drug (NSAID), such as ibuprofen (Advil, Motrin), to reduce the pain and swelling. You may need to use crutches at first to avoid placing weight on the knee or wear a brace to help the kneecap stay in place.
Once the pain and swelling diminish, physical therapy may be recommended to strengthen the muscles around the knee and improve joint stability. Most people are able to resume their normal activities in six to eight weeks.
Surgery could be recommended under any of the following circumstances:
- The dislocation caused damage to the bones, cartilage or tendons of the knee.
- The kneecap dislocates repeatedly.
- The patella is misaligned in the joint.
- The knee joint is unstable.
The decision to perform surgery and the recommended surgical approach (a minimally invasive procedure or traditional surgery) depend on several factors, including the severity and frequency of the dislocations, the age and activity level of the patient, and the presence of other knee injuries or conditions.
UCSF Health medical specialists have reviewed this information. It is for educational purposes only and is not intended to replace the advice of your doctor or other health care provider. We encourage you to discuss any questions or concerns you may have with your provider.