6 March 2012
The online edition of the Lancet has published concerns that thousands of artificial knee joints are implanted each year in the UK without sound evidence of their long-term safety and effectiveness.
The article is not the first to raise doubts about the evidence on orthopaedic joint implant safety and effectiveness. New guidance was issued to hip implant patients last month after concerns about muscle, bone and neurological problems as it is feared metal ions of cobalt and chromium could leak from the implants into the blood.
Some 49,000 people in the UK who have undergone hip replacements will now need annual blood tests. Writing in the Lancet today, experts called for better long-term monitoring of patients undergoing knee replacement, one of the most common surgical procedures in developed countries, so that the necessary data can be gathered.
According to the international team of British, Australian and Swedish experts, these procedures have occurred "often with little or no evidence of effectiveness or cost effectiveness".
Professor Andrew Carr, one of the authors from Oxford University, said:
"The regulatory framework for new implants varies worldwide but has been generally much less rigorous than 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.
"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. Further it has been suggested that surgeries will only continue to increase as a result of an ageing population and obesity levels."
His concerns relate to the lack of reliable information being made available to Surgeons as the demand for knee replacements continue to grow. Without careful monitoring of the variety of implants available on the market, surgeons are unable to make informed decisions about how to achieve the best results for patients.
Jill Paterson, Partner in the product liability team at Leigh Day & Co, represents a number of patients who have suffered problems following the failure of their knee implants. She acted for a group of Australian patients who suffered problems following the failure of their DePuy LCS Duofix knee systems.
She has also recently been instructed to pursue a claim on behalf of a patient who received a Zimmer NexGen LPS femoral component as part of his knee replacement surgery. He was told that he required revision surgery after an x-ray revealed that the polyethylene part of his component had worn.
Certain lots of Nexgen System were recalled in September 2010 due to “a manufacturing non-conformance, specifically an undersized cam radius”. The nonconforming cam radius poses a potential risk of polyethylene delamination and fatigue fracture.
Jill Paterson said:
"The Lancet article is the latest in a long list of reports concerning the problems with the current system of surveillance of medical devices. It is high time for change."