Evaluation of Gait and Slip Characteristics for Adults with Mental Retardation

Adults with mental retardation (MR) experience a greater number of falls than their non-disabled peers. To date, efforts to understand the causes for these falls have primarily involved qualitative studies that use largely subjective measures to quantify stability. Performing a more objective biomechanical gait analysis may better explain the reasons for these fall accidents and provide repeatable measures that can be used for comparison to determine the effectiveness of interventions intended to reduce slip-related falls. A gait analysis was conducted to quantify normal walking and slip response characteristics for adults with MR as well as a group of non-disabled ageand gender-matched peers. Kinetic and kinematic data were collected and a number of variables relating to gait pattern, slip propensity, and slip severity were calculated to compare the differences between groups. Results showed that adults with MR exhibit slower walking speeds, shorter step lengths, and greater knee flexion at heel contact suggesting that their gait patterns share more similarities with the elderly than with healthy adults of an equivalent age. Unexpectedly, the MR group demonstrated a lower required coefficient of friction (RCOF) and slower heel contact velocity which, alone, would suggest a reduced slip propensity as compared with the healthy group. A greater peak sliding heel velocity and greater slip distance measures, however, indicate greater slip severity for the MR group. The findings of this study suggest that falls in this population may be attributed to delayed response to slip perturbation as measured by slip distances. Evaluation of Gait and Slip Response in Adults with MR iii. ACKNOWLEDGEMENTS Thanks to Dr. Lockhart for his support and advice during my graduate career. Together weve met both obstacles and success, but each has been a learning experience which has helped me to become a better researcher. Id like to thank Prakriti Parijat and Jian Liu for all their help with data collection and for answering any questions I had about data analysis. Id like to extend a very special thank you to Karen Poe, Debbie Overfelt, and all the wonderful staff members at the Southwestern Virginia Training Center (SWVTC). Thank you for all your hard work in selecting and transporting the participants to and from Virginia Tech, and thank you for your continued cooperation and support. I greatly enjoyed working with everyone from SWVTC, and thanks to all the participants who made the trip from Hillsville, VA to be involved in this study. Many thanks also to Virginia Tech and the State of Virginia for funding this project, and thank you Dr. Michael Madigan and Dr. Gunnar Brolinson for serving on my committee. Id like to thank my family for their constant love and support. Mom, youve been my role model and my hero. Thank you for providing me with the opportunity to get an education and for encouraging me in my academics. Youve been more than a mother; youve been a great friend. I aspire to be the type of woman you are and hope that I am one day able to raise a family with as much love and care as youve given to all your kids. Dad, youve always expressed your love and pride. Thank you for your confidence in me. Rich, youve always treated me like your own daughter; I appreciate the bond weve shared and the active role youve played in my life. To my brothers and sisters: were a big, crazy brood and I wouldnt be the person I am without your individual influences. No matter where life might take me I know the one place Ill always belong and always be loved is at home with my family. Mom, Rich, Sarah, Nick, Little Nick, Kyrene, Lauren, Olivia, and Dad  I love you always. Also to the great friends Ive made here at Virginia Tech, youve been like a second family to me. I could not have been successful here without having you guys in my corner. Thank you all for your friendship, encouragement, advice, and, perhaps above all, your humor. Its hard to find friends who understand and accept you so wholly, and Ive been extremely fortunate to find several here at Virginia Tech. I wish each of you the best of luck in your professional and personal lives, and I thank you for all the memories weve made together. Evaluation of Gait and Slip Response in Adults with MR iv. Finally, thanks to my dog Cooper. He endured a lot of lonely nights during the writing of this thesis when I was too busy to play. Still, he always greeted me with excitement, served as a running buddy when I needed to work off some stress, and provided cuddle therapy when I was feeling discouraged. Hes a goofy but loyal companion and, whether he knows it or not, hes helped me with this academic achievement. Thanks the Coop! Evaluation of Gait and Slip Response in Adults with MR v. TABLE OF CONTENTS ABSTRACT ii ACKNOWLEDGEMENTS iii TABLE OF CONTENTS v LISTS OF TABLES vii LISTS OF FIGURES viii LISTS OF EQUATIONS ix ABBREVIATIONS x