New Infuse Study Contradicts Earlier Findings

Stanford, CAA bioengineered bone growth protein that has been used routinely in spinal fusions since 2002 has been linked to partial or permanent male sterility, according to a study posted today (May 25) online at The Spine Journal.

The finding, stemming from a study conducted by researchers at Stanford University, appears to contradict similar studies conducted by the protein's manufacturer, Medtronic.

The New York Times reported this morning that previously published reports regarding "Infuse" by researchers paid by the manufacturer noted that while male sterility was, indeed, indentified as a potential side effect, the referenced complication was attributed to surgical technique rather than the protein itself.

The findings of this latest study, headed by Stanford surgeon Dr. Eugene Carragee, suggests that the male sterility complication is linked to the product itself and at a higher rate of risk than previously identified—or when compared with men who underwent a more traditional means of anterior lumbar fusion, via a bone graft.

Carragee based his findings on a study of 240 of his patients treated with either bone graft or Infuse since 2002. Of 69 men who were treated with Infuse rather than bone graft, five developed a complication related to sterility. In contrast, only one patient out of 174 who received bone graft developed the complication.

Of the six, the sterility complication resolved itself in half of the patients.

The surgeons who conducted the original studies on behalf of Medtronic, defended their findings and stressed that their financial compensation from Medtronic—described in the Times article as reaching "millions of dollars" each—had no bearing on their findings.

Dr. Carragee, who also edits The Spine Journal, questioned why the original study authors failed to break out study participants between Infuse patients and those receiving bone grafts in a manner that in Carragee's view is the standard way to present clinical trial data.

One of the original study authors countered that in his view retrospective studies are of limited value.

"It is important that men who are considering having children have the opportunity to weigh the risks of the various available procedures," said Dr. Carragee, in comments published May 25 in The New York Times.