Loading...

Design of a Novel Loading Mechanism for in Vitro Spine Testing

Sharif, Mohammad Reza | 2012

2534 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44461 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Parnianpour, Mohamad; Narimani, Roya
  7. Abstract:
  8. In this project, we use a novel mechanism to control the lumbar rotational profile and also the disc pressure of L3/L4 and L4/L5. Spine, as one of the most important parts of human musculoskeletal system, helps human beings to walk on two feet without much energy consumption. Any problem in this part may cause moving disorders or pain. To heal severe spine disorders, many different methods like surgery and implantation are adopted. To be sure of proper functionality in the human body, these methods should be tested clinically in advance. Cadaver spine testing in vitro, is accepted as a gold standard to evaluate new methods. One of the main challenges facing spine in vitro tests is how to reconstruct in the lab, the complex loading pattern in one’s body. Pure moment is the most important method of spine loading in vitro. But because of its disadvantages, i.e. incorrect intradiscal pressure, intervertebral rotation and instability, revising this method has been considered for at least the last 15 years. A follower load – a load which follows the spine curvature in order to remain perpendicular on all vertebrae - method has been proposed as a modification to solve for some of its problems, i.e. instability. However, even in follower load method the intervertebral rotation and intradiscal pressure are not similar to what happens in one’s body. So any method which can provide us true intervertebral rotation and intradiscal pressure has a great contribution to in vitro tests. In this project we develop almost conceptually a cable mechanism to help us control intervertebral rotations and intradiscal pressures of L3/L4 and L4/L5 to match measured data in vivo. Accordingly a simplified model of lumbar (L1/S1) has been constructed using MSC.Adams. Solving for inverse kinematics and equilibrium equations of the mechanism, the model is fed feed-forward control commands using Matlab. Simulation results were used to evaluate the suggested mechanism. Many different loading configurations were considered in this project whose results are reported. Also a modification for follower load method has been proposed. Our results show the capability of the suggested mechanism to control not only the intervertebral rotations, but also the intradiscal pressures, however, using a follower load beside this mechanism, helps to reduce cable forces
  9. Keywords:
  10. Lumbar Spine Portion ; Load Simulation ; Follower Load ; Cable Mechanism ; Physiologic Loading

 Digital Object List

 Bookmark

...see more