Louisiana Tech University Louisiana Tech Digital Commons Doctoral Dissertations Graduate School Winter 2007 Understanding standing Christopher Storey Louisiana Tech University Follow this and additional works at: https://digitalcommons.latech.edu/dissertations Part of the Biomedical Engineering and Bioengineering Commons Recommended Citation Storey, Christopher, "" (2007). Dissertation. 545. https://digitalcommons.latech.edu/dissertations/545 This Dissertation is brought to you for free and open access by the Graduate School at Louisiana Tech Digital Commons. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of Louisiana Tech Digital Commons. For more information, please contact [email protected]. UNDERSTANDING STANDING by Christopher Storey, BS MS A Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy College of Engineering and Science Louisiana Tech University March 2007 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. UMI Number: 3259725 Copyright 2007 by Storey, Christopher All rights reserved. INFORMATION TO USERS The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleed-through, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. ® UMI UMI Microform 3259725 Copyright 2007 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, Ml 48106-1346 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LOUISIANA TECH UNIVERSITY THE GRADUATE SCHOOL 12/11/2006_____________________ Date We hereby recommend that the dissertation prepared under our supervision by Christopher Michael Storev _____________________________________________________ entitled Understanding Standing _____________________________________________________________ be accepted in partial fulfillment of the requirements for the Degree of Doctorate of Philosophy in Biomedical Engineering ___________________________________________ Supervisor of Dissertation Research / Head of Department QWrrtedtcctl /v?c/U'tesMc Department Recommi tion concurred in: Advisory Committee Director of Graduate Studies lean of me Graduate School H V Dean of the College GS Form 13 (5/03) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ABSTRACT Research Objectives: Psychophysical acceleration threshold is a tool for detecting deficits in dynamic postural control. Our lab has shown differences in the acceleration threshold among young adults, elderly adults, and elderly adults with diabetes. Electromyography, Semmes-Weinstein monofilaments, and hearing tests investigate the underlying physiological mechanisms for the detriments in postural control. Due to peri- sway perturbations, the motion of a person’s sway affects the signal to noise ratio for perturbed stance. Since increases in sway range accompany postural instabilities, sway entrainment will allow us to investigate changes in acceleration threshold at different points in sway. The center of pressure, observed for entrainment, only changes due to rotations about joints, specifically the ankle. The current method to model rotation about the ankle is a single orthogonal joint, and therefore inaccurate. Methods: The SLIP-FALLS-STEPm Platform has lead to the ability to accurately measure and observe interactions in the range of postural sway. The combination of the platform with other testing modalities such as camera tracking systems, force mats, and accelerometers will allow for a comprehensive testing scheme. The new scheme can be combined with the induced sway produced by a sub-threshold sinusoidal entrainment process. The nonorthogonal modelling is programmed in Matlab®. Results: For constant displacements, anterior accelerations thresholds via two- alternate forced choice (2AFC) showed differences in postural stability in mature, iii Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. iv diabetic individuals with peripheral neuropathy (DPN) and those who are neurally intact (DNI) compared to healthy mature adults (HMA), which corresponded with previous results of lateral perturbations. Both DNI and DPN had significantly higher thresholds for acceleration via 2AFC than HMA at 1 and 4 mm displacements (p < 0.01 and p<0.05) and Semmes-Weinstein monofilaments. For psychophysical amplitude threshold detection, we used our modified Single-Interval-Adjustment-Matrix to obtain amplitude thresholds for subthreshold frequency entrainment. Conclusion: The anterior acceleration thresholds show that peripheral neuropathy is not the sole cause for postural instability with diabetes. The ability to control the motion of sway will allow us to describe acceleration threshold throughout the range of sway. With a realistic ankle model, we will be able to better simulate postural dynamics. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. APPROVAL FOR SCHOLARLY DISSEMINATION The author grants to the Prescott Memorial Library o f Louisiana Tech University the right to reproduce, by appropriate methods, upon request, any or all portions o f this Dissertation. It is understood that “proper request” consists o f the agreement, on the part o f the requesting party, that said reproduction is for his personal use and that subsequent reproduction will not occur without written approval o f the author of this Dissertation. Further, any portions o f the Dissertation used in books, papers, and other works must be appropriately referenced to this Dissertation. Finally, the author of this Dissertation reserves the right to publish freely, in the literature, at any time, any or all portions o f this Dissertation. Author Date GS Form 14 (5/03) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. DEDICATION I would like to dedicate this work To my Family, and Noor who supported me throughout. vi Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OF CONTENTS ABSTRACT...........................................................................................................................iii DEDICATION.......................................................................................................................vi LIST OF TABLES.............................................................................................................. xiii LIST OF FIGURES............................................................................................................ xiv ACKNOWLEDGMENTS.................................................................................................xvii CHAPTER 1: INTRODUCTION/LITERATURE REVIEW............................................. 1 1.1 Balance................................................................................................1 1.2 Posture Studies ................................................................................... 2 1.3 Studying Standing .............................................................................. 3 1.4 Diabetes...............................................................................................3 1.4.1 Peripheral Neuropathy .............................................................3 1.4.2 Balance......................................................................................5 1.4.3 Hearing ....................................................... 5 1.5 Quantitative Analysis ......................................................................... 6 1.6 Sway Metrics ......................................................................................7 1.7 System Modulation ............................................................................ 8 1.8 Threshold Detection ...........................................................................9 1.9 Induced Sway ....................................................................................10 1.10 Posture Model ....................................................................................11 vii Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. viii CHAPTER 2: METHODS AND MATERIALS............................................................. 14 2.1 SLIP-FALLS-STEPm....................................................................... 14 2.1.1 Original SLIP-FALLS- STEPm System ...............................14 2.1.2 Platform ..................................................................................16 2.1.3 Controller ...............................................................................16 2.1.4 Computer-Controller Integration ..........................................17 2.2 Data Collection ................................................................................. 17 2.2.1 Calculations for ......................................................................17