Patella Dislocation Causes, Symptoms & Treatment Options

Overview

In a healthy knee, the patella tracks centrally within the femoral groove during movement. This alignment allows efficient force transfer and protects the knee joint. In cases of patellar instability, the kneecap fails to stay centered and may slide or shift—most commonly toward the outside (lateral side) of the knee.

A patellar dislocation occurs when the kneecap shifts out of its normal position in the groove of the thigh bone. It typically happens suddenly after a twisting movement, fall, or direct blow to the knee, but it may also occur more easily in individuals with muscle weakness or abnormal knee alignment. Recurrent kneecap dislocations can damage the surrounding cartilage and ligaments, potentially leading to chronic pain, instability, and long-term knee problems.

What causes Patella Dislocation?

Patella dislocation occurs when forces acting on the knee overpower the structures that normally keep the kneecap centered in its groove. These forces may be anatomical, traumatic, or activity-related.

1. How Does a Patella Dislocation Happen?

A patella dislocation often occurs during a sudden movement that places rotational stress on the knee. This typically happens when:

• The foot is firmly planted on the ground
• The knee twists inward
• The body changes direction quickly

This mechanism forces the kneecap sideways—most commonly to the outside of the knee—resulting in a lateral patella dislocation. In some cases, direct trauma, such as a blow to the knee, can also cause a dislocated kneecap.

2. Underlying Causes of a Knee Cap Dislocation

Several factors can increase the likelihood of patella instability and dislocation, including:

• Shallow or uneven femoral groove, which prevents proper tracking of the kneecap
• Loose or overstretched ligaments, often hereditary
• Weak thigh muscles, particularly the quadriceps
• Poor alignment of the legs or feet, such as knock knees or flat feet
• Previous patella dislocation, which increases the risk of recurrence

Sports Commonly Associated With Patella Dislocation

Patellofemoral instability is frequently seen in sports that involve jumping, pivoting, or rapid direction changes. These include:

• Football
• Basketball
• Soccer
• Gymnastics
• Wrestling
• Ice Hockey
• Volleyball

Athletes in these sports are more prone to patella dislocations due to repetitive stress and sudden movements placed on the knee joint.

Symptoms

Dislocated kneecap  symptoms can range from mild discomfort to severe pain depending on whether the kneecap is partially or fully displaced.

When the kneecap is not tracking correctly, you may experience:

• A sensation that the knee is loose or unstable
• Slipping, grinding, catching, or popping during movement
• Pain at the front of the knee, especially with activity

If a full patella dislocation occurs, symptoms are usually more severe and may include:

• Sudden, intense knee pain
• Rapid swelling
• Visible deformity where the kneecap appears out of place
• Inability to bend or straighten the knee
• Difficulty bearing weight

In many cases, the kneecap may move back into place on its own, however, pain, swelling, and instability often persist.

Common symptoms include:

• Knee buckling or giving way
• Kneecap visibly shifting to the side
• Catching or locking during movement
• Increased pain when climbing stairs or sitting for long periods
• Stiffness and reduced range of motion
• Creaking or cracking sounds
• Swelling around the knee

Non-operative treatment

Non-surgical management is typically the first line of patella dislocation treatment, especially after an initial episode.

Conservative treatments may include:

• Rest and activity modification
• Ice to reduce swelling
• Physical therapy to strengthen the quadriceps and hip muscles
• Bracing to stabilize the kneecap and improve alignment

Targeted exercises can improve muscle balance and reduce the risk of future dislocations.

(Exercise Program PDF referenced)

Patellar Dislocation

Surgical Treatment

Surgery may be recommended if patella instability continues despite conservative care or if multiple dislocations occur. Surgical intervention can also address damage to cartilage or ligaments caused by repeated knee cap dislocations.

The specific surgical approach depends on:

• Severity of instability
• Degree of cartilage damage
• Alignment issues
• Frequency of dislocations

Your orthopedic surgeon will determine the most appropriate procedure based on individual anatomy and injury pattern.The most common surgical procedure is called Medial patellofemoral ligament (MPFL) reconstruction: This is the most common surgery for recurrent patella dislocation. It involves rebuilding the ligament that helps keep the kneecap centered in the groove, improving stability and reducing the risk of future dislocations.