Tumour fears over hip joint debris

HIGH levels of potentially cancer-causing metal particles have been found in the liver, lymph glands, bone marrow and spleen of patients fitted with artificial hips and other joints.

In one patient, the levels of cobalt detected in the bone marrow were several thousand times the norm, according to researchers who now want more detailed investigations into possible effects of the metals they found.

Doctors who carried out research in post-mortem examinations, the Bristol Wear Debris Analysis team, stress that no link has been established between the debris and disease, but say that potential damage to organs cannot be ruled out.

The team's report says: "There is concern that the metals used in prostheses [artificial body parts] may cause neoplasia [tumours] since they are potentially carcinogenic in other situations."

One of the problems is that there is no adequate reporting system for tumours among people with implants, despite appeals six years ago for an international register.

The Bristol group found that patients whose artificial joints were classed as worn had the highest concentrations of chromium, aluminium and cobalt.

In their research, published in The Journal of Bone Surgery, the team says: "Most worrying is the possibility of distant effects. Two independent studies based on small numbers of cases have suggested that there is a three-fold risk of lymphoma and leukaemia 10 years after joint replacements, and in our subjects the highest metal levels were found in bone marrow and lymph nodes, not in the local tissue."

The report emphasises that the link between debris and disease is controversial and Professor Louis Solomon, professor of orthopaedic surgery, and the team leader, says that after more than 10 million joint replacements performed worldwide there has beenno report showing a definite link between the operation and any type of cancer.

But, he says, the team is recommending that manufacturers should get together with surgeons to develop implants with less potential for wear.