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.
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.
Original language | English |
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Pages (from-to) | 74-80 |
Number of pages | 7 |
Journal | Medical Engineering & Physics |
Volume | 41 |
Early online date | 31 Dec 2016 |
DOIs | |
Publication status | Published - Mar 2017 |
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Sabina Gheduzzi
- Department of Mechanical Engineering - Senior Lecturer
- Centre for Bioengineering & Biomedical Technologies (CBio)
- Centre for Integrated Materials, Processes & Structures (IMPS)
Person: Research & Teaching, Core staff, Affiliate staff
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Tony Miles
- Department of Mechanical Engineering - Professor Emeritus
Person: Honorary / Visiting Staff