Osteoarthritis is a problem with the cartilage in joints. Over time, the cartilage breaks down until the bones, which were once separated by cartilage, 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 there is knee pain and disability from damage that can be seen on X-rays.

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 cemented to the bones.

Rehabilitation, or rehab, is usually intense after surgery. Most people start to walk with a walker or crutches the day after surgery and 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, you may only need pain medicines that you can buy without a prescription. Stronger medicines that are used to treat osteoarthritis include:
  • Steroid injections.
  • Hyaluronan injections.
  • Opioids.
• 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.
• Physical therapy or occupational therapy.
• 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. Wedged insoles or cushioned shoes may help redistribute weight and take some of the stress off of your knee.

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. Medicine may help.
• 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.

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.
• You don't have health problems that would make it dangerous for you to have surgery.