Date of Award

5-2009

Document Type

Thesis

Degree Name

Master of Science (MS)

Program

Biomedical Engineering and Imaging

Research Advisor

Denis DiAngelo, Ph.D.

Committee

Denis DiAngelo, Ph.D. Brian Kelly, Ph.D. Gladius Lewis, Ph.D.

Keywords

biomechanics, spine, disc replacement

Abstract

Surgical options for lumbar spinal disorders are rapidly expanding. One seemingly promising area is the lumbar disc replacement. Design specifications vary among the manufacturers based upon differing perceptions of ideal motion. Comparison studies are important in quantifying different features for future improvements but are currently lacking. The objective of this study was to compare the biomechanical properties of three currently available treatments: disc replacement with ProDisc-L, disc replacement with Maverick, and a pedicle screw fixation. It was hypothesized that structural designs differences of ProDisc-L and Maverick could be distinguished in both motion and loading patterns. It was also hypothesized that either disc replacements offered preservation of harvested motion at all motion levels whereas the pedicle screw fixation would not. Using a previously established non-destructive testing protocol, measurements of motion and flexibility were obtained. Seven human cadaver lumbar spines (L1-S1) were tested in flexion, extension, left and right lateral bending, and left and right axial rotation. Testing conditions, in order, were the harvested state, ProDisc-L at L5-S1, Maverick at L5-S1, and a pedicle screw fixation at L5-S1. ProDisc-L was less flexible than Maverick in flexion but otherwise similar. ProDisc-L and Maverick did not offer any differences in percent rotation contribution compared to the harvested state. Pedicle screw fixation both decreased the operative level and increased adjacent level rotation in flexion-extension and axial rotation. ProDisc-L and Maverick represent a similar class of disc replacements. The two devices are expected to offer similar outcomes in patients while fixation cannot.

DOI

10.21007/etd.cghs.2009.0356

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