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A continuous pure moment loading apparatus for biomechanical testing of multi-segment spine specimens
J T Lysack1, J P Dickey, G A Dumas
1Department of Surgery, Division of Orthopaedics and Clinical Mechanics Group, Queen's University, Kingston, Ontario, Canada. 3jtl@qlink.queensu.ca
Abstract:
An apparatus is described that enables the application of continuous pure moment loads to multi-segment spine specimens. This loading apparatus allows continuous cycling of the spine between specified flexion and extension (or right and left lateral bending) maximum load endpoints. Using a six-degree-of-freedom load cell and three-dimensional optoelectronic stereophotogrammetry, characteristic displacement versus load hysteresis curves can be generated and analyzed for different spinal constructs of interest. Unlike quasi-static loading, the use of continuous loading permits the analysis of the spine's behaviour within the neutral zone. This information is of particular clinical significance given that the instability of a spinal segment is related to its flexibility within the neutral zone. Representative curves for the porcine lumbar spine in flexion-extension and lateral bending are presented to illustrate the capabilities of this system.