Hettlich, Bianca F.Allen, Matthew J.Glucksman, Gabriela S.Fosgate, Geoffrey TheodoreLitsky, Alan S.2015-06-302015-06-302014-11Hettlich, BF, Allen, MJ, Glucksman, GS, Fosgate, GT & Litsky, AS 2014, 'Effect of an intervertebral disk spacer on stiffness after monocortical screw / polymethylmethacrylate fixation in simulated and cadaveric canine cervical vertebral columns', Veterinary Surgery, vol. 43, no. 8, pp. 988-994.0161-3499 (print)1532-950X (online)10.1111/j.1532-950X.2014.12165.xhttp://hdl.handle.net/2263/45811OBJECTIVE : To determine the biomechanical effect of an intervertebral spacer on construct stiffness in a PVC model and cadaveric canine cervical vertebral columns stabilized with monocortical screws/polymethylmethacrylate (PMMA). STUDY DESIGN : Biomechanical study. SAMPLE POPULATION : PVC pipe; cadaveric canine vertebral columns METHODS : PVC model – PVC pipe was used to create a gap model mimicking vertebral endplate orientation and disk space width of large-breed canine cervical vertebrae; 6 models had a 4-mm gap with no spacer (PVC group 1); 6 had a PVC pipe ring spacer filling the gap (PCV group 2). Animals – large breed cadaveric canine cervical vertebral columns (C2-C7) from skeletally mature dogs without (cadaveric group 1, n=6, historical data) and with an intervertebral disk spacer (cadaveric group 2, n=6) were used. All PVC models and cadaver specimens were instrumented with monocortical titanium screws/PMMA. Stiffness of the 2 PVC groups was compared in extension, flexion, and lateral bending using non-destructive 4- point bend testing. Stiffness testing in all 3 directions was performed of the unaltered C4-C5 vertebral motion unit in cadaveric spines and repeated after placement of an intervertebral cortical allograft ring and instrumentation. Data were compared using a linear mixed model approach that also incorporated data from previously tested spines with the same screw/PMMA construct but without disk spacer (cadaveric group 1). RESULTS : Addition of a spacer increased construct stiffness in both the PVC model (P< .001) and cadaveric vertebral columns (P<.001) compared to fixation without a spacer. CONCLUSIONS : Addition of an intervertebral spacer significantly increased construct stiffness of monocortical screw/PMMA fixation.en© 2014 by The American College of Veterinary Surgeons. This is the pre-peer reviewed version of the following article : Effect of an Intervertebral Disk Spacer on Stiffness After Monocortical Screw/Polymethylmethacrylate Fixation in Simulated and Cadaveric Canine Cervical Vertebral Columns, Veterinary Surgery, vol. 43, no. 8, pp. 988-994. 2014, doi :10.1111/j.1532-950X.2014.12165.x. The definite version is available at : http://onlinelibrary.wiley.comjournal/10.1111/(ISSN)1532-950XIntervertebral disk spacerStiffnessBiomechanical effectCadaveric canine cervical vertebral columnsMonocortical screwsPolymethylmethacrylate (PMMA)Postprint Article