Patients who have received a metal-on-metal hip replacement require careful follow-up to detect possible cobalt and chromium toxicity, cautions a prominent orthopaedic surgeon. In a rapid online publication in the Medical Journal of Australia, Professor Ross Crawford of Brisbane's Prince Charles Hospital and co-authors report the first Australian patients with a DePuy ASR (articular surface replacement) prosthesis to have high serum metal ion levels, which are potentially associated with systemic toxicity.

Systemic toxicity may cause alterations in neurological, respiratory, cardiac and endocrine function.

"We are concerned that cobalt toxicity may be under-recognised, particularly if patients consult doctors who may not be aware of the details of the patient's hip replacement and the potential for release of cobalt into the circulation," they write.

"In an accompanying editorial, Professor Stephen Graves, Director of the Australian Orthopaedic Association National Joint Replacement Registry, said that the ASR devices were identified as having more than twice as many revision surgeries compared to all other similar prostheses combined. The ASR devices were withdrawn from the Australian market in 2009.

More than 5500 Australian patients have received these devices, but it is unclear how many will need revision surgery.

"Surgeons currently have no information on whether a hip should be revised based simply on the patient's serum metal ion levels," said Professor Graves.

He cautioned that revision surgery should not be undertaken without a good indication because it is associated with significant morbidity and mortality risks.

Professor Graves also noted the importance of surgeons holding transparent relationships with device manufacturers.

Medical Journal of Australia