Imperial Consultants

The Implant Retrieval Centre is based at Imperial College London and holds the world’s largest collection of metal-on-metal hips, with over 700 components from current generation devices. Artificial hips have, for the past ten years, been increasingly made of metal for both parts of the joint rather than the more traditional metal and plastic combination.

Recently though surgeons are concerned over the number of patients with metal-on-metal hips who experience severe tissue and bone damage or sometimes just unexplained pain with no other abnormality found. Recalls have been issued for some products and some patients have needed replacement surgery within only a year or two, experiencing severe pain after implantation.

As joint heads of the Implant Retrieval Centre, Alister Hart and John Skinner (based at the Royal National Orthopaedic Hospital), along with colleagues from Imperial, are investigating the cause of failure. The reasons behind the tissue and bone damage is not clear, though it’s thought it may be an immunological response to the small metal particles that end up in the body from the rubbing of metal-on-metal.

“At the moment we have theories about why it occurs, but no real evidence.” explains Mr Hart. “We’re also working to develop a biocompatibility test so that in future we know what metals someone will react badly to – currently there’s no way to tell.”

Mr Hart’s Implant Centre is funded through nine orthopaedic companies and produces analytical reports on the failed metal hips sent to them. Their industrial experience combined with the cutting-edge research at Imperial enables the centre to lead the way in artificial hip research.

Engineers, immunologists and orthopaedic surgeons are all part of the centre, using their large collection of failed hips to validate their research. The diversity of the medical and engineering expertise at Imperial enables their work to follow new paths too. Imperial’s MRI scanners have been calibrated to scan metal hips effectively – usually a difficult test because of the metal artefacts introduced to the image from the hips.

The centre’s close links with industry means they can keep the work they do relevant to the real world and provides the basis of pain-free hip replacements for the future.

What can the London Implant Retrieval Centre do?

• Provide a medical or surgical opinion for patients with painful metal-on-metal hip replacements, including the ASR hip replacement.
• Produce factual hip analysis reports of failed metal-on-metal hip replacements for use by implant manufacturers and lawyers (these reports have become the industry accepted format of reporting).

For more information on how Imperial’s biomedical engineering expertise can help your organisation, please contact us.