The DePuy Pinnacle hip implant acts as a replacement socket utilizing a metal ball that sits atop the thigh bone. Dr. David Langton of the University Hospital of North Tees in the United Kingdom performed a study with 243 women and 191 men, with 489 metal-on-metal Pinnacle hip replacements. According to CBC News, the study combined data from north England with data from the national registry.
Patients were monitored for an average of 7.5 years post-surgery. Of these hips, 71 had to be surgically removed and replaced. “This device was found to have an unacceptably high revision rate,” researchers said.
From 2006 on, implants had a higher risk of revision in comparison with those manufactured before 2006. It was felt by the researchers that the revisions were due to variations in the manufacturing process between batches.
In 2008, DePuy admitted to an “error in measuring techniques.” Regardless of how small the discrepancy might be, the errors likely caused the device to be sized incorrectly and caused pain and injury to thousands of patients, The Legal Examiner reported.
Metal-on-metal hip implants have decreased in numbers in the past five years, reports CBC News. A criticism of the studies done is that the numbers may not be accurate as not all patients attended follow-up clinics. Therefore, those who did not attend, were assumed to not have negative symptoms.