What is Joint Replacement?
When only some of the joint is damaged, a surgeon may be able to repair or replace just the damaged parts. When the entire joint is damaged, a total joint replacement is done. To replace a total hip or knee joint, a surgeon removes the diseased or damaged parts and inserts artificial parts, called prostheses or implants. These prostheses are considered medical devices, which are regulated by the Food and Drug Administration.

Risks:
• Blood clots in the legs (deep vein thrombosis), which can dislodge and move to the lungs (pulmonary embolus)
• Pneumonia
• Infection that requires removal of the prosthesis
• Prosthesis dislocation
• Heterotopic bone formation (extra bone growth that can cause stiffness)

Outlook (Prognosis)
The results of hip prosthesis surgery are usually excellent. The operation relieves pain and stiffness, and most patients (over 80%) need no help walking.

With time -- sometimes as long as 20 years -- the artificial joint will loosen and revision surgery will become necessary. Younger people may wear out the lining of their new cup and need it replaced before the prosthesis loosens.

Recovery
You will remain in the hospital for 3 to 5 days after surgery. However, some people may need to stay temporarily at a rehabilitation unit or long-tern care center until mobility has improved and they are safely able to live independently. These centers will provide intensive physical therapy to assist you in regaining muscle strength and flexibility in the joint.

Be careful after surgery that you don't dislocate the prosthesis. The new hip will not have the same range of movement of the original joint, although you should eventually be able to return to your previous level of activity. While you should avoid vigorous sports such skiing, or contact sports, many people go on to play tennis and golf quite successfully.

The use of crutches or a walker may be necessary for as long as 3 months, although most people who did not use them before are able to walk without them in several weeks.

Many surgeons place their patients on blood thinners for several weeks after surgery to help prevent blood clots. These may be taken in the form of pills (either Coumadin or aspirin) or injections.

Knee Replacement
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.

Knee Replacement Surgery
The largest joint in the body, the knee joint is formed where the lower part of the thighbone (femur) joins the upper part of the shinbone (tibia) and the kneecap (patella). Shock-absorbing cartilage covers the surfaces where these three bones touch.

In a standard total knee replacement, the damaged areas of the thighbone, shinbone and kneecap are removed and replaced with prostheses. The ends of the remaining bones are smoothed and reshaped to accommodate the prostheses. Pieces of the artificial knee are typically held in place with bone cement.

A knee replacement usually involves three to four days in the hospital. The recovery period depends on a patient's general health, age, and other factors, but many people can resume their normal activities four to eight weeks after surgery.

The Risks of Replacement
Like any surgery, hip and knee joint replacement carries certain life-threatening risks, such as infection, blood clots and complications from anesthesia. Other complications include nerve damage, dislocation or breakage after surgery, and wearing out or loosening of the joint over time. After hip replacement surgery, one leg may be shorter than the other.

Infection is an ongoing risk for people with joint replacements. Not only can it occur in the hospital, but it can happen years later if bacteria travel through the bloodstream to the replacement area.

In the rare case that an infection spreads to the new joint and does not clear up with antibiotic treatment, the joint must be replaced. This usually requires two surgeries--one to remove the infected joint and another surgery later to insert the new joint. Between surgeries, the infection is treated with antibiotics.

The Wear Problem
The most commonly used joint prostheses for knees and hips are made of metal and plastic. The metal is usually titanium or a mixture of cobalt and chromium. The plastic is a high-density polyethylene.

although the metal in a prosthesis is highly polished and the polyethylene is intended to be wear-resistant, the daily rubbing of these surfaces against each other during normal movements creates tiny particles of debris. After many years, these wear particles may damage the surrounding bone, loosen the prosthesis, and require another knee or hip joint replacement.

"Any time you have parts moving against each other, there has to be wear."

Surgical Techniques
People are seeking minimal-incision knee and hip replacement surgery, says Engh. Instead of the traditional 6- to 12-inch-long incision used in a standard total knee replacement, some surgeons are performing the surgery through a 4- to 5-inch incision. And instead of the typical 10- to 12-inch incision in a total hip replacement, surgeons are operating through one 4-inch cut or two 2-inch cuts.

"The [minimal-incision surgery] technique minimizes trauma to muscles, tissue and tendons and has less bleeding during surgery," says Garino. Patients have less pain after surgery, enabling them to walk with full weight sooner. The hospital stay is usually reduced as well.

Not all patients are candidates for minimal-incision surgery. People who are obese, have had knee surgery, or those with unusual anatomy may be excluded.

How Do You Know It's Time for Surgery?
• you are unable to sleep at night because of the pain
• you've tried a series of different medications that don't help alleviate the pain, or the medication you have been on no longer works
• you feel that the pain from your arthritis is keeping you from regular outings, such as visiting friends, going shopping or taking a vacation
• your activity is restricted to the point where you have trouble getting out of a chair, going up stairs, getting off the toilet, or getting up from the floor.

What to Ask the Surgeon?
• What makes someone a good candidate for joint surgery?
• What are the risks involved in joint surgery?
• Would there be any other non-surgical treatments I haven't yet tried that would ease my pain and help me move more easily?
• How would surgery help my particular problem?
• What would not change after the operation?
• How long is the recovery process?
• What is involved in the recovery process?
• What type of procedure would you recommend for me?
• How often in the past year have you performed this operation?
• Can you tell me what the outcome (decreased pain, improved function) has been for most of these patients?
• Can you provide the names of several people I could contact to discuss their experiences with surgery?