In an extraordinary move, a group of spine specialists are publicly repudiating the research of other experts that has backed the widespread use of a Medtronic bone growth product. In a series of reports published in a medical journal on Tuesday, the specialists called the research misleading and biased.

The repudiation, appearing in a full issue of The Spine Journal devoted to the topic, represents a watershed in the long-running debate over conflicts of interest for the sponsorship of scientific studies by makers of drugs and medical devices. It is extremely rare for researchers to publicly chastise colleagues, and editors of leading medical journals said they could not recall an instance in which a publication had dedicated an entire issue for such a singular purpose.

Medtronic, the nation’s biggest maker of medical devices, has been facing intensifying scrutiny over its promotion of Infuse, the bone growth product at the center of the controversy. The bioengineered material is used primarily in spinal fusions, a procedure in which spinal vertebrae are joined to reduce back pain.

Infuse is used in about a quarter of the estimated 432,000 spinal fusions performed in this country each year. The articles published on Tuesday charge that researchers with financial ties to Medtronic overstated Infuse’s benefits and vastly understated its risks by claiming there were none.