Knee replacement is surgery for people with severe knee damage. Knee replacement can relieve pain and allow you to be more active. Your doctor may recommend it if you have knee pain and medicine and other treatments are not helping you anymore.
When you have a total knee replacement, the surgeon removes damaged cartilage and bone from the surface of your knee joint and replaces them with a man-made surface of metal and plastic. In a partial knee replacement, the surgeon only replaces one part of your knee joint. The surgery can cause scarring, blood clots, and, rarely, infections. After a knee replacement, you will no longer be able to do certain activities, such as jogging and high-impact sports.
Causes
The most common reason to have a knee joint replaced is to relieve severe arthritis pain. Your doctor may recommend knee joint replacement if:
- You are having pain from knee arthritis that keeps you from sleeping or doing normal activities
- You cannot walk and take care of yourself
- Your knee pain has not improved with other treatment
- You understand what surgery and recovery will be like
Most of the time, knee joint replacement is done in people age 60 and older. Younger people who have a knee joint replaced may put extra stress on the artificial knee and cause it to wear out early and not last as long.
Treatment
Damaged cartilage and bone are removed from the knee joint. Man-made pieces are then placed in the knee.
These pieces may be placed in the following places in the knee joint:
- Lower end of the thigh bone — This bone is called the femur. The replacement part is usually made of metal
- Upper end of the shin bone, which is the large bone in your lower leg — This bone is called the tibia. The replacement part is usually made from metal and a strong plastic
- Back side of your kneecap — Your kneecap is called the patella. The replacement part is usually made from a strong plastic
You will not feel any pain during the surgery. You will have one of these two types of anesthesia:
- General anesthesia — This means you will be asleep and unable to feel pain
- Regional (spinal or epidural) anesthesia — Medicine is put into your back to make you numb below your waist. You will also get medicine to make you sleepy. And you may get medicine that will make you forget about the procedure, even though you are not fully asleep
After you receive anesthesia, your surgeon will make a cut over your knee to open it up. This cut is often 8 to 10 inches (20 to 25 centimeters) long. Then your surgeon will:
- Move your kneecap (patella) out of the way, then cut the ends of your thigh bone and shin (lower leg) bone to fit the replacement part
- Cut the underside of your kneecap to prepare it for the new pieces that will be attached there
- Fasten the two parts of the prosthesis to your bones. One part will be attached to the end of your thigh bone and the other part will be attached to your shin bone. The pieces can be attached using bone cement or screws
- Attach the underside of your kneecap. A special bone cement is used to attach this part
- Repair your muscles and tendons around the new joint and close the surgical cut
The surgery takes about 2 hours.
Most artificial knees have both metal and plastic parts. Some surgeons now use different materials, including metal on metal, ceramic on ceramic, or ceramic on plastic.
Recovery
You will stay in the hospital for 1 to 2 days. During that time, you will recover from your anesthesia and from the surgery itself. You will be asked to start moving and walking as soon as the first day after surgery.
Full recovery will take 4 months to a year.
Some people need a short stay in a rehabilitation center after they leave the hospital and before they go home. At a rehabilitation center, you will learn how to safely do your daily activities on your own.
The results of a total knee replacement are often excellent. The operation relieves pain for most people. Most people DO NOT need help walking after they fully recover.
Most artificial knee joints last 10 to 15 years. Some last as long as 20 years before they loosen and need to be replaced again. Total knee replacements can be replaced again if they get loose or wear out. However, in most cases the results are not as good as the first time. It is important not to have the surgery too early so you will need another surgery at a young age or have it too late when you will not benefit the most.
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