Total hip replacement is one of the most successful and cost effective interventions in medicine.1 ,2 It offers reliable relief of pain and considerable improvement in function in patients suffering with osteoarthritis or inflammatory arthritis of the hip.3-7 Currently about 50 000 hip replacements are performed in the United Kingdom annually while worldwide the number is over 300 000. Two thirds of these are performed in patients over 65 years of age.8 Ninety to ninety five per cent of patients can expect to have their total hip replacement functioning at 10 years,8 and in 85% they will still be functioning at 20 years.9

Although 85% of patients undergoing total hip replacement have a diagnosis of osteoarthritis,8 inflammatory arthritis, both seropositive and seronegative, is an important indication for total hip replacement and can offer tremendous improvements in quality of life even in the very young.10 In rheumatoid arthritis it has been estimated that the cost to the community of total hip replacement will be recuperated within an average 1.5 years because of savings made on medical and social care.2

Quality of life after surgery approximates that of a healthy reference population.4 Improvements in pain, energy levels, sleep, social, and sexual function are all observed.4 ,7 Oxygen demands on activity are decreased and walking ability improves.5 ,11 Most of these improvements are seen within three months of surgery.5 These gains in quality of life allow large numbers of patients to retain their independence and function more actively in society.