These failures usually required the patients who had received the Durom Cup implant to undergo a revision surgery to have the device removed.
Despite the recall, Zimmer maintained that its investigation proved the Durom Cup was safe and effective when used as intended. The company did acknowledge that all metal-on-metal implant devices made from a single metal sheet are known to be technically challenging to implant.
Zimmer also noted that the primary benefits of this type of hip implant construction reduced the risk of hip dislocation and preserved more of the natural cavity of the hip joint. These benefits should be weighed against the surgical skill requirements needed to perform the procedure.
If you had a Zimmer Hip Replacement and are having problems or complications with the implant please call our Patient Advocates today at (800) 452-0949 or fill out the form on this page.
Zimmer Consultant Gave Alert
Larry Dorr, M.D., a noted orthopaedic surgeon and also a consultant to Zimmer Holdings, Inc., first alerted the company to problems with the Durom Cup in 2007. His concerns stemmed from his observations of an abnormally high failure rate among his patients who received the implant.
Dorr sent a letter to the membership of the American Association of Hip and Knee Surgeons (AAHKS) in 2008 detailing 10 revision surgeries out of 165 hip replacement procedures using the Durom Cup. Four more patients also needed revision surgery, he said. The failures came within the first two years after the initial surgery.
|In his letter, Dorr made the following points:|
|During the first year after the implant, patients’ X-rays showed no indications of problems, such as lines through which X-rays passed or movement. Revisions were performed because the patients exhibited classic signs of a loose implant.|
|The fixation surface on the Durom Cup was not adequate.|
|There was a circular cutting surface on the edge of the device that
prevented it from fully seating.
Dorr stopped using the device after the initial revision surgeries and notified the Food and Drug Administration (FDA) about the number of revisions.
Zimmer Challenged Surgeon’s Allegations
Zimmer responded to Dorr by accusing him of not having the technical competence to implant the device properly. Despite its allegation against Dorr, Zimmer conduct its own investigation.
It began with an analysis of its manufacturing processes and retesting the device to be sure it complied with manufacturing specification. Zimmer also verified that the plasma-sprayed coatings on the device met with FDA requirements and compared favorably with the coatings used by its competitors.
Documentation from production lots, especially any lots associated with revision surgery, were examined for defects. In the review, Zimmer found no problems with the materials, design or manufacture of the Durom Cup.
Zimmer Examined Clinical Data
Zimmer then reviewed 12 clinical sites in the United States and Europe. The chosen clinics had the highest patient volume for Durom Cup implants. More than 3,100 cases were analyzed, 1,300 of which were of U.S. patients.
Zimmer said it discovered that in U.S. sites where the proper surgical technique was used, the revision surgery rate was 1.5 percent. However, in sites that didn’t employ proper technique the rate could be as high as 5.7 percent.
Once its investigation was completed, Zimmer voluntarily recalled the Durom Cup from the U.S. market until it could re-label the product and provide additional training to orthopaedic surgeons on the proper positioning of the device. The recall lasted from July until August 2008, during which time the device remained in non-U.S. markets.
Orthopaedic Surgeons Report Cases of Device Failure
After the instances of reported failure of the Durom Cup were reported, the FDA detailed Dorr’s claims in its newsletter, MedSun. It discussed evidence from a total hip replacement using a Durom Cup, in this case a 50-mm acetabular component, metal-on-metal, with a 44-mm inner diameter and a 44-mm diameter metallic head.
The patient’s hip “never really got better.” It got worse in the two months after surgery. The woman had discomfort and remained on crutches after eight weeks, even though X-rays showed no change in the position of the construct including the cup and doctors noted no loosening of the device.
“This case confirms what Dr. Dorr wrote in his letter to the AAKHS that X-rays taken early on after surgery showed no evidence of loosening of the device; and that the surgeon had to rely on clinical indications that the device was changing position.”