Medial Patellofemoral Ligament Injury

What is a medial patellofemoral ligament injury?

The kneecap, or patella, sits in a groove in the thighbone (femur). A ligament called the medial patellofemoral ligament, or MPFL, holds it in place. The MPFL is located on the inside of the knee and connects the kneecap to the femur or inner thighbone, helping to keep the kneecap centered in the bone groove. If the MPFL gets torn or stretched, it takes much less force to dislocate the kneecap.

Learn more about knee anatomy

What causes an MPFL injury?

A number of conditions can put stress on the MPFL and stretch or tear it. They include:

• Forceful contact, like a direct blow to the knee
• Forceful twisting or turning
• Kneecap dislocation

What are the symptoms of an MPFL injury?

Symptoms of an MPFL injury include:

• A sense that the knee is buckling and can no longer support your weight
• The kneecap slips off to the side of the joint and no longer feels as though it is in the proper position
• A catching sensation in the knee joint when you bend or straighten your leg
• Pain in the front of your knee that increases with activity
• Knee pain while sitting
• Stiffness or swelling in the knee
• Creaking or cracking sounds when you move your knee

Learn more about unstable kneecap

How is a medial patellofemoral ligament injury diagnosed?

Your doctor will diagnose an MPFL injury based on:

• Your medical history, including whether you have ever dislocated your kneecap
• Your symptoms (such as the location of the pain)
• The activities that make the pain better or worse
• A physical examination of the movements and strength of your knee

Your doctor may also order diagnostic imaging, including an X-ray or MRI, to confirm the diagnosis.

How is an MPFL injury treated nonsurgically?

Nonsurgical treatment options for an MPFL injury include:

• A knee brace
• Physical therapy
• Rest

What are the surgical treatment options for an MPFL injury?

The goal of surgery is to:

• Restore knee stability
• Regain full range of motion
• Allow a return to athletic activities in the future

Before surgery, patients are prescribed physical therapy to work on regaining full motion and to decrease knee swelling. All patients wear a brace to protect the knee before surgery.

MPFL reconstruction surgery

This is the most common surgery used to address an MPFL injury.

• The physician takes one of the patient’s hamstrings, or a hamstring from a cadaver
• Then, the physician makes a new ligament to replace the damaged MPFL
• This is outpatient surgery that can be performed in about an hour

After surgery, patients are advised to work closely with a physical therapist. Physical therapy is critical to regaining full knee motion and strength.

Additional resources for you

• Check out the article: What Are the Risks of an Unstable Kneecap?
• Find out: Do You Have an Unstable Kneecap?
• More from Dr. Skendzel on unstable kneecaps: Surgical Options for Unstable Kneecaps
• More on Summit’s Sports Medicine services
• From American Academy of Orthopedic Surgeons (trusted external resource): Unstable Kneecap