Most British patients with all-metal artificial hips should be followed up for life with annual tests to check for problems, Britain's medical regulator said on Tuesday.

Patients with large-head implants should have blood tests to check for metal ions and magnetic resonance imaging scans (MRI) if they have raised metal levels or show adverse symptoms, the Medicines and Healthcare Products Regulatory Agency (MHRA) said.

It issued the new clinical guidelines to doctors about the artificial hips after some patients reported problems that needed more surgery or caused other health problems.

The regulator said around 49,000 patients out of 65,000 with all-metal hips were in a high-risk category.

The move will fuel controversy about the regulation of medical devices in Europe in the wake of a scandal over France's Poly Implant Prothese (PIP) breast implants. Critics argue European oversight is too lax to spot substandard products.

'Metal-on-metal' hips were developed to be more durable than traditional implants, which combine a metal or ceramic ball with a plastic socket.

But patients receiving some all-metal hips turned out to be more likely to need repeat surgery than those who got implants made of other materials. They also produce debris that can release chromium and cobalt ions into the blood, causing health problems.

In 2010, Johnson & Johnson issued a massive recall of an all-metal hip implant system that failed at a higher-than-expected rate, and last month the company took a charge of more than $3 billion largely related to the recall.

The new guidance does not affect all-metal hip resurfacing systems with no stem sticking into the bone, such as Smith & Nephew's Birmingham Hip Resurfacing joints.  - Reuters