Why did surgeons apparently overlook complications linked to the Infuse Bone Graft in so many clinical trials? This is something that the Senate Finance Committee is currently investigating. Many surgeons received money from makers Medtronic Inc. for consulting and other work.

Senator Max Baucus, chairman of the Senate Finance Committee, said:

"Reports that doctors conducting medical trials while on Medtronic's payroll may have hidden serious side effects for patients are deeply troubling. We need to do everything we can to ensure companies aren't concealing serious medical complications from patients just to increase profits."

The Senate Committee has demanded an extensive list of documents, including financial communications and records between Medtronic and doctors. The company has been warned not to destroy any of the documents and their data, or make them inaccessible.

Infuse, also known as bone morphogenetic protein-2, is a bioengineered protein; it is used instead of real bone in a significant number of graft operations. It was approved by the FDA for limited purposes in 2002 - the fusing together of vertebrae in the lower spine, using a frontal approach. However, it is widely used for wider purposes (doctors are allowed to do this once a product has been approved). About 85% of Infuse use is off-label.

The US Department of Justice has been investigating Medtronic as a result of allegations of off-label marketing of Infuse.

According to Medtronic, Infuse has been implanted into over 500,000 patients and is used by approximately 2,300 surgeons in the USA.

A series of reports in Journal Sentinel/MedPage Today are said to have prompted the ongoing Senate inquiry. According to the reports, several complications linked to Infuse Bone Graft that occurred in Medtronic sponsored human trials between 2000 and 2009 were not reported.

Independent researchers at Stanford University found evidence of a link between Infuse and male sterility. Their findings were published in the Spine Journal.

Experts say the wider usage of Infuse Bone Graft has occurred in large part thanks to the papers that did not report complications.

Apparently, tens of millions of dollars have been paid by Medtronic over the last ten years to spinal surgeons and authors of reports in royalty payments and consulting fees.

In 2008, the FDA issued a safety alert concerning the use of Infuse Bone Graft in the neck. However, it is still widely used in surgeries of the lumbar spine.

When Infuse came onto the market, doctors no longer needed to harvest bones from patients' hips, resulting in an increase in the number of spinal fusion procedures - a 15-fold increase from 2002 to 2007, according to a JAMA study.

Medtronic says its product labeling warns of three complications - abnormal bone growth, swelling in the neck and throat, and sterility in males.

Written by Christian Nordqvist