We depend on our knees for many different activities. Most of the time, our knees are working well, so we don’t think about them as we go about our day. But an injury like a dislocated kneecap is extremely painful and makes it difficult to walk or even move your knee. A dislocated kneecap needs immediate treatment.

The kneecap, also known as the patella, sits on top of the knee. It protects your knee and supports the muscles, tendons and ligaments in the joint. A kneecap dislocation is a common injury that occurs when the kneecap “pops” out of its place. Read on to learn more about the symptoms, causes and treatments for a dislocated kneecap.

What happens when your kneecap is dislocated and “pops” out of place?

The kneecap sits on top of the knee in a groove on top of the thighbone (trochlear groove), and it helps keep your knee supported. Your kneecap is held in place by tendons and ligaments in the knee joint. When you straighten and bend your knee, the kneecap moves up and down in the groove.

A dislocated kneecap is typically caused by a sudden twist of the knee or an impact to the knee. When the kneecap is dislocated, it moves out of the groove to another part of the knee, typically toward the outside of the knee. This locks the knee and puts strain on the surrounding ligaments, sometimes even tearing them.

There are two different types of dislocated kneecap injuries, including acute dislocation and chronic dislocation.

Acute kneecap dislocation

If a dislocated kneecap comes on suddenly after a specific injury or incident, you’re probably dealing with an acute kneecap dislocation. In these cases, you’ll most likely know what caused the dislocated kneecap.

Acute kneecap dislocations are most often caused by a direct impact to the knee or by a sharp pivot or twist. A heavy fall can also cause a dislocated kneecap, but that’s less common. Athletes who play football, hockey and other contact sports are at a higher risk of a dislocated kneecap. Dancers, tennis players and other athletes who need to quickly pivot are also more likely to develop an acute kneecap dislocation.

Chronic kneecap dislocation

Some people experience chronic patellar instability, a condition that causes the kneecap to frequently slip out of the groove. This may be due to a stretched ligament or other chronic conditions, and causes chronic kneecap dislocations. People with overly loose ligaments are also susceptible. Chronic kneecap dislocations are more frequent and aren’t related to a specific cause, like an acute kneecap dislocation.

Feeling like your knee is unstable or that your knee is buckling while you walk are both signs of chronic kneecap dislocation.

Kneecap subluxation

A kneecap subluxation (patellar subluxation) is similar to a dislocated kneecap and occurs when the kneecap partially moves within the groove but doesn’t move completely out of it. People with a kneecap subluxation can still walk and move their knee, but the kneecap will likely feel unstable and uncomfortable – it may also cause a popping sound or swelling. Knee subluxation can be caused by an injury or patellar instability.

Symptoms of a dislocated kneecap

There are many symptoms that might indicate you have a dislocated kneecap.

• A popping noise in the knee
• The kneecap is visually out of place
• Intense pain in the knee
• Knee buckling
• Locking of the knee, limited mobility
• Inability to walk
• Sudden swelling around the knee
• Bruising around the knee

How is a dislocated kneecap diagnosed?

Most of the time, a primary care doctor or an orthopedic specialist can diagnose a dislocated kneecap from a physical exam. To get a full picture of what’s going on with your knee, your doctor might recommend imaging tests like an X-ray or MRI. That’s because a dislocated kneecap can damage the cartilage in the knee and cause torn ligaments.

If you think you may have a dislocated kneecap and need immediate care, look for an orthopedic urgent care near you.

Treatments for patella dislocation

A dislocated kneecap is a treatable condition that requires immediate care. Most of the time, a doctor will be able to put the kneecap back into the groove manually. This will correct the joint and make it possible for your doctor to treat lingering symptoms or issues caused by the injury.

Once the kneecap is back in place, your doctor might recommend a brace or a splint to support your joint while you fully heal. Home remedies like over-the-counter pain relief and rest, ice, compression and elevation (RICE) may be recommended to manage pain and swelling. In most cases, it can take 6-8 weeks to fully recover from a kneecap dislocation. However, you’ll likely be able to walk on the injured knee after only a few days.

Physical therapy may also be recommended to strengthen the muscles and ligaments around the knee as you heal. During physical therapy, your therapist will guide you through exercises and stretches designed specifically to improve your strength, mobility and flexibility.

In rare cases, surgery might be needed to heal ligament tears or remove damaged cartilage caused by a kneecap dislocation. Your doctor will talk with you about what type of surgery they recommend and help you prepare.

When to see a doctor for a dislocated kneecap

If you think your kneecap is dislocated, visit an orthopedic urgent care as soon as possible. The more quickly you receive care, the sooner you’ll begin your recovery.

At TRIA, our orthopedic urgent care is here for you seven days a week. There’s no appointment needed, just choose the location most convenient for you and walk in.

Frequent asked questions (FAQs) about dislocated kneecaps