BMJ on Hip Implants – No Evidence of Safety

The British Medical Journal (BMJ) recently published an article that shows the glaring oversight of regulators to ensure patient safety from defective medical devices in the European Union. Its findings echo what has happened in the U.S. and unfortunately, the reasons are the same.

The research from the University of Oxford, “Primary hip replacement prostheses and their evidence base: systematic review of literature,” looked at the existing literature to determine that 24 percent of hip prostheses available in the United Kingdom (UK) in 2011 were in use despite the fact there was no evidence of human safety and efficacy.

Their conclusion – the current way devices are regulated in the UK “seems to be entirely inadequate.”

Researchers looked through the National Joint Registry of England and Wales. We know from the way the Stryker and DePuy metal-on-metal hips were introduced in the U.S. through the Food and Drug Administration’s 510(k) program, that permanently implanted medical devices are allowed onto the market with no reviews for safety and efficacy. Unfortunately the European Union (EU) is following our lead.

In the EU the European Medicines Agency is the equivalent of the FDA in the U.S. however the EU uses 76 notifying bodies or individual offices to approve new medical devices. Since hip prostheses are considered Class III medical devices, they must be compared to an existing product on the market (similar to our “substantial equivalent” standard for approval).

In the EU, the National Joint Registry (NJR) was established in 2001 to collect data on hip and knee replacements. The reporting became mandatory two years ago and National Health Service hospitals must report to the registry.

A secondary agency, the Orthopaedic Data Evaluation Panel (ODEP) requests reporting follow-up data on the hip prostheses, but it is not mandatory. A failure rate of no more than 10 percent or less at 10 years (10A) is the highest failure rate allowed. Any product on the market three years or less is considered pre-entry. Other devices enter the market as “unclassified” meaning they have no relevant data on safety or efficacy submitted by the manufacturer. Regardless, they may still be cleared for implantation. This study tried to determine how many devices which fell in the latter category are being used in clinical practice.

Data came from the NJR’s 2012 report on hip replacements on 118 brands of prosthesis. From the NJR there were 142 different femoral stems (brand names) including both cemented and uncemented; and 119 acetabular cups, both cemented and cementless used in a hip replacement in 2011. Rating best were cemented stems (85%) followed by cementless stems (72%). Cemented cups (40%) and cementless cups (3%) followed. They had an ODEP rating of 10A, the optimal rating.

Of the unclassified or pre-entry prosthesis brands, 48% showed no evidence submitted of effectiveness from human trials. For primary hip replacements, 8% of those implanted in 2011 and recorded by the NJR had no evidence of effectiveness or safety. The authors estimate this is an undercounting, as registries often are. One in four devices had submitted no evidence to guarantee safety.

The authors conclude that using a substantial equivalent as a benchmark to allow a new device onto the market does not reflect the impact even a small change in design can have on the effectiveness or lifespan of the implant.

The British Orthopaedic Association is calling for a radical change in the way devices are regulated in the EU. The study concludes a more rigorous approach is needed to regulate medical devices, especially when no evidence is being submitted. Considering the high failure rate of metal-on-metal (MoM) hip prosthesis, this would seem evident.