Medtronic Infuse Bone Graft Linked to Sterility Problems for Men: Study

Stanford University researchers have found that side effects of Medtronic’s Infuse bone growth agent could be linked to sterility in male recipients. 

The findings of the study, published in The Spine Journal, contradict those of Medtronic-sponsored researchers in 2009, who blamed incidents of sterility involving the liquid bone graft on the techniques used by surgeons.

The findings of this latest study led the lead researcher, Dr. Eugene J. Carragee, who also edits The Spine Journal, to conclude that the problem probably lies with Medtronic Infuse itself.

Dr. Carragee looked at about 240 patients he performed an anterior lumbar fusion on several years ago. He found that he treated 69 of those patients with Medtronic Infuse and five of the men developed a complication known as retrograde ejaculation, where the semen is pumped into the bladder instead of the urethra, making the subject effectively sterile.

Of the 174 men he treated with a bone graft instead of with Infuse, only one man developed the problem. In half of the cases, the sterility problems were only temporary. However, the other three men may suffer permanent sterility.

Carragee concluded that his study, along with “multiple lines of evidence” from other sources strongly suggest that Medtronic Infuse side effects are linked to an increased risk of male sterility.

Infuse is a bioengineered bone morphogenetic protein (BMP) used to encourage bone growth and replace spinal disks by filling the gaps between vertebrae. It was approved by the FDA in 2002 and generated about $900 million in sales for Medtronic, the manufacturer, in the last fiscal year.

Some health care professionals have long suspected a link between Infuse and male sterility, but in 2009 researchers sponsored by Medtronic found no link. Their findings raised questions by other medical researchers, who pointed out that Medtronic paid them millions in consulting fees. Their study, which determined that male sterility in the anterior lumbar fusion surgeries were the fault of the doctors, failed at the time to identify which patients were given Infuse. They later revealed that out of the six cases of sterility, five of the men were treated with Infuse. The researchers claimed that the findings were not statistically significant, and say that Carragee’s sample size is too small to support his findings.

Other researchers and the FDA have also noticed an increased rate of male sterility among Medtronic Infuse patients. The FDA’s own clinical trials found that 6.4% of Infuse recipients suffered from retrograde ejaculation, compared to 1.4% of a control group. Carragee’s study indicated a rate of 6.7% sterility in the Infuse patients, compared with up to 1.6% in typical bone graft patients.

Sterility is just the latest complication associated with Infuse, which already has a warning about the risk of male sterility on the label. The BMP has also been associated with serious and life-threatening complications caused by airway compression when used “off-label” in the cervical spine.

A number of patients have had to receive respiratory support tracheotomies, insertion of feeding tubes, anti-inflammatory medications and additional surgery after experiencing problems with Medtronic Infuse after a cervical spine surgery. This has often been caused by swelling of the neck and led to an FDA warning to healthcare providers in July 2008 that highlighted at least 38 reports of cervical spine fusion problems with Infuse. Most of these Medtronic Infuse problems occurred within 2 to 14 days after surgery.