Four major intervertebral cages have been approved by the Food and Drug Administration (FDA) for use in humans: the Brantigan Interbody fusion Cage, the Ray Threaded Fusion Cage, the Bagby and Kuslich cage, and, most recently, the Trabecular Metal™ Cage. Comprised of 98 percent tantalum and 2 percent vitreous carbon, Trabecular Metal™ has the highest coefficient of friction of any implant material on the market, allowing for optimal initial implant-bone fit. Furthermore, the unique porous structure of Trabecular Metal™ provides significantly more space for tissue ingrowth to occur, facilitating a more cohesive implant-bone interface as well as long-term stability of the implant.