Is it the device or the technique?

Those days are gone. Dr. Berger started complaining to Zimmer a while back that one of its artificial-knee models was failing prematurely, and he went public recently with a study that he says proves it. Zimmer told him that the problem was not the artificial knee, but his technique, and pointed to data overseas indicating that the knee was safe.


Last year, Zimmer did not give Dr. Berger a new contract. The company says it routinely rotates consultants.

“I trained hundreds of doctors for them and made them tens of millions,” Dr. Berger said in interview here, in which he also lambasted Zimmer executives as dissembling, out-of-touch bureaucrats. “So was this just a coincidence? Maybe it was. Maybe it wasn’t.”...

Amid the booming use of artificial joints in the United States, the breakup between Dr. Berger and Zimmer highlights what experts say is a troubling situation for patients and doctors: when disputes arise about orthopedic implant safety, there are no independent referees or sources of information because no one tracks the performance of the devices.

“There is no way of knowing who is right because we don’t have the data,” said Dr. Kevin J. Bozic, a professor of orthopedic surgery at the University of California, San Francisco....

While producers of implanted heart devices have a voluntary system in which outside panels investigate problems, American makers of orthopedic devices do not. Many of the artificial joints that surgeons like Dr. Berger use, including the Zimmer knee at issue, are cleared under law by the Food and Drug Administration for sale without testing in patients. In addition, no one in the country tracks the long-term performance of artificial hips and knees, a $6.7 billion annual business that surged as baby boomers reached middle age....

As he tells it, his relationship with Zimmer frayed over a version of a widely used Zimmer knee, known as the NexGen. The model at issue, called the NexGen CR-Flex, is designed to provide a greater range of motion than the standard NexGen.

Most surgeons implant an artificial knee using a cement-like adhesive to bond the thigh bone to the portion of the device that bends. But some specialists, like Dr. Berger, try to avoid adhesives because the cement can break down and cause device failure. So Zimmer also sells an uncemented version of the CR-Flex that relies instead on the bone naturally fusing with the implant.

-Surgeon vs. Knee Maker: Who’s Rejecting Whom?