Hip implants ‘catastrophic failure’

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NM Hip Xray INLSA A hip X-ray shows the DePuy ASR XL hip implant on the right. On the left, the hip joint has been resurfaced and capped.

A Durban specialist has warned surgeons in the country who fail to carry out checks on patients with suspected failed metal-on-metal hip implants, saying the illnesses caused by certain implants could be very serious.

Durban hip replacement specialist and incoming president of the SA Arthroplasty Society Rob McLennan-Smith, however, has also slammed recent media reports that these hip implants cause cancer, saying the allegation was irresponsible and unfounded.

He said certain implants, and in particular those manufactured by Johnson & Johnson subsidiary DePuy – which recalled more than 90 000 of its Acetabular Surface Replacement (ASR) metal-on-metal implants in 2010 – were found to cause metallosis and lesions requiring corrective surgery. However, no conclusive proof was found of the implants causing cancer.

DePuy also offered to pay for the surgery required by the affected patients.

McLennan-Smith said the failure of the ASR implants was caused by a technical design fault in the metal cup in the pelvis, which, if not angled correctly, caused wear to the metal used to replace the top of the femur.

“The illnesses caused by the design fault are very serious, but it is important we set the record straight on the allegations about cancer,” he said.

NM Hip Implant Durban surgeon Rob McLennan-Smith shows the DePuy ASR XL hip implant. More than 90 000 of the implants were recalled in 2010 by the company due to its failure in a high number of patients in the UK. Pictures: Colleen Dardagan INLSA

While neither SA nor the US have registries of implants, about five years ago the registries in Britain and Australia started picking up “catastrophic rates of failure” – in some centres up to about 49 percent – in DePuy’s ASR XL metal-on-metal stem implant. In August 2010 the implant was recalled and surgeons were advised to check their patients.

“They had to do x-rays, blood tests and physically examine them,” said McLennan-Smith.

“In some cases there was only an increase in fluid around the joint, whereas in others, destructive lesions were eating away at the muscles, causing complications due to soft tissue destruction.

“Also, the metal particles in some cases were distributed into the blood stream, causing chromosomal abnormalities. Eight cases of neurological reactions such as visual impairment, hearing loss and dizziness were reported worldwide,” he said.

McLennan-Smith said while an ASR registry was now established in SA and surgeons who did the operations regularly were tracing the more than 3 000 in the country and urging them to come in for check-ups, he warned there were those “who had only done a few replacements ops – 10 or 20” who might not be checking up on their patients.

“Lawyers are watching this situation very closely. Surgeons could find themselves in hot water if they do not find their patients and ask them to come in and be examined and then check them annually thereafter,” he said.

The Westville hospital-based McLennan-Smith said he was now employing a full-time staffer to keep tabs on his 506 patients who have the ASR and of which 2.5 percent, after check-ups, required corrective surgery.

“It has been a big learning curve for us, but it’s also a big problem, which we are taking very seriously,” he said.

McLennan-Smith recommend that any patient with a total hip replacement should be aware of what implant they had in them.

“Particularly young people – and if they have any symptoms they must have them checked as a matter of urgency.”

However, he stressed that not all metal-on-metal implants caused problems. - The Mercury

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