By Anjali Athavaley
A small percentage of patients who received replacement knee surgeries using a type of component made by Zimmer Holdings Corp. (ZMH) experienced an unexpected problem that can lead to the destruction of the implant, according to the abstract of a single-center study to be presented at a medical meeting this week.
The study, conducted by researchers at the Mayo Clinic in Rochester, Minn., is scheduled to be presented Thursday at a meeting of the American Academy of Orthopaedic Surgeons. Researchers looked at 1,373 total knee replacements performed at the center between 2000 and 2011 using a Zimmer NexGen knee with a specific type of tibial component. According to the abstract, 3.9% of the knees failed for various reasons.
A problem where the implant becomes loose from the surrounding bone accounted for 50% of total failures. More than 80% of the failures associated with that problem occurred because of isolated debonding, where the implant comes loose from cement.
Isolated debonding has not been seen before with other implants used at the center. It is unclear how widespread the problem is.
"We have spoken to high-volume users of the system, and they haven't reported any similar events," said Garry Clark, a Zimmer spokesman. He said the component in question represents 1.2% of Zimmer's tibial sales.
Tao Levy, an analyst at Collins Stewart, said in a note that while the specific component doesn't generate a material amount of revenue for Zimmer, "we believe a greater understanding of the factors surrounding the unexpected failure mechanism ... is important in determining whether this is an irrelevant study or something more significant that may impact other components."
Zimmer shares fell a fraction in recent trading to $62.17. The stock is up 16.4% this year.
-By Anjali Athavaley, Dow Jones Newswires; 212-416-4912; firstname.lastname@example.org