Fig. 2

X-ray of the implant inserted between C5 and C6. As this x-ray shows, most of the implant, being made of radiolucent PEEK, cannot be seen on the x-ray. But two of the four vertical tantalum pins can be seen here (the two vertical lines connecting the C5 and C6 vertebral bodies); they serve to indicate the position of the implant on x-rays. Along the edge of the endplates of the vertebral bodies, we can also see two wavy lines, which are the titanium coating of the toothed top and bottom surfaces of the implant. This image thus illustrates how thin the coating of titanium is, and how it follows the form of the implant’s toothed top and bottom surfaces. The small insert is an electron-microscope image (provided by the implant manufacturer), which shows the titanium coating from another specimen of this same model of implant used in the study