title: The performance of a hydrogel nucleus pulposus prosthesis in an ex vivo canine model.
abstract: A nucleus pulposus prosthesis (NPP) made of the hydrogel N-vinyl-2-pyrrolidinone copolymerized with 2-(4'-iodobenzoyl)-oxo-ethyl methacrylate has recently been developed. The special features of this NPP, i.e. intrinsic radiopacity and its ability to swell in situ to fill the nucleus cavity and restore disc height, were investigated ex vivo in canine spinal specimens. L7-S1 intervertebral discs were isolated from three canine spinal specimens, and the dimensions of the nuclei pulposi were measured. Based on these averaged measurements, the NPP prototype was made and inserted in its dry form (xerogel) into a canine cadaveric spinal segment and allowed to swell overnight at 38 degrees C. The integrity of the NPP and the filling of the nucleus cavity were assessed before and after swelling, using radiography, computed tomography, and magnetic resonance imaging. The ability of the NPP to restore disc height was assessed on radiographs of 10 spinal specimens. Thereafter the NPP was macroscopically assessed in situ by dissection of the spinal specimen. Both on imaging and macroscopically, 9/10 NPPs appeared to have a near perfect fit and disc height was restored in 8/10 spinal segments. The NPP may thus be an acceptable treatment option for low back patients meeting the requirements for NPP treatment.
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, PO Box 80.154, NL-3508 TD, Utrecht, The Netherlands. n.bergknut@uu.nl
authors.forename: Niklas
authors.initials: N
authors.lastname: Bergknut
authors.forename: Lucas A
authors.initials: LA
authors.lastname: Smolders
authors.forename: Leo H
authors.initials: LH
authors.lastname: Koole
authors.forename: George
authors.initials: G
authors.lastname: Voorhout
authors.forename: Ragnvi E
authors.initials: RE
authors.lastname: Hagman
authors.forename: Anne-Sofie
authors.initials: AS
authors.lastname: Lagerstedt
authors.forename: Ketie
authors.initials: K
authors.lastname: Saralidze
authors.forename: Herman A W
authors.initials: HA
authors.lastname: Hazewinkel
authors.forename: Albert J
authors.initials: AJ
authors.lastname: van der Veen
authors.forename: Björn P
authors.initials: BP
authors.lastname: Meij
mesh_terms: D000818:Animals; D004285:Dogs; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000494:pharmacology*; D020007:Implants, Experimental; D007403:Intervertebral Disc / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000473:pathology / Q000601:surgery; D008279:Magnetic Resonance Imaging; D023421:Models, Animal; D019919:Prosthesis Implantation; D014057:Tomography, X-Ray Computed
chemical_list: D020136:Hydrogel, Polyethylene Glycol Dimethacrylate