1 June 2001
The charity that helped champion the UK’s first artificial hip is striving to boost the long-term performance of the costly operation, in a new pioneering study.
With backing of almost £40,000 from leading medical research charity, Action Research, a team of scientists at both London and Southampton are hoping to shed new light on why so many hip implants fail.
The results could help reduce the expense and pain of many secondary operations.
More than 50,000 artificial hip replacements are carried out each year in the UK, and approximately one per cent of the population benefit from surgery.
Hip replacements however - most of which use cemented implants - have a limited lifespan, and in 18 per cent of cases a repeat operation is required at a total cost of £32m per annum. This also limits the effectiveness of artificial joints for younger patients.
The major cause of failure in the cement cases is the mechanical loosening of the joint. But with insufficient knowledge of exactly how this happens, Dr Nader Saffari, of the Department of Mechanical Engineering, University College London, says it is currently difficult to develop new and improved prosthesis designs.
The research team aims to identify how and where the cemented hip joint fails by developing state-of-the-art techniques similar to those being used in the aerospace industry.
The first is called acoustic emission (AE), which uses sound waves to record the progression of defects in the cement layer and where the cement attaches to the bone and joint. The second uses high frequency ultrasonic waves to examine the site of the damage located by the AE method.
Both techniques have been successfully used in monitoring cracks and defects in aeroplane components and materials.
Dr Saffari is leading the ultrasonic work, while colleagues Dr Martin Browne and Dr Mark Taylor, both based at the University of Southampton’s Faculty of Engineering, will be focusing on the acoustic emission techniques.
Dr Saffari, who says he’s thrilled to be awarded the Action Research funding, adds that the study will enable newly designed implants to be assessed at the development stage, thereby helping predict how effective they will be. He adds: ‘This in turn, will reduce the incidence of loosening, and the resulting need for revision surgery.
‘Apart from the obvious financial savings to the NHS, longer lasting artificial joints will also be more beneficial for the treatment of younger patients.’
The study might also provide useful information for other disorders requiring cemented implants, such as total knee replacements.
Action Research pioneered artificial hip joint surgery in the1960s, and has continued to fund projects to increase the life-expectancy of hip joints.
A booklet produced by the charity, entitled The Hip Operation: What you need to know, is designed to give patients an insight into what to expect from such surgery. For a copy, send a £2.50 cheque payable to Action Research, Vincent House, North Parade, Horsham, West Sussex, RH12 2DP.
Action Research launched its Touching Lives campaign this year, which aims to raise £1.5m for vital medical research to benefit children and families across the UK. Visit the charity’s newly-launched website at www.action.org.uk
Action Research is dedicated to helping overcome disease and disability for children, families and the elderly across the UK. The charity’s Touching Lives Campaign aims to raise £2m for vital medical research and more details can be found at www.action.org.uk
For further information and interviews, please contact Nicole Duckworth in the Action Research press office on 01403 327403 Fax: 01403 210541, or email email@example.com
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Fact-file: *There are two basic methods for securing the artificial hip joint; In cemented joints the surgeon makes holes in the femur (the large thigh bone) and pelvis, which are slightly larger than the artificial components to be inserted, and the gaps between the parts and the bone is filled by a special cement.
*In cementless joints; the surgeon fixes the replacement unit into holes which are bored exactly to the shape of the artificial joints.
*Cemented joints are slightly easier to fit than cementless ones because they require less precision in the way that the hole is drilled in the bone. Patients usually recover more quickly and can be mobile in a matter of days, rather than weeks, as patients with cementless surgery often find.
*Cemented joints however, are not without their flaws as they are more difficult to replace.
*For this reason, younger people - who are at a risk of requiring repeat surgery in their lifetime - are often given cementless treatment.
*Osteoarthritis is the most common reason for having an artificial hip, but people with rheumatoid arthritis, osteoporosis or some physical injury to the hip may also benefit from a new joint.