Skip to main content

Welcome to the Circle Health Group website. We've changed our name from BMI Healthcare.

Kneecap joint replacement surgery

A kneecap replacement operation is a procedure to replace the patella (kneecap) in the knee joint.

A kneecap replacement operation is a procedure to replace the patella (kneecap) in the knee joint. The procedure involves replacing damaged bone and cartilage with plastic or metal components.

The procedure is also known as patellofemoral replacement or patellofemoral arthroplasty. Patellofemoral refers to the section of the knee that includes the kneecap and the groove in the thigh bone in which the kneecap sits.

Because only part of the knee is resurfaced, this type of surgery is often called a partial knee replacement. The surgery is commonly used to treat patients with knee osteoarthritis, where the cartilage, which protects the bones in the knee, has gradually worn away. A lack of cartilage in the knee exposes the bones, which leads to a painful movement of the joint.

The knee can be divided into three components; the inside (medial), the outside (lateral) and the kneecap (patellofemoral compartment). If the kneecap alone is affected by arthritis then an artificial joint can replace just this single component.

In a patellofemoral joint replacement, an implant is used to replace the kneecap. The patellofemoral artificial implant is usually made from a combination of plastic and metal.

You will be considered for a kneecap replacement if non-surgical treatments are no longer effective at managing pain. The bone and cartilage damage also needs to be limited to just the kneecap and the groove in the thigh bone for this procedure to be viable.

You may need a kneecap joint replacement surgery if you are experiencing reduced mobility in the affected leg, severe pain, stiffness and swelling. Everyday tasks, such as using the stairs, are becoming increasingly difficult.

The osteoarthritis slowly wears away the cartilage beneath the kneecap to expose the bone. Once this occurs, the bone becomes damaged. If the damage is confined to the kneecap, your consultant may recommend a kneecap replacement.

Not only can a new knee joint make walking easier, but you should feel much less pain and improved mobility. As well as physical improvements to your health, you may find that your mood and mental wellbeing improves after surgery due to the reduction or elimination of pain.

Kneecap replacement surgery is carried out in hospital under general anaesthetic and local anaesthetic is injected into your knee at the end of the operation so you wake up with no pain.

You would normally be admitted the evening before the operation if it is in the morning, or early on the day if your operation is scheduled for the afternoon or the evening. This allows you time to settle in and prepare for the procedure.

You will not be able to eat for eight hours prior to surgery although you will be able to drink small amounts of water up to four hours before surgery. The operation itself takes around 60 minutes.

During the procedure, your orthopedic surgeon will make a small cut down the front of your knee. The damaged cartilage is then inspected. The bone is prepared and the damaged cartilage is removed.

The kneecap is then replaced with a patellofemoral artificial joint. The implant is usually bonded onto the bones using special cement. The incision is closed with stitches or clips.

Afterwards your knee will be tightly bandaged to help minimise swelling. Small drainage tubes may also be left in for up to 48 hours.

You are likely to stay in hospital for three to four days after the operation. A physiotherapist will show you some exercises that will help you to walk the day after the operation. You will gradually progress from using crutches to using walking sticks.

Once you are fully weight-bearing and can manage to walk up and down stairs, you will be allowed to go home.

The knee dressing can be peeled off easily 10 days after the surgery and, as the stitches are internal, they do not need to be removed.

You will be given a cold compress or 'Cryocuff' along with instructions on how to cool your knee, which is important and aids recovery. You will see your consultant once again six weeks after your operation to review your progress.

Patellofemoral knee replacement recovery time is moderate and reasonably quick. Following the operation, you are likely to need four to six weeks off work and refrain from driving during that time.

There are several advantages of a patella replacement over a full knee replacement. A smaller incision means there is less scarring, less post-operative discomfort and a quicker recovery.

Because the knee anatomy remains intact, only the kneecap is replaced, the joint has a better range of motion.

A kneecap replacement procedure is considered to be a viable alternative to a total knee replacement surgery if you meet the right conditions for the procedure.

Kneecap replacement surgery is a relatively new procedure that has given good results to date. It also promises to be a long-lasting solution to osteoarthritis damage of the kneecap.

There are, however, some potential complications you should be aware of. These only affect less than 4% of patients.

  •  Infection can occur, although our theatres have ultra-clean air operating conditions keeping infection rates at 1-2%.
  • Blood clots are possible in any major joint replacement surgery but again are in the 1-4% category and have well established treatments including aspirin.
  • A small patch of numb skin can be present on the outer part of the knee near the kneecap, this will improve over time.
  • The knee will have some stiffness after the operation although we are aiming for full range of movement once things have settled down.
  • There is small chance of patellofemoral replacement failure.

Specialists offering Kneecap joint replacement surgery

Mr Neil Hunt

Consultant Specialist Knee Surgeon


The Huddersfield Hospital

View profile Book online

Mr Graham Walsh

Consultant Orthopaedic Knee & Sports Injuries Surgeon

MBBS BSc.(Hons) MRCS FRCSEd(Tr &Orth)

The Huddersfield Hospital

View profile Book online