Orthopedic surgeons have received hundreds of millions of dollars from joint implant manufacturers in recent years, according to a recent report.
In 2007, five device makers said they had paid surgeons more than $198 million, with 43 payments exceeding $1 million.
While the number of payments appears to have dropped since 2007, the average dollar amount has gone up, based on data from the three manufacturers that disclosed physician payments made in the last several years.
"There is a lot of money flowing back and forth," said Jason Hockenberry of Emory University, whose findings are published in the Archives of Internal Medicine.
Those financial ties represent anything from consulting fees to royalties to research support. Some argue they are necessary to drive medical innovations, but others fear they could end up harming patients as well.
Doctors getting industry money could be quicker to use implants from the companies paying them, for instance, or downplay the side effects of those products in their research.
The new results come as the U.S. Senate investigates whether surgeons paid by Medtronic, a medical device maker not included in the current study, failed to report sterility and other complications stemming from the company's bone-growth implant Infuse.
"There is evidence from other studies that these relationships drive practice one way or another," said Dr. Seth Leopold, of the University of Washington School of Medicine, who was not involved in the new work.
An orthopedic surgeon himself, Leopold chose to sever all ties to device makers in 2005.
"I felt there was no way I'd be able to convince people that these dollars did not affect my clinical decisions," he told Reuters Health.
After seeing the new report, Leopold added, he realized he was just "a smalltime guy."
Hockenberry's findings are based on data released after the five largest orthopedic implant makers -- Biomet Orthopedics, DePuy Orthopedics, Smith & Nephew, Stryker Orthopedics and Zimmer -- settled a kickback probe with the U.S. Department of Justice in 2007.
That year, the companies made more than 1,000 physician payments. In 2008, after the companies found out they'd have to disclose those relationships, the number fell by almost half.
But the three companies that continue to voluntarily disclose payments increased the amount of money they paid doctors by more than 40 percent between 2008 and 2010.
The mean, or mid-range, amount of individual payments also rose slightly, from $212,740 in 2007 to $233,108 in 2010.
"If you are concerned about your physician's loyalties you should by all means ask them," said Hockenberry, stressing that the majority don't have industry ties.
"The reality is, only four percent of all orthopedic surgeons are receiving funds," he said.
It is currently unclear what impact commercial relationships have on patient care. Hockenberry said he'd like to know more about the doctors who stopped taking industry money after the 2007 settlement and those who continued to do so.
"We would also love to be able to tie this to clinical practice," he said.
One way to do so would be to establish a universal device registry for all the implants patients get, so that it would be possible to look at the link between company payments and physician practice patterns.
According to the Patient Protection and Affordable Care Act passed last year, manufacturers must report payments of more than $10 by 2013, and this information will be freely available online.
But in an editorial on the new study, Dr. Robert Steinbrook of Yale School of Medicine in New Haven, Connecticut, said disclosure alone isn't enough.
"The disclosure of industry payments should not divert attention from the real issues with regard to conflict of interest," he writes.
"These are the minimization or elimination of financial ties between physicians and industry in areas other than research support, bona fide consulting related to basic and clinical research, and legitimate payments related to intellectual property. Although many well-publicized examples with regard to conflict of interest involve physicians in specific fields, such as orthopedics or psychiatry, the issues are similar for all specialties."