Metal-on-metal hip patients need medical tests.

More than 50,000 patients with “metal-on-metal” hips are being told to undergo X-rays and blood tests after watchdogs found they are far more toxic than previously thought.

Every person fitted with the devices is being advised to have checks in a safety alert issued by the Medicines and Healthcare Products Regulatory Agency (MRHA).

Concerns have been consistently raised about the devices with watchdogs previously recommending patients with particular types of implant, or troublesome symptoms, to undergo tests.

But the new advice means 56,000 patients - everyone with “metal-on-metal” hips - should undergo a series of medical tests to establish if they are suffering muscle or bone damage, and metal toxicity.

The safety alert could result in thousands of people undergoing revision surgery to replace the implants.

The MHRA said the alert had been issued because of growing evidence that muscle damage caused by the implants can become progressively worse, and even irreversible, without patients suffering symptoms.

Surgeons are particularly concerned about consequences for women who will be told to undergo annual checks for the rest of their lives even if no concerns are detected.

Metal-on-metal implants were introduced in the UK in the 1990s when they were promoted as offering better mobility than those which use a metal ball and plastic socket.

They were seen as a better option for younger patients, who are generally more active and put more pressure on the joint.

MHRA clinical director of medical devices, Dr Neil McGuire, said: “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 indicates patients are likely to have the best outcomes if these problems are detected early, monitored and treated if necessary. If people have any questions about their hip replacement they should speak with their GP or implanting surgeon.”

MHRA says that not every patient with such hip implants would need to have them removed. Revision surgery will be recommended only if scans, blood tests or pain measurement scores suggest the devices are causing unseen harm.

Men suffering symptoms which could signify muscle damage will undergo annual checks, and while those without will have tests at least every three years.

In 2013, NHS hospitals were told to stop fitting most metal-on-metal hip replacements after a study found unacceptably high failure rates among 17,000 patients. The guidelines said the NHS should stop using any hip implant with a failure rate higher than five per cent at five years, ruling out most types of metal-on-metal implants.

In 2010, two hip implants which accounted for around 10,000 of the metal-on-metal hips fitted in the UK since 2003, were withdrawn from the market after safety concerns.

Richard Wood of the CNCI team said, "we are aware from cases we have dealt with that monitoring and treatment of patients with MoM hips has not always been implemented consistently. In some patients the damage can be serious and lead to significant, lifelong disability. With appropriate monitoring and treatment the impact of damage can be restricted. Patients who have concerns about any MoM hip should seek medical advice to ensure that their condition is properly monitored".