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Hundreds of people who received allegedly faulty hip replacements are suing the manufacturer at the High Court.

The hearing is thought to be one of the largest product liability group actions ever heard in the UK.

DePuy denies that its metal-on-metal implants were defective and caused some patients to need more surgery than was necessary.

Sales of the Pinnacle Ultamet device were discontinued in August 2013.

Lawyers claim their clients were affected by the release of metal particles from the implants, which can damage the surrounding tissues and cause symptoms such as pain and swelling.

Some 312 people who were fitted with the Pinnacle Ultamet hip joint say they have had to have remedial surgery after it failed prematurely.

During the first day of the hearing, the court was told that after 10 years the metal joint involved had a failure rate up to six times higher than alternatives made from other materials.

Wear over time

Metal-on-metal implants replace the hip joint with a metal ball and cup.

Hundreds more metal-on-metal claims against a number of other manufacturers are said to be on hold pending the outcome of the trial, which is expected to last until the end of January.

DePuy said: "We have no greater responsibility than to the patients who use our products. The device is backed by a strong record of clinical data showing reduced pain and restored mobility for patients suffering from chronic hip pain. We are committed to the long-term defence of the allegations in this litigation."

Earlier this year, the Medicines and Healthcare products Regulatory Agency said every patient with a metal-on-metal prosthetic hip should have regular check-ups to spot any complications.

The watchdog had previously recommended that only patients with particular types of implant, or troublesome symptoms, undergo tests.

"Although the majority of patients with these metal-on-metal devices have well-functioning hips, it is known some may develop soft tissue reactions related to their implant.

"The clinical advice we have received indicates patients will likely have the best outcomes if these problems are detected early, monitored and treated if necessary," the MHRA said when it updated its advice.

About 56,000 UK patients have had a metal-on-metal hip device implanted.