Effectiveness of Protective Equipment for the Prevention of Sports-Related Concussions in Youth

Transcription

1 Effectiveness of Protective Equipment for the Prevention of Sports-Related Concussions in Youth Stefan M. Duma, Steven Rowson, Joel Stitzel, Ray Daniel, Bryan Cobb, Tyler Young, Brock Strom, Craig McNally, Anna MacAlister, Gunnar Brolinson, Mike Goforth, Mark Rogers, John Shifflett, Alex Powers, Chris Whitlow, Jill Urban, Joseph Maldjian, Elizabeth Davenport Presented to the Institute of Medicine Committee Sport-Related Concussions in Youth February 25, Washington DC

2 VT WFU Brain Injury Research Team Virginia Tech Duma Rowson Daniel Cobb VT-VCOM / Sports Med MacAlister Young Strom McNally Brolinson Goforth Rogers Shifflett Wake Forest Stitzel Powers Whitlow Maldjian Urban Davenport

3 Financial Disclaimer No financial interest in SIMBEX, HITS, or any other helmet related sensor or product No financial interest in Riddell, or any helmet manufacturer No helmet expert witness consulting Speaking fees donated to buy new helmets for youth teams in south-west Virginia.

4 Funding Sources National Institutes of Health National Inst. Of Child Health & Human Development, R01HD Department of Transportation National Highway Traffic Safety Administration Department of Defense US Medical Research and Material Command Toyota Motor Corporation Toyota Central Research and Development Labs

5 Presentation Outline Part 1: Injury Biomechanics Background Reducing injuries in auto-safety by reducing risk Part 2: Three Fundamental Questions: Is head acceleration correlated to concussion risk? Do helmets differ in their ability to reduce head acceleration? Are there clinical data demonstrating differences in the ability of helmets to reduce concussion risk? Part 3: Youth Football Study Preliminary Data

6 Automobile Analogy

7 Federal Motor Vehicle Safety Standards (FMVSS) are pass / fail FMVSS 208 Frontal Impact FMVSS 214 Side Impact Fixed Barrier 30 mph 33.5 mph 20 mph MDB

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9 New Car Assessment Program(NCAP) NHTSA rates safety on 5 star scale 20 mph Fixed Barrier 35 mph Injury risk to the head, neck, chest, and femur frontal and side tests (rollover is ratio calculation) 38.5 mph Total Risk = 1 (1 Risk head )*(1 Risk neck ) *(1 Risk chest )*(1 Risk femur ) Overall risk = 5/12 * frontal + 4/12 * side + 3/12 * rollover

10 New Car Assessment Program (NCAP) NHTSA rates safety on 5 star scale Injury risk to the head, neck, chest, and Fixed Barrier femur are considered for frontal and side A star rating is assigned based the overall tests (rollover is ratio calculation) 20 mph risk of serious injury from all tests combined 35 mph A total injury risk for each testing configuration is computed Stars Each 2 overall injury risk 1 is weighted based on exposure and summed to compute overall risk 0% 10% 15% 20% 40% 100% Overall Risk 38.5 mph Total Risk = 1 (1 Risk head )*(1 Risk neck ) *(1 Risk chest )*(1 Risk femur ) Overall risk = 5/12 * frontal + 4/12 * side + 3/12 * rollover

11 ~1968 FMVSS 208 (pass/fail) ~1978 NCAP frontal (stars) 44,525 ~1997 NCAP side 33,808

12 We do not know 100% about everything, but know enough to make safety advances Active Research in all Current and Future Body Regions Head injury (HIC) Neck injury (Nij) Chest compression Abdomen Femur loads Pelvis Tibia Ankle complex

13 We do not know 100% about everything, but know enough to make safety advances Active Research in all Current and Future Body Regions Head injury (HIC) Neck injury (Nij) Accelerations Loads Injury Risk Chest compression Abdomen Femur loads Pelvis Tibia Ankle complex

14 Concussion Incidence Minimization Rule Changes 3 Strategies: Reduce exposure to head impact Rule changes Proper technique Most Effective Better Equipment Proper Technique + Reduce concussion risk for remaining head impacts Improve helmet design Fewest Concussions

15 Part 2: Three Fundamental Questions:

16 Age Definitions Generalized Football Values: League Rules May Vary Age IOM Youth Definition 21 Helmet Type: Youth Football Adult Football Level of Play: Elementary School Football Middle School Football High School Football 19 College Football 21 NFL 23

17 Is head acceleration correlated with concussion risk?

18 Experimental Concussion Research Cadaver Data Animal Data NFL Data Volunteer Data

19 Experimental Concussion Research Cadaver Data Animal Data NFL Data Volunteer Data 1954 Ford funds WSU 1961 Gurdjian, Lissner origin of WSTC 1966 Gadd: GSI or SI (General Motors) 1971 Versace: HIC (Ford) 1997 Mertz: scaling 2007 Hardy: brain strain and pressure

20 Risk of Skull Fracture Risk of AIS 4 Brain Injury Cadaver Data Mertz Scaling Data Risk of Skull Fracture Risk of AIS 4 Brain Injury HIC 15 =1000 = 16% HIC 15 =1000 = 17% HIC 15 = 700 = 5% HIC 15 = 700 = 4% ms HIC ms HIC (Mertz, 1997)

21 Cadaver Data Hardy: In Situ Brain Strain Football helmet impacts Linear and Rotational Accelerations Neutral Density Targets As accelerations increase, brain pressure and motion increase 5 mm Hardy et al (2007)

22 Experimental Concussion Research Cadaver Data Animal Data NFL Data Volunteer Data 1954 Ford funds WSU 1961 Gurdjian, Lissner origin of WSTC 1966 Gadd: GSI or SI (General Motors) 1971 Versace: HIC (Ford) 1997 Mertz: scaling 2007 Hardy: brain strain and pressure As linear acceleration increases, risk of injury increases. As linear and rotational acceleration increase, brain pressure and motion increase

23 Experimental Concussion Research Cadaver Data Animal Data NFL Data Volunteer Data 1954 Ford funds WSU 1961 Gurdjian, Lissner origin of WSTC Over 200 Primate tests performed in six sets from Gadd: GSI or SI (General Motors) 1966 Ommaya, Hirsch first primate tests 1971 Versace: HIC (Ford) 1997 Mertz: scaling 2007 Hardy: brain strain and pressure As linear acceleration increases, risk of injury increases. As linear and rotational acceleration increase, brain pressure and motion increase

24 Animal Data Summary of Six Sets of Primate Tests 1966 Ommaya, Hirsch Rotation alone could not cause concussion, needed impact 1980 Ono JARI Human Tolerance Curve Skull fracture and concussion curves 1971 Ommaya, Hirsch Rotation accounts for ½ of brain injury, linear accounts for the other half 1971 Gennarelli, Ommaya, Thibault linear and rotational acceleration relating to concussion 1972 Gennarelli, Thibault, Ommaya Rotation related to diffuse brain injury 1981 Gennarelli Directional dependence of brain injury 1982 Gennarelli, Thibault DAI and coma 1982 Gennarelli, Thibault Sub-dural hematoma 1985 Thibault, Gennarelli Rotation and diffuse brain injury 1971 Unterharnscheidt Both linear and rotational acceleration are important for brain injury 1983 Hodgson Higher linear and rotational acceleration associated with increase brain injury

25 Experimental Concussion Research Cadaver Data Animal Data NFL Data Volunteer Data 1954 Ford funds WSU 1961 Gurdjian, Lissner origin of WSTC Over 200 Primate tests performed in six sets from Gadd: GSI or SI (General Motors) 1971 Versace: HIC (Ford) 1997 Mertz: scaling 2007 Hardy: brain strain and pressure As linear acceleration increases, risk of injury increases Ommaya, Hirsch first primate tests More recent analysis: 1985 Ommaya:4500r/s2 concussion 1992 Margulies,Thibault DAI at 16,000 r/s Arbogast, and Margulies: properties 2003 Gennarelli: concussion values 2009 Davidsson: DAI As linear and rotational acceleration increase, brain pressure and motion increase

26 Rotational Velocity (rad/s) (Ommaya, 1985) Animal Data Ommaya: Tolerance to Concussion Scaled from Primates 10, Pulse Duration Time in ms ,000 Rhesus Monkey 100 Chimpanzee Man 10 1,000 10, ,000 1,000, Rotational Acceleration (rad/s 2 )

27 Rotational Acceleration (rad/s 2 ) Animal Data Gennarelli: Rotational Acceleration and Concussion Pure Sagittal Pure Lateral 30 Oblique None Mild Concussion Classical Concussion Severe Concussion Mild DAI Moderate DAI Severe DAI (Gennarelli, 1985; Gennarelli, 2003)

28 Animal Data Rotational Acceleration Comparison Concussion DAI NFL Volunteer DAI

29 Experimental Concussion Research Cadaver Data Animal Data NFL Data Volunteer Data 1954 Ford funds WSU 1961 Gurdjian, Lissner origin of WSTC Over 200 Primate tests performed in six sets from Gadd: GSI or SI (General Motors) 1971 Versace: HIC (Ford) 1997 Mertz: scaling 2007 Hardy: brain strain and pressure As linear acceleration increases, risk of injury increases. As linear and rotational acceleration increase, brain pressure and motion increase 1966 Ommaya, Hirsch first primate tests More recent analysis: 1985 Ommaya:4500r/s2 concussion 1992 Margulies,Thibault DAI at 16,000 r/s Arbogast, and Margulies: properties 2003 Gennarelli: concussion values 2009 Davidsson: DAI As linear and rotational accelerations increase, brain injury in primates increases

30 Experimental Concussion Research Cadaver Data Animal Data NFL Data Volunteer Data 1954 Ford funds WSU 1961 Gurdjian, Lissner origin of WSTC Over 200 Primate tests performed in six sets from Gadd: GSI or SI (General Motors) 1971 Versace: HIC (Ford) 1997 Mertz: scaling 2007 Hardy: brain strain and pressure As linear acceleration increases, risk of injury increases. As linear and rotational acceleration increase, brain pressure and motion increase 1966 Ommaya, Hirsch first primate tests More recent analysis: 1985 Ommaya:4500r/s2 concussion 1992 Margulies,Thibault DAI at 16,000 r/s Arbogast, and Margulies: properties 2003 Gennarelli: concussion values 2009 Davidsson: DAI As linear and rotational accelerations increase, brain injury in primates increases Mid-90s to present: extensive research utilizing dummy reconstructions and other evaluations 2003: Pellman, Viano HIII reconstructions 2003: King, analysis of tests with model

31 Injury Probability Injury Probability NFL Data (King, 2003) King: Linear and Rotational Acceleration 53 NFL Cases: 22 injury and 31 Non-injury P < P < Linear Acceleration (m/s 2 ) Angular Acceleration (rad/s 2 )

32 Concussion Injury Risk Concussion Injury Risk NFL Data Pellman: Linear and Rotational Acceleration 58 NFL Cases: 25 injury and 33 Non-injury P = P = Linear Acceleration (g) Rotational Acceleration (rad/s 2 ) Severity Index SI (Pellman, 2003)

33 Experimental Concussion Research Cadaver Data Animal Data NFL Data Volunteer Data 1954 Ford funds WSU 1961 Gurdjian, Lissner origin of WSTC Over 200 Primate tests performed in six sets from Gadd: GSI or SI (General Motors) 1971 Versace: HIC (Ford) 1997 Mertz: scaling 2007 Hardy: brain strain and pressure As linear acceleration increases, risk of injury increases. As linear and rotational acceleration increase, brain pressure and motion increase 1966 Ommaya, Hirsch first primate tests More recent analysis: 1985 Ommaya:4500r/s2 concussion 1992 Margulies,Thibault DAI at 16,000 r/s Arbogast, and Margulies: properties 2003 Gennarelli: concussion values 2009 Davidsson: DAI As linear and rotational accelerations increase, brain injury in primates increases Mid-90s to present: extensive research utilizing dummy reconstructions and other evaluations 2003: Pellman, Viano HIII reconstructions 2003: King, analysis of tests with model Linear and rotational accelerations are significantly correlated to concussion risk

34 Experimental Concussion Research Cadaver Data Animal Data NFL Data Volunteer Data 1954 Ford funds WSU 1961 Gurdjian, Lissner origin of WSTC Over 200 Primate tests performed in six sets from Gadd: GSI or SI (General Motors) 1971 Versace: HIC (Ford) 1997 Mertz: scaling 2007 Hardy: brain strain and pressure As linear acceleration increases, risk of injury increases Ommaya, Hirsch first primate tests More recent analysis: 1985 Ommaya:4500r/s2 concussion 1992 Margulies,Thibault DAI at 16,000 r/s Arbogast, and Margulies: properties 2003 Gennarelli: concussion values 2009 Davidsson: DAI Mid-90s to present: extensive research utilizing dummy reconstructions and other evaluations 2003: Pellman, Viano HIII reconstructions 2003: King, analysis of tests with model 2003 Present, instrumented high school and college football players As linear and rotational acceleration increase, brain pressure and motion increase As linear and rotational accelerations increase, brain injury in primates increases Linear and rotational accelerations are significantly correlated to concussion risk

35 Helmet Instrumentation Two parallel systems during past 10 years HIT System 6DOF Device (VT) Volunteer Data 6 Accelerometers mounted normal to the skull 3 Linear and Resultant Rotational Accelerations ~$1,000/helmet Validated by NFL, others 12 Accelerometers mounted tangential 3 Linear and 3 Rotational Accelerations (6DOF) ~$10,000/helmet Validates HIT System

36 Teams Using the HIT System Total Number of Impacts Collected at Virginia Tech Cumulative HITS Data Collection 200, , , , , ,000 80,000 60,000 40,000 20, Virginia Tech 195,000+ impacts recorded at Virginia Tech 2,000,000+ impacts recorded at all institutions Virginia Tech Virginia Tech Virginia Tech Virginia Tech Virginia Tech Virginia Tech Volunteer Data Virginia Tech Virginia Tech Virginia Tech North Carolina North Carolina North Carolina North Carolina North Carolina North Carolina North Carolina North Carolina North Carolina Oklahoma Oklahoma Oklahoma Oklahoma Oklahoma Oklahoma Oklahoma Oklahoma Oklahoma Dartmouth Dartmouth Dartmouth Dartmouth Dartmouth Dartmouth Dartmouth Dartmouth Arizona State Arizona State Brown Brown Brown Brown Brown Brown Indiana Indiana Indiana Indiana Indiana Indiana Indiana Illinois Minnesota Wake Forest Wake Forest 1 High School 5 High Schools 5 High Schools 2 High Schools 3 High Schools 4 High Schools 4 High Schools 4 High Schools 4 High Schools 1 Youth Team 5 Youth Teams

37 True Positive Rate True Positive Rate Rotational Acceleration (rad/s/s) True Positive Rate True Positive Rate Combined Linear and Rotational Risk Risk Contours 1% 50% 25% 10% 5% 75% 90% ROC Curves False False Positive Positive Rate Rate 1 Volunteer Data AUC = HITS Data 63,011 Impacts 244 Concussions Linear Acceleration (g) (Rowson and Duma, ABME, 2013) AUC = NFL Data 58 Impacts 25 Concussions False False Positive Positive Rate Rate

38 Linear Acceleration Comparison NFL Data 25 Concussions 98 +/- 27 g Volunteer Data 105 Concussions 105 +/- 27 g Two very different methodologies, resulting concussion values nearly identical Strong evidence in determination of accelerations involving concussions (Pellman, 2003; Broglio, 2010; Guskiewicz 2007, 2011; Mihalik, 2007; Rowson, 2011)

39 Rotational Acceleration Comparison Concussion DAI NFL Volunteer DAI

40 Experimental Concussion Research Cadaver Data Animal Data NFL Data Volunteer Data 1954 Ford funds WSU 1961 Gurdjian, Lissner origin of WSTC Over 200 Primate tests performed in six sets from Gadd: GSI or SI (General Motors) 1971 Versace: HIC (Ford) 1997 Mertz: scaling 2007 Hardy: brain strain and pressure As linear acceleration increases, risk of injury increases Ommaya, Hirsch first primate tests More recent analysis: 1985 Ommaya:4500r/s2 concussion 1992 Margulies,Thibault DAI at 16,000 r/s Arbogast, and Margulies: properties 2003 Gennarelli: concussion values 2009 Davidsson: DAI Mid-90s to present: extensive research utilizing dummy reconstructions and other evaluations 2003: Pellman, Viano HIII reconstructions 2003: King, analysis of tests with model 2003 Present, instrumented high school and college football players As linear and rotational acceleration increase, brain pressure and motion increase As linear and rotational accelerations increase, brain injury in primates increases Linear and rotational accelerations are significantly correlated to concussion risk Linear and rotational accelerations are significantly correlated to concussion risk

41 Is head acceleration correlated with concussion risk? Yes, as shown by the evidence.

42 Concussions and Head Impact NFL Data 25 Concussions 100% from head impact Volunteer Data 105 Concussions 100% from head impact Evidence clearly illustrates concussions are caused by head impacts Non-head impact related symptoms are very rare and not the primary problem (Pellman, 2003; Broglio, 2010; Guskiewicz 2007, 2011; Mihalik, 2007; Rowson, 2011)

43 Do helmets differ in their ability to reduce head acceleration?

44 NOCSAE Drop Test Linear acceleration only NOCSAE headform Various drop heights Various directions

45 Helmet Comparison: Top Impact from 60 inch Drop Height VS Adams A2000 Riddell Severity Index NOCSAE Pass / Fail Threshold Adams A2000 Riddell Peak Acceleration (g) Adams A2000 Riddell 360

46 Linear Impactor Style Test HIII Head and Neck Linear and Rotational Accelerations Various impact speed and directions

47 NFL Extensive Helmet Testing (Viano, 2006): 10 newer helmets compare against the standard VSR-4 Found 6%- 14% reduction in linear acceleration Found 10% - 23% reduction in rotational acceleration (Viano, 2011a): 2010 helmets compared to those in the 1970s Linear and rotational accelerations dramatically reduced, variation by helmet type (Viano, 2011b): Modern helmet performance 4 of 17 showed significant improvement in reduction of head accelerations

48 STAR Rating System for Football Helmets STAR: Summation of Tests for the Analysis of Risk 4 6 STAR E h R a L 1 H 1 Combines true impact exposure with an unbiased risk analysis using real world biomechanical data to assess helmet safety for consumers. (Rowson and Duma, 2011)

49 STAR Ratings of Current Helmets 5 Stars: Best Available Riddell 360 Rawlings Quantum Plus STAR Value: Cost: $ STAR Value: Cost: $ Stars: Good Rawlings Quantum Riddell Revolution IQ STAR Value: Cost: $ STAR Value: Cost: $ Riddell Revolution Speed STAR Value: Cost: $ Schutt Air XP STAR Value: Cost: $ Stars: Very Good Schutt ION 4D STAR Value: Cost: $ Stars: Adequate Xenith X2 STAR Value: Cost: $ Schutt DNA Pro + STAR Value: Cost: $ Schutt Air Advantage STAR Value: Cost: $ Rawlings Impulse Xenith X1 STAR Value: Cost: $ STAR Value: Cost: $ Star: Marginal Riddell VSR4 NR: Not Recommended STAR Value: Cost: Not Applicable Used helmets were tested to provide a reference Riddell Revolution STAR Value: Cost: $ Adams A2000 Pro Elite STAR Value: Cost: $

50 Do helmets differ in their ability to reduce head acceleration? Yes, as shown by the evidence.

51 Are there clinical data demonstrating differences in the ability of helmets to reduce concussion risk?

52 Compare Two Popular Helmets Riddell Revolution Riddell VSR4 Acceleration Metrics: NFL: Top group VT: 4 STARs (54% risk reduction) = > < Acceleration Metrics NFL: 2 nd Group VT: 1 STAR (Viano, 2011b; Rowson and Duma, 2011)

53 Clinical Evidence Part 1 Collins et al. (2006) Studied over 2141 high school players Revolution reduced risk of concussion by 31% Peer reviewed, 5 of 6 comments positive (p = 0.03) Primary criticism from Dr. Cantu s letter Older VSR4 helmets compared to newer Revolution helmets, and that older helmets test worse than newer This is not supported by any evidence: there are no publications or data sets that show older helmets are worse

54 Clinical Evidence Part 2 Rowson and Duma, 2012a 9 year study of Virginia Tech football players All new helmets Same team physician Controlled for exposure All helmets were instrumented with sensors 153,486 head impacts for 308 players Revolution reduced risk of concussion by 85% (p = 0.03) Eliminates only previous criticisms of the Collins work By accounting for exposure, more accurate comparison of helmet performance

55 Clinical Evidence Part 3 Current study, to be published in 2013 (Due to IOM copyright, cannot show all details) 13 college teams All instrumented to account for impact exposure All good/new equipment All have very good medical oversight Revolution significantly reduces the risk of concussion compared to the VSR4

56 Are there clinical data demonstrating differences in the ability of helmets to reduce concussion risk? Yes, as shown by the evidence.

57 5,000,000 Football Players in US NFL 2,000 Players College 100,000 Players High School 1,300,000 Players 6 to 13 years old 3,500,000 Players 70% of football players are between 6 and 13 years old

58 Four Youth Publications Pending (Due to IOM copyright, cannot show all details) Head Impact Exposure in Youth Football Part 1: Elementary School Ages 7 to 8 Years and the Effect of Returning Players Head Impact Exposure in Youth Football Part 2: Elementary School Ages 9 to 12 Years and the Effect of Practice Structure Head Impact Exposure in Youth Football Part 3: Middle School Ages 12 to 14 Years Head Impact Exposure in Youth Football Part 4: High School Ages 14 to 18 Years and Cumulative Impact Analysis Submitted, under review, expected to be published in 4 8 weeks.

59 VT-WFU Youth Study 6 8 Year Olds Auburn Mites 12 Instrumented Players 9 11 Year Olds Blacksburg Juniors 17 Instrumented Players Year Olds Blacksburg Middle School 12 Instrumented Players Age Year Olds South Fork Jr Pee Wee 22 Instrumented Players Year Olds South Fork Pee Wee 21 Instrumented Players Year Olds Ronald Wilson Reagan High School 40 Instrumented Players Head Impact Biomechanics Game and Practice Data Collection Cognitive Testing Pediatric ImPACT Testing for 12.5 years old and under Imaging Baseline, Injury, and Post-Season Instrumentation transmitted impact data to computer during play Helmets were instrumented for each game and practice Adult ImPACT Testing for 12.5 year old and over Linear and Rotational Head Acceleration Measurements FE Modeling for Tissue Response Investigating Correlations fmri: MEG:

60 HIT System Helmet Instrumentation Two parallel systems during past 10 years 6DOF Device (VT) 6 Accelerometers mounted normal to the skull 3 Linear and Resultant Rotational Accelerations ~$1,000/helmet Validated by NFL, others 12 Accelerometers mounted tangential 3 Linear and 3 Rotational Accelerations (6DOF) ~$10,000/helmet Validates HIT System

61 Child Head Acceleration Measurement Data collected wirelessly for every game and practice

62 Game Impact: 20g 40g Range

63 Practice Impact: 50g+ Impact

64 Pediatric Head Impact Data 6 8 Year Olds Auburn Mites 12 Instrumented Players 9 11 Year Olds Blacksburg Juniors 17 Instrumented Players Year Olds Blacksburg Middle School 12 Instrumented Players Age Year Olds South Fork Jr Pee Wee 22 Instrumented Players Year Olds South Fork Pee Wee 21 Instrumented Players Year Olds Ronald Wilson Reagan High School 40 Instrumented Players Players Impacts 50 th 95 th 3,061 11,978 3, instrumented players under 18 years old 16 g 34,96019 head g impacts recorded 21 g 8 players sustained concussions 37 g 46 g 60 g 16, g 58 g Injuries

65 Conclusions 1. Injury biomechanics involves reducing risk 2. Head acceleration is correlated to concussion risk 3. Helmets vary in their ability to reduce head acceleration 4. Helmets that reduce head acceleration result in lower risk of concussion on the field 5. Youth head impact exposure can be high, especially in practices Much more biomechanical research is needed relative to youth programs in three key areas: regulations, coaching, equipment

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69 Effectiveness of Protective Equipment for the Prevention of Sports-Related Concussions in Youth Stefan M. Duma, Steven Rowson, Joel Stitzel, Ray Daniel, Bryan Cobb, Tyler Young, Brock Strom, Craig McNally, Anna MacAlister, Gunnar Brolinson, Mike Goforth, Mark Rogers, John Shifflett, Alex Powers, Chris Whitlow, Jill Urban, Joseph Maldjian, Elizabeth Davenport Presented to the Institute of Medicine Committee Sport-Related Concussions in Youth February 25, Washington DC