Patellar/Knee Cap Instability

Patellar instability refers to a condition where the kneecap (patella) moves out of its normal position. It most commonly involves a partial or complete kneecap dislocation, often occurring during athletic activity or a twisting injury. This condition is especially common among teenagers, young adults, and athletes.

When the kneecap slips out of place repeatedly, it can lead to chronic pain, instability, cartilage damage, and a loss of confidence in the knee. If left untreated, it may also contribute to early arthritis and long-term mobility issues.

What Is Patellar Instability?

The kneecap usually sits in a groove at the end of the thigh bone (femur) and glides smoothly as the knee bends and straightens. Several structures help stabilize the patella, including ligaments, bone alignment, and the shape of the femoral groove. When these stabilizing structures are damaged or misaligned, the kneecap may begin to shift or dislocate.

Common Causes of Patellar Instability

• Traumatic injury, such as a direct blow or twisting motion

• Shallow femoral groove (trochlear dysplasia)

• Loose or stretched ligaments

• High-riding kneecap (patella alta)

• Family history of knee instability

Symptoms of Kneecap Instability

• Sensation of the kneecap “popping out” or shifting

• Pain in the front of the knee, especially during activity

• Swelling or bruising after a dislocation

• Difficulty walking, squatting, or going down stairs

• Decreased confidence in the stability of the knee

Surgical Treatment Options for Patellar Instability

Surgical intervention may be recommended for patients with recurrent dislocations or structural issues. Several advanced procedures are available to restore the kneecap’s proper alignment and function.

MPFL Reconstruction

The medial patellofemoral ligament (MPFL) is the primary restraint that prevents the kneecap from shifting outward. When this ligament is torn during a dislocation, it often does not heal properly. MPFL reconstruction involves using a graft to recreate the damaged ligament and restore medial stability.

Tibial Tubercle Osteotomy (TTO)

A tibial tubercle osteotomy can be performed in cases where the kneecap tracks abnormally due to poor alignment. This procedure repositions the bony attachment of the patellar tendon to shift the kneecap into a more stable location. The goal is to reduce pressure on the cartilage and prevent further dislocations.

Trochleaplasty

Some patients are born with a shallow or misshapen femoral groove known as trochlear dysplasia. Trochleaplasty is a specialized procedure that reshapes and deepens this groove, allowing the kneecap to sit more securely during movement.

Recovery and Rehabilitation

Recovery from patellar instability surgery typically involves:

• Initial rest and bracing to protect the surgical repair

• Physical therapy to regain strength, flexibility, and range of motion

• Gradual return to activity, usually between 4 to 6 months

• Return to sports with surgeon clearance, often around 6 to 9 months

A personalized rehab program is essential for long-term success. Working closely with your surgeon and physical therapist helps ensure a safe and strong return to your normal activities.

Preventing Future Dislocations

• Strengthen the quadriceps and core muscles

• Focus on balance and neuromuscular control

• Avoid high-risk movements until cleared by your care team

• Monitor symptoms and seek early evaluation if instability recurs