RT Journal Article SR Electronic T1 A comparison of the shock-absorbing properties of cervical disc prosthesis bearing materials JF International Journal of Spine Surgery JO Int J Spine Surg FD International Society for the Advancement of Spine Surgery SP 48 OP 54 DO 10.1016/j.esas.2011.01.002 VO 5 IS 2 A1 Michael C. Dahl A1 Stephen Jacobsen A1 Newton Metcalf, Jr A1 Rick Sasso A1 Randal P. Ching YR 2011 UL http://ijssurgery.com//content/5/2/48.abstract AB Background Data Cervical arthroplasty offers theoretical advantages over traditional spinal fusion, including elimination of adjacent segment disease and elimination of the risk of pseudoarthrosis formation. Initial studies of cervical arthroplasty have shown promising results, however, the ideal design characteristics for disc replacement constructs have not been determined. The current study seeks to quantify the differences in the shock absorption characteristics of three commonly used materials in cervical disc arthroplasty.Methods Three different nucleus materials, polyurethane (PU), polyethylene (PE) and a titanium-alloy (Ti) were tested in a humidity- and temperature-controlled chamber. Ten of each nucleus type underwent three separate mechanical testing protocols to measure 1) dynamic stiffness, 2) quasi-static stiffness, 3) energy absorption, and 4) energy dissipation. The results were compared using analysis of variance.Results PU had the lowest mean dynamic stiffness (435 ± 13 N/mm, P < .0001) and highest energy absorption (19.4 ± 0.1 N/mm, P < .0001) of all three nucleus materials tested. PU was found to have significantly higher energy dissipation (viscous damping ratio 0.017 ± 0,001, P < .0001) than the PE or TI nuclei. PU had the lowest quasi-static stiffness (598 ± 23 N/mm, P < .0001) of the nucleus materials tested. A biphasic response curve was observed for all of the PU nuclei tests.Conclusions Polyurethane absorbs and dissipates more energy and is less stiff than either polyethylene or titanium.Level of Evidence Basic Science/Biomechanical Study.Clinical Relevance This study characterizes important differences in biomechanical properties of materials that are currently being used for different cervical disc prostheses.