MORE OF THE HELMET / CONCUSSION STORY Patrick J. Bishop, Ph.D., Professor Emeritus, University of Waterloo, Adjunct Professor, University of Ottawa

SOME THINGS WE ALREADY KNOW IMPORTANCE OF SIDE IMPACTS HELMETS AND CONCUSSIONS STANDARDS FOR HELMETS WHAT WE CAN DO NOW STAR RATING SYSTEM FOR HELMETS IMPACT SENSORS MORE OF THE STORY

SOME THINGS WE ALREADY KNOW Concussion is :  A Brain Injury  Involves White Matter Strain  Non-Catastrophic but Persistent  Related to Rotational Motion of the Head / Brain

ROTATION OF THE HEAD Three Planes of Rotation: Sagittal Plane---nodding yes Coronal Plane---lateral rotation Axial Plane---spinning Concussion Possible in Any Plane or Combination of Planes

HEAD CONTACT LOCATIONS AND CONCUSSION PROFESSIONAL FOOTBALL NFL STUDY (Pellman, et. al., 2003) HEAD / HEAD / GROUND, OBLIQUE TO FACE- MASK, SIDE / BACK OF HELMET COLLEGE FB, SOCCER, HOCKEY (Delaney, et. al., 2006) SIDE / TEMP. FOR FB, SOC, HELMET CONTACT IN FOOTBALL, FACE / JAW 33% of COLLEGE HOCKEY CONCUSSIONS N H L 85% TO THE SIDE OF THE HEAD

BEWARE OF SIDE IMPACTS AS ANGULAR MOTION APPROACHES THE CORONAL PLANE: THE EXTENT OF AXONAL INJURY INCREASES THE DURATION OF COMA INCREASES (Ommaya, A. and Gennarelli, 1984)

CONCUSSION SEVERITY PLAYERS WITH PROLONGED CONCUSSION SYMPTOMS Patrice Bergeron Marc Savard Justin Morneau Sidney Crosby Alex Charlebois KNOW WHERE THE PLAYER WAS STRUCK ! ! !

HELMETS AND CONCUSSIONS DEMANDS & LIMITATIONS OF SPORT HELMETS Mass---depends on the sport, from ~.6 to 1.2 Kg Liner---max thickness < 2 ~ 2.5 cm --- stiffness is crucial High Energy Collisions Single or Multiple Blows ? Removed or not Removed ? Pass “Mirror Test”---it looks like a _______ helmet REQUIRED TO PROTECT AGAINST FOCAL HEAD INJURY (AND EXPECTED TO PROTECT AGAINST CONCUSSION)

MODELING A HELMET LINER dF = k R dx, and dx = cdF where c = k -1 k R = (k 1 ∙ k 2 ) ∙ (k 1 + k 2 ) -1 k R < k 1 or k 2

WHY HELMETS DON’T WORK FOR CONCUSSION RISK REDUCTION INTENDED USE: Intervene on Focal Head Injury HOW EVALUATED ? Blunt Trauma Model by Drop Test of a Head-form CRITERION MEASURE Linear Acceleration Proper Metric for T B I Poor Metric for Concussion

LINEAR ACCELERATION Biomechanical Concerns Head Free of Constraint ? Blow Through Head C of M (occasionally) Brain Bulk Modulus is High (2,068 Mpa / 300,000 psi) Eccentric Blows ??? Brain Shear Modulus is Low (.07 Mpa / 10 psi)

CONCUSSION AND HELMETS Helmets of No Use Against Blows to Face Correlation Between L. Acceleration and Axonal Strain is Very Poor Concussion Related to Rotational Acceleration Need a New Metric that Relates Axonal Strain to Rotational Acceleration

STANDARDS FOR SPORT HELMETS C S A: Hockey, Skiing A S T M: Hockey, Skiing, Others NOCSAE: Football, Others C P S C: Cycling I S O/E N: Hockey, Skiing, Others REDUCED RISK OF FOCAL HEAD INJURY

WHAT ARE STANDARDS GROUPS DOING? Assume That Something Can Be Done Add a Test For Rotational Motion Head/Neck Form What to Measure How to Measure Threshold Limit Related to Strain Valid, Repeatable, Reproducible

WHAT CAN / MUST WE DO NOW?? Reduce Head Exposure in Sport Football: > 100 head hits / season Hockey: > 200 head hits / season Reduce “Contact” Practices / Week No Head Hits / Head Checking Good Neck Strength / Conditioning Helmets in Good Repair Helmets Fit Well and Properly Worn

VT STAR RATING FOR HELMETS Purports to Rate Helmets on Ability to Reduce Concussion Risk Football Helmets: Hockey Helmets:

PROBLEMS WITH STAR RATINGS FOOTBALL: Linear Acceleration as Criterion Measure Assessing C. R. Via a Drop Test Protocol Assessing C. R. in a Laboratory Test HOCKEY: Exposure Rates are very Suspect Test Protocol is for Board Hits --- not a major cause of Concussions in Hockey Assessing C. R. in a laboratory RESULTS OF STAR RATINGS Larger Helmets---Likely not a good thing! VT Ratings are not a substitute for CSA or NOCSAE

IMPACT SENSORS Claim to Measure Impact Severity in Sports Usually Attached to Helmet, sometimes inside Use Linear Acceleration Detectors Send Signals to Sidelines re “strength” of a Blow Problems With Sensors What are they measuring? What is the Threshold for Severity? Validity, Reliability, Reproducibility Issues Impact Frequency Counter?? Sensors are Not a Substitute for Expert Clinical Diagnosis of Concussion

CLOSING REMARKS Keep up the Concussion Fight ! Wear your Helmet ! Keep your stick on the ice ! Remember, “ some people can have all the lights on and still be in the dark”--- Maxine. Thanks for your kind attention.