Why get knee replacement surgery?
The No. 1 reason to have a knee replacement is to relieve knee pain caused by severe arthritis. The second reason would be to gain back loss of function.
Before you can get a knee replacement surgery, doctors will try to use all other measures of repairing the knee first. These measures include anti-inflammatory medicines, certain types of injections and physical therapy. If you end up maximizing all of those options and still have considerable pain, you will likely become a candidate for knee replacement surgery.
What happens when you do it?
There is a misconception that a total knee replacement is removing the whole end of the thigh bone and whole top of the shin bone, where the knee comes together. This is misnomer.
With total knee replacement, surgeons resurface the end of the joint with a prosthesis, or artificial body part. For example, with the thigh bone, surgeons place a metal cap on the end of the thigh bone, forming part of an artificial joint.
There are bands of tissue in the knee, usually white and fibrous, that connect bones, known as ligaments. Doctors generally don't do anything to the ligaments on the outside or inside part of the knee. However, they have to sacrifice the ligaments in the middle of the knee to be able to place the prosthesis inside, which will serve the same role as the ligaments did.
Does it hurt?
With a knee replacement surgery, doctors try reducing the invasiveness of the surgery. This is one element that can help minimize pain.
Also, before and during surgery, doctors will use nerve blocks, which are anesthetic agents injected directly near a nerve to block pain, along with other types of injections in the knee during the surgery.
Typically, the pain after surgery is often less than the pain from the arthritis the person has. It's important to keep in mind that knee replacement surgery is a major surgery, but it can be tolerable with oral pain medications.
Some research suggests that, after a person has a knee replacement surgery, barometric pressure, changes in the weather, can affect pain that he or she feels.
How long does it take to recover?
After six weeks from the time of surgery, you're about 80 percent recovered from the whole process. It takes a year with any joint replacement to fully recover.
At six weeks, you're off your walker or crutches and probably moving around well.
Proprioception, which is your mind's ability to understand where your knee is in space, takes time. After about a year, your knee will likely fully feel more like your own knee.
You also must undergo physical therapy, sometimes multiple days a week, for about six to eight weeks, starting immediately after surgery.
What are the risk factors?
The biggest risk when placing any prosthesis in the body is infection. Anything mechanical doesn't have blood supply, so your body's immune system can fight against the prosthesis' presence.
Other risks specifically with knee replacement surgery are blood clots and risks from anesthetic.
Patients can also have complications that cause their knee to not feel like their own knee. Their knee can feel stiff or continue to feel painful. Those are the major complications that surgeons try to avoid.
Overall, the risk of infection or blood clotting is about 1 percent. Diabetes and obesity can increase the chance for complications.
Do you need follow-up surgeries?
Typically with knee replacement, doctors tell patients that they hope their joint will last them 15 years to 20 years. Improvements in the materials used in knee replacement help improve these odds.
At 10 years from the time of surgery, about 95 percent of patients have the same knee prosthesis.
It decreases about 1 percent per year, so at 15 years, about 90 percent of patients still have the same prosthesis, and at 20 years, about 85 percent. Doctors' goal is for patients to have the same prosthetic knee for the full 15 years to 20 years.
A person's weight, activity level and other medical issues also affect how long the prosthetic knee will last.