Preliminary evaluation of new intrinsically radiopaque hydrogels for replacing the nucleus pulposus

Treatment of early degenerative disc disease can, in some cases, be accomplished through implantation of a synthetic prosthesis for the nucleus pulposus. This treatment is attractive, since the annulus fibrosus—as well as the function of the disc—is preserved. This study reports on two new synthetic hydrogels which were specifically designed as fully radiopaque prosthetic nucleus biomaterials. Moreover, the new materials were engineered in such a way that they swell in situ (i.e., after implantation) to such an extent that they will fill the entire nucleus cavity. We describe: (i) assessment of the biocompatibility of the new biomaterials in an in vivo animal model, (ii) implantation of the new prosthesis in an ex vivo animal model (porcine spine), followed by (iii) assessment of the visibility of the entire nucleus prosthesis through both CT and MRI. The results further substantiate the idea that the concept of implantation of a prosthesis for the nucleus pulposus can benefit from contemporary insights and developments of novel synthetic biomaterials with intrinsic radiopacity.