Joint replacement patients benefit from cutting edge work by Oxford researchers
JOINT replacement surgery for thousands of patients in the UK is being dramatically improved – thanks to the cutting edge work of a research team working at Oxford University and the Nuffield Orthopaedic Centre.
In two separate and significant developments, the team has established a new system for screening new hip replacements before they go on the market - which could prevent disasters associated with poor designs of hip replacement.
And thanks to the results of a second research project, a proportion of people who need knee replacement operations should soon be able to undergo surgery as day case patients, and recover far more quickly than before.
Both projects, carried out by a team led by Professor John O'Connor of the Department of Engineering Science, and orthopaedic surgeon David Murray, were highlighted by leading medical research charity the Arthritis Research Campaign during its Research Week (June 7-13). The charity has contributed to the research grants of more than £200,000 for the past three years.
The awareness week focused on the enormous success of joint replacement surgery over the past few years; the development of ever-better surgical techniques, and the resulting benefits to patients. It also aimed to restore public confidence in joint replacement following public concern earlier this year over the failure of one type of hip replacement.
"There are currently more than 60 different types of total hip replacement on the market in the UK, and many new ones are being introduced each year," explained Mr Murray. " Unfortunately some of these, like the Capital hip, will have poor results. It is therefore essential that a system for screening new hip replacements before they are released on the market is established."
For the past seven years, with funding from the ARC, the team has been using a measurement technique called Roentgen Stereophotogrammetric Analysis (RSA), which involves stereo x-rays to measure how the implant moves relative to the supporting bone in 3D – with an accuracy of a few tenths of a millimetre.
Recent studies have given major insights into the way implants function, and how they may fail in the long term. More importantly, they have provided a data base against which new implants can be compared.
It is therefore possible to screen new implants before they are released onto the open market," added Mr Murray. "The ideal way for all the new implants to be screened would be to establish satellite RSA centres where the new joints can be studied, and the x-rays could then be analysed at these centres or centrally at Oxford."
In the second research program, the Oxford team is investigating ways of restoring normal knee motion after knee replacement surgery; testing the movement of the elbow joint, with the long-term of goal of designing better surgical replacements; and trying to explain the reasons for the failure of surgery to correct foot deformities.
The clinical knock-on effect is already benefiting patients. The Oxford Knee, developed by Professor O'Connor and orthopaedic surgeon John Goodfellow, has been shown to work extremely well at ten years. Mr Murray and the joint replacement surgeons at Oxford have now developed a technique for implanting this knee replacement with a small incision.
"The ability to insert this knee joint through a limited incision is likely to represent a substantial advance in knee replacement surgery," said Professor O'Connor. "Patients should recover far more rapidly with the minimally invasive approach, and it should be possible for the procedures to be done as a day case.
"The operation causes much less damage to the soft tissues around the knee. And as a result, post-operative pain and suffering is minimised and the complications should be less frequent and less severe."
Research into the mechanics of human joints has been conducted by the department's research group since the late 1960's, involving collaboration with surgeons from the Nuffield Orthopaedic Centre, and from abroad.
In their early experiments, simple testing rigs were used to test new artificial joints, and the data was recorded by hand. Later, more complicated rigs were constructed, and data logged directly to a computer.
The current ARC grant is to fund a new computer for data acquisition and analysis, up-to-date software, and electronic power supplies and amplifiers.
