More data on knee replacements needed

Writing in the medical journal the Lancet, they say there is a lack of reliable information for surgeons to compare outcomes for different implants and surgical techniques. Furthermore, they say there is very little or no evidence for the effectiveness of many implants on the market.

‘Joint replacement has been an outstanding success but further improvements can be achieved by understanding: who should have surgery, when they should have surgery and which is the best implant,’ says lead author Professor Andrew Carr of Oxford University’s Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences (NDORMS).

‘In a phrase, we need to move to “personalised surgery” so we get it right for patients all the time, not some of the time.’

The Oxford researchers, along with colleagues at Lund University in Sweden and the University of Adelaide in Australia, point out that new implant designs are continually being introduced by orthopaedic manufacturers. They say there is a need for more information about the effectiveness of new implants.

‘The regulatory framework for new implants varies worldwide but has been generally much less rigorous than for new drugs,’ explains Professor Carr. ‘Currently proof of safety of implanted materials is all that is required prior to approval for clinical use, rather than evidence for clinical effectiveness.’

He notes that implants and devices are currently estimated to cost the UK £15 billion per year compared to £13 billion for drugs, yet we don’t know so much about their effectiveness.

National registries of joint replacements are one of the few sources of comparative information for patients and surgeons. These registries collect data on patient characteristics, type of implant, surgical technique and surgeon experience.

While registries have typically recorded measures like how quickly knee replacements need to be redone (revision surgery), there is little on the effect of the surgery on patients’ quality of life.

‘We need to include information in national registries not just about the need for revision surgery but also information on patients’ pain, level of mobility and overall satisfaction,’ says Professor Carr.

While such monitoring can and should be improved, says Professor Carr, he does add: ‘Patients should be reassured that knee replacement surgery has proved to be one of the outstanding success stories of modern medicine and has resulted it significant quality of life gains for people with end stage arthritis.’

Knee replacement is amongst the most common surgical procedures in developed countries. More than 77,500 total knee replacements were performed in the UK in 2009 alone.

There is likely to be a dramatic increase in knee replacement surgery over the next two decades with an ageing population, rising rates of obesity, and replacements increasingly being used with younger patients. That will mean greater costs, and substantial increases in the likelihood of revisions and complications.

‘In an increasingly ageing population, the need to maintain function and minimise pain has to be a priority for health care,’ says Professor Carr.