Therese Wood Photo: Paul Harris

THOUSANDS of Australians have had hip replacements that are suspected to be faulty, but many are unlikely to know because their surgeons are not obliged to tell them.

Three years after health authorities withdrew two defective Johnson & Johnson hip implants, new figures show 31 other implants have performed badly in recent years with higher than anticipated failure rates.

Australia’s National Joint Replacement Registry shows more than 16,000 people have received these suspect prostheses. Most are still being used, but two have been recalled by the Therapeutic Goods Administration this year. Another 10 have been subjected to TGA ”hazard alerts”.

The implants recalled this year are the ABGII Modular Femoral Stem and Modular Neck systems and the MITCH TRH modular head. At least 900 people have received them.

While surgeons are asked to contact patients who have the recalled implants or those on hazard alerts, patients with the remaining 19 implants may not receive any information about the higher than expected failure rates. One of them has a revision rate of 15 per cent at five years compared to a 4 per cent revision rate for similar implants.

The head of the registry, Professor Stephen Graves, said although surgeons were sent registry reports annually to inform them of under-performing implants, they were not asked to tell former patients about them unless the TGA recalled the implants or issued a hazard alert about them.

”There isn’t a system that is sort of activated to say patients need to be notified, but if the device is recalled, that system comes into play,” he said.

However, Professor Graves said not all implants with higher than anticipated revision rates were defective. He said many factors can play a role in the revision rate, including the instruments used to implant them, the surgeons’ level of experience and the approach they used. For this reason, he said implants with high rates are reviewed by the TGA and a panel of experts to decide whether they need to be recalled.

The latest registry report showed a dramatic increase in the failure rate of the faulty Johnson & Johnson DePuy ASR hip implants, with 44 per cent of people having them revised five years after receiving them. Professor Graves said a good implant has a revision rate of 2.5 per cent at five years.

More than 1100 of the 5500 Australians who received them are now part of a class action against Johnson & Johnson. There are fears some of them have been poisoned by metal ions in the device.

Therese Wood, a mother of two who is part of the class action, has had to have two operations on her right hip after receiving the ASR implant in 2007 at the age of 44. Since then, she has experienced chronic pain, high blood pressure, hearing loss and dizziness. She struggles to walk without limping and fears what the metal in her original implant has done.

”There’s some talk that extremely high levels of chromium and cobalt poisoning can cause things like cardiomyopathy (heart muscle disease) and lung cancer,” she said. ”To read that and even wonder about the possibility is awful … It’s been a pretty scary time.”

To see the implants with high failure rates, visit: www.dmac.adelaide.edu.au/aoanjrr/publications.jsp