Factors related to disability in arthritis are similar to those related to disease progression.⁷ Some of these risk factors cannot be modified (eg, genetic predisposition, family history, female sex, age) but others (eg, injury, obesity, quadriceps muscle strength, misalignment, and inflammatory or septic arthritis) are potentially modifiable or preventable. For the most part, addressing these factors involves non-pharmacological strategies.

Disability in arthritis is the result of the combination of three main factors: the arthritis itself; inactivity; and the ageing process.

A vicious cycle develops whereby inactivity over long periods may be the major cause of disability, compounded by the progress of arthritis. The tendency in our society to become less active with age is part of the problem, as is the common belief that osteoarthritis is simply a "wear and tear" disease made worse by exercise and movement.

Prolonged inactivity can lead to proteoglycan loss from articular cartilage and will thus enhance cartilage breakdown. Muscle weakness and wasting will also ensue. Quadriceps weakness is a well-documented risk factor for the progression of disability and radiological damage in osteoarthritis of the knee. Recent research has demonstrated the beneficial effect of movement and activity on all joint tissues — cartilage, bone, muscle and ligament.⁸

Aerobic and resistance exercises have been shown to help with many of the physiological and psychological factors associated with arthritis: muscle weakness; decreased flexibility; poor endurance; fatigue; depression; and low pain threshold.

All patients presenting with symptomatic osteoarthritis should be given education, an exercise prescription and suggestions for pain relief and weight loss. The importance of non-pharmacological treatments should be stressed early, and these treatments should be continued throughout the course of the disease.

Non-pharmacological interventions are listed in Box 1. Not all have been evaluated in controlled trials and many have potential for a powerful placebo response (eg, massage, spa therapy). As osteoarthritis of the knee tends to be associated with the most disability, most clinical trials for osteoarthritis have been done in this patient group. Treatments supported by randomised controlled trial evidence for symptom relief in osteoarthritis are listed in Box 2.

Most studies in patients with rheumatoid arthritis have focused on pharmacological interventions, but randomised controlled trials have shown that patient education, cognitive-behavioural therapy aimed at improving coping skills, exercise therapy and dietary changes to increase the intake of omega-3 oils can all reduce symptoms and improve quality of life.

As being overweight and obese are also major risk factors in the development of osteoarthritis, exercise programs aimed at increasing energy expenditure and fitness and leading to weight loss should help to decrease the load on the involved joint and decrease pain.

One of the major issues concerning rheumatoid arthritis and exercise involves learning to manage fatigue. Fatigue is a common complaint of any condition associated with chronic pain. Patients need help to manage the fatigue with the gradual introduction of exercises. Teach patients to observe fatigue in themselves, get them to gauge how much activity is possible before fatigue sets in, and try to ascertain whether the fatigue is caused by the disease process, "a flare", inactivity or depression, and manage accordingly. Achieving an improved level of aerobic fitness will reduce fatigue.

Hydrotherapy is also used widely for the rehabilitation process after total knee or hip replacement surgery.

These programs include information about disease processes, medications and their actions and reactions, together with goal setting for exercises and pain management strategies. They focus on patients taking more control of their disease.

A small number of randomised controlled trials suggest that intra-articular injections of a cross-linked polymer derived from hyaluronan can reduce pain, stiffness and physical disability associated with knee osteoarthritis for an average duration of six months when compared with placebo (saline) injections.^23,24 A recent review of available preparations supports their use for symptom modification.²⁵ Not all patients with osteoarthritis gain the symptom relief, and the more advanced the x-ray and clinical changes, the lower the rate of success. No disease-modifying or structure-modifying effects have been identified and the effect on natural synovial fluid and hyaluronic acid production remains to be determined. The product has been registered for use in Australia as a device, implying that it has only mechanical effects as a joint lubricant and shock absorber. However, it is only retained in the joint for about one week, yet symptomatic benefits can last for several months. It can be associated with temporary flares of increased pain and swelling in the joint post-injection.

While open-label studies among patients with advanced knee osteoarthritis have suggested that some can delay surgery, this has not been tested in a long-term controlled setting. The treatment is not recommended in the setting of inflammatory synovitis, such as crystal-induced arthritis or rheumatoid arthritis. A number of different preparations of varying molecular weight are available internationally. A Cochrane review of the efficacy of these intra-articular preparations is currently under way.

A recently published study performed among patients with knee osteoarthritis over three years showed gradual deterioration and increased narrowing of the joint space on x-ray among patients receiving placebo, but no such deterioration among the glucosamine group.²⁷ The authors concluded that glucosamine may help prevent cartilage breakdown if taken long-term (two to three years). The study has generated considerable editorial comment and debate. It has been criticised for the use of x-rays as the measure of cartilage structure and function. Further long-term studies using more sensitive measures, such as cartilage and bone turnover markers and magnetic resonance imaging, are required before these "nutraceuticals" can be considered disease- or structure- modifying agents for osteoarthritis.

Trials so far have been performed in Europe, where the glucosamine is prepared as a pharmaceutical agent. There is no guarantee that products not prepared to the same stringent requirements will have the same potency or efficacy. However, they do appear to alleviate symptoms in some patients with osteoarthritis, they don't appear to have any significant side effects or toxicity, and laboratory studies suggest they have anabolic effects on chondrocytes in cartilage cultures. No published data are available on their use in rheumatoid arthritis.

Topical capsaicin depletes substance P locally in the tissues, thereby reducing the chemical stimulation of the nociceptor pain fibres. Its benefits were initially documented for painful peripheral neuropathy. More recent reviews of capsaicin studies in osteoarthritis concluded that there was benefit for pain relief in osteoarthritis when compared with placebo, and all published guidelines for osteoarthritis management now recommend its use.^33-35

1. Arthritis Foundation of NSW. The arthritis handbook. 2nd ed. Chapter 11: Exercise. Sydney: Maclennan & Petty, 1996: 120-132.
2. Lorig K, Fries J. The arthritis helpbook. 3rd ed. Sydney: Addison-Wesley Publishing Co, 1993.

Reprints will not be available from the authors.
Correspondence: Associate Professor Lyn March, Department of Rheumatology, Royal North Shore Hospital, St Leonards, NSW 2065.
lmarcATdoh.health.nsw.gov.au