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Osteoarthritis

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of the most common form of arthritis.

Alternative Names

Arthritis - osteoarthritis

Surgery

Different surgical procedures are available as a final measure to relieve pain and increase function in patients with osteoarthritis. Certain surgical procedures can help relieve pain if medications fail. Even with these procedures, however, joint replacement may still be needed later on.

Arthroscopy

Arthroscopy is performed to clean out bone and cartilage fragments that, in theory at least, may cause pain and inflammation. More than 650,000 of these procedures are done on arthritic knees each year in the U.S., and about half of patients report less pain after the procedure.

A rigorous 2002 trial, however, found that arthroscopic knee surgery was no more effective than sham surgery, (in which surgeons only pretended to operate on the knee), for relief of osteoarthritic pain or stiffness. The study, which followed patients at a Veterans Affairs hospital for 2 years, has called into serious question whether the popular $5,000 procedure has any real benefits for osteoarthritis beyond what might be achieved by a placebo response. Research and debate continues on whether arthroscopy provides true benefits for those with osteoarthritis and, if so, which patients it may most help.

Joint Replacement (Arthroplasty)

When osteoarthritis becomes so severe that pain and immobility make normal functioning impossible, many people become candidates for artificial (prosthetic) joint implants using a procedure called arthroplasty. Hip replacement is the most established and successful replacement procedure, followed by knee replacement. Knee replacement, in fact, has a slightly better long-term success rate than hip replacement. Other joint surgeries (shoulders, elbows, wrists, fingers) are less common, and some arthritic joints (in the spine, for instance) cannot yet be treated in this manner. When two joints, such as both knees, need to be replaced, having the operations done sequentially rather than at the same time may result in fewer complications.

Candidates. The primary indications for surgery are pain and significant limitations of movement, including walking, that cannot be treated by less invasive therapies. Some experts suggest, however, that joint replacement should be considered earlier rather than as a last resort. They argue that patients who wait until they are severely disabled do not recover as completely as those who have the procedure earlier.

Patients who may not be good candidates are those with the following conditions:

• Severe neurologic, emotional, or mental disorders
• Severe osteoporosis
• Other chronic medical conditions
• Obesity

Surgeons often prefer to delay prosthetic implantation in younger patients, because implants wear out and they will require at least one revision procedure later on. Newer, more long-lasting materials, however, may help reduce the rate of re-operations.

Procedure Description. Although the following is mostly a description of hip replacement surgery, the principles are similar for other arthroplasties.

The surgeon removes the ball and socket joint that joins the pelvis and thigh bone (femur) and replaces it with an artificial joint (a prosthesis). It is composed of two pieces:

• A cup-like device fits in the hip socket (called the acetabula ), which has been hollowed out. This ball-and-socket cup is positioned to form the new joint.
• A metal shaft, or stem, with a polished metal ball at the top, is inserted into the narrow center of the femur.

The prosthesis is usually made of a metal alloy and plastic. A ceramic implant may prove to last longer than other materials and be a safe option for younger patients.

There are different options available for attaching it to the adjoining bones:

• A cement made of polymethylmethacrylate (usually preferred for older patients who generally have thinner bones).
• So-called cementless implants, in which the prosthesis is coated with a porous material that allows bone to grow into and eventually adhere to the device. These implants are usually used for patients younger than age 65, who are likely to need repeat surgery in their lifetime.

Complications. Complications can occur, and, although uncommon, some can be life-threatening. There is a 1% chance of death within 3 months of an initial procedure and a 2.6% risk after a repeat procedure. The risks are highest in the first 3 months. Those at highest risks for complications are elderly adults, men (compared to women), African Americans, and those with serious medical conditions.

Specific complications include the following:

• Deep blood clots (known as deep vein thrombosis) and pulmonary embolism. Deep blood clots can develop in the legs after this surgery. This poses a very small risk (0.9%) for pulmonary embolism -- a dangerous condition in which the clot travels to the lungs. Anticoagulants (blood thinners) are important for preventing blood clots. These drugs include warfarin and low-molecular weight heparin. Anticoagulant therapy is given during the hospital stay and continued for several weeks at home. The patient also wears specially fitted elastic stockings to help prevent clots. Patients who are overweight are at higher than average risk for post-operative blood clots
• Infection. Wound infection occurs in about 0.2% of joint replacements and requires prompt removal of the implant to treat the infection. A new prosthesis must be re-implanted at a later time. Any pre-existing infection must be treated and cured before surgery is performed. (Older women should be aware of urinary tract infections, which may require postponing surgery.) After surgery, patients should take certain precautions. For example, they should take antibiotics before invasive dental procedures or other surgery because bacteria can be introduced into the bloodstream and infect the areas around the artificial joints.
• Hip dislocation. Occurs in about 3.1% of first hip procedures. The rate is much higher (14.4%) in revision operations.

• Pain. Thigh pain can occur after hip replacement. Porous hip prostheses are more likely to produce thigh pain than cement implants, although advanced techniques using a tapered shaft are reducing this complication.
• Failure. The primary reason for implant failure is osteolysis (bone destruction) caused by long-term wear. The main source of wear is from tiny particles released from the prosthesis.
• Other complications. These include uneven leg lengths, nerve damage that can cause numbness or weakness, urinary tract infections, delayed healing, and allergic reactions to the metal. Long-term, there have been rare reports of a possible autoimmune response, in which loose particles released from the prosthetic device trick certain immune system factors into attacking healthy cells. Any incidence of unexplained weight loss and fatigue may be symptoms of this uncommon event.

Rehabilitation. Aside from the surgeon's skill and the patient's underlying condition, the success rate depends on the kind and degree of activity the joint receives following replacement surgery.

The patient is urged and aided into getting out of bed and walking the day after surgery. Most hip replacement patients leave the hospital within a week and can walk with crutches within 2 to 4 weeks, recovering fully in about 3 months.

Physical therapy takes about 6 weeks to rebuild adjoining muscle and strengthen surrounding ligaments. Studies suggest that an exercise program started before surgery and resumed afterward can improve recovery. Continuous passive motion (CPM) is an effective regimen for knee replacement patients. It uses a mechanical device that slowly moves the joint through an arc of motion for an extended period of time. It is used to prevent scar tissue from developing. In one review, a combination of physical therapy and CPM were more beneficial than physical therapy alone.

Limitations After Surgery. While many patients find that joint replacement provides remarkable pain relief and restores some mobility, they need time to adjust to the artificial joint.

Limitations after hip surgery include:

• Usually patients with new hips are able to walk several miles a day and climb stairs, but they cannot run.
• Prosthetic hips should not be flexed beyond 90 degrees, so patients must learn new ways to perform activities requiring bending down (like tying a shoe).

Limitations after knee surgery include:

• Walking distance improves in 80% of patients after knee replacement surgery, but patients still cannot run.
• Only slightly more than half of patients report improvement in stair climbing. (Artificial knee joints generally have a range of motion of just 110 degrees.)

Failure Rates. Infection is a major cause of early failure and always requires revision. Improper balancing of the ligaments and other tissues surrounding the joint and resulting poor joint stability is also a common reason for failure of arthroplasties. Surgical expertise is important for avoiding this complication.

Older cement prostheses have a particularly high rate of bone loss and loosening due to cement deterioration. In general, studies report reoperation rates of over 30% after 10 years. Fortunately, advances in cement and prosthetic implants are improving the implant survival rates and reducing the need for revision procedures.

Uncemented arthroplasty using porous material has shown good results for the hip, although it may be less successful for knee replacement. In spite of short-term success, longer experience with this method suggests it may not be superior to cement prostheses. Failure of bone to grow into the porous material is a relatively common event, a problem that does not occur with cement prostheses. Some experts recommend cement implants over cementless ones for total knee arthroplasty.

Revision Arthroplasty

A repair procedure called arthroplasty revision may be used in cases where the original transplant fails. The specific procedure depends on whether the bone defects that occurred are contained or uncontained .

• Contained defects can be repaired with small bone grafts, the use of cement, or oversized cementless implants as required.
• Uncontained defects are more severe and may require a large bone graft or specially constructed implants to restore bone.

If a second arthroplasty is required, the potential for complications is magnified: more bone is cut, more blood is lost, and the operation takes longer. Patients are also generally older and more vulnerable to complications.

Other Joint Procedures

Resection Arthroplasty. In resection arthroplasty, a false joint of scar tissue is created. This procedure is used most often in treating arthritis of the foot.

Osteotomy. If only a certain section (the medial compartment) of the knee is damaged and deformed by osteoarthritis, the surgeon may choose to perform osteotomy:

• A surgeon opens the knee.
• The surgeon performs a  debridement (removal of damaged tissue) in the joint to eliminate the loose or torn fragments that are causing pain and inflammation.
• The bone is then reshaped to remove the deformity.
• The procedure may ease symptoms and slow disease progression. It is best used in heavier adults who are under 60 years old.

Hemicallotasis. Hemicallotasis is a procedure for the knee that may be a less invasive alternative to osteotomy. The surgeon attaches the knee with pins to an external frame-like device that lengthens the deformed part of the knee over several weeks. The patient is mobile during this period. Infections at the pin site are the most common complications.

Arthrodesis. If the affected joint cannot be replaced, surgeons can perform a procedure called arthrodesis that eliminates pain by fusing the bones together. The patient must understand, however, that fusing the bones makes movement of the joint impossible. Bone fusion is most often done in the spine and in the small joints of the hands and feet.

Unicompartmental Knee Arthroplasty. Unicompartmental knee arthroplasty (also called unicondylar knee arthroplasty) may be a useful procedure in cases of limited knee damage. It is recommended for relatively sedentary patients who are 60 years or older and not obese. It may relieve pain and delay the need for a total knee replacement. The procedure involves a small incision and insertion of small implants. It retains important knee ligaments, which preserve more movement than a total knee replacement.

Cartilage Transplants. An interesting technique called autologous chondrocyte implantation, also called chondroplasty or the Carticel approach, is used for knees damaged by injuries. In this procedure, arthroscopy is used to first remove cartilage in eroded areas. The results have been good to excellent, although long-term benefits are questionable. Whether it has any benefit for older patients with osteoarthritis is not yet known. Other cartilage transplant procedures are also under study.

Hip Resurfacing. An experimental surgical alternative to total hip replacement involves scraping the surfaces of the hip joint and femur and placing a metal cap over the bone. The procedure preserves much of the bone, so that a standard hip replacement can be done years later if needed. It may provide more stability, a faster recovery, and greater range of motion, making it a potentially good option for young, physically active patients.

• Review Date: 4/19/2006
• Reviewed By: Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital

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