A recent study in the online journal BMJ Open determined that Johnson & Johnson’s DePuy Pinnacle metal-on-metal hip implants have a rate of revision surgery because of defective manufacturing that causes high levels of metal particles released into the bloodstream.
“This device was found to have an unacceptably high revision rate,” said senior author David John Langton. “Bilateral prostheses, those implanted into female patients and devices implanted in later years were found to be at greater risk. A significant number of explanted components were found to be manufactured with bearing diameters outside of the manufacturer’s stated tolerances. Our findings highlight the clinical importance of hitherto unrecognized variations in device production.”
BMJ Open is an online, open access journal, dedicated to publishing medical research from all disciplines and therapeutic areas. The study was published in April 2016.
Litigation is centered in US District Court for the Northern District of Texas, MDL No. 2244, assigned to Judge Ed Kinkeade. On June 10 the court ordered bellwether trials in 7 cases.
Signs of failure
Patients implanted with a DePuy Pinnacle MoM (metal on metal) hip prostheses were invited to a clinical examination, blood metal ion measurements, radiographs and targeted imaging.
489 MoM Pinnacle hips were implanted into 434 patients (243 women and 191 men). Of these, 352 patients attended the MoM recall clinics. 64 patients had died during the study period. For the purposes of survival analysis, non-attendees were assumed to have well-functioning prostheses.
- The majority of explanted devices exhibited signs of taper junction failure. Risk factors for revision were bilateral MoM prostheses, smaller Pinnacle liners, and implantation in 2006 and later years.
- A significant number of devices were found to be manufactured out of their specifications. This was confirmed with analysis of the wider data set from the Northern Retrieval Registry (NRR).