Football Helmet to Reduce the Risk of Subdural Brain Hemorrhaging and Concussions by Reducing Rotational Acceleration

Doug BrowneJeff MarkleTyler Severance

What Causes Subdural Hemorrhage? Subdural hemorrhaging occurs when the

blood vessels that connect the dura to the brain rupture

This can happen when the brain moves relative to the dura, causing the connecting vessels to stretch and burst Due to a higher density of CSF relative to brain

tissue density The maximum strain was found in research and

verified in Vanderbilt cadaver lab during advisor guided dissection

Rotational Acceleration From cadaveric studies, the connecting blood vessels

undergo permanent deformation at 20% strain and total rupture at 150% strain which occurs at accelerations between 4,500 and 10,000 rad/s2

Rotational Acceleration Dangers in Football Already proven that collisions in

football often exceed dangerous levels of rotational acceleration

In all levels of football (high school, college and professional) top 1% of collisions reach critical levels of rotational acceleration

Collisions cannot be prevented without drastic change in the sport; however, helmet design can be modified

NOCSAE

The National Operating Committee on Standards for Athletic Equipment is the governing body that regulates standards for football helmets.

Helmets are only required to prevent against levels of translational acceleration that would cause skull fractures.

Southern Impact Research Center Tests helmets for NOCSAE and does

a lot of independent research on helmets.

Met with Technical Director David Halsted who shed light on many problems with designing a new, improved helmet

SIRC Drop Test Setup

SIRC Projectile System

Helmet Design Problems (remove slide?) Helmet it not well coupled to the

head during a collision Athletes can suffer brain injury even

when head is not involved in the collision

Current helmets are effective at dampening blows to the head (difficult to improve upon), but this is a different issue than lowering overall angular acceleration

Design Problems to Overcome After meeting with Dave Halsted, it became

apparent that this problem is more complex than was initially predicted

He mathematically proved that changing cushion design would have minimal, if any, impact on helmet function

What we’ve done so far

After meeting with Mr. Halsted, it became apparent that this problem is more complex than we initially imagined.

Together, we identified three main issues our team could “tackle” Helmet weight Relatively large range of motion Detection of potential brain injury

New Helmet Design

Lightweight helmet that keeps the same levels of protection against linear acceleration as current models

Include in the helmet a device that indicates when dangerous levels of rotational acceleration have been reached.

Attempt to create a seat belt based design to prevent the head from reaching the peak levels during the collision

Thinking outside the box

The seat belt theory has potential, but a helmet alone won’t regulate the motion

Shoulder pads can be included to transform the system from just a head to the entire upper torso

Perhaps it will be possible to tether the helmet to the pads

+ =+ ?

Other Possibilities Another issue that can be addressed is that a

significant number of subdural hemorrhages are undetected (sources vary widely )

Possible to create a safety feature that would indicate when dangerous levels of acceleration have been reached

Apply accelerometers to the back of the helmet which could signal that a player should be removed from play and examined by a professional

What we’re doing now We are currently developing a prototype helmet that

will be able to be tested using the equipment at the SIRC

Taking/modifying elements from different current helmets so we don’t have to manufacture many new parts

Attempting to procure a set of shoulder pads to use in our design Via local high schools

Searching for suitable accelerometers to use as a potential indicator

Continuing to run ideas by Mr. Halstead to assess our progress

Planning a future trip to Knoxville for more testing

Steps to come

If all goes as planned, we will have a working prototype that can be tested by the end of March

Further testing and modification can occur as needed for the rest of the semester

References Huang HM, Lee MC, Chiu WT, Chen CT, Lee SY: Three-dimensional finite

element analysis for subdural hematoma. J Trauma 47: 538–544, 1999.

Depreitere B, Van Lierde C, Vander Sloten J, Van Audekercke R, Van Der Perre G, Plets C et al.: Mechanics of acute subdural hematomas resulting from BV rupture. Journal of Neurosurgery 104(6): 950-956, 2006.

Löwenhielm P: Strain tolerance of the vv. cerebri sup. (BVs) calculated from head-on collision tests with cadavers. Z Rechtsmedizin 75:131–144, 1974.

Gennarelli TA, Thibault LE: Biomechanics of acute subdural hematoma. J Trauma 22:680–686, 1982.

Lee MC, Ueno K, Melvin JW: Finite element analysis of traumatic subdural hematoma, in Proceedings of the 31st Stapp Car Crash Conference. New York, NY, Society of Automotive Engineers, 1987, pp 67-77.

References Con’t

Lee MC, Haut RC: Insensitivity of tensile failure properties of human BVs to strain rate: implication in biomechanics of subdural hematoma. J Biomech 22(6-7): 537-42, 1989.

Forbes JA, Withrow TJ: Biomechanics of Subdural Hemorrhage in American Football. Vanderbilt University, 2010

Final Note:

To learn more about Southern Impact Research Center, please visit: http://

www.youtube.com/watch?v=hwA-hiFu4Xw

http://www.soimpact.com/