An Introduction to Continuum Phenomena in Biomedical Engineering Eric A. Nauman, Ph.D., Director, HIRRT Laboratory

Transcription

1 An Introduction to Continuum Phenomena in Biomedical Engineering Eric A. Nauman, Ph.D., Director, HIRRT Laboratory School of Mechanical Engineering, Weldon School of Biomedical Engineering, Department of Basic Medical Sciences

2 A Brief History 1972 Moorhead, MN

3 A Brief History 1972 Moorhead, MN 1995 B.M.E. University of Delaware

4 A Brief History 1972 Moorhead, MN 1995 B.M.E. University of Delaware 1998 M.S. University of California, Berkeley 2000 Ph.D. University of California, Berkeley

5 A Brief History 1972 Moorhead, MN 1995 B.M.E. University of Delaware 1998 M.S. University of California, Berkeley 2000 Ph.D. University of California, Berkeley Assistant Professor of Biomedical Engineering Tulane University

6 A Brief History 1972 Moorhead, MN 1995 B.M.E. University of Delaware 1998 M.S. University of California, Berkeley 2000 Ph.D. University of California, Berkeley Assistant Professor of Biomedical Engineering Tulane University 2004 Present Assistant/Associate/Full Professor of Mechanical Engineering, Biomedical Engineering and BMS

7 Other things I do

8 The Eye is Even More Amazing Than You Think The eye focuses light on the retina which then uses biochemistry to transmit signals through the optic nerve head and on to the brain Visual processing requires about 30% of your cortext (compared to 8% for touch and 3% for hearing) There is a weak spot

9 The Lamina Cribrosa Holds the Back of the Eye Together Idealized models allow us to calculate the mechanical properties and mass transport characteristics of the tissue.

10 The Mechanics of the LC are Directly Related to Glaucoma

11 Bone Fractures and Ruptures of Tendons and Ligaments Not all bone fractures are traumatic but most of them are. There are lots of ways to hurt yourself.

12 Bone Fractures and Ruptures of Tendons and Ligaments Not all bone fractures are traumatic but most of them are There are lots of ways to hurt yourself

13 Basketball Injuries are Related to Head Injuries in Football? Kevin Ware Kevin Ware - High Definition

14 Tendon and Ligament Injuries!

15 Tendon and Ligament Injuries!

16 Tendon and Ligament Injuries!

17 Tendon and Ligament Injuries!

18 18 of 84 The Knee in Detail

19 Multi-scale Models of Vascular Transport for Drug Delivery Extravascular Flux Red Blood Cell Plasma Skimming Layer Cell Interstitial Space Intravascular Space Vessel Wall Extravascular Space 19

20 Let s Talk about Brain Injury Why is it important? Military Sports Motor Vehicle Collisions What can we do? Develop methods to detect, prevent, and treat TBI based on quantitative data and continuum level modeling

21 So Why Do We Study Football Players?

22 The Original Question Why do some players, who have similar magnitude and number of blows to the head, sustain concussions and others do not? What we learned Our current definitions of TBI need to be re-examined in light of advances in medical imaging.

23 Traumatic Brain Injury TBI Case Definition (CDC, 1995): Injury to the head with one or more of - Skull fracture, Concussion - Observed or self-reported decrease/loss of consciousness - Amnesia - Neurological or neuropsychological abnormality - Diagnosed intracranial lesion (hemorrhage, contusion, penetrating wound) - Death resulting from head trauma

24 Redefining Brain Injury On November 1, 2010, the world s perception of what constitutes traumatic brain injury began to change.

25 Traditional Concussion Mechanics

26 Concussion Biomechanics Not a contact phenomenon Brain does not hit cranial vault Rotational shear and pressure gradients Whiplash induces concussions (Ommaya 1968) Concussions without head motion (Gurdjian 1976) Frontal lobe (anterior fossa) a critical injury ROI in biomechanics and in CTE (Ommaya 1974; McKee 2009) Time Adapted from P.V. Bayly, et al. J Neurotrauma Aug; 22(8):

27 Concussion Biomechanics Focal Injury Coup/contrecoup phenomenon Primary axotomy & hematoma Diffuse injury Possibly a result of whole-brain shearing Rotational acceleration Tied to focal & diffuse injury Rotational strains may induce motor/ consciousness deficits Not reflected in any head injury criteria P.V. Bayly, et al. J Neurotrauma Aug; 22(8):

28 Imaging Quanti+ies Injury... P213 (Season 4) Symptoms Do Not Pre-Season P121 (Season 2) Concussion! (24 hrs) Normal Control Pre-Season Healthy

29 Football Helmet Telemetry Football: Helmet Impact Telemetry (HIT ) System (Simbex; Lebanon, NH) Measures six linear accelerations Approximates linear acceleration at head center of mass Approximates impact location Soccer: Prototype sensor (X2Impact, LLC; Seattle, WA) Concept similar to HIT System Image from Chicago Tribune, 6 October 2010

30 Concussed Players Exhibit Deficits in Multiple Locations

31 Scatter plot for COI+/FOI+ group

32 Scatter plot for COI-/FOI- group

33 Scatter plot for COI-/FOI+ group

34 Microstructural Models Must Account for Multiple Cell Types

35 What Do All These Problems Large Deformations Hierarchical Structure Fluids and Solids Interact (sometimes gases too) Multiaxial Have in Common? Nonlinear Constitutive Laws Need to Connect to Medical Imaging