The DePuy Pinnacle hip device sits inside a metal liner with a metal ball that works at the top of the thigh bone acting as a replacement socket. Dr. David Langton of the University Hospital of North Tees in Stockton, in the United Kingdom, led a study with 243 women and 191 men, with 489 metal-on-metal Pinnacle hip replacements. The study combined data from northern England with data from the national registry, according to CBC News.
Patients were monitored for an average of 7.5 years after surgery. Of the 489 followed hip replacements, 71 had to be surgically removed and replaced. “This device was found to have an unacceptably high revision rate,” said researchers.
From 2006 on, implants showed higher risk of revision in comparison with those manufactured before 2006. It was felt by the research group that the revisions were due to variations in manufacturing between batches.
In 2008, DePuy admitted to an “error in measuring techniques.” Regardless of how small the discrepancy might be, the errors caused the device to be sized incorrectly and caused pain and injury to thousands of patients, reported The Legal Examiner.
As a result, metal-on-metal hip implants have gone down in numbers in the past five years, reports CBC News. A criticism of the studies done is that not all patients attended follow-up clinics, so those who did not attend, were assumed to not have negative symptoms, CBC News reported.