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Citation |
Holsgrove TP, Miles AW, Gheduzzi S. Med. Eng. Phys. 2016; 41: 74-80. |
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Affiliation |
Centre for Orthopaedic Biomechanics, Department of Mechanical Engineering, University of Bath, Bath, BA1 7AY, UK. |
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Copyright |
(Copyright © 2016, Institute of Physics and Engineering in Medicine, Publisher Elsevier Publishing) |
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DOI |
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PMID |
28043781 |
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Abstract |
In-vitro testing protocols used for spine studies should replicate the in-vivo load environment as closely as possible. Unconstrained moments are regularly employed to test spinal specimens in-vitro, but applying such loads dynamically using an active six-axis testing system remains a challenge. The aim of this study was to assess the capability of a custom-developed spine simulator to apply dynamic unconstrained moments with an axial preload. Flexion-extension, lateral bending, and axial rotation were applied to an L5/L6 porcine specimen at 0.1 and 0.3Hz. Non-principal moments and shear forces were minimized using load control. A 500N axial load was applied prior to tests, and held stationary during testing to assess the effect of rotational motion on axial load. Non-principal loads were minimized to within the load cell noise-floor at 0.1Hz, and within two-times the load-cell noise-floor in all but two cases at 0.3Hz. The adoption of position control in axial compression-extension resulted in axial loads with qualitative similarities to in-vivo data. This study successfully applied dynamic, unconstrained moments with a physiological preload using a six-axis control system. Future studies will investigate the application of dynamic load vectors, multi-segment specimens, and assess the effect of injury and degeneration. Language: en |