A top bone specialist has called for widespread monitoring of patients with total knee replacement (TKR) implants, in addition to rigorous safety checks for new implant designs.

Prof Andrew Carr, Professor of Orthopaedic Surgery at the University of Oxford, UK, says there is an alarming lack of evidence of the long-term safety or cost-effectiveness for many of the different types of implants on the market.

His warning comes just a week after a media report claimed that patients with 'metal on metal' artificial hip implants may be exposed to dangerously high levels of toxic metals, despite the hazards being known and recorded for decades.

The joint Newsnight/British Medical Journal investigation last week prompted an alert by the UK watchdog, the Medicines and Healthcare Products Regulatory Agency (MHRA), urging surgeons to monitor patients with these metal on metal artificial hips for the life of the implant.

Orthopaedic surgeons in Ireland also plan to extend the recommended patient screening period from five years to the life of the implant.

Prof Carr said there is mounting evidence to suggest that the results of published clinical trials for individual knee replacements report better outcomes than those available from national joint replacement registries.

He stressed that these registries, which collect information on patients, type of implant, surgical technique, and surgeon experience, are one of the few sources of accurate and objective information for patients and surgeons.

"Without high-quality, unbiased, and reliable information, surgeons cannot make informed decisions about how to achieve the best outcome in each clinical situation," he explained in an overview of knee replacement surgery published recently in The Lancet seminar series.

Despite the thousands of hip, knee and ankle joint replacement operations that take place in Ireland every year, there is no National Joint Replacement Registry in this country.

However, irishhealth.com has learned that this situation may be about to change as the HSE is due to decide in the coming weeks on the viability of setting up a national joint registry. This follows more than 12 months of meetings between the HSE and orthopaedic surgeons.

Prof Carr was quick to assure patients that these joint replacement procedures are predominantly safe and offer significant benefits.

"Patients should be reassured that knee replacement surgery has proved to be one of the outstanding success stories of modern medicine and has resulted in significant quality of life gains for people with end stage arthritis," he said.

But he was critical of the regulatory framework governing implants, which he said varied greatly worldwide, in sharp contract to the rigorous rules for new drugs.

"Currently, proof of safety of implanted materials is all that is required prior to approval for clinical use, rather than evidence for clinical effectiveness," said Prof Carr, who is also Head of Oxford's Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences.

"Widespread surveillance of existing implants is urgently needed alongside the carefully monitored introduction of new implant designs as part of well conducted large-scale randomised trials."

Since the first knee replacement was performed in 1968, the numbers of artificial knee replacements have increased every year. In the UK, rates for women increased from 43 per 100 000 person-years in 1991 to 137 in 2006.

The VHI paid out almost €30 million in 2010 on knee replacement surgeries for 1,888 customers in Ireland. Knee replacement is the second most expensive treatment in this country - after heart bypass - costing an average of €13,845 per patient.

Prof Carr cautioned that our ageing population, rising obesity rates, and joint replacements increasingly being fitted in younger patients will lead to a dramatic rise in demand for knee replacement surgery over the next two decades, which will have huge economic implications.

He suggested that improving patient selection for surgery and investing more funds into emerging new treatments, including managing arthritis at earlier stages and reversing or slowing down the progression of disease, could reduce the demand for knee-replacement surgery.

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