What is osteoarthritis?

Osteoarthritis is the most common form of arthritis. Almost half of people over 60 and virtually all over 80 years of age have osteoarthritis, but it has also been found in a few people under 21.

Osteoarthritis has been called ‘wear and tear’ arthritis but a number of factors are involved. It occurs as a result of the mechanical breakdown of the structures of the joints. This happens most often in the large weight-bearing joints – the knees, hips and spine. It also often affects the hands. There is no cure for arthritis but there are many ways of managing the condition.

Healthy joint Smooth cartilage protects bone surfaces.	Osteoarthritic joint Rough, worn cartilage results in joint damage.

How does it affect joints?

In a healthy joint, a firm rubbery material called cartilage covers the end of each bone. This cartilage acts as a cushion, or shock absorber, and provides a smooth, slippery surface between the bones.

The first major change in osteoarthritis is softening and pitting of the smooth cartilage surface. With time, sections of cartilage may be worn away completely, leaving the ends of the bones unprotected (see right hand picture above).

Without their normal gliding surface, joints become painful and difficult to move. As the cartilage continues to break down, the joint loses its shape, and the bone underneath thickens and grows out at the sides, further reducing movement.

What causes osteoarthritis?

For years, osteoarthritis was thought to be a result of normal wear and tear during a person’s lifetime. But researchers now recognise that several factors lead to its development. These are biological factors, age, damage by joint injury or infection, long term obesity, an occupation involving heavy physical work and a family history of osteoarthritis.

An injury such as a fracture or torn cartilage may result in osteoarthritis later in life. Being overweight over a long period of time is also thought to speed up the process.

Some forms of osteoarthritis do run in families, especially the form that affects the finger joints. However, in general, heredity is not a major reason for having osteoarthritis.

The precise causes and mechanisms leading to osteoarthritis are still unknown.

Symptoms of osteoarthritis

Osteoarthritis progresses slowly and develops over many years. It is often very mild and does not always have many symptoms even though x-rays may show joint changes. Sometimes, however, the symptoms are more pronounced and may include any or all of the following:

Pain and stiffness
Pain in a joint tends to increase with use but it is important to stay mobile and use any recommended pain relief. Stiffness, however, usually occurs when the joint has been rested.

Swelling
Swelling occurs when irritation of the synovial membrane (joint lining) causes an outpouring of extra joint fluid – just as your eye produces tears when irritated. But in the joint, the extra fluid cannot escape as easily, and so it causes swelling. This most often occurs in the weight-bearing joints in the hips, knees and spine.

Creaking or cracking
Creaking or cracking sensations with joint movement reflect a loss of the cartilage and the smooth gliding movement of the joint that cartilage should provide.

Bony growths
As a result of the changes in the affected joint, the ends of the bones can change shape, forming bony spurs called osteophytes. These may be felt as hard and bony swellings. They are especially apparent when osteoarthritis affects the finger joints.

Muscle weakness
The joint may feel unstable as if it is about to give way. 

TIP: If you have sudden redness, swelling, tenderness and aching in a joint, you should get this checked by your doctor without delay.

Diagnosis

There are no specific blood tests for osteoarthritis, but tests may be made to exclude other forms of arthritis. Your doctor will ask what you are able to do and what aggravates your pain. A physical examination will be carried out with close attention to your affected joints.

X-rays help the diagnosis but are not a good guide to the severity of future symptoms. They may show extensive change, but this does not always mean great pain or disability will result.

Treatment

Treatment cannot reverse the changes that have already taken place in the joints, but there is still much that can be done, especially to slow down the disease process and control the symptoms. It is important to gain proper medical attention so the most disabling effects of the disease can be avoided. Neglect and delay are the worst enemies in overcoming osteoarthritis.

Your doctor is likely to advise a treatment that takes into account the severity of the disease, what joints are affected, your symptoms, other medical problems, your age, occupation and everyday activities.

Treatment options may include:

• Medication – pain relievers help reduce pain and stiffness but do not treat the arthritis. Regular paracetamol is usually recommended as the pain reliever to try first. Others such as non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen may also be recommended.
• Exercise – regular exercise can also help reduce pain and stiffness. Options include walking, swimming, Tai Chi and gentle exercise classes.
• Heat/cold treatment – heat (eg, a warm shower or bath) can help with pain and stiffness. However, if a joint is inflamed a cold pack can help (and heat should not be applied).
• Injections – occasionally, injection into a joint with steroids to reduce inflammation or with a lubricant substance to temporarily ease joint movement may be used.
• Surgery – if joint damage is severe, a joint replacement may be necessary.
• Complementary therapies – there is some evidence to show glucosamine sulphate and fish oil may be helpful. Discuss with your doctor whether either would be useful for you.

Living with osteoarthritis

Osteoarthritis can have a big impact on your lifestyle but you can make a big difference in how you manage day-to-day activities. Most of the  disability in the early stages of osteoarthritis can be reversed with a programme of low-impact exercises (eg, swimming) and losing weight if necessary. Pain control and relaxation are also important to allow you to perform such activity. To reduce unnecessary stress on your joints, it may be necessary to modify your home or workplace - an occupational therapist can help with this.

TIP: Call 0800 663 463 to speak to an arthritis educator from Arthritis New Zealand, or see their website [contact details further below].

Related topics

See also: Arthritis and exercise; Medications for arthritis; Protecting joints

Images provided by The StayWell Company © 2001. All rights reserved. Original material provided by everybody. Updated November 2011.