Your knee is a complex joint, but you can think of it as having three main compartments. Patellofemoral replacement, also known as kneecap replacement, is a special kind of partial knee replacement for people with damage to only one of those compartments: the patellofemoral compartment.
That’s the part of your knee at the very front. It’s made up of your kneecap (patella) and the groove in your thighbone (femur), called the trochlear groove. When the smooth cartilage covering these bones wears away, they can rub against each other, causing pain and making it hard to move.
In a patellofemoral replacement, a surgeon replaces the damaged parts with artificial ones, usually made of metal and plastic. This creates a new, smooth surface for your kneecap to glide on, so you can move your knee without pain.
Why It’s Done
A patellofemoral replacement is a great option for people with a specific type of knee problem: isolated patellofemoral arthritis. This means the arthritis is only affecting the front part of your knee, and the other two compartments are still healthy.
This procedure might be right for you if:
- You have pain in the front of your knee, especially when you do things like go up and down stairs, squat, or get up from a chair.
- Your pain hasn’t gotten better with other treatments, like physical therapy, injections, or pain medication.
- X-rays show that the damage is only in the patellofemoral compartment of your knee.
Because it’s a less invasive surgery than a total knee replacement, a patellofemoral replacement can offer several benefits, including:
- A smaller incision
- Less pain and swelling after surgery
- A quicker recovery
- A more natural feeling in your knee
Common Symptoms and Causes
The main symptom of patellofemoral arthritis is a dull, aching pain in the front of your knee. You might also notice:
- A grinding or popping sound when you move your knee
- Stiffness or swelling in your knee
- Your knee buckling or giving way
Patellofemoral arthritis can be caused by a number of things, including:
- Wear and tear over time: This is the most common cause. As you age, the cartilage in your knees can start to break down.
- An injury to your kneecap: A fracture or dislocation can damage the cartilage and lead to arthritis.
- Patellar instability: This is when your kneecap doesn’t track properly in the groove of your thighbone, causing it to rub against the bone and wear away the cartilage.
- Mal-alignment: If your leg isn’t straight, it can put extra stress on your kneecap and lead to arthritis.
Common Risk Factors
Certain factors can increase your risk of developing patellofemoral arthritis, including:
- Age: The risk of arthritis increases as you get older.
- Obesity: Excess weight puts extra stress on your knees.
- Genetics: Some people are more likely to develop arthritis because of their genes.
- Previous knee injuries: A history of kneecap fractures or dislocations can increase your risk.
- Certain activities: Jobs or sports that involve a lot of squatting or kneeling can put extra stress on your knees.
What to Expect
Here’s a general idea of what to expect before, during, and after a patellofemoral replacement:
Before the Procedure
- You’ll meet with your surgeon to discuss the procedure and make sure it’s the right choice for you.
- You may need to have some tests, like an X-ray or MRI, to get a better look at your knee.
- Your doctor will give you instructions on how to prepare for surgery, including what to eat and drink and what medications to take.
During the Procedure
- Patellofemoral replacement is usually done under general or spinal anesthesia, so you won’t feel any pain.
- The surgeon will make a small incision in the front of your knee.
- They’ll remove the damaged cartilage and a small amount of bone from the back of your kneecap and the groove in your thighbone.
- Then, they’ll attach the artificial parts, called implants, to the bone with a special cement. The implant on your kneecap is a plastic button, and the one on your thighbone is a thin metal shield.
- Finally, the surgeon will close the incision with stitches or staples.
- The whole procedure usually takes about an hour.
After the Procedure
- You’ll be taken to a recovery room, where you’ll be monitored for a few hours.
- You may need to stay in the hospital for a night or two, but some people can go home the same day.
- You’ll be given pain medication to help you stay comfortable.
- You’ll start physical therapy soon after surgery to help you regain your strength and range of motion.
- You’ll need to use crutches or a walker for a few weeks to keep weight off your knee.
- Most people can return to their normal activities within a few months.
It’s important to remember that everyone’s recovery is different. Your doctor and physical therapist will work with you to create a personalized recovery plan.
