The kneecap normally moves up and down in a groove at the front of the knee. Its position and movement are influenced by the shape of the knee and by the way the tendon below the kneecap is attached to the shin bone.

In some people, the kneecap repeatedly slips out of place (recurrent dislocation of patella) because the kneecap and the attachment below it are not properly aligned.

Tibial tuberosity transfer is an operation in which the bony attachment of the tendon below the kneecap is carefully moved to a more suitable position. This can improve the movement and stability of the kneecap.

The operation is usually considered when abnormal alignment is an important part of the problem and simpler treatment alone is unlikely to provide adequate stability.

When is tibial tuberosity transfer needed?

Not everyone with an unstable or painful kneecap needs this operation.

Tibial tuberosity transfer may be considered when:

• The kneecap repeatedly slips out of place (recurrent dislocation of patella)

• The kneecap does not move properly within its groove

• The attachment below the kneecap is positioned too far to one side

• There is excessive pressure on one part of the kneecap

• The kneecap remains unstable despite appropriate treatment

• The patient's knee has a combination of problems that cannot be corrected with ligament reconstruction alone

The exact procedure depends on the reason for the instability and the shape of the individual knee.

What is tibial tuberosity transfer?

The tibial tuberosity is the small area of bone at the upper part of the shin bone where the tendon below the kneecap attaches.

During the operation, a small piece of this bone is carefully separated while keeping the tendon attached to it.

The piece of bone is then moved to a more suitable position and fixed there with small screws.

Moving this attachment changes the direction in which the kneecap is pulled. This can help the kneecap move more normally and improve its stability.

The exact direction and amount of movement depend on the problem being treated.

What does the operation achieve?

Moving the attachment below the kneecap can be used to correct different problems.

Depending on the patient's knee, it may help to:

• Improve the position of the kneecap

• Reduce the tendency of the kneecap to slip out

• Improve the way the kneecap moves

• Reduce excessive pressure on a damaged part of the kneecap

• Improve the tracking of the kneecap during bending and straightening

In patients with repeated kneecap dislocation, tibial tuberosity transfer may sometimes be performed together with reconstruction of the ligament that helps hold the kneecap in place.

What happens during the operation?

The operation is performed through an incision at the front of the knee.

A small piece of bone where the tendon below the kneecap attaches is carefully separated.

The bone is then moved to the planned position. It is fixed securely with screws and allowed to heal in its new position.

The surgeon checks the movement of the kneecap before completing the operation.

The exact amount and direction of movement are planned according to the patient's knee shape and the problem being treated.

What are the benefits?

When appropriately selected, tibial tuberosity transfer can:

• Improve kneecap stability

• Reduce the chance of repeated kneecap dislocation

• Improve the movement of the kneecap

• Reduce excessive pressure on damaged areas of the kneecap

• Improve pain caused by abnormal kneecap movement

• Help patients return to normal activities and, after rehabilitation, sports

The operation is particularly useful when the position of the attachment below the kneecap is an important part of the problem.

What is recovery like?

Because a small piece of bone has been moved, the bone needs time to heal in its new position.

In the early period, walking may need to be protected and knee movement may be increased gradually.

Rehabilitation usually includes:

• Controlling pain and swelling

• Gradually increasing knee movement

• Strengthening the muscles around the knee

• Gradually increasing weight on the leg

• Improving balance and control

• Returning gradually to normal activities

The exact rehabilitation programme depends on how much the bone was moved and whether another procedure was performed at the same time.

When can I return to sports?

Return to sports takes longer than returning to normal daily activities because the moved piece of bone needs to heal properly.

Running, jumping and sports involving sudden changes of direction are introduced only after the knee has regained adequate movement, strength and control and the bone has healed sufficiently.

The return to sport is therefore gradual and varies from patient to patient.

What are the risks?

Tibial tuberosity transfer is a commonly used operation when appropriately indicated, and serious complications are uncommon.

Possible problems include:

• Infection

• Bleeding or blood clots

• Knee stiffness

• Continued pain

• Problems with healing of the moved piece of bone

• Pain around the screws

• Continued kneecap instability

• Excessive pressure on the kneecap

• The need for another operation

Careful planning of the amount and direction of movement is important to achieve the desired result.

Frequently Asked Questions

Does everyone with a dislocating kneecap need tibial tuberosity transfer?

No. The operation is used when the position of the attachment below the kneecap is an important reason for the instability. Many patients can be treated without moving this attachment.

Is tibial tuberosity transfer painful?

Some pain and swelling are expected after the operation. These usually improve gradually with appropriate pain treatment and rehabilitation.

How long does recovery take?

Recovery takes several months because the moved piece of bone needs time to heal. Everyday activities usually return before running and sports.

Can I return to sports after tibial tuberosity transfer?

Many appropriately selected patients can return to sports after the bone has healed and the knee has regained sufficient strength and control. The return should be gradual.

Will the screws need to be removed?

Not usually. The screws can generally remain in place. However, some patients may feel discomfort from the screws after the bone has healed, and they may occasionally need to be removed.