Letters to the Editor: Football helmet design and concussion

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To The Editor We find it astonishing that JNSPG continues to publish articles on football concussion that only serve to retard scientific progress (Rowson S, Duma SM, Greenwald RM, et al: Can helmet design reduce the risk of concussion in football? Technical note. J Neurosurg 120:919–922, April 2014).2 It is obvious that the reviewers were more impressed by statistics than inspecting the data that produced these findings.

The notion that Division I college football programs are roughly equivalent is laughable. The two Ivy League schools, Brown and Dartmouth, play 25.83% fewer games than Virginia Tech or Oklahoma. The latter two schools would be better compared to NFL teams, as each had/has a style and intensity of play that is consistent with professional teams.

In that light, the lack of recorded concussions should have been a red flag. The teams studied reported 1.33 concussions per team per year and averaged 0.11 concussions per game. While the authors suggest the rate of concussion is consistent with that of Division I schools, it simply betrays that most NCAA schools fail to report concussions, not that this sample had any validity. During the same period, the NFL, an organization not noted for its willingness to record concussions, documented more than 3 times the incidence of concussion than this sample.

The authors also represent that this is not an epidemiological study but rather an unbiased retrospective product comparison. In this light, the authors claimed the data were controlled for exposure. Given that star players and starters are more likely to be provisioned more modern equipment, and coaches promote policies intended to keep these highly valuable players on the field (especially in revenue-generating programs), it would clearly bias the results toward the Revolution helmet. Stars and starters have more exposure but would be less likely to record a concussion.

One must also consider the differences in product design with respect to the accommodation of sensors. The VSR4 was designed in the 1980s, long before sensors were considered by helmet manufacturers as a product extension. The Revolution was designed concurrently with the Head Impact Telemetry System (HITS) and might have been conceived to allow the introduction of sensors with-out affecting the helmet's fit. Torg and colleagues have reported that a helmet's fit, as opposed to its design or age, explains differences in the number of recorded concussions (JS Torg et al., presented at the American Academy of Orthopedic Surgeons Specialty Day, February 11, 2012).

Furthermore, we find it disturbing that engineers, who are well represented among the authors, would claim that simply thickening the outer shell of the helmet would reduce the forces generated by tackling. It is reminiscent of 1950s and 1960s automobile designers who increased the weight of vehicles and stiffened car bodies in the mistaken belief that these measures would enhance safety. Instead, the efforts resulted in more and more serious injuries from traffic accidents. Might we expect athletes to engage in more aggressive behavior, based upon the belief that a particular helmet mitigates the risk of a brain injury, whether true or not? The force needs to be dissipated. Is it transmitted into the head, neck, and spine? What are the long-term health consequences? Should we expect more long-term neurological afflictions based on poor quality studies endorsing so-called concussion mitigation technologies?

Finally, it is distressing that the authors suggest that this study confirms the findings of two earlier studies. Confirming results of two poorly conducted experiments merely demonstrates some degree of precision, not accuracy. In fact, the Collins paper referenced in the article has been subject to inquiry by the members of the US Senate.1 Years after Riddell promoted the sale of the Revolution helmet based on this study, governmental scrutiny compelled coauthor Joseph Maroon and UPMC to state that the findings were misrepresented and to distance themselves from the results.

We find it difficult to believe that the authors can make any claims regarding a difference in the risk of concussion between these two products. Given this study's obvious lack of rigor, JNSPG reviewers should have been far more critical of this study, as it will be used as a means of promoting the sale of expensive new products.

Disclosure

The authors report no conflict of interest.

References

  • 1

    Collins MLovell MRIverson GLIde TMaroon J: Examining concussion rates and return to play in high school football players wearing newer helmet technology: a three-year prospective cohort study. Neurosurgery 58:2752862006

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  • 2

    Rowson SDuma SMGreenwald RMBeckwith JGChu JJGuskiewicz KM: Can helmet design reduce the risk of concussion in football? Technical note. J Neurosurg 120:9199222014

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Keywords:

Response

We appreciate Mr. Comrie's and Mr. Morey's interest in our study and their thoughts on the role helmets play in reducing concussion risk in football players. With this response, we simply aim to address inaccurate statements in their letter.

Mr. Comrie and Mr. Morey are wrong in their various statements suggesting the data set is not valid for addressing this and other important scientific questions. This research has been ongoing for over a decade, has been extensively published in peer-reviewed journals, and is both consistent and complementary to historical biomechanical studies evaluating protective equipment and head injury.1–5,9–11,13,14,16,17,19,24 The medical staff at each institution actively participated in this research, and the concussion rates reported are supported by epidemiological studies on athletes with similar demographic characteristics.15 It is simply not accurate to suggest that the concussion rate in collegiate football should be the same as the NFL.

Mr. Comrie and Mr. Morey are wrong in their descriptions of the design process and timeline of the two helmet types. The VSR4 was introduced in 1993 and the Revolution was introduced in 2002. The initial HITS design was first implemented in 2003 and was compatible with VSR4 helmets.11 As Revolution helmets became widely available, a new HITS model was created and made available for use in 2005. Neither helmet was initially designed with the intention to incorporate helmet instrumentation; rather, HITS was developed to fit within existing helmet space without affecting helmet fitment or performance. Our study period (2005–2010) spanned the time when both instrumented helmet types were regularly in use.

Mr. Comrie and Mr. Morey are wrong in pointing to a helmet's fit explaining differences in the number of recorded concussions. Not a single study in a peer-reviewed journal has found a helmet's fit to influence concussion rates. However, over 60 years of research within the injury biomechanics community has shown that as head acceleration decreases, the risk of brain injury decreases.12,16,22 The risk of concussion and head acceleration also correlate strongly in our on-field head-impact data.20,21,23

Mr. Comrie and Mr. Morey are wrong in implying that we reported any data regarding a thicker shell and that the Revolution has a thicker shell than the VSR4. In fact, the Revolution shell is thinner than the VSR4. Moreover, the key design differences are the increased padding and the optimized shell geometry in the Revolution compared to the VSR4. Laboratory tests and on-field head-impact data clearly demonstrate differences in the ability of helmets to reduce head acceleration resulting from impact. Helmets that better modulate impact energy transfer to the head, reduce head acceleration, and, as a result, reduce concussion risk.

Mr. Comrie and Mr. Morey are wrong in their automotive analogy suggesting that design cannot be optimized to reduce concussion risk. It is ironic that they bring up this analogy given our extensive background in automobile safety. Contrary to what Mr. Comrie and Mr. Morey claim, stiffening vehicle structures and optimizing design have led to steady reductions in fatality rates associated with motor vehicle crashes for almost 50 years.18

Mr. Comrie and Mr. Morey are wrong in their interpretation of the US Senate inquiry into the Collins et al. 2006 study.7 The Federal Trade Commission (FTC) did open an investigation into Riddell's promotional materials based on that study; however, after extensively reviewing and analyzing the underlying science, the FTC closed the investigation and took no action. We can only interpret this to mean that the FTC found no reason to refute the science in the Collins et al. 2006 study.

In summary, the purpose of our study was not to identify any specific helmet as being superior, but to answer the general question of whether or not helmet design can influence concussion rates in football. This question was addressed by performing a retrospective analysis on a preexisting dataset that consisted of head-impact data paired with clinical data on diagnosed concussions from 8 separate institutions. Like all scientific studies, there are of course limitations and we clearly acknowledge these in our article. However, our study presents the best available data for answering this timely and important question. Accounting for the number of head impacts that players experienced in each helmet is critical to accurately assessing concussion rates by helmet type, and it addresses major limitations of previous and emerging studies investigating this topic. The data presented in our study clearly indicate that advancing helmet design plays a role in reducing concussion rates in football.

Helmet design is just one part of a multipronged approach to minimizing concussions in football. Rule and regulation changes are perhaps most important, as they will limit the number of head impacts in football.6,8 When incidental head impacts do occur, having the best head protection available will further reduce risk. Going back to the automobile safety analogy, this is similar to requiring seatbelt use and mandating airbags in all vehicles, in addition to optimizing vehicle structure. Together, efforts like these have continued to reduce traffic-related fatalities in the US. The same can be done for concussions in football.

References

  • 1

    Beckwith JGGreenwald RMChu JJCrisco JJRowson SDuma SM: Head impact exposure sustained by football players on days of diagnosed concussion. Med Sci Sports Exerc 45:7377462013

    • Search Google Scholar
    • Export Citation
  • 2

    Beckwith JGGreenwald RMChu JJCrisco JJRowson SDuma SM: Timing of concussion diagnosis is related to head impact exposure prior to injury. Med Sci Sports Exerc 45:7477542013

    • Search Google Scholar
    • Export Citation
  • 3

    Broglio SPSchnebel BSosnoff JJShin SFend XHe X: Biomechanical properties of concussions in high school football. Med Sci Sports Exerc 42:206420712010

    • Search Google Scholar
    • Export Citation
  • 4

    Broglio SPSurma TAshton-Miller JA: High school and collegiate football athlete concussions: a biomechanical review. Ann Biomed Eng 40:37462012

    • Search Google Scholar
    • Export Citation
  • 5

    Brolinson PGManoogian SMcNeely DGoforth MGreenwald RDuma S: Analysis of linear head accelerations from collegiate football impacts. Curr Sports Med Rep 5:23282006

    • Search Google Scholar
    • Export Citation
  • 6

    Cobb BRUrban JEDavenport EMRowson SDuma SMMaldjian JA: Head impact exposure in youth football: elementary school ages 9–12 years and the effect of practice structure. Ann Biomed Eng 41:246324732013

    • Search Google Scholar
    • Export Citation
  • 7

    Collins MLovell MRIverson GLIde TMaroon J: Examining concussion rates and return to play in high school football players wearing newer helmet technology: a three-year prospective cohort study. Neurosurgery 58:2752862006

    • Search Google Scholar
    • Export Citation
  • 8

    Crisco JJGreenwald RM: Let's get the head further out of the game: a proposal for reducing brain injuries in helmeted contact sports. Curr Sports Med Rep 10:792011

    • Search Google Scholar
    • Export Citation
  • 9

    Crisco JJWilcox BJBeckwith JGChu JJDuhaime ACRowson S: Head impact exposure in collegiate football players. J Biomech 44:267326782011

    • Search Google Scholar
    • Export Citation
  • 10

    Crisco JJWilcox BJMachan JTMcAllister TWDuhaime ACDuma SM: Magnitude of head impact exposures in individual collegiate football players. J Appl Biomech 28:1741832012

    • Search Google Scholar
    • Export Citation
  • 11

    Duma SMManoogian SJBussone WRBrolinson PGGoforth MWDonnenwerth JJ: Analysis of real-time head accelerations in collegiate football players. Clin J Sport Med 15:382005

    • Search Google Scholar
    • Export Citation
  • 12

    Duma SMRowson SThe biomechanics of concussion: 60 years of experimental research. Slobounov SMSebastianelli WJ: Concussions in Athletics New YorkSpringer2014. 115137

    • Search Google Scholar
    • Export Citation
  • 13

    Duma SMRowson S: Past, present, and future of head injury research. Exerc Sport Sci Rev 39:232011. (Letter)

  • 14

    Guskiewicz KMMihalik JPShankar VMarshall SWCrowell DHOliaro SM: Measurement of head impacts in collegiate football players: relationship between head impact biomechanics and acute clinical outcome after concussion. Neurosurgery 61:124412532007

    • Search Google Scholar
    • Export Citation
  • 15

    Guskiewicz KMWeaver NLPadua DAGarrett WE Jr: Epidemiology of concussion in collegiate and high school football players. Am J Sports Med 28:6436502000

    • Search Google Scholar
    • Export Citation
  • 16

    Hardy WNKhalil TBKing AI: Literature review of head injury biomechanics. Int J Impact Engng 15:5615861994

  • 17

    Mihalik JPBell DRMarshall SWGuskiewicz KM: Measurement of head impacts in collegiate football players: an investigation of positional and event-type differences. Neurosurgery 61:122912352007

    • Search Google Scholar
    • Export Citation
  • 18

    National Highway Traffic Safety Administration: Traffic Safety Facts 2010 Washington, DCUS Department of Transportation(http://www-nrd.nhtsa.dot.gov/Pubs/811659.pdf) [Accessed May 15 2014]

    • Search Google Scholar
    • Export Citation
  • 19

    Rowson SBrolinson GGoforth MDietter DDuma SM: Linear and angular head acceleration measurements in collegiate football. J Biomech Eng 131:0610162009

    • Search Google Scholar
    • Export Citation
  • 20

    Rowson SDuma SM: Brain injury prediction: assessing the combined probability of concussion using linear and rotational head acceleration. Ann Biomed Eng 41:8738822013

    • Search Google Scholar
    • Export Citation
  • 21

    Rowson SDuma SM: Development of the STAR evaluation system for football helmets: integrating player head impact exposure and risk of concussion. Ann Biomed Eng 39:213021402011

    • Search Google Scholar
    • Export Citation
  • 22

    Rowson SDuma SM: The Virginia Tech response. Ann Biomed Eng 40:251225182012

  • 23

    Rowson SDuma SMBeckwith JGChu JJGreenwald RMCrisco JJ: Rotational head kinematics in football impacts: an injury risk function for concussion. Ann Biomed Eng 40:1132012

    • Search Google Scholar
    • Export Citation
  • 24

    Schnebel BGwin JTAnderson SGatlin R: In vivo study of head impacts in football: a comparison of National Collegiate Athletic Association Division I versus high school impacts. Neurosurgery 60:4904962007

    • Search Google Scholar
    • Export Citation

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Article Information

Contributor Notes

Please include this information when citing this paper: published online June 27, 2014; DOI: 10.3171/2014.2.JNS14294.
Headings
References
  • 1

    Collins MLovell MRIverson GLIde TMaroon J: Examining concussion rates and return to play in high school football players wearing newer helmet technology: a three-year prospective cohort study. Neurosurgery 58:2752862006

    • Search Google Scholar
    • Export Citation
  • 2

    Rowson SDuma SMGreenwald RMBeckwith JGChu JJGuskiewicz KM: Can helmet design reduce the risk of concussion in football? Technical note. J Neurosurg 120:9199222014

    • Search Google Scholar
    • Export Citation
  • 1

    Beckwith JGGreenwald RMChu JJCrisco JJRowson SDuma SM: Head impact exposure sustained by football players on days of diagnosed concussion. Med Sci Sports Exerc 45:7377462013

    • Search Google Scholar
    • Export Citation
  • 2

    Beckwith JGGreenwald RMChu JJCrisco JJRowson SDuma SM: Timing of concussion diagnosis is related to head impact exposure prior to injury. Med Sci Sports Exerc 45:7477542013

    • Search Google Scholar
    • Export Citation
  • 3

    Broglio SPSchnebel BSosnoff JJShin SFend XHe X: Biomechanical properties of concussions in high school football. Med Sci Sports Exerc 42:206420712010

    • Search Google Scholar
    • Export Citation
  • 4

    Broglio SPSurma TAshton-Miller JA: High school and collegiate football athlete concussions: a biomechanical review. Ann Biomed Eng 40:37462012

    • Search Google Scholar
    • Export Citation
  • 5

    Brolinson PGManoogian SMcNeely DGoforth MGreenwald RDuma S: Analysis of linear head accelerations from collegiate football impacts. Curr Sports Med Rep 5:23282006

    • Search Google Scholar
    • Export Citation
  • 6

    Cobb BRUrban JEDavenport EMRowson SDuma SMMaldjian JA: Head impact exposure in youth football: elementary school ages 9–12 years and the effect of practice structure. Ann Biomed Eng 41:246324732013

    • Search Google Scholar
    • Export Citation
  • 7

    Collins MLovell MRIverson GLIde TMaroon J: Examining concussion rates and return to play in high school football players wearing newer helmet technology: a three-year prospective cohort study. Neurosurgery 58:2752862006

    • Search Google Scholar
    • Export Citation
  • 8

    Crisco JJGreenwald RM: Let's get the head further out of the game: a proposal for reducing brain injuries in helmeted contact sports. Curr Sports Med Rep 10:792011

    • Search Google Scholar
    • Export Citation
  • 9

    Crisco JJWilcox BJBeckwith JGChu JJDuhaime ACRowson S: Head impact exposure in collegiate football players. J Biomech 44:267326782011

    • Search Google Scholar
    • Export Citation
  • 10

    Crisco JJWilcox BJMachan JTMcAllister TWDuhaime ACDuma SM: Magnitude of head impact exposures in individual collegiate football players. J Appl Biomech 28:1741832012

    • Search Google Scholar
    • Export Citation
  • 11

    Duma SMManoogian SJBussone WRBrolinson PGGoforth MWDonnenwerth JJ: Analysis of real-time head accelerations in collegiate football players. Clin J Sport Med 15:382005

    • Search Google Scholar
    • Export Citation
  • 12

    Duma SMRowson SThe biomechanics of concussion: 60 years of experimental research. Slobounov SMSebastianelli WJ: Concussions in Athletics New YorkSpringer2014. 115137

    • Search Google Scholar
    • Export Citation
  • 13

    Duma SMRowson S: Past, present, and future of head injury research. Exerc Sport Sci Rev 39:232011. (Letter)

  • 14

    Guskiewicz KMMihalik JPShankar VMarshall SWCrowell DHOliaro SM: Measurement of head impacts in collegiate football players: relationship between head impact biomechanics and acute clinical outcome after concussion. Neurosurgery 61:124412532007

    • Search Google Scholar
    • Export Citation
  • 15

    Guskiewicz KMWeaver NLPadua DAGarrett WE Jr: Epidemiology of concussion in collegiate and high school football players. Am J Sports Med 28:6436502000

    • Search Google Scholar
    • Export Citation
  • 16

    Hardy WNKhalil TBKing AI: Literature review of head injury biomechanics. Int J Impact Engng 15:5615861994

  • 17

    Mihalik JPBell DRMarshall SWGuskiewicz KM: Measurement of head impacts in collegiate football players: an investigation of positional and event-type differences. Neurosurgery 61:122912352007

    • Search Google Scholar
    • Export Citation
  • 18

    National Highway Traffic Safety Administration: Traffic Safety Facts 2010 Washington, DCUS Department of Transportation(http://www-nrd.nhtsa.dot.gov/Pubs/811659.pdf) [Accessed May 15 2014]

    • Search Google Scholar
    • Export Citation
  • 19

    Rowson SBrolinson GGoforth MDietter DDuma SM: Linear and angular head acceleration measurements in collegiate football. J Biomech Eng 131:0610162009

    • Search Google Scholar
    • Export Citation
  • 20

    Rowson SDuma SM: Brain injury prediction: assessing the combined probability of concussion using linear and rotational head acceleration. Ann Biomed Eng 41:8738822013

    • Search Google Scholar
    • Export Citation
  • 21

    Rowson SDuma SM: Development of the STAR evaluation system for football helmets: integrating player head impact exposure and risk of concussion. Ann Biomed Eng 39:213021402011

    • Search Google Scholar
    • Export Citation
  • 22

    Rowson SDuma SM: The Virginia Tech response. Ann Biomed Eng 40:251225182012

  • 23

    Rowson SDuma SMBeckwith JGChu JJGreenwald RMCrisco JJ: Rotational head kinematics in football impacts: an injury risk function for concussion. Ann Biomed Eng 40:1132012

    • Search Google Scholar
    • Export Citation
  • 24

    Schnebel BGwin JTAnderson SGatlin R: In vivo study of head impacts in football: a comparison of National Collegiate Athletic Association Division I versus high school impacts. Neurosurgery 60:4904962007

    • Search Google Scholar
    • Export Citation
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