Surgeons conducting clinical trials to test a Medtronic Inc bone-growth protein used in spine surgery, some of whom got at least $62 million from the company, failed to report serious complications in their research papers, the Wall Street Journal reported.

Fifteen of the surgeons got at least $62 million from the company over the past decade, the paper said, citing an analysis of Medtronic documents and disclosures on the company's website.

A new study in the Spine Journal said serious complications including cancer, sterility, infections, bone dissolution and worsened back and leg pain, occurred in 10 to 50 percent of patients who were administered Infuse or a sister product in 13 clinical trials funded by Medtronic and conducted by the surgeons between 2000 and 2010, the Wall Street Journal said.

These complications weren't reported in research papers the surgeons wrote on those trials, even though the papers were peer-reviewed, the study said.

A U.S. Senate committee is investigating whether surgeons who were paid consulting and other fees by Medtronic failed to note the complications of Infuse.

The company last week said the three main side effect concerns raised by the committee are listed as warnings on the product labels, as approved by the U.S. Food and Drug Administration.

In a statement, Omar Ishrak, Medtronic's chief executive, on Tuesday said the Spine Journal study does not raise questions about the data Medtronic submitted to the FDA in the approval process.

"Based on that data, we strongly believe that the safety profile reported to the FDA and summarized in the product label support the safe use of rhBMP-2 for the identified indications," he said. The company will continue to investigate questions surrounding researchers' potential conflicts of interest and refine policies as needed, he said.

A company spokesman declined additional comment.