Date of Award

12-2006

Document Type

Thesis

Degree Name

Master of Science (MS)

Program

Biomedical Engineering

Research Advisor

Denis J. DiAngelo, Ph.D.

Committee

Richard Kasser, Ph.D., PT Michael Yen, Ph.D.

Keywords

cervical spine, two-level disc arthroplasty, two-level fusion, biomechanical testing

Abstract

In vitro biomechanical studies comparing two-level cervical disc arthroplasty with two-level fusion were completed using an established cadaveric cervical spine model. Three conditions were tested: non-instrumented, instrumented with two-level fusion (C5-C6 and C6-C7), and instrumented with two-level arthroplasty (C5-C6, C6-C7) using the Prestige Low-Profile (Medtronic Sofamor Danek, Memphis TN) or ProDisc-C (Synthes Spine, West Chester PA) prosthetic disc. Specimens were tested non-destructively in physiologic flexion-extension, lateral bending, and axial rotation to an end-limit load of 3-Nm or 45o rotation. Rotations at the superior, implanted, and inferior motion segment units (MSU) of the instrumented conditions were normalized to the non-instrumented condition and analyzed using one-way ANOVA and Student-Newman-Keuls test (p < 0.05). Two-level fusion significantly decreased motion at the implanted levels compared to the harvested condition and significantly increased motion at adjacent levels. The motion response at the implanted levels of the two-level Prestige did not significantly differ from the harvested condition, except in flexion, extension and combined flexion plus extension. The ProDisc-C prosthesis showed a similar motion response to the harvested condition at the implanted levels except in flexion, and left axial rotation. Upon direct comparison of the two devices, the Prestige-LP had significantly greater motion in extension and the ProDisc-C had significantly greater motion in axial rotation relative to the harvested condition. Differences in motion between the devices were due to differences within the mechanical designs. The Prestige-LP is a more mobile device in the anterior-posterior plane, which explains the increase in motion in extension, while the ProDisc-C prosthesis has a more constrained design. Overall, two-level disc arthroplasty maintained motion at the implanted levels and did not show a significant difference at adjacent levels, indicating two-level arthroplasty may be a viable alternative treatment for multi-level degenerative cervical disc disease.

DOI

10.21007/etd.cghs.2006.0111

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