Osteoarthritis is a problem that affects all parts of the joint. For example, when cartilage breaks down, the bones start to rub against each other. This causes damage to tissue and bone. The symptoms of osteoarthritis include joint pain, stiffness after inactivity, and limited motion.

Knee replacement surgery may be used when a person can no longer control knee pain with other treatments and when the pain disrupts their life.

The surgeon covers the ends of the damaged thighbone and lower leg bone, and usually the kneecap, with artificial (man-made) surfaces that are lined with metal and plastic. The artificial pieces are usually cemented to the bones.

Rehabilitation, or rehab, is usually intense after surgery. Most people start to walk with a walker or crutches the day of surgery. And they begin physical therapy right away. Your doctor may advise you to ride a stationary bike to strengthen your leg muscles and improve how well you can bend your knee. Rehab will take several weeks, but you should be able to start walking, climbing stairs, sitting in and getting up from chairs, and doing other daily activities within a few days.

Surgery is only for people with severe osteoarthritis who do not get pain relief from medicine, home treatment, or other methods and who have lost a lot of cartilage. Surgery relieves severe, disabling pain and may restore the knee's ability to work properly.

Besides knee replacement, the other types of surgeries used are:

There are a number of treatments for arthritis in the knee that don't involve surgery:

• Medicine. If your pain is mild, over-the-counter pain medicines may help. These include acetaminophen (for example, Tylenol) and nonsteroidal anti-inflammatory drugs, such as ibuprofen (for example, Advil, Motrin) or naproxen (for example, Aleve). But if these don't get rid of your pain, you may need a stronger prescription medicine. Be safe with medicines. Read and follow all instructions on the label.
• Pain-relieving gels or creams, such as capsaicin.
• Steroid shots. Steroid shots may provide rapid pain relief. But for some people, this benefit only lasts a few weeks.
• Ice or heat. Heat may help you loosen up your joints before an activity. Ice is a good pain reliever after activity or exercise.
• Exercise. Exercise helps because it makes your muscles stronger, which lowers the stress on your knees. But make sure to talk to your doctor about what kind of activity is best for you.
• Losing weight, if you're overweight. Losing weight helps take some of the stress off of your joints.
• Physical therapy. This includes specific exercises that can help you stretch and strengthen your muscles and reduce pain and stiffness.
• Walking aids. There are many devices you can use to take some of the stress off of your knee. These include crutches, walkers, braces, and tape. You may also be able to reduce the stress on your knee by wearing the right shoes or by adding insoles to your shoes. Talk to your doctor or physical therapist about what would be best for you.

Some other things that you may try include:

• Acupuncture. It involves putting very tiny needles into your skin at certain places on your body to try to relieve pain. Some people find that acupuncture helps. But there is not a lot of medical research to support the use of acupuncture for knee arthritis.
• Dietary supplements, such as glucosamine and chondroitin, fish oil, or SAM-e. Some people feel that these supplements help. But medical research does not prove that they work. Talk to your doctor before you take these supplements.

Most people have much less pain after knee replacement surgery and are able to return to many of their activities. But as with any surgery, there are some risks, including:

• Lack of good range of motion. After surgery, some people can't bend their knee far enough to do their daily activities, even after several weeks.
• Dislocated kneecap. If this happens, the kneecap may move to one side of the knee, and it will "pop" back when you bend your knee. It usually needs to be treated with another surgery. But this problem is not common.
• Blood clots. These can be dangerous if they block blood flow from the leg back to the heart or move to the lungs. They are more common in older people, those who are very overweight, those who have had blood clots before, and those who have cancer.
• Wound-healing problems. These are more common in people who take steroid medicines or who have diseases that affect the immune system, such as rheumatoid arthritis and diabetes. People who have any sort of artificial material in their bodies, including artificial joints, have a risk of infection around the material. But infection is rare. There is also a small risk of infection with any surgery.
• Instability in the joint. The knee may be unstable or wobbly if the replacement parts are not properly aligned. You may need a second surgery to align the parts correctly so that your knee is stable.
• The usual risks of general anesthesia. Problems from anesthesia are not common, especially in people who are in good health overall. But all anesthesia has some risk.

Pain relief with surgery

The evidence about knee replacement surgery suggests that most people are happy with the results.

Take a group of 100 people who have the surgery. Six months after knee replacement, about 80 out of 100 people have less pain and can do more activities than they could before the surgery.^{footnote 1}

Need for repeat surgery

Most artificial knees last for many years. But they can wear out or have other problems. Some people have to repeat the surgery to have the joint replaced again.

Take a group of 100 people who have the surgery. Within 20 years after surgery, about 10 out of 100 will need to have the knee replaced again.^{footnote 2}

Problems after surgery

The evidence suggests that, like most surgeries, knee replacement may have some risks.

Take a group of 100 people who have the surgery. About 4 out of 100 people have a serious complication like a joint infection, a blood clot, or a heart attack within 3 months after surgery. If you are older or have other health problems, your risk may be higher. ^{footnote 6, footnote 4, footnote 5, footnote 3footnote 7}

Your doctor might recommend knee replacement if:

• You have very bad arthritis pain, and other treatments have not helped.
• You have lost a large amount of cartilage.
• Your knee pain is keeping you from being active enough to keep up your strength, flexibility, balance, or endurance.
• You don't have health problems that would make it dangerous for you to have surgery.