The kneecap is held in place by several strong tissues around the knee. One important ligament on the inner side of the knee helps prevent the kneecap from slipping out of its normal position (recurrent dislocation of patella).

This ligament is called the medial patellofemoral ligament (MPFL).

When the kneecap repeatedly slips out of place, this ligament can become stretched or torn. In some patients, MPFL reconstruction can restore stability and reduce the chance of the kneecap slipping out again.

What is MPFL reconstruction?

MPFL reconstruction is an operation used to improve the stability of the kneecap in people who have repeated kneecap dislocations or ongoing instability.

During the operation, a strong tendon is used to create a new ligament that takes over the job of the damaged ligament. The new ligament is placed along the inner side of the knee and attached to the kneecap and thigh bone (femur).

The aim is to keep the kneecap in its normal position while still allowing it to move normally.

When is MPFL reconstruction needed?

Not everyone who dislocates their kneecap needs an operation.

Treatment depends on how many times the kneecap has slipped out, how unstable the knee feels, the person's age and activity level, and the shape and position of the bones around the knee.

MPFL reconstruction may be considered when:

• The kneecap has slipped out repeatedly (recurrent dislocation of patella)

• The knee continues to feel unstable despite appropriate treatment

• The patient has difficulty with normal activities because of fear or feeling that the kneecap may slip out

• There is a high chance of the kneecap dislocating again

Sometimes the kneecap is unstable because of the shape or position of the bones around the knee as well as damage to the ligament. In these situations, another procedure may be needed in addition to MPFL reconstruction.

What happens during the operation?

The operation is performed through small cuts around the knee.

A strong tendon is used to make a new ligament. It is placed along the inner side of the knee and attached to the kneecap and thigh bone.

The new ligament is positioned carefully so that it keeps the kneecap stable without making it too tight.

The surgeon also checks the knee for other problems that may be contributing to the instability.

Where does the new ligament come from?

A tendon is used to make the new ligament.

Usually, a tendon from the patient's own body can be used. In some situations, another suitable tendon may be used.

The choice depends on the patient's age, activity level, previous operations and the condition of the knee.

What are the benefits of MPFL reconstruction?

When the operation is appropriate, it can:

• Make the kneecap more stable

• Reduce the chance of another dislocation

• Reduce the feeling that the kneecap is going to slip out

• Improve confidence while walking and exercising

• Help the patient return to normal activities

• Allow many patients to return to sports after proper rehabilitation

The best results are achieved when the reason for the kneecap instability is properly identified and treated.

What is recovery like?

Recovery takes place gradually.

Initially, treatment focuses on reducing pain and swelling and getting the knee moving safely. Exercises are then increased step by step to rebuild the strength and control of the leg.

Recovery usually includes:

• Exercises to improve knee movement

• Exercises to strengthen the muscles around the knee

• Gradually increasing walking

• Balance exercises

• Progressive strengthening

• Sport-specific exercises when appropriate

The exact recovery plan depends on the operation performed and whether any additional procedure was needed.

When can I return to sports?

Returning to sports takes longer than returning to normal daily activities.

Before returning to running, jumping or sports that involve sudden changes in direction, the knee should have regained good movement, strength and control.

The return to sport should therefore be gradual and based on how well the knee has recovered rather than simply on a fixed number of weeks after surgery.

Many patients can return to sports after successful surgery and appropriate rehabilitation.

What are the risks of MPFL reconstruction?

MPFL reconstruction is a commonly performed operation, and serious complications are uncommon.

Possible problems include:

• Infection

• Bleeding or blood clots

• Knee stiffness

• Continued pain

• The kneecap remaining unstable

• The kneecap becoming too tight

• Another kneecap dislocation

• Problems with the tendon used for the new ligament

• The need for another operation

Careful positioning of the new ligament and appropriate rehabilitation are important for achieving a stable and naturally moving kneecap.

Frequently Asked Questions

Can MPFL reconstruction stop my kneecap from dislocating again?

The operation is designed to make the kneecap more stable and reduce the chance of another dislocation. The result also depends on the shape and position of the bones around the knee. If another problem is contributing to the instability, it may also need to be treated.

Will I be able to play sports after MPFL reconstruction?

Many patients can return to sports after successful surgery and rehabilitation. The return should be gradual and should only happen after the knee has regained adequate strength, movement and control.

How long does recovery take?

Recovery is gradual. Normal walking and everyday activities usually return before running and sports. The exact time varies depending on the operation and whether any additional procedure was performed.

Does everyone with a dislocated kneecap need MPFL reconstruction?

No. Many people with a first-time kneecap dislocation can be treated without surgery. An operation is more commonly considered when the kneecap continues to dislocate or remains unstable despite appropriate treatment.

Is MPFL reconstruction the only operation for a repeatedly dislocating kneecap?

Not always. Some people have differences in the shape or position of the bones around the knee that contribute to the problem. If these are significant, another operation may be needed along with MPFL reconstruction (like tibial tuberosity transfer or trochleoplasty).