To win over the FDA, Johnson & Johnson set out to establish that Charite discs work at least as well as Bagby and Kuslich, or BAK, cages used in spinal fusions. But Rosen saw an immediate problem with the study design. "The stand-alone BAK is a failed operation; it hasn't been done in years," Rosen says. "So they picked the worst possible operation to compare these things to." Sarah Colamarino, a spokeswoman for the DePuy Spine unit of Johnson & Johnson, says the BAK was "the standard treatment for single-level degenerative disc disease" at the time the study began. Regardless, Rosen claims the company still failed to prove its case. An FDA transcript shows that the agency's own statistician portrayed the study as "strongly biased" in favor of Charite. The statistician also noted that the company had excluded important data about patients involved in the randomized clinical trials. Rosen, for one, wants to know exactly what happened to the first 71 patients who underwent disc replacements during the "training" part of the study. After formally requesting that information -- and being stonewalled -- he has yet to learn much beyond what surfaced during last year's FDA hearing. "It should be noted that the rate of adverse events was higher in the training subjects group compared to the randomized subjects in the study," Serio del Castillo, one of the FDA's lead reviewers for the disc, said during the hearing process. "However, please note that the training subjects were not included in the assessment of safety." Instead, Rosen says, Johnson & Johnson ignored the first patients who underwent the surgery -- a full 25% of the group -- and simply counted the later cases instead. Ranjan Gupta, an award-winning medical researcher who has landed major grants from the National Institutes of Health, sees reason for concern.