EPIDEMIOLOGY AND BIOMECHANICAL ANALYSIS OF FACIAL FRACTURES Joseph M Cormier Dissertation submitted to the faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy In Biomedical Engineering Committee Dr. Stefan M. Duma, Ph.D., Chair Dr. H. Clay Gabler, Ph.D., Co-chair Dr. James R. Funk, Ph.D. Dr. Michael L. Madigan, Ph.D. Dr. Joel D. Stitzel, Ph.D. February 6, 2009 Blacksburg, Virginia Keywords : face, risk, frontal, nasal, maxilla, mandible, FOCUS, NASS Copyright 2009, Joseph M. Cormier EPIDEMIOLOGY AND BIOMECHANICAL ANALYSIS OF FACIAL FRACTURES Joseph M Cormier (ABSTRACT ) The purpose of this dissertation is to examine the occurrence of facial fractures in automotive collisions and to determine the tolerance of the facial bones to blunt impact. The effects of restraint use, impact severity and impact direction on facial fractures were evaluated using the NASS-CDS database. The association between brain injury and facial fractures was also examined. The tolerance of the frontal bone, nasal bone, maxilla and mandible was determined using the flat surface of a cylindrical impactor. The influence of anthropometric measures and geometrical descriptors on the tolerance of the facial bones is also presented. The force-displacement response of each impacted region was also determined and response corridors were created. These corridors were used to evaluate the biofidelity of the FOCUS headform under the same impact conditions. Mathematical models were also created to predict the force and displacement resulting from facial impact. The data contained in this dissertation can be used to determine the risk of facial fracture as a function of impact force and evaluate the biofidelity of models simulating facial impact. ii ACKNOWLEDGEMENTS There are a lot of people who helped me through my doctorial career. At work, the employees at BRC were always supportive and willing to help in any way possible and at Virginia Tech the students and professors at the Center for Injury Biomechanics went out of their way to help me with my experiments and improve the analyses involved in the work. My advisor, Stefan Duma has been involved in my academic career since beginning my master’s degree. He has always wanted me to excel and without his support, I would not have made it through my doctorial pursuit. His support and guidance has helped make me a better researcher and will continue to help me throughout my career. Dr. Joel Stitzel has been an inspiration to me since working with him while obtaining my master’s degree. He has always been very willing to help and cared about the success of the other students as much as his own. I would like to thank the remainder of my committee, Dr. Michael Madigan, Dr. Clay Gabler and Dr. Jim Funk for their help in making the dissertation better and their willingness to take the time to help me during my graduate studies. Lastly, I owe a great deal of thanks to my friends and family for their continued support throughout my academic career. Especially my mom and sister for always giving me a reason to continue and look forward to the too few times we could see each other. Thank you very much for all your love and support. iii TABLE OF CONTENTS (Abstract)........................................................................................................................ii Acknowledgements........................................................................................................iii List of Figures..............................................................................................................viii List of Tables ...............................................................................................................xiii Chapter 1:......................................................................................................................1 The Epidemiology of Facial Injuries in Automotive Collisions ...................................1 Introduction.....................................................................................................................1 Methodology...................................................................................................................2 Results ............................................................................................................................4 Overall Trends.........................................................................................................4 Frontal Impacts........................................................................................................6 Injury Sources .........................................................................................................8 Risk of Facial Fracture...........................................................................................10 Side Impacts..........................................................................................................12 Injury Sources .......................................................................................................13 Risk of Facial Fracture...........................................................................................14 Discussion.....................................................................................................................16 Conclusions...................................................................................................................18 References.....................................................................................................................19 Chapter 2:....................................................................................................................20 The Relationship Between Facial Fractures and Brain Injuries in Automotive Collisions......................................................................................................................20 Introduction...................................................................................................................20 Methodology.................................................................................................................21 Results ..........................................................................................................................22 Overall Trends.......................................................................................................22 Frontal Impacts......................................................................................................23 Injury Sources .......................................................................................................25 Side Impacts..........................................................................................................29 Injury Sources .......................................................................................................31 Discussion.....................................................................................................................33 Conclusions...................................................................................................................34 References.....................................................................................................................36 Chapter 3:....................................................................................................................37 A Review of Studies Investigating Facial Tolerance ..................................................37 Introduction...................................................................................................................37 Literature Review..........................................................................................................38 Flat Impactors........................................................................................................38 Cylindrical Impactors ............................................................................................39 HIC Development..................................................................................................41 Methodology.................................................................................................................46 Analysis of HIC Development ...............................................................................47 Analysis of Facial Impact Studies ..........................................................................47 Results ..........................................................................................................................48 iv Facial Impact Studies.............................................................................................48 Frontal Bone..........................................................................................................48 Nasal Bone ............................................................................................................52 Maxilla ..................................................................................................................53 HIC Development Studies .....................................................................................55 Discussion.....................................................................................................................56 Conclusions...................................................................................................................58 References.....................................................................................................................62