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Osteoarthritis is the deterioration of the joints that becomes more common with age. The knees and hands are most often affected, with pain and stiffness ranging from mild to severe.
Imagine life without our bony skeletons. There'd be nothing to do but lie around singing 'Don't get around much anymore.' Our skeleton gives us a framework to support and protect internal organs like the brain, lungs and the heart and acting in concert with the muscles, allows us to get around.
But what makes this mobility possible are the joints those bits of joinery that allow the ends of the bones to move over each other in complex ways, so we can bend our arms and legs, wiggle our toes, walk, run, bowl an off spinner, and so on.
All of which places tremendous strain on the joints, and in later years they tend to deteriorate, developing a condition called osteoarthritis (often abbreviated to OA). All animals with skeletons are prone to this condition with the exception of bats and sloths, and that's because they spend so much time hanging upside down. Osteoarthritis has existed since the time the skeleton first appeared: fossils of primitive vertebrates like fish, amphibians, dinosaurs, and mammoths show evidence of the condition.
We don't exactly know what causes osteoarthritis. It used to be thought it was simply a wear-and-tear disease (unlike rheumatoid arthritis, which is an active inflammatory disease). It's now thought to be a consequence of what happens when the joint's normal mechanisms of repair and remodelling break down in later years. A million years ago humans were lucky to live past their thirties so evolution didn't take into account that we might one day be living into our eighties and beyond and we'd still need healthy functioning joints.
A joint is where two bony surfaces are carefully shaped to fit together to bear weight, and to move freely over one another which they do thanks to a shiny, gristly material called cartilage that covers the ends of the bones, providing a smooth surface and acting as a shock absorber.
Covering the joint and holding it together is a tough, fibrous capsule. Its inner lining, the synovial membrane, produces a substance called synovial fluid to lubricate the joint and nourish the cartilage.
In osteoarthritis, the following things may happen:
This process may affect any joint in the body, though the knees and hands are most commonly affected, followed by the spine, hips, ankles and shoulders. Elbows and wrists aren't usually affected. Usually between one and four separate joints are involved.
There are some variations on this theme. When osteoarthritis occurs in the spine, for example, it's most common in the neck or lower back region. In this case the discs between the spinal bones or vertebrae also wear down. This type of osteoarthritis is called spondylosis or spondylitis.
Sometimes osteoarthritis occurs predominately in the hands; this type occurs frequently within families and most often affects the end joints in the fingers, producing bony growths or nodules known as Heberden's nodes.
Osteoarthritis is most commonly a disease of middle age onwards, though young people can sometimes get it too. It affects women more commonly than men. One in three people over 60 will have osteoarthritis; over the age of 70 almost everyone has some degree of the condition (though it will often be so mild it doesn't cause any symptoms).
It's more likely where there is:
The symptoms of osteoarthritis are variable. Some people get only mild pain and stiffness; in others the symptoms are severe and disabling.
In most cases, osteoarthritis is easy for a doctor to diagnose from the history of pain and stiffness and from an examination of the affected joint(s). The doctor might order an X-ray, which shows the characteristic changes in the joints, but often this is not necessary. Sometimes other tests are needed, such as blood tests or a fluid sample taken from the joint, mainly to rule out other types of arthritis, like rheumatoid arthritis. Generally the diagnosis is pretty clear from the history and clinical examination.
Treatment isn't so easy though. There's no outright cure for osteoarthritis, but a variety of treatments can help people control and reduce the effects of the disease. The aims of these are to reduce pain and lessen stiffness as much as possible, to improve joint function and mobility, and to preserve quality of life as much as possible.
Painkillers and anti-inflammatories. Paracetamol helps relieve pain, and is low on side effects. Aspirin and medications known as non steroidal anti-inflammatory drugs (NSAIDs) will help not just pain, but inflammation too, so are generally a bit more effective. Individual reactions to NSAIDs vary, with irritation of the stomach being the most frequent side effect. Older NSAIDs include indomethacin, sulindac, ibuprofen, diclofenac and naproxen; and there are also newer NSAIDs called the COX-2 inhibitors such as rofecoxib and celecoxib.
The COX-2 inhibitors are said to produce less gastric bleeding, but have been shown to increase the risk of heart disease in 2004, rofecoxib (trade name Vioxx) was withdrawn from the market. Recent evidence suggests there may be an increased risk of heart disease with the older NSAIDs as well.
Exercise. This is very important for people with osteoarthritis, as it helps to decrease pain, keep joints mobile, increase muscle strength, strengthen bones and ligaments, prevent joint deformities, and increase fitness and wellbeing in general. Gentle exercises are best, such as walking, Tai Chi and/or hydrotherapy (that is, water exercises the warmth and buoyancy of the water makes movement much easier).
In severe cases, surgical treatments like replacement of hips, knees and (less commonly) shoulders with artificial prostheses, will relieve pain and improve mobility.
Keeping weight down means there's less stress on the hips and knees (unfortunately there's no one diet that will cure the condition, though).
Minimising stresses on joints. This is achieved by being aware of activities and body positions that stress individual joints and aggravate the symptoms. It may mean modifying activities like house chores and leisure pastimes. There are many different aids and equipment available that can help maintain function and these can be arranged through an occupational therapist. The home may need to be modified by replacing steps with a ramp, for example.
Alternative treatments. As is often the case in chronic conditions where a cure isn't possible, there are many alternative and complementary treatments available for osteoarthritis. Two of the most common are glucosamine and chondroitin. These are dietary supplements that are also produced naturallyin the body to make cartilage. Some clinical trials have shown they do help (though only about as much as placebo treatments) and they don't have the more serious side effects of other osteoarthritis drugs.
The more proactive a person is in managing their condition, the less joint pain, stiffness and disability they'll experience.
Reviewed by Richard Day, Professor of Clinical Pharmacology, University of New South Wales
Last modified 19/01/2007
First published: 16/03/2006