Hey Doc do you own this joint?

A study by researchers at the University of Michigan and elsewhere found that doctors who own a piece of surgery centers are significantly more likely to perform a large number of operations than those without such an ownership stake. The researchers raised the possibility that ownership by doctors of surgery centers could result in unnecessary operations.

So, you might want to ask your doctor about his or her financial relationship with a center.

The researchers examined five common types of outpatient procedures – certain ear procedures, carpal tunnel releases, cataract excisions, colonoscopies, and knee arthroscopies – at surgery centers in Florida from 2003 through 2005.

In addition to correlating ownership interest in surgery centers with higher surgical volumes, the researchers wrote in the study published in the journal Health Affairs that "our data reveal that the acquisition of ownership status coincided with significant increases in a physician's use of carpal tunnel release, cataract excision, colonoscopy, and knee arthroscopy."

Because owning a stake in a center allows the doctors to share in profits, the researchers noted such arrangements create potential conflicts between patients' needs and surgeons' financial interests. And, they noted that between 2000 and 2007, the number of surgery centers eligible to get payments from the federal Medicare program rose 50 percent to 5,349.

"Insofar as physicians feel pressure to see their investment succeed, physician owners may lower their thresholds for intervention, exposing the health care system to the harms and additional costs associated with unnecessary treatment," the researchers wrote.