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In This Report

•	Highlights
•	Introduction
•	Causes
•	Symptoms
•	Conditions with Similar Sym...
•	Risk Factors
•	Diagnosis
•	Prognosis
•	Lifestyle Changes
•	Medications
•	Alternative and Complementa...
•	Surgery
•	Resources
•	References

Related Reports

•	Rheumatoid arthritis
•	Foot pain
•	Gout

Encyclopedia

•	Osteoarthritis
•	Arthritis

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Osteoarthritis

Highlights

Pain Medications

• Nonsteroidal anti-inflammatory drugs (NSAIDs) and COX-2 inhibitors work equally well for pain management, but both types of drugs increase the risk for heart attacks, according to an important report from the U.S. Agency for Healthcare Quality and Research.
• The prescription NSAID diclofenac (Voltaren, Cataflam) may present a higher risk for heart attack than other NSAIDs, suggests a 2006 Journal of the American Medical Association study.
• Standard osteoarthritis medications provide moderate pain relief for only 2 - 3 weeks, suggests a 2007 review in the European Journal of Pain.

Acupuncture

Acupuncture may be helpful for people with knee and hip osteoarthritis, according to several 2006 studies:

• An Annals of Internal Medicine study of 1,007 people with chronic osteoarthritis knee pain indicated that patients who received acupuncture plus standard care had greater improvement than those who received only physical therapy and anti-inflammatory drugs.
• An Arthritis and Rheumatism study of 3,663 patients with chronic osteoarthritis knee or hip pain suggested that acupuncture plus routine care can provide significant improvements in pain relief and quality of life. In both studies, the benefits of acupuncture were sustained for up to 6 months after treatment completion.

Exercise and Knee Osteoarthritis

Weight-bearing exercise (walking, jogging) neither prevents nor increases the risk of knee osteoarthritis in healthy middle-aged and elderly people, suggests a 2007 study in Arthritis and Rheumatism.

Risk of Hip Osteoarthritis

About 1 in 4 Americans can expect to develop osteoarthritis of the hip at some point in life, according to research presented at the 2006 American College of Rheumatology annual meeting. Body weight is a factor. People who are normal weight have a 20% risk, compared to those who are overweight (25%) or obese (39%).

Introduction

Osteoarthritis, also known as degenerative joint disease, is the most common form of arthritis. Scientists now believe osteoarthritis results from a combination of genetic abnormalities and joint injuries. In this disorder, an affected joint experiences a progressive loss of cartilage, the slippery material that cushions the ends of bones.

Osteoarthritis is a chronic disease of the joint cartilage and bone, often thought to result from "wear and tear" on a joint, although there are other causes such as congenital defects, trauma, and metabolic disorders. Joints appear larger, are stiff and painful, and usually feel worse with increased use throughout the day.

As a result, the bone beneath the cartilage undergoes changes that lead to bony overgrowth. The tissue that lines the joint can become inflamed, the ligaments can loosen, and the associated muscles can weaken. The patient experiences pain when using the joint. In addition to humans, nearly all vertebrates suffer from osteoarthritis, including porpoises and whales, as did long-extinct terrestrial travelers such as dinosaurs.

Click the icon to see an animation about osteoarthritis.

Joints

Joints are designed to provide flexibility, support, stability, and protection. These functions, essential for normal and painless movement, are primarily supplied by specific parts of the joint: the synovium and cartilage.

Synovium. The synovium is a membrane that surrounds the entire joint. It is filled with synovial fluid, a lubricating liquid that supplies nutrients and oxygen to cartilage.

Cartilage. The cartilage is a slippery tissue that coats the ends of the bones. Cartilage is one of the few tissues in the body that does not have its own blood supply. It has a number of essential components:

Click the icon to see an image of the synovial membrane and cartilage in the knee joint.

• Chondrocytes. Chondrocytes, the basic cartilage cells, are critical for balance and function.
• Water. Cartilage contains a high percentage of water, although it decreases with age. About 85% of cartilage is water in young people, and about 70% is water in older individuals.
• Proteoglycans. These are large molecules that help make up cartilage. Their important value is their capacity to bond to water, which ensures the high-fluid content in cartilage.
• Collagen. This is the critical protein in cartilage. It forms a mesh to give support and flexibility to the joint. Collagen is the main protein found in all the connective tissues of the body, including the muscles, ligaments, and tendons.

The combination of the collagen meshwork and the high water content, tightly bound by proteoglycans, creates a resilient and slippery pad in the joint, which resists the compression between bones during muscle movement. The synovial fluid lubricates and provides oxygen and nutrients to the bloodless cartilage.

Osteoarthritis: The Disease Process

Deterioration of Cartilage. Osteoarthritis develops when cartilage in a joint deteriorates. The process is usually slow.

• In the early stages of the disease the surface of the cartilage, or even the synovium in some people, becomes inflamed and swollen. There is a loss of proteoglycan molecules and other tissue components that cause water loss. Fissures and pits appear in the cartilage.
• As the disease progresses and more tissue is lost, the cartilage loses elasticity and fluid. It becomes increasingly prone to damage due to repetitive use and injury.
• Eventually large amounts of cartilage are destroyed, leaving the ends of the bone within the joint unprotected.

To compound the process, bone around arthritic joints is not structurally normal. As the body tries to repair damage to the cartilage, problems can develop:

• Clusters of damaged cells or fluid-filled cysts may form around the bony areas or near the fissures.
• Fluid pockets may also form within the bone marrow itself, causing swelling. The marrow, which runs up through the center of bone, is rich in nerve fibers, and such injuries may be an important source of pain in many patients with osteoarthritis.
• Bone cells may respond to damage by multiplying, growing, and forming dense, misshapen plates around exposed areas.
• At the margins of the joint, the bone may produce outcroppings, on which new cartilage cells (chondrocytes) proliferate and grow abnormally.

Location of Osteoarthritis

Unlike some other types of arthritis, such as rheumatoid arthritis, osteoarthritis does not spread through the entire body. (In other words, it is not systemic.) Rather, it affects one or several joints. Osteoarthritis affects joints differently depending on their location in the body.

• Osteoarthritis is commonly found in joints of the fingers, feet, knees, hips, and spine.
• It sometimes occurs in the wrist, elbows, shoulders, and jaw, but is not common in these locations.

Causes

The biologic factors leading to the deterioration of cartilage in osteoarthritis are not entirely understood. Many experts believe that osteoarthritis results from a genetic susceptibility that causes some biologic response to injuries to the joint, which in turn leads to progressive deterioration of cartilage. In addition, the ability to make repairs becomes progressively limited as cartilage cells age.

Aging Cells

Although osteoarthritis generally accompanies aging, osteoarthritic cartilage is chemically different from normal aged cartilage. As chondrocytes (the cells that make up cartilage) age, they lose their ability to make repairs and produce more cartilage. This process may play an important role in the development and progression of osteoarthritis.

Genetic Factors

Researchers report a high correlation of osteoarthritis between parents and children or between siblings. Genetic factors are thought to be involved in about half of osteoarthritis cases in the hands and hips and a somewhat lower percentage of cases in the knee. A number of genes are under investigation that might contribute to an inherited risk.

For example, mutations in the ank gene may be important in some cases. The ank gene regulates pyrophosphate, a chemical that inhibits the formation of mineral deposits, and may protect the cartilage in joints. Mutations in the ank gene then may result in lower pyrophosphate levels in the joint, leading to accumulation of mineral deposits and arthritis. (About 60% of people with osteoarthritis have mineral deposits in their cartilage.)

Another gene, called the osteoprotegerin gene, is important in regulating bone and cartilage formation. Mutations in this gene may play a role in osteoarthritis.

Inflammatory Response and Matrix Metalloproteinases

The inflammatory response is an overreaction of the immune system to an injury or other assault in the body, such as an infection. This response causes specific immune factors, called cytokines, to gather in injured areas and cause inflammation and damage to body tissue and cells. The inflammatory response plays an important role in rheumatoid arthritis and other muscle and joint problems associated with autoimmune diseases. It has generally been believed that inflammation plays at most a minor role in osteoarthritis and is more likely to be a result -- not a cause -- of the disease.

However, recent studies suggest that inflammation may play an important role in the progression of osteoarthritis and its chronic nature. For example, a 2003 study found evidence of severe inflammation in the lining of the joints in 30% of patients with osteoarthritis. Still, the effects of the inflammatory response in osteoarthritis are likely to be different from those in rheumatoid arthritis and less severe.

Some theories on how this response may contribute to osteoarthritis involve overproduction of enzymes called matrix metalloproteinases or MMPs (also called collagenases). In large amounts they break down collagen, the building blocks of cartilage. Some studies suggest that immune factors called vascular endothelial growth factor (VEGF) are overproduced during the inflammatory response and in turn increase production of MMPs.

Another theory suggests that the inflammatory response is triggered by the changes and injuries in the bone that occur during osteoarthritis. According to this theory, immune factors released in this process diffuse into the cartilage, where they suppress cartilage cell growth and activate MMPs.

Injuries

Joint injuries are the starting point in the disease process. Osteoarthritis sometimes develops years after a single traumatic injury to or near a joint. One large study found that by age 65, osteoarthritis developed in almost 14% of those who had joint injuries as young adults, compared to just 6% in those without earlier injuries. Patients with knee injuries were five times more likely to have osteoarthritis in the injured knee than those without injuries, and patients with hip injuries were more than three times more likely to develop arthritis in the injured hip. Proper treatment of injuries, such as surgical repair of ligament tears in the knee with a strong rehabilitation approach, may help to prevent the development of osteoarthritis.

Other Medical Conditions that Can Cause Osteoarthritis

Other causes of osteoarthritis include:

• Bleeding disorders such as hemophilia that cause bleeding to occur in the joint
• Disorders such as avascular necrosis that block the blood supply near the joint
• Complications of persistent, inflammatory arthritic conditions, particularly chronic gout, pseudogout, or rheumatoid arthritis
• Conditions that cause iron build-up in the joints such as hemochromatosis

Symptoms

The pain of osteoarthritis typically begins gradually and progresses slowly over many years. People under age 40 may have the condition with no symptoms at all. Osteoarthritis is commonly identified by the following symptoms:

• The most common symptom of osteoarthritis in any joint is pain that worsens during activity and gets better during rest. As the disease advances, the pain may occur even when the joint is at rest.
• Pain is generally described as aching, stiffness, and loss of mobility.
• The pain may behave like a roller coaster, with bad spells followed by periods of relative relief.
• Pain seems to increase in humid weather.
• Some people experience muscle spasm and contractions in the tendons.
• Osteoarthritis in the knee may cause a crackling-like noise (called crepitus) when moved.

Symptoms by Location

Hand. Osteoarthritis of the hand occurs most often in older women and may be inherited within families. The following joints are most frequently affected:

• Distal interphalangeal (DIP) joint. The first joint below the fingertips is the most common location of osteoarthritis of the hand. These joints can develop bony growths known as Heberden's nodes.
• Carpometacarpal (CMC) joint. The joint at the base of the thumb, where the thumb joint connects with the wrist, is the second most common location.
• Proximal interphalangeal (PIP) joint. The middle joints of the fingers can also develop osteoarthritis. These joints may develop small, solid lumps (nodules) known as Bouchard's nodes.

Click the icon to see an image of osteoarthritis.

Recent studies suggest that osteoarthritis of the hand may predict the later development of osteoarthritis in the hip or knee. A 2005 study found that patients with hand osteoarthritis were three times more likely to develop hip arthritis. Osteoarthritis of the hand also slightly increased the risk for knee osteoarthritis.

Knee. Osteoarthritis is particularly debilitating in the weight-bearing joints of the knees. The joint is usually stable until the disease reaches an advanced stage when the knee becomes enlarged and swollen. Although painful, the arthritic knee usually retains reasonable flexibility.

Osteoarthritis can cause loss of cartilage in the knee. The meniscus, the cartilage pad between the joint formed by the thighbone and the shinbone, plays an important role in protecting the joint. It acts as a shock absorber. In knee surgery called meniscectomy, the doctor removes the damaged cartilage. However, a 2006 study suggested that preserving the meniscus, even if it is damaged, is better than removing it. Researchers showed that even a small amount of meniscus helps protect the joint and prevent osteoarthritis from worsening. Experts recommend that patients try lifestyle changes (exercise and weight loss), braces, and medication before undergoing knee surgery.

Click the icon to see an image of the knee joint.

Hips. About 1 in 4 people will develop hip arthritis over the course of their lifetime. Being obese increases the risk. Osteoarthritis frequently strikes the weight-bearing joints in one or both hips. Pain develops slowly, usually in the groin and on the outside of the hips, or sometimes in the buttocks. The pain also may radiate to the knee, confusing the diagnosis. Those with osteoarthritis of the hip often have a restricted range of motion (particularly when trying to rotate the hip) and walk with a limp, because they slightly turn the affected leg to avoid pain.

Click the icon to see an image of the hip joint.

Spine. Osteoarthritis may affect the cartilage in the disks that form cushions between the bones of the spine, the moving joints of the spine itself, or both. Osteoarthritis in any of these locations can cause pain, muscle spasms, and diminished mobility. In some cases, the nerves may become pinched, which also produces pain. Advanced disease may result in numbness and muscle weakness. Osteoarthritis of the spine is most troublesome when it occurs in the lower back or in the neck, where it can cause difficulty in swallowing.

Click the icon to see an image of the spine.

Shoulder. Osteoarthritis is less common in the shoulder area than in other joints, but it may develop in the shoulder joint (the glenohumeral joint). In such cases, it is most often associated with a previous injury, and patients gradually develop pain and stiffness in the back of the shoulder. Osteoarthritis also can develop in the acromioclavicular (AC) joint, which is between the shoulder blade and the collarbone. However, it rarely causes symptoms in this location.

Conditions with Similar Symptoms

Numerous conditions have symptoms of joint aches and pains. Something as benign as sleeping on a bad mattress to the serious afflictions associated with cancer can mirror symptoms of osteoarthritis. Other problems that can cause aches and pains in the joints include physical injuries, infections, tendinitis, and poor circulation. A number of rare genetic diseases attack the joints.

Osteoarthritis can generally be distinguished from other joint diseases by considering several factors together:

• Osteoarthritis usually occurs in older people and is located in only one or a few joints
• The joints are less inflamed than in other arthritic conditions
• Progression of pain is usually gradual.

A few of the most common disorders that can be confused with, or may even accompany, osteoarthritis are discussed below.

Rheumatoid Arthritis

Osteoarthritis may be confused with rheumatoid arthritis, particularly when osteoarthritis affects multiple joints in the body. Rheumatoid arthritis begins in the synovial membrane rather than the cartilage. It normally occurs earlier in life than osteoarthritis, often striking people in their 30s and 40s. Rheumatoid arthritis affects many joints, and often occurs symmetrically on both sides of the body. People generally have morning stiffness that lasts for at least an hour. (Stiffness from osteoarthritis usually clears up within half an hour.)

X-rays show changes in the bones that differ from those occurring in osteoarthritis. In rheumatoid arthritis, blood tests often show a specific antibody, known as rheumatoid factor, which is not present with osteoarthritis. In another blood test, levels of a factor called erythrocyte sedimentation rate (ESR) are often elevated in rheumatoid arthritis, but they are generally normal in osteoarthritis. Rheumatoid arthritis also does not usually show up in the fingertips where osteoarthritis is common.

Rheumatoid arthritis is a body-wide (systemic) autoimmune disease that initially attacks the synovium, a connective tissue membrane that lines the cavity between joints and secretes a lubricating fluid.

Click the icon to see an image of osteoarthritis vs. rheumatoid arthritis.

Chondrocalcinosis

Chondrocalcinosis is a disease in which certain calcium crystals known as CPPD (calcium pyrophosphate dihydrate) are deposited in the joints. It affects about 25% of the population and can accompany and even worsen osteoarthritis. The problem has been called pseudogout or pseudo-osteoarthritis, in the latter case particularly when it affects the knees. A doctor can usually differentiate between the two disorders, however, because chondrocalcinosis usually damages other joints (such as wrists, elbows, and shoulders) that are not usually affected by osteoarthritis. The condition may explain why some patients with osteoarthritis receive benefit from colchicine, a drug used for gout and other crystal-induced joint diseases.

Charcot's Joint

Charcot's joint occurs when an underlying disease, usually diabetes, causes nerve damage in the joint, which leads to swelling, bleeding, increased temperature, and changes in bone. There may be a loss of sensation that leads to an increased risk for injury from overuse.

Risk Factors

Osteoarthritis is the most common type of arthritis. In the U.S., about 12.1% of Americans (21 million people) age 25 and older have osteoarthritis. The prevalence in osteoarthritis increases as people age. Experts estimate that by 2030, 20% of Americans (72 million people) age 65 years and older will be at risk for developing osteoarthritis.

Gender

Before age 45, osteoarthritis occurs more frequently in males (although it is not common in younger adults). After age 55, it develops more often in females. In a 2000 study, 33% of women had osteoarthritis compared to 25% of men. Some research suggests that women may also experience greater muscle and joint pain, in general, than men. And, women also tend to be undertreated for pain compared to men. The causes of such differences in pain sensitivity and treatment are largely unknown and most likely are due to a complicated mix of biologic, psychologic, and social factors.

Education

The incidence is highest in lower educational levels. In a 2000 study, 41% of adults with less than a high school education had arthritis compared to 21% of college graduates.

Geography

Although the average rate of osteoarthritis among older adults in the U.S. is 60%, it can vary widely in certain geographical regions. In the U.S., the rates in older adults are lowest (34%) in Hawaii and highest (70%) in Alabama. In general, the highest prevalence of arthritis in America occurs in the central and northwestern states.

Ethnicity and Inheritance

The rate of osteoarthritis varies by ethnic group. In the U.S., Caucasians and African-Americans have higher rates of arthritis than Hispanics or other ethnic groups. Osteoarthritis also tends to favor specific joints over others in certain ethnic groups. The following are some examples:

• Older African-American men are about 33% more likely than Caucasian men to have hip osteoarthritis. In one study, although men in both groups had equal risks for arthritic knees, African-American men were more likely to have arthritis in both knees and to have more severe cases. Although comparable disparities in knee arthritis were observed between African-American and Caucasian women, they might be explained by greater average weight among African-American women. The study could not account for the differences among men, however.
• Asians appear to have a higher incidence of osteoarthritis in the knee, an equal risk for osteoarthritis in the spine, and a lower risk for osteoarthritis in the hips than Caucasians.

Genes that determine the angles, amount of force, and other structural factors in the hip joints, or genes that regulate the chemistry in the joints, may account for ethnic differences.

Physical and Anatomical Factors

Some researchers suggest that a number of people have anatomical abnormalities, such as mismatched surfaces on the joints, which could be damaged over time by abnormal stress. Legs of unequal length or skewed feet can cause jerky movement and may cause osteoarthritis. One study reported that those whose knees bent inward ("knock-kneed") or outward ("bow-legged"), for example, were more likely to have progressive osteoarthritis of the knee.

Obesity

Obesity, defined as being 20% over one's healthy weight, places people (particularly women) at increased risk for osteoarthritis. It also worsens osteoarthritis once deterioration begins. This higher risk is due to increased weight on the joints. However, being obese also increases the risk for osteoarthritis in the fingers as well as the knees and hips, suggesting that being overweight may contribute to osteoarthritis in other ways. Some research indicates that obesity may produce an inflammatory response, which is now a major suspect in age-related diseases -- not only osteoarthritis but also heart disease. [See In-Depth Report #53: Weight control and diet.]

Work and Leisure Factors

Because injuries can trigger the disease process, people whose work or leisure activities place them at risk for muscle and joint injuries may face a higher risk for osteoarthritis later on.

Workers at Higher Risk. Certain occupations that require repeated stressful motions (such as squatting or kneeling with heavy lifting) can contribute to deterioration of cartilage. One study suggested that workers whose jobs require kneeling or squatting for more than an hour a day are at high risk for knee osteoarthritis. (In the study, jobs that involved heaving lifting, climbing stairs, or walking also posed some, but not as high, a risk. Being heavier compounded the chances for osteoarthritis.)

Exercise. There has been some question about the role of strenuous exercise in osteoarthritis. Sports that definitely pose a higher risk for osteoarthritis are those that require repetitive or direct joint impact (such as football), twisting, or both (baseball pitching, soccer).

Marathon runners, however, have a relatively low rate of osteoarthritis. Some scientists speculate that running enhances cartilage health because the rhythmical compression of cartilage expels wastes and promotes absorption of nutrients.

In any case, regular and moderate exercise is important for everyone and does not increase the risk for osteoarthritis. In fact, a 2006 study of middle-aged and elderly people found that recreational weight-bearing exercise (walking, jogging) neither protects against nor increases the risk for osteoarthritis. Furthermore, many factors associated with a sedentary life (muscle weakness, obesity) are associated with a higher risk for osteoarthritis.

Diagnosis

Osteoarthritis is often visible in x-rays. Cartilage loss is indicated by certain images:

• If the normal space between the bones in a joint is narrowed.
• If there is an abnormal increase in bone density.
• If bony projections, cysts, or erosions are evident.
• X-rays can also reveal any cysts that might develop in osteoarthritic joints. If other conditions are suspected or if the diagnosis is uncertain, additional tests are necessary.
• An MRI may show evidence of osteoarthritis that x-rays miss.

X-rays are a form of electromagnetic radiation (like light); they are of higher energy, however, and can penetrate the body to form an image on film. Structures that are dense (such as bone) will appear white, air will be black, and other structures will be shades of gray depending on density. X-rays can provide information about obstructions, tumors, and other diseases, especially when coupled with the use of barium and air contrast within the bowel.

Blood Tests

Blood test results may help diagnose or rule out osteoarthritis. Some examples include:

• Elevated levels of rheumatoid factor (specific antibodies in the synovium) and so-called erythrocyte sedimentation rates (ESR or sed rate) indicate rheumatoid arthritis.
• Hyaluronic acid (HA), a joint lubricant, is being tested as a potential biomarker for osteoarthritis. High levels of HA may indicate increased risk for osteoarthritis.
• Elevated levels of a factor called C-reactive protein, which is produced by the liver in response to inflammation, are proving to be good predictors of osteoarthritic progression in the knee.

Tests of the Synovial Fluid

If the diagnosis is uncertain or infection is suspected, a doctor may attempt to withdraw synovial fluid from the joint using a needle. There will not be enough fluid to withdraw if the joint is normal. If the doctor can withdraw fluid, problems are likely, and the fluid will be tested for factors that might confirm or rule out osteoarthritis:

• Cartilage cells in the fluid are signs of osteoarthritis.
• A high white blood cell count is a sign of infection.
• High uric acid in the fluid is an indication of gout.

Click the icon to see an animation on gout.

• Other factors may be present that suggest different arthritic conditions, including Lyme disease and rheumatoid arthritis.
• In people with known osteoarthritis, researchers may look for certain factors in synovial fluid (sulfated glycosaminoglycan, keratin sulfate, and link protein) that can suggest a more or less severe condition.

Prognosis

Osteoarthritis itself is not life-threatening, but a person's quality of life can significantly deteriorate from pain and loss of mobility. The negative effects on activities and physical and mental health are significant regardless of age, educational level, or gender. Only heart disease has a greater impact on work. Five percent of those who leave the work force do so because of osteoarthritis. Unless alleviated by medication or corrected by surgery, advanced osteoarthritis can force the patient to forgo even relatively low-impact activities, such as walking. No treatment can cure osteoarthritis, and none can alter its progression with certainty, but many available therapies can relieve symptoms and significantly improve the quality of life.

Lifestyle Changes

Many doctors suggest first trying lifestyle changes to reduce stress on affected joints. Physical therapy and supportive devices can be helpful. Intensive education on how to protect and care for an osteoarthritic joint may help patients avoid multiple visits to their doctor.

Occupational Changes

Once osteoarthritis has been diagnosed, patients should reduce shock to the affected joint. Hammering away at deteriorating cartilage is likely to speed up the degeneration. People in occupations requiring repetitive and stressful movement should explore ways to reduce trauma. Adjusting the work area or substituting tasks that produce less stress on joints helps reduce shock.

Exercise

Joints require motion to stay healthy. Long periods of inactivity cause the arthritic joint to stiffen and the adjoining tissue to atrophy. A moderate exercise program that includes low-impact aerobics and power and strength training has benefits for osteoarthritic patients, even if exercise does not slow down the disease progression. Exercise helps:

• Reduce stiffness and increase flexibility. It may also help improve the strength and elasticity of knee cartilage.
• Promote weight loss.
• Improve strength, which in turn improves balance and endurance.
• Reduce stress and improve feelings of well being, which helps patients cope with the emotional burden of pain.

Exercise especially helps patients with mild-to-moderate osteoarthritis in the hip or in the knee. Many patients who begin an aerobic or resistance exercise program report less disability and pain. They are better able to perform daily chores and remain more independent than their inactive peers. Older patients and those with medical problems should always check with their doctor before embarking on an exercise program.

Three types of exercise are best for people with osteoarthritis:

• Strengthening exercise
• Range-of-motion exercise
• Aerobic, or endurance, exercise

Strengthening Exercise. Strengthening exercises include isometric exercises (pushing or pulling against static resistance). Isometric training builds muscle strength while burning fat, helps maintain bone density, and improves digestion.

Some experts encourage patients to emphasize strengthening leg muscles as a first treatment step, before using pain relievers. Patients who rely on painkilling drugs may overuse knees, which do not have muscle tissue sufficiently strong enough to protect the joints from further damage. However, some studies suggest that building up thigh muscles may worsen osteoarthritis in people whose knees are misaligned (for instance those who are "bow-legged" or "knock-kneed"). Such individuals should check with a physical therapist for the best options. Strengthening the thigh muscles is certainly protective for people who have not yet developed osteoarthritis.

Exercise, such as weightlifting, helps build muscle that is usually lost with age and puts stress on bones, helping keep them strong and healthy.

Range-of-Motion Exercise. These exercises increase the amount of movement in a joint and muscle. In general, they are stretching exercises. The best examples are yoga and tai chi, which focus on flexibility, balance, and proper breathing. In one study, older adults who practiced the gentle movement, breathing, and meditation exercises of tai chi for 10 weeks reported less pain than their peers who did not learn the technique.

Click the icon to see an image of cholesterol.

Aerobic (Endurance) Exercise. These exercises help control weight and may reduce inflammation in some joints. Low-impact workouts also help stabilize and support the joint. Cycling and walking are beneficial, and swimming or exercising in water is highly recommended for people with arthritis. (Patients with osteoarthritis should avoid high-impact sports, such as jogging, tennis, and racquetball.)

Click the icon to see an image of exercise.

Physical Therapy

In addition to exercise, manipulation of muscles and joints by a trained therapist may be helpful. In one study, patients who had a combination of physical therapy and an exercise program reported 30 - 40% improvement after only two to four visits.

Weight Reduction

Overweight patients with osteoarthritis can lessen the shock on their joints by losing weight. Knees, for example, sustain an impact three to five times the body weight when descending stairs. Losing 5 pounds of weight can eliminate 20 pounds of stress on the knee. The greater the weight loss, the greater the benefit. [For more information, see In-Depth Report #53: Weight loss and diet.]

Vitamins and Other Dietary Factors

Plant Chemicals. A large study reported significant improvement in symptoms when patients took extracts from avocados and soybeans called saponins. Another study noted that although these substances did not relieve hip pain, they did slow progression of joint deterioration. Soy has chemicals called isoflavones that may have additional benefits, such as preventing bone loss.

Fish Oil and Omega-3 Fatty Acids. Omega-3 fatty acids, which are found in fish oil, canola oil, black currant or primrose seed oils, and flax seeds, have anti-inflammatory properties and may help protect against cartilage deterioration. Supplements of omega-3 fatty acids, such as docosahexaenoic (DHA) and eicosapentaneoic (EPA) acids that are found in fish oil, are available.

Vitamin B3 (Niacin). Some research suggests that vitamin B3 may have some benefits for people with osteoarthritis.

Click the icon to see an image of the benefits of vitamin B3.

Click the icon to see an image of the sources of vitamin B3.

Calcium and Vitamin D. Calcium and vitamin D are important for strong bones. Although osteoarthritis is primarily a disease of joints, bone strength is also important, particularly in older people.

Click the icon to see an image of osteoporosis.

Many experts now recommend 1,000 mg of calcium a day for most adults and 1,200 - 1,500 mg for adolescents. Pregnant women, postmenopausal women not on estrogen therapy, and those on corticosteroids should get 1,500 mg per day; breast feeding women should get 2,000 mg/day. Because calcium supplements increase the risk for kidney stones, an upper limit of 2,500 mg is recommended.

Current guidelines recommend 400 IU of vitamin D per day and 600 IU per day after age 60. Lack of sunlight and unhealthy diets contribute to deficiencies in vitamin D. Good dietary sources include fortified milk, sardines, herring, salmon, tuna, liver, dairy products, and egg yolks. Although supplements are often necessary, vitamin D can be toxic in high doses, and no one should take more than 1,200 IU per day.

Selenium. Selenium is a trace mineral found in grains, nuts, vegetables, and some meats and seafood. Preliminary research suggests that people who do not get enough selenium in their diet may be more likely to develop knee osteoarthritis. Researchers are investigating whether selenium supplements may help protect against osteoarthritis and prevent it from worsening.

Heat and Ice

Ice. When a joint is inflamed (particularly in the knee) applying ice for 20 - 30 minutes can be effective. If an ice pack is not available, a package of frozen vegetables works just as well.

Heat Treatments. Patients afflicted with osteoarthritis of the hands can relieve pain with hot soaks and warm paraffin application. Osteoarthritis of the hip can be treated with heating pads.

Interestingly, moving to a warm climate does not seem to make much difference. According to one study, people who live in warmer places are actually more sensitive to small shifts in temperature than people who live in cold damp climates, and they experience pain as readily as their northern peers do in response to larger temperature shifts.

Mechanical Aids

A wide variety of devices are available to help support and protect joints:

• Splints or braces, worn while the joint is at rest or in use, help align joints and properly distribute weight. They are used most frequently to treat arthritic hands, wrists, knees, ankles, and feet. Many of these devices allow some movement within the affected joint and do not restrict nearby joints. They are usually made from lightweight metal, leather, elastic, foam, and moldable plastic with easy-to-use Velcro straps. Any brace, splint, or other device for joint protection should be custom-fitted by a physical or occupational therapist, or an orthotist. Poorly fitting or improperly used orthoses can cause more harm than good.
• Using elastic supports on affected joints may benefit some people. For example, in one study, wearing insoles plus elastic straps supporting the ankle joint helped overweight women with osteoarthritis in the knee. It is important to consult with a doctor about how to use elastic supports.
• Wrapping the knee with special therapeutic tape that provides support to specific parts of the joint may be effective. In one trial, patients experienced a 40% reduction in pain within a few days. They wore the tape for 3 weeks, and pain relief continued for 3 more weeks following treatment. The tape should be applied by physical therapists or other trained health professionals. Longer-term studies are needed to determine any continuous benefits.
• Wearing shock-absorbing soles in shoes or orthopedic shoes can help in daily activities and during gentle exercise. Heel wedges in the shoes can sometimes help patients avoid knee replacement surgery.
• A neck brace or corset may relieve back pain.
• A firm mattress also often proves beneficial.
• In extreme cases of back pain, lying in traction might be necessary.
• Canes, crutches, or walkers offer benefits to patients with advanced arthritis.
• Specially designed hip protectors, worn under the clothes, can also protect against hip fractures in elderly patients with impaired mobility who are apt to fall.

Medications

Many medications are available for relieving the symptoms of osteoarthritis. A major analysis indicated that drug therapy is generally more effective than non-drug treatments (surgery, acupuncture). However, a 2006 review of knee osteoarthritis studies found that pain-relief medications generally help only for the first 2 - 3 weeks of treatment. The following are some of the medications used in mild-to-severe cases:

• Acetaminophen
• Nonsteroidal anti-inflammatory drugs (NSAIDs) or COX-2 inhibitors
• Capsaicin
• Tramadol
• Narcotic pain relievers (oxycodone, oxymorphone, or morphine)
• Glucosamine and chondroitin (see Alternative and Complementary Medicine section)

Acetaminophen

Acetaminophen (Tylenol, Anacin-3, Panadal, Phenaphen, Valadol, and others) is currently the first choice for treating osteoarthritis. However, several major analyses report that acetaminophen is less effective than NSAIDs in reducing moderate-to-severe pain. Because acetaminophen has fewer side effects, most experts suggest trying this drug first, then switching to an NSAID if acetaminophen does not provide sufficient pain relief.

Side Effects. Acetaminophen is inexpensive and generally safe. It poses far less of a risk for gastrointestinal problems than NSAIDs and does not appear to increase the risk for miscarriage (as NSAIDs do), even when used regularly.

It does have some adverse effects, however, and the daily dose should not exceed 4 grams (4,000 mg). Patients who take high doses of this drug for long periods are at risk for liver damage, particularly if they drink alcohol and do not eat regularly.

The kidneys are responsible for removing wastes from the body, regulating electrolyte balance and blood pressure, and the stimulation of red blood cell production.

Nonsteroidal Anti-Inflammatory Drugs (NSAIDs)

Nonsteroidal anti-inflammatory drugs (NSAIDs) block prostaglandins, the substances that dilate blood vessels and cause inflammation and pain. There are dozens of NSAIDs:

• Over-the-counter NSAIDs include aspirin, ibuprofen (Advil, Nuprin, Motrin IB, Rufen), naproxen (Aleve, Naprosyn), ketoprofen (Actron, Orudis KT).
• Prescription NSAIDs include ibuprofen (Motrin), naproxen (Naprosyn, Anaprox), flurbiprofen (Ansaid), diclofenac (Voltaren, Cataflam), tolmetin (Tolectin), ketoprofen (Orudis, Oruvail), nabumetone (Relafen), dexibuprofen (Seractil), indomethacin (Indocin), meloxicam (Mobic, generic).
• Topical NSAIDs delivered in gels, creams, or patches do not appear to provide any long-term benefits in reducing arthritic pain. A review of clinical trial data, published in 2004, suggested that guidelines that recommend topical NSAIDs for treatment of osteoarthritis should be revised.

Many experts now recommend that patients use oral NSAIDs for only a short period of time. A 2004 review, published in the British Medical Journal, suggested that long-term use of NSAIDs does not actually reduce osteoarthritis pain and may increase patients’ risk of experiencing side effects. High dosages of NSAIDs can cause heart problems (such as increased blood pressure), kidney problems, and stomach bleeding.

In April 2005, the Food and Drug Administration (FDA) asked drug manufacturers of prescription NSAIDs to include with their products the same boxed warning used for the COX-2 inhibitor celecoxib (Celebrex). This boxed warning emphasizes an increased risk for cardiovascular events and gastrointestinal bleeding in people taking these drugs. The FDA also requested manufacturers of over-the-counter NSAIDs to revise their labels to include more specific language concerning potential cardiovascular and gastrointestinal risks. Due to its proven heart benefits, aspirin was excluded from these labeling revisions.

A 2006 comprehensive report from the U.S. Agency for Healthcare Quality and Research indicated that both NSAIDs and COX-2 inhibitors are equally effective for pain relief and pose similar risks for heart attacks. The report found that one particular NSAID, naproxen (Aleve, Naprosyn), presents less risk of heart attack for some patients. A 2006 Journal of the American Medical Association study suggested that diclofenac (Voltaren, Cataflam) may pose a higher risk for heart attack than other NSAIDs. All patients should talk to their doctors before switching any medications.

Click the icon to see an image of a gastric ulcer.

COX-2 Inhibitors (Coxibs)

Coxibs inhibit an inflammation-promoting enzyme called COX-2. This drug class was initially thought to provide benefits equal to NSAIDs but cause less gastrointestinal distress. However, following numerous reports of cardiovascular events, as well as skin rashes and other adverse effects, the FDA has been re-evaluating the relative risks and benefits of this drug class. Rofecoxib (Vioxx) and valdecoxib (Bextra) have been withdrawn from the United States market. Celecoxib (Celebrex) is still available, but patients should discuss with their doctors whether this drug is appropriate and safe for them.

A newer COX-2 inhibitor, etoricoxib (Arcoxia) is approved in 60 countries but not the United States. A 2006 Lancet study indicated that etoricoxib is similar to the NSAID diclofenac in risks for heart attack and stroke. (However, diclofenac has already been shown to have a higher risk of heart attack than any other NSAID, so some experts do not find this study result reassuring.) Etoricoxib caused more high blood pressure and fluid retention (edema) than diclofenac. Etoricoxib appeared to pose a lower risk than diclofenac for uncomplicated upper gastrointestinal problems, (obstruction, perforation, bleeding, ulcers), but there was little difference between the two drugs for more serious gastrointestinal complications. In 2007, the FDA rejected an application to market etoricoxib in the U.S.

Capsaicin

Capsaicin is a component of hot red peppers and may bring pain relief when used as a skin cream (Zostrix). This is the only skin preparation that does more than just mask pain or reduce it temporarily. Capsaicin seems to reduce a substance in the body, known as substance P, which contributes both to inflammation and the delivery of pain impulses from the central nervous system. A small amount of capsaicin must be applied to the area of inflammation about four times a day. During the first few days of use, the patient will experience a warm, stinging sensation when the cream is applied. This sensation goes away, and pain relief usually begins within 1 - 2 weeks.

Tramadol

Tramadol (Ultram) is a pain reliever that has been used as an alternative to opioids. It has opioid-like properties but is not as addictive. (Dependence and abuse have been reported, however.) It can cause nausea but does not cause severe gastrointestinal problems, as NSAIDs can. Some patients experience severe itching. A combination of tramadol and acetaminophen (Ultracet) is now available and provides more rapid pain relief than tramadol alone with more long-lasting benefits than acetaminophen. Side effects are the same as for each of these drugs.

Narcotics

Narcotics, pain-relieving and sleep-inducing drugs that act on the central nervous system, are the most powerful medications available for the management of moderate to severe pain. There are two types of narcotics:

• Opiates, which are derived from natural opium (morphine and codeine).
• Opioids, which are synthetic drugs. They include oxycodone (Percodan, Percocet, Roxicodone, Oxycontin), hydrocodone (Vicodin), oxymorphone (Numorphan), and fentanyl (Duragesic).

Although the use of narcotics for arthritic pain is controversial, many studies have suggested that they are rarely addictive for pain sufferers except among patients with a history of substance abuse. Some experts believe that opioids have a place in osteoarthritis treatment when milder drugs are not effective or appropriate. For example, a 2006 study suggested that a fentanyl skin patch may offer pain relief and improved function to some patients with severe knee or hip osteoarthritis who have not been helped by, or who cannot tolerate, NSAIDs or weaker opioids.

The use of such drugs may be beneficial when included as part of a comprehensive pain management program. Such a program involves screening prospective patients for possible drug abuse and then regularly monitoring those who are taking it, adjusting the dose as necessary to achieve an acceptable balance between pain relief and side effects. Common side effects include anxiety, constipation, nausea and vomiting, dizziness, drowsiness, paranoia, urinary retention, restlessness, and labored or slow breathing. Unfortunately, opioid abuse among young people is a major concern.

Corticosteroids

When pain becomes a major problem and less potent pain relievers are ineffective, doctors may resort to corticosteroid (steroid) injections, usually by administering a shot into the affected joint every 3 months. Corticosteroid shots are useful only if inflammation is present in the joint. Relief from pain and inflammation is of short duration, and this treatment is rarely used for chronic osteoarthritis. These drugs may not be as effective for women as for men.

Corticosteroids mask pain, and the patient must be very careful to avoid over-use of the affected joints. Patients are usually advised not to have more than two or three injections a year, since there is some concern that repeated injections over the long term may be harmful. A reassuring study found no greater disease progression in people who had injections every 3 months for 2 years compared to those who were given sham injections on the same schedule. Because long-term use of corticosteroids has many potentially serious side effects, steroid medications are never given orally or systemically for the treatment of osteoarthritis.

Hyaluronic Acid Injections (Viscosupplementation)

Injections of hyaluronic acid (Hyalgan, Synvisc, Artzal, Nuflexxa) into the joint -- a procedure called viscosupplementation -- is now recommended as one of the treatments for osteoarthritis. Hyaluronic acid is a naturally occurring substance in joints that acts as a lubricant for slow movements and a shock absorber for fast motions. In high amounts, it also may have anti-inflammatory effects.

• Patients receive a series of three to five injections once a week.
• The drug is injected into the joint.
• A health care worker will apply local anesthetic because these viscous (sticky) injections require a large needle.
• Patients need to avoid weight-bearing activities for about 48 hours after each shot.

Hyaluronic injections appear to be about as effective as NSAIDs and corticosteroid injections for relieving pain, at least in men, and they have no adverse effects in the stomach or intestines. One study reported that between 39 - 56% of patients were at least nearly free of weight-bearing pain up to 24 weeks after the final injection. In another study, response was judged better or much better for 87% of knees after a second course, which was administered about 8 months later. Nevertheless, a number of studies on viscosupplementation have shown little or no benefits, particularly in women, and more research is needed to determine if they are useful. Injections are also expensive. Accurate placement of the needle directly into the knee joint space is important and may be difficult, even for experienced doctors, if there is no fluid build-up in the joint. Best success rates are with a specific approach into the kneecap called the lateral midpatellar.

Side Effects. Serious adverse reactions are rare. The most common side effects, pain at the injection site and knee pain and swelling, are usually mild and temporary. More research is needed to confirm benefits and long-term risks.

Investigational Therapies

Researchers are studying various drugs that may provide pain relief or stop the disease process itself:

• Bisphosphonates such as alendronate (Fosamax) and risedronate (Actonel) help prevent bone loss in people with osteoporosis. They are currently being investigated for osteoarthritis as well. A 2005 study reported that risedronate may delay joint destruction in patients with knee osteoarthritis.
• Lidocaine, a local anesthetic, is available in patch form (Lidoderm) and has been used specifically for herpes zoster pain. Early studies indicate that it may provide significant pain relief for osteoarthritis.
• Tetracycline antibiotics, such as doxycycline, may have a role to play in treating osteoarthritis. At low concentrations, the drug reduces the production of collagenases, which are enzymes critical to disease development and progression. Initial results from clinical trials suggest that doxycycline may help delay joint space narrowing.
• Licofelone is a drug that inhibits both the COX enzyme plus an inflammatory substance called lipoxygenase 5. Early trials indicate it may be effective and safer than either NSAIDs or COX-2 inhibitors.
• Diacerein inhibits an inflammatory substance in arthritic joints called interleukin-1b. It has shown promise in clinical trials. A 2006 review indicated that diacerein may be slightly better than NSAIDs for pain relief.
• Botulinum toxin type A (Botox) injections may provide sustained pain relief for patients with knee osteoarthritis according to research presented at the 2006 American College of Rheumatology annual meeting.
• Nitric oxide increases blood flow in the mucous lining and secretions of mucus and bicarbonate. Combining nitric oxide with NSAIDs may reduce the adverse effects on the gastrointestinal tract.
• Trials of gene therapies that either fight joint degradation or strengthen cartilage are in very early stages.

Alternative and Complementary Medicine

Glucosamine hydrochloride and chondroitin sulfate are natural substances that are part of the building blocks found in and around cartilage. Extracts have been used in Europe for more than a decade to reduce pain and improve mobility in patients with osteoarthritis. For many years, researchers in the U.S. have been studying whether these dietary supplements really work for relieving osteoarthritis pain.

In 2006, the New England Journal of Medicine published the results from a major trial sponsored by the U.S. National Institutes of Health. Researchers compared the effects of glucosamine and chondroitin, alone and in combination, with the COX-2 inhibitor celecoxib (Celebrex) in nearly 1,600 patients with knee osteoarthritis. The dietary supplements were also compared with placebo (an inactive substance). Patients took the assigned substance once a day for 6 months.

The results indicated that, for most patients, neither glucosamine nor chondroitin were better than placebo in relieving knee pain. However, for patients with moderate-to-severe pain, a combination of glucosamine and chondroitin was significantly more effective than the other remedies. Celebrex worked best for patients with mild pain.

The next stage of the study will evaluate whether glucosamine and chondroitin, alone and in combination, can halt the progression of knee osteoarthritis.

Research presented at the 2006 American College of Rheumatology annual meeting suggested that chondroitin may prevent joint narrowing in patients with knee osteoarthritis.

Dosage. There are no current standard recommended dosages. Patients in the GAIT trial took 1,500 mg of glucosamine and 1,200 mg of chondroitin.

Side Effects. The safety records of both substances appear excellent. Long-term effects are still unknown, but studies of up to 3 years have reported no significant side effects. However, there are some concerns that glucosamine may affect insulin and blood sugar (glucose) metabolism. Patients with diabetes should not take glucosamine without first talking to their doctors.

Other Herbs and Supplements

Oral Enzymes. People in Europe have used natural enzymes -- including bromelain, trypsin, papain, and rutin -- to treat arthritic pain. Such enzymes have been marketed alone and in combinations (Wobenzym, Phlogenzym). They are not painkillers, and any benefits derived from them may take several weeks.

Ginger (Zingiberaceae). A 2001 study of patients with knee arthritis found that an extract of ginger reduced pain while standing and after walking. By using ginger, patients were able to reduce their pain medications after 6 weeks. Side effects included mild digestive upset.

S-adenosylmethionine (SAMe). S-adenosylmethionine (SAMe, pronounced "Sammy") is a synthetic form of a natural byproduct of the amino acid methionine. It has been marketed as a remedy for both depression and arthritis. Some research suggests that it may work as well as NSAIDs for short-term treatment of osteoarthritis. Other studies suggest that it may help rebuild damaged cartilage.

Acupuncture

Acupuncture is being increasingly used to reduce osteoarthritis pain. The technique is painless and involves the insertion of small fine needles at select points in the body. Several study reviews have found that acupuncture provides at least short-term pain relief for osteoarthritis of the knee. Other studies have suggested that acupuncture’s benefits are mainly due to a strong placebo effect, or to the psychologically beneficial effects of close contact with health care providers.

In 2004, researchers published results from an important clinical trial that studied the effects of acupuncture on nearly 600 people with osteoarthritis of the knee. The results indicated that acupuncture can relieve pain and improve function. Several 2006 studies of thousands of patients with chronic osteoarthritis pain compared acupuncture to conventional treatment (physical therapy, anti-inflammatory drugs). These studies showed positive results and suggested that acupuncture’s benefits may be sustained for up to 6 months after treatment. In any case, acupuncture appears to be a safe and beneficial addition to standard therapy for certain patients, such as pregnant women, who cannot take most pain medications.

Acupuncture, hypnosis, and biofeedback are all alternative ways to control pain. Acupuncture involves the insertion of tiny sterile needles, slightly thicker than a human hair, at specific points on the body.

Transcutaneous Electric Nerve Stimulation

Transcutaneous electric nerve stimulation (TENS) uses low-level electrical pulses to suppress pain. Patients are barely aware of the sensation. According to one study, the optimal treatment length is 40 minutes. A variant (sometimes called percutaneous electrical nerve stimulation, or PENS) applies these pulses through a small needle to acupuncture points. A review of trials reported that both methods were better than placebo (sham treatments) in treating osteoarthritis of the knee, although additional well-designed studies are needed.

Low-Level Laser Therapy

Low-level laser therapy (LLLT) generates extremely pure light in a single wavelength. It does not produce heat and is painless. Some researchers are combining LLLT with transcutaneous electric nerve stimulation (TENS). Studies report widely varying results, with some showing significant reductions in pain and others reporting no effect. The differences may be due to different approaches, and standardized methods are needed to determine any benefits.

Hydrotherapy

Hydrotherapy, also called spa therapy or balneotherapy, is an ancient therapy that uses bathing in mineral baths for soothing pain. Although many studies report positive results, including improved quality of life, very few have been rigorously conducted. A major analysis reported weak evidence on any real effect on pain or quality of life, but some patients may find comfort from this pleasant therapy.

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 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.

Click the icon to see an illustrated series detailing knee arthroscopy surgery.

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.

Click the icon to see an illustrated series detailing knee joint replacement surgery.

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.

Click the icon to see an illustrated series detailing hip joint replacement surgery.

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.

Click the icon to see an image of a dislocated hip.

• 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 - 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. 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. Hip resurfacing is a surgical alternative to total hip replacement. It 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.

Resources

• www.rheumatology.org -- American College of Rheumatology
• www.arthritis.org -- Arthritis Foundation
• www.niams.nih.gov -- National Institute of Arthritis and Musculoskeletal and Skin Diseases
• www.aaos.org -- American Academy of Orthopaedic Surgeons
• www.fda.gov/cder/drug/infopage/cox2 -- FDA NSAID and COX-2 Inhibitor Information

References

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Cannon CP, Curtis SP, FitzGerald GA, Krum H, Kaur A, Bolognese JA, et al. Cardiovascular outcomes with etoricoxib and diclofenac in patients with osteoarthritis and rheumatoid arthritis in the Multinational Etoricoxib and Diclofenac Arthritis Long-term (MEDAL) programme: a randomised comparison. Lancet. 2006 Nov 18;368(9549):1771-81.

Chou R, Helfland M, Peterson K, Dana T, Roberts C. Comparative Effectiveness and Safety of Analgesics for Osteoarthritis. Comparative Effectiveness Review No. 4. (Prepared by the Oregon Evidence-based Practice Center under Contract No. 290-02-0024.) Rockville, MD: Agency for Healthcare Quality and Research. September 2006.

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Langford R, McKenna F, Ratcliffe S, Vojtassak J, Richarz U. Transdermal fentanyl for improvement of pain and functioning in osteoarthritis: a randomized, placebo-controlled trial. Arthritis Rheum. 2006 Jun;54(6):1829-37.

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