The kneecap normally moves up and down in a groove at the front of the thigh bone. This groove helps guide the kneecap as the knee bends and straightens.

In some people, this groove is too shallow or has an abnormal shape. As a result, the kneecap may not stay securely in its normal path and may repeatedly slip out of place.

Trochleoplasty is an operation that reshapes this groove to give the kneecap a better path to move in.

It is a specialized operation used only in selected patients with significant abnormality of the groove.

When is trochleoplasty needed?

Not everyone with a dislocating or unstable kneecap needs trochleoplasty.

It may be considered when:

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

• The groove for the kneecap is significantly too shallow or abnormally shaped

• The abnormal groove is an important reason for the kneecap instability

• Appropriate non-surgical treatment has not provided adequate stability

• Other procedures alone are unlikely to provide enough stability

The shape of the groove is assessed using scans of the knee along with a clinical examination.

Trochleoplasty is generally reserved for patients with a significant abnormality of the groove rather than being performed routinely for every kneecap dislocation.

What is trochleoplasty?

Trochleoplasty is an operation that reshapes the groove in the thigh bone in which the kneecap moves.

The surgeon carefully changes the shape of the groove so that the kneecap can sit more securely within it and follow a more normal path during knee movement.

The exact technique depends on the shape of the groove and the patient's individual problem.

In some patients, trochleoplasty is performed together with reconstruction of the ligament that helps keep the kneecap in place or another procedure to correct the position of the kneecap.

What happens during the operation?

The operation is performed through a surgical cut at the front of the knee.

The groove in which the kneecap moves is carefully examined. The surgeon then reshapes the abnormal part of the groove to create a more suitable path for the kneecap.

The aim is to provide enough depth and the correct shape to guide the kneecap without making the groove excessively deep or tight.

The knee is moved through its range of motion during the operation to check that the kneecap moves smoothly in its new path.

What are the benefits of trochleoplasty?

When appropriately selected, trochleoplasty can:

• Improve the stability of the kneecap

• Reduce the chance of repeated kneecap dislocation

• Improve the way the kneecap moves

• Reduce the feeling that the kneecap may slip out

• Improve confidence during walking and exercise

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

The best results are achieved when the abnormal shape of the groove is an important cause of the patient's kneecap instability.

What is recovery like?

Recovery is gradual.

In the early period, the focus is on controlling pain and swelling and safely restoring knee movement. Exercises are then introduced progressively to improve strength and control.

Rehabilitation usually includes:

• Exercises to improve knee movement

• Strengthening the muscles around the knee

• Gradually increasing walking

• Balance and control exercises

• Progressive strengthening

• Gradual return to running and sports when appropriate

If trochleoplasty is performed together with another operation, recovery may take longer and the rehabilitation programme may be different.

When can I return to sports?

Returning to sports takes longer than returning to everyday activities.

The knee needs to regain good movement, strength and control before running, jumping and sports involving sudden changes of direction are resumed.

Return to sports is gradual and depends on how the knee has recovered rather than simply on a fixed number of weeks after surgery.

What are the risks?

Trochleoplasty is a specialized operation and is performed only when there is a clear reason for it.

Possible problems include:

• Infection

• Bleeding or blood clots

• Knee stiffness

• Continued pain

• Continued kneecap instability

• Problems with the healing of the bone and cartilage

• Excessive pressure on the kneecap

• Development or worsening of knee arthritis over time

• The need for further surgery

Careful patient selection and accurate reshaping of the groove are important for achieving a good result.

Frequently Asked Questions

Does everyone with a dislocating kneecap need trochleoplasty?

No. Trochleoplasty is reserved for patients whose kneecap instability is significantly related to an unusually shallow or abnormal groove. Many patients can be treated without this operation.

Is trochleoplasty the same as MPFL reconstruction?

No. They treat different problems. MPFL reconstruction creates a new ligament to help hold the kneecap in place, while trochleoplasty changes the shape of the groove in which the kneecap moves. Some patients may need both procedures.

How long does recovery take?

Recovery takes several months and varies between patients. Everyday activities usually return before running and sports.

Can I return to sports after trochleoplasty?

Many appropriately selected patients can return to sports after recovery and rehabilitation. The return should be gradual and should wait until the knee has regained sufficient movement, strength and control.

Is trochleoplasty a major operation?

It is a specialised knee operation that changes the shape of the bone and the surface on which the kneecap moves. It is therefore reserved for patients in whom the shape of the groove is an important cause of instability.