Patellar Dislocation Symptoms, Causes, and Treatments

A patellar dislocation, also known as a kneecap dislocation, occurs when the bone that sits atop the knee (the kneecap) comes out of the groove at the knee joint. Typical signs of a dislocated kneecap include a visible distortion of the kneecap, pain and swelling, and difficulty straightening or bending your knee. Kneecap dislocation requires medical intervention and usually takes about six weeks to heal.

Kneecap Dislocation Symptoms

Patellar dislocations have some tell-tale signs. Common symptoms of a kneecap dislocation include

  • Kneecap is visibly out of place
  • Severe pain accompanied by sudden bruising and swelling
  • Being unable to bend or straighten the knee
  • An audible and painful popping sensation

This injury will render your leg temporarily immobile, and you’ll need to seek help quickly. Patellar dislocations are considered medical emergencies.

How is a patellar dislocation diagnosed?

A dislocated knee can usually be identified by a medical professional on sight. They can also safely relocate the kneecap into its proper position. Even if you can see a visible distortion in the kneecap, do not attempt to relocate it yourself — you can cause further damage that is much more difficult to treat.

Is a patellar dislocation the same as a knee dislocation?

A patellar dislocation is an injury to the kneecap, whereas a dislocated knee involves the thigh bone (femur) and shinbone (tibia). When this type of dislocation occurs, called a tibiofemoral dislocation, the femur and tibia no longer connect at the joint. These types of injuries are rarer and usually much more serious, as they can cause greater damage and can compromise blood flow to the leg.  A patellar dislocation does not. . They are generally more challenging to repair as well.

Can you walk with a dislocated patella?

A loss of mobility will accompany a dislocated patella. You will probably be unable to straighten or bend your knee. Since a dislocated kneecap can cause damage to your ligaments, you should not attempt to walk on it. Instead, seek medical help quickly, so that a professional can properly realign your knee. If you are able to walk, you may have a patellar subluxation rather than a dislocation. 

Sometimes a dislocated knee will correct itself. However, even in those cases, you should still seek medical help as quickly as possible, because the dislocation can damage ligaments, tendons, and blood vessels in the surrounding area.

What Is a patellar subluxation?

A patellar subluxation is a temporary dislocation of the kneecap from the groove in the femur. When you experience this type of injury, you may notice pain, swelling, and a popping sound. You can treat your subluxation with ice and rest; however, if your knee continues to pop, if you don’t see improvement with ice and rest, or if you can’t put weight on your knee, then you should seek medical intervention.

Causes of Patellar Dislocation

Generally speaking, kneecap dislocation is caused by sudden trauma to the knee that forces it out of place. Collision with another object or the ground is a frequent reason these injuries occur. However, patellar dislocations have a number of common causes:

  • Collision with another object or the ground
  • Sudden change of direction while the leg is firmly planted on the ground
  • Weak leg muscles that no longer properly support the knee joint
  • Misalignment in the kneecap

Risk Factors for Patellar Dislocation

Patellar dislocations can happen as a result of blunt force trauma, such as a sudden fall or an accident. However, certain factors can put you at higher risk for a dislocated kneecap. For instance, having a dislocation in the past can raise your risk of it happening again in the future.

In addition, some individuals are more likely to develop patellar dislocations than others:

  • Dancers and athletes, especially if their movements require them to keep their legs firmly planted on the ground and then twisting suddenly. High-impact sports also increases your risk.
  • Teenagers, because ligaments and joints are looser while growing.
  • Larger and taller individuals, because their joints experience more pressure.
  • Women, because they tend to have wider hips and looser ligaments.
  • People who have experienced a dislocated kneecap in the past are at higher risk for recurrence.

According to the Cleveland Clinic, a number of hereditary conditions may also increase your risk of patellar dislocation, including Larson Syndrome, Arthrogryposis, Diastrophic Dysplasia, Nail-Patella Syndrome, Down Syndrome, and Ellis-Van Creveld Syndrome.

What is Runner's Knee?

Runner’s Knee is a common term for Patellofemoral Pain Syndrome, or pain in the front of the knee. It gets its name because it’s an injury commonly experienced by runners and athletes. Some of the symptoms are similar to patellar subluxation, such as a popping sound in the knee, pain, and swelling.

Runner’s Knee can be caused by overuse and overtraining by athletes, so you should treat it when you notice pain or swelling. Sometimes the way an individual walks naturally can put them at higher risk for Runner’s Knee. In these cases, more supportive shoes or additional arch support can help alleviate the condition.

Do I need a Runner's Knee brace?

The most common forms of treatment for Runner’s Knee include rest, ice, and taking a break from physical activity until the pain or swelling subsides. As mentioned above, arch support can also provide some relief. For further support, you can wrap your knee with elastic bandages or use a device called a patellar strap. However, don’t use supportive devices in lieu of rest. Rest is very important to patellar injury recovery.

Treatment of Patellar Dislocations

Patellar dislocations must be treated by a medical professional. Attempting to relocate your kneecap by yourself could result in much more damage to both the kneecap and the tendons and ligaments around it. Sometimes the kneecap will move back into place naturally, but if it has been fully dislocated, you should still seek medical help to rule out further damage to the surrounding area.

Reduction (aka Relocation)

Reduction is the process of repositioning the kneecap. It can be very painful, which is another reason not to attempt it without seeking medical help. Your healthcare provider can give you anesthesia to make the procedure as comfortable as possible.


Some dislocated knees will require surgical correction. This is more common in cases where a patient has repeatedly experienced dislocation, although according to Orthopedic Specialists, “Some surgeons are starting to recommend preventative surgery to repair the medial patellofemoral ligament (MPFL) after the first kneecap dislocation. This is because repeated dislocations can damage cartilage, leading to an increased risk of arthritis.”

Surgery can tighten the muscles in the area to provide the kneecap with more support. In rare instances, the surgery may focus on cutting and repositioning the bone directly.

Physical Therapy

After a medical professional facilitates a reduction, you’ll be sent home and instructed to rest the knee, elevate it occasionally, and take pain medication for swelling and discomfort. Additionally, you will probably be referred to a physical therapist for a rehabilitation regiment. Completing these exercises on schedule is a vital component of recovery. They enable the kneecap to heal in a healthy way that prevents more problems in the future.

Can I heal my kneecap dislocation at home?

As we noted above, there are definitely some cases in which the kneecap will return to its original position without intervention. However, even in these instances, you could experience damage to the area around the knee. You should still seek immediate medical help in order to receive an x-ray and make sure that the knee is properly repositioned and check for any further damage.

Schedule an appointment at Alexander Orthopaedics today.

Kneecap dislocation is considered a medical emergency, so don’t hesitate to go to the ER if you experience one. For followup care or surgery, schedule an appointment at Alexander Orthopaedics today, and let us help you reduce your risk for another dislocation or further injury.

Schedule an appointment today, and a member of our team will contact you within 24 hours to discuss your knee treatment plan.