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Osteoarthritis

Arthritis in general, and osteoarthritis in particular, are increasingly becoming global problems. According to the website of the Arthritis Foundation, "The United Nations, the World Health Organization and 37 countries have proclaimed the years 2000-2010 as the Bone and Joint Decade. The global initiative is intended to improve the lives of people with musculoskeletal disorders, such as arthritis, and to advance understanding and treatment of musculoskeletal disorders through prevention, education and research."

"The 10-year global initiative launched by United Nations Secretary General Kofi Annan urges governments around the world to start taking action to draw attention to the growing pervasiveness and impact of musculoskeletal diseases and to reduce the social and financial burdens to society."

"The World Health Organization estimates that several hundred million people already suffer from bone and joint diseases, with dramatic increases expected due to a doubling in the number of people over 50 years of age by 2020." (From the Arthritis Foundation).

In the United States alone, more than 20% of the adult population suffers from some form of arthritis - or greater than one in every 5 adults. Musculoskeletal complaints such as arthritis constitute more than 130 million patient visits to doctors annually in the U.S., costing over $200 billion each year. According to the Centers for Disease Control and Prevention, it is expected that by 2030 nearly 70 million adults in the U.S. will have been diagnosed with some form of arthritis. (From the National Center for Chronic Disease Prevention and Health Promotion).

There are more than 100 forms of arthritis, which literally means "joint inflammation". Of all these various types, the most common is osteoarthritis, which, as its name implies, refers to inflammation of the bone as well as of the joint - from the Greek words "osteo", meaning "bone", "arthro" meaning "joint", and the "-itis" suffix which indicates inflammation.

It is estimated that by the age of 65, 80% of people show radiographic evidence (visible on X-rays) of osteoarthritis, although only 60% will be symptomatic. Also referred to as degenerative joint disease or "arthrosis", osteoarthritis primarily affects the cartilage, causing breakdown and eventual loss of the cartilage itself in one or more joints. Cartilage acts as a "cushion" between the bones of the joints, allowing bones to glide over one another smoothly and painlessly. Cartilage covers the ends of the bones, absorbing energy from the shock and friction of physical activity. In osteoarthritis, the surface of the cartilage breaks down and is worn away, allowing the bones under the cartilage to rub against each other. Pain, swelling, stiffness and loss of joint flexibility are common symptoms.

More than half of the U.S. population age 65 or older has osteoarthritis in at least one joint. In people under age 45 it occurs most frequently in males, but after age 55 it occurs 3 times more frequently in females than in males. (From the Arthritis Foundation).

In the past, osteoarthritis was considered to be almost exclusively an older person's disease. Now, however, it is understood that people of all ages can, and do, suffer from osteoarthritis. Although the frequency of occurrence is still more common in the elderly, osteoarthritis may also develop in younger people as the result of a joint injury, a joint malformation or a genetic defect. Osteoarthritis can affect children, adults, and even animals. It is not uncommon for horses to suffer from equine osteoarthritis, and it has been estimated that one in every 5 adult dogs in the U.S. is afflicted with canine osteoarthritis. Indeed, the study of osteoarthritis in animals constitutes a major area of research, and much of the scientific progress that has been made in the treatment of human osteoarthritis is the result of studies that have been conducted on animals who suffer with this affliction. The susceptibility of numerous species to osteoarthritis has been well documented throughout history, as osteoarthritis is known to be one of the oldest medical disorders on earth. There is archeological evidence that early primates, and even dinosaurs, lived with osteoarthritis. (From NIAMS - National Institute of Arthritis and Musculoskeletal and Skin Diseases).

Although osteoarthritis can occur in any joint, most often it affects the hands, knees, hips, and spine, most commonly at the neck or lower back. Different characteristics of the disease depend on the specific joints that are affected.

The causes of osteoarthritis are numerous, but are usually related to the natural aging process in combination with hereditary and environmental factors. Sports, heavy lifting, excessive use of particular joints, injury, being overweight, and just the general physical wear and tear of life can all contribute to osteoarthritis. Even in the absence of traumatic injury, osteoarthritis can still result from a perfectly normal and healthy lifestyle. This common ailment is simply a common example of the fact that few things in this world are capable of lasting forever - not even human joints.

In those cases where osteoarthritis results from normal aging, it is known as "primary osteoarthritis". When it occurs prematurely, as a result of any other type of cause - such as injury, congenital disorders, hormonal imbalance, etc. - it is known as "secondary osteoarthritis".

In primary osteoarthritis, the protein component of cartilage naturally degenerates with age, as the water content of the cartilage increases. With years of repetitive use of the joints, cartilage can become irritated and inflamed, which in turn causes swelling and pain. In secondary osteoarthritis, it is generally believed that an imbalance of enzymes from extreme mechanical stress may promote degeneration and damage within the cartilage cells themselves and in the lining of the joint. Ordinarily, when the enzymes are in balance, a natural breakdown of cartilage continually occurs, but so does the simultaneous regeneration of cartilage. When there is an enzymatic imbalance, however, the joint cartilage breaks down faster than it is capable of being rebuilt. Eventually, the joint can lose its normal shape, and bone spurs (small growths of "osteophytes") may also grow on the edges of the joint. Increasing damage and pain can be experienced when bits of bone or cartilage break off and float inside the joint space. Osteoarthritis often develops slowly, as some people may not experience any symptoms, while others will experience acute pain, and others may be debilitated by their symptoms. Symptoms can also appear sporadically, punctuated by pain-free intervals. Pain is usually worse after repetitive use of the joint(s) and usually worse towards the end of the day. Pain can also occur, however, after long periods of inactivity.

There is no single test for determining osteoarthritis, and diagnosis is made through an evaluation of clinical history in combination with a physical examination that may include X-rays, MRI, CT, blood tests, joint aspiration and a battery of other evaluations. In recent years, C-reactive protein (CRP) has also been used in the diagnostic process, since CRP is a sensitive marker of inflammation in general. A more detailed description of such biomarkers that are useful in the identification of osteoarthritis may be found at the website of the American Association for Clinical Chemistry.

Conventional treatment has typically included medication, exercise, weight control, a healthy diet, the application of heat, relaxation techniques, physical therapy, occupational therapy, and in severe cases, surgery. Joint replacement, fragment removal, and the repositioning and fusing of bones are common surgical procedures that are routinely used in the treatment of osteoarthritis. (From NIAMS - National Institute of Arthritis and Musculoskeletal and Skin Diseases).

Strength training, flexibility exercises, and aerobics conditioning are also important in maintaining overall physical health for anyone suffering from osteoarthritis. Although not typically prescribed as part of a conventional medical treatment, glucosamine, chondroitin sulfate and omega 3 fatty acids have also been found to be important in maintaining and restoring joint health.

Regardless of the particular cause, however, cartilage is always the main factor influencing osteoarthritis, its progression and treatment. The severity of osteoarthritic symptoms will be directly proportional to the extent of deterioration of one's cartilage.

As previously described, cartilage is a hard but slippery coating that covers the ends of each bone. It acts as a "shock absorber" for the energy of physical movement that is transferred throughout the body with each motion. Cartilage exists in every joint of the body, no matter how small or how large. In osteoarthritis, this shock-absorbing cartilage breaks down and wears away. Cartilage contains both fluid and elastic tissue which together reduce friction as the joints moves. By the time a person reaches 50 years of age, there is a 90% chance that some visible change will have occurred in the cartilage throughout the joints of the body. When cartilage has worn down to the extent that bone rubs against bone, osteoarthritis is the official diagnosis. The weight-bearing joints such as the hips, knees and spine are the most commonly affected locations in osteoarthritis.

Depending on the extent of the damage and deterioration of the cartilage, resulting symptoms may include pain, swelling and loss of motion. The pain and stiffness in the afflicted joints may increase in duration and intensity over time, and in the most advanced stages of osteoarthritis, the grating sound of bone crunching against bone may be heard. When osteophytes (small deposits of bone, or bone spurs) form on the edges of a joint, the result is increased pain and a more severely limited range of motion. When a joint becomes swollen, this is known as "erosive inflammatory osteoarthritis".

Unlike some other forms of arthritis, such as rheumatoid arthritis, osteoarthritis affects only joint function and does not affect skin tissue, the lungs, the eyes, blood vessels, nor organs of the body.

According to the Arthritis Foundation, "At this time, there is no known cure for osteoarthritis." Most forms of treatment therefore have dealt with the alleviation and management of pain.

For osteoarthritis that occurs in the knee, a series of injections of hyaluronic acid directly into the knee joint - known as "viscosupplementation" - has been shown to produce a certain degree of pain relief in some patients. Any of the steroidal hormones known as glucocorticoids are sometimes also injected with the hyaluronic acid, as even low-grade inflammation can cause significant pain and difficult mobility. In the most severe cases of osteoarthritis, surgery with joint replacement is often seen as the only option.

Whether or not surgery is recommended, conventional medical treatment for osteoarthritis generally employs the use of NSAIDs (nonsteroidal anti-inflammatory drugs) such as aspirin and ibuprofen. In fact, half of all NSAID prescriptions in the U.S. are for various forms of arthritis. NSAIDs in general constitute a large class of medications that are used to treat both pain and inflammation, and are therefore frequently used in the treatment of all types of arthritis. A number of NSAIDs are available over the counter, such as ibuprofen (Advil, Motrin), naproxen sodium (Aleve) and ketoprofen (Orudis, and Oruvail). Additionally, there are more than a dozen others, including a subclass of NSAIDs known as COX-2 inhibitors, that are available only by prescription.

All NSAIDs work according to the same principle, which is by blocking prostaglandins, which contribute to inflammation and pain. However, since each NSAID is a different chemical, each NSAID therefore has a slightly different effect on the body; each NSAID also comes with its own particular list of warnings and contraindications. Most NSAIDs only cause gastrointestinal irritation, which can include ulcers, bleeding and perforation of the stomach or intestine; some NSAIDs can also damage kidney function, however, and may cause other long-term problems. The longer a person uses NSAIDs, the more likely he or she is to have side effects, ranging from mild to serious. One should also be cautious of interactions between medications, as many other drugs cannot be taken together with NSAIDs, because the NSAIDs will alter the ways in which the body uses or eliminates these other drugs.

According to the website of the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), a division of the National Institutes of Health (NIH), "The U.S Food and Drug Administration has warned that long-term use of NSAIDs, or use by people who have heart disease, may increase the chance of a heart attack or stroke. So it's important to work with your doctor to choose the one that's safest and most effective for you. Side effects can also include stomach upset and stomach ulcers, heartburn, diarrhea, and fluid retention. For unknown reasons, some people seem to respond better to one NSAID than another." (From NIAMS - National Institute of Arthritis and Musculoskeletal and Skin Diseases).

In any type of therapy that is used, the key to treating osteoarthritis successfully lies in the treatment of cartilage, and in the restoration of the health of the cartilage itself. In understanding the role of cartilage in osteoarthritis, it is important to understand the role of cartilage in the physiology of a healthy joint. Every joint contains a "capsule", which is a tough membranous sac that encloses all the bones and other parts of the joint; inside of the capsule is the synovium - a thin membrane that secretes synovial fluid. Synovial fluid in turn lubricates the joint and keeps the cartilage smooth and healthy. In a healthy joint, the ends of the bones are encased in smooth cartilage. The capsule and fluid protect the cartilage, muscles and connective tissues.

Ligaments, tendons, and muscles also surround the bones and joints, and allow the joints to bend and move. The tough, cord-like ligaments connect one bone to another, while the tendons are fibrous cords that connect the muscles to the bones. Muscles, in turn, are bundles of specialized cells which, when stimulated by nerves, either relax or contract to produce movement.

Not only is cartilage the key to healthy joints, but its deterioration can affect the health and function of all surrounding tissue as well. If the cartilage of a particular joint is damaged, likewise, the health of the related ligaments, tendons and muscles will also be compromised.

Between 65 to 80 percent of cartilage is water, with its remaining components being collagen, proteoglycans, and chondrocytes. Collagen is a family of fibrous proteins, which constitute the building blocks of skin, tendon, bone and other connective tissues. Proteoglycans in turn consist of proteins and sugars, and strands of proteoglycans interweave with collagen to form a mesh-like tissue, which allows cartilage to flex and absorb physical shock. Chondrocytes, which are found throughout the cartilage, are the cells that produce cartilage and help it to stay healthy as it grows. Sometimes, however, chondrocytes release enzymes that destroy the collagen and other proteins. A major focus of research in osteoarthritis involves trying to discover the precise role that chondrocytes play over the lifespan of cartilage.

When it has not been damaged, cartilage is capable of heroic weight-bearing, shock-absorbing and friction-dissipating properties. Once it has been damaged, however, its capacity for repair is extremely limited. Cartilage is poorly supplied by nerves, blood vessels and the lymphatic system - a fact which simply compounds the difficulty and complexity of repairing injured cartilage.


 

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