Back in February, the BMJ reported that a whole class of implant—in this case large diameter metal-on-metal total hip replacement—was allowed to enter the global market without any clinical studies to assess their safety and effectiveness. Hundreds of thousands of patients around the world may have been exposed to toxic metal ions released from the hips and the potential risks from this that have been known and well documented for decades.

The article drew a range of responses. Some surgeons were angry as they felt the resurfacing technique had been wrongly drawn in.  It wasn’t—the feature clearly stated that it worked well in certain groups of patients. Patients also wrote in to question why hip replacements were allowed to continue to be sold when it was known that irreversible damage could occur.

Graham Isaacs and Simon Sinclair responded on behalf of DePuy, which manufactures one of the products featured in the article.. The company took exception to the “alarmist” nature of the feature and offered an explanation of events in the feature. You can read the reply here:

In turn, the BMJ responded with very detailed follow up letter containing further information. This allowed for further exploration of the problems that seem pervasive in medical implant regulation. This included a lack of independent studies; surgical trends with little evidence underpinning them; conflicts of interest pervading the published literature; and a lack of transparency to name but a few.

However, what is particularly apparent is how, once again, the medical literature can not be relied upon to give an answer. Despite it being recognised “that one of the effects of having metal bearing surfaces would be that constituents of cobalt and chromium would be released locally and systemically”, very little in the published literature to date deals in detail with these concerns.

Deborah Cohen is investigations editor, BMJ