A revolution in preventing fatal craniovertebral junction injuries: lessons learned from the Head and Neck Support device in professional auto racing

Abstract

Fatal craniovertebral junction (CVJ) injuries were the most common cause of death in high-speed motor sports prior to 2001. Following the death of a mutual friend and race car driver, Patrick Jacquemart (1946-1981), biomechanical engineer Dr. Robert Hubbard, along with race car driver and brother-in-law Jim Downing, developed the concept for the Head and Neck Support (HANS) device to prevent flexion-distraction injuries during high-velocity impact. Biomechanical testing showed that neck shear and loading forces experienced during collisions were 3 times the required amount for a catastrophic injury. Crash sled testing with and without the HANS device elucidated reductions in neck tension, neck compression, head acceleration, and chest acceleration experienced by dummies during high-energy crashes. Simultaneously, motor sports accidents such as Dale Earnhardt Sr.'s fatal crash in 2001 galvanized public opinion in favor of serious safety reform. Analysis of Earnhardt's accident demonstrated that his car's velocity parallel to the barrier was more than 150 miles per hour (mph), with deceleration upon impact of roughly 43 mph in a total of 0.08 seconds. After careful review, several major racing series such as the National Association for Stock Car Auto Racing (NASCAR) and Championship Auto Racing Team (CART) made major changes to ensure the safety of drivers at the turn of the 21st century. Since the rule requiring the HANS device in professional auto racing series was put in place, there has not been a single reported case of a fatal CVJ injury.

Full text

HISTORICAL VIGNETTE
J Neurosurg Spine 25:756–761, 2016
The invention of gasoline-fueled combustion en-
gines in the early 1880s was soon followed by the
rst-ever organized automobile racing competition,
a 50-mile reliability test in an 1894 race from Paris to
Rouen, France. The average speed of the winners of this
historic race was just over 10 miles per hour (mph).5 The
year 1896 brought the rst oval track, a 1-mile irregular
dirt track in Cranston, Rhode Island.4
High-Speed Auto Racing
It was not long before the dangers of motor sports be-
came apparent. From 1990 to 2002 alone, 204 drivers died
at motor sports events, in addition to 29 spectators, 5 of
them children.13 In comparison, the Journal of Combat-
ive Sport/EJMAS reported a total of 488 boxing-related
deaths, with two-thirds due to cranial or cervical inju-
ries, from January 1960 to August 2011.26 The high risk
of injury in auto racing necessitated the development of
novel safety featu res such as multipoint seat belt restraints,
durable helmets, Lexan multilayer windshields, and less
ammable fuel, along with softer retaining walls and high
fences for the protection of both drivers and spectators in
the event of a crash.
There has been a constant coevolution between the en-
hanced safety of new racing technologies and the nuanced
risks they bring. For example, the development of seat belts
in race cars was initially met with resistance. Although
seat belts prevented race car drivers from being ejected
from the car in the event of a crash, these devices were
scorned for increasing the potential risk of being trapped
inside a ammable crashed vehicle.16 The evolution of met-
ABBREVIATIONS AIS = Abbreviated Injury Scale; ATD = Anthropomorphic Testing Device; CART = Championship Auto Racing Team; CVJ = craniovertebral junction; FIA
= Fédération Internationale de l’Automobile; GM = General Motors; HANS = Head and Neck Support; IARV = Injury Assessment Reference Value; mph = miles per hour;
NASCAR = National Association for Stock Car Auto Racing; SAE = Society of Automotive Engineers; SFI = SFI Foundation, Inc.; TBI = traumatic brain injury.
SUBMITTED March 20, 2015. ACCEPTED October 6, 2015.
INCLUDE WHEN CITING Published online July 12, 2016; DOI: 10.3171/2015.10.SPINE15337.
A revolution in preventing fatal craniovertebral junction
injuries: lessons learned from the Head and Neck Support
device in professional auto racing
Anand Kaul, BS,1 Ahmed Abbas, BS,1 Gabriel Smith, MD,1 Sunil Manjila, MD,1 Jonathan Pace, MD,1
and Michael Steinmetz, MD2,3
1Department of Neurosurgery, University Hospitals, Case Medical Center; 2Department of Neurosurgery, Case Western Reserve
University, MetroHealth Medical Center; and 3Center for Spine Health, Neurologic Institute, Cleveland Clinic, Cleveland, Ohio
Fatal craniovertebral junction (CVJ) injuries were the most common cause of death in high-speed motor sports prior
to 2001. Following the death of a mutual friend and race car driver, Patrick Jacquemart (1946–1981), biomechanical
engineer Dr. Robert Hubbard, along with race car driver and brother-in-law Jim Downing, developed the concept for the
Head and Neck Support (HANS) device to prevent exion-distraction injuries during high-velocity impact. Biomechanical
testing showed that neck shear and loading forces experienced during collisions were 3 times the required amount for
a catastrophic injury. Crash sled testing with and without the HANS device elucidated reductions in neck tension, neck
compression, head acceleration, and chest acceleration experienced by dummies during high-energy crashes. Simul-
taneously, motor sports accidents such as Dale Earnhardt Sr.’s fatal crash in 2001 galvanized public opinion in favor of
serious safety reform. Analysis of Earnhardt’s accident demonstrated that his car’s velocity parallel to the barrier was
more than 150 miles per hour (mph), with deceleration upon impact of roughly 43 mph in a total of 0.08 seconds. After
careful review, several major racing series such as the National Association for Stock Car Auto Racing (NASCAR) and
Championship Auto Racing Team (CART) made major changes to ensure the safety of drivers at the turn of the 21st
century. Since the rule requiring the HANS device in professional auto racing series was put in place, there has not been
a single reported case of a fatal CVJ injury.
http://thejns.org/doi/abs/10.3171/2015.10.SPINE15337
KEY WORDS ring fracture; Head and Neck Support device; HANS device; automotive racing; craniovertebral junction;
trauma
©AANS, 2016J Neurosurg Spine Volume 25 • December 2016756

Preventing craniovertebral junction injuries: the HANS device
J Neurosurg Spine Volume 25 • December 2016 757
al helmets led to their replacing the predominant cloth or
leather helmets by the 1950s, but despite the added poten-
tial benet of reducing blunt skull trauma, metal helmets
also introduced a new set of risks in the potentially lethal
exion-distraction forces at the craniovertebral junction
(CVJ). One study investigated helmet weight and the risk
of fatal skull base injury in motorcyclists and concluded
that the overall risk was 9.2%, and that for riders whose
helmets weighed more than 1.5 kg there was a statistically
signicant increase in the incidence of these injuries.14
The HANS Device
Dr. Robert Hubbard, a biomechanical engineer at
Michigan State University, and his brother-in-law Jim
Downing, a race car driver, developed the concept for
the Head and Neck Support (HANS) device following
the death of a mutual friend and race car driver, Patrick
Jac quema rt (1946–1981).11 Hubbard’s extensive career as a
biomechanical crash engineer gave him insight into the se-
verity of accelerative forces placed on the CVJ of drivers.
The initial prototype of the HANS device was designed to
t elegantly over the driver’s shoulders and attach to the
helmet, allowing for increased resistance to exion and
distraction vectors during deceleration, deecting trans-
lational head motion into the torso (Fig. 1).11 The helmet
did not signicantly limit the driver’s vision, because the
driver’s head could maintain some lateral and rotational
movement due to the use of xed-length sliding tethers on
either side of the helmet.
To study the neck tension loading felt by drivers during
crashes, Hubbard et al. used crash sled tests, Anthropo-
morphic Testing Devices (ATDs), and the injury thresh-
old value guidelines developed by General Motors (GM)
(Figs. 2 and 3, and Video 1).11,18,19
VIDEO 1. Crash comparisons using an ATD with and without the
HANS device. Courtesy of Dr. Robert Hubbard, the copyright
holder. Click here to view.
Predictive thresholds are known for severe CVJ injury,
with axial tension exceeding 740 lbs and forward neck
shear exceeding 700 lbs.17 While conducting sled tests
performed with and without the HANS device, Hubbard
et al. found a signicant reduction in neck loading when
the device was used, from 1350 lbs to 296 lbs (Fig. 4).
Neck tension and shear forces were found to be 1120 and
750 lbs, respectively, without the use of the HANS device.
With the use of the HANS device Hubbard et al. found that
neck tension and shear were only 210 lbs each, well below
the injury threshold.11 These authors also examined dif-
FIG. 1. A: Photograph of the HANS device coinventors: Dr. Robert Hubbard (left) with race car driver and brother-in-law Jim
Downing (right). B: The first-generation HANS device (1990). The device was designed to fit over the shoulders of the driver and
attach to the helmet to stabilize the CVJ by restricting head motion and dissipating neck loads into the torso. C: Fixed-length and
adjustable-length tethers are used to attach the device to the helmet. This allows for some freedom of movement when driving,
while still ensuring proper restraint of the head during a collision. Panel A reprinted with permission from “Saving Racing’s Neck.”
Car and Driver, April 2004 (copyright Richard Dole), and panels B and C reprinted with permission from Hubbard RP, Begeman
PC, Downing JR: Biomechanical Evaluation and Driver Experience with the Head and Neck Support. SAE Technical Paper, 1994.
Figure is available in color online only.
FIG. 2. Crash test sled used by Mercedes Benz. Crash test dummies
are placed in ATDs that can be used to simulate loads on a driver under
various collision conditions. The ATD can be set up to model different
driving positions, impact angles, and crash velocities. Cameras can be
seen mounted around the ATD to record the motion of the dummy during
the collision testing. Photograph courtesy of Dr. Robert Hubbard. Figure
is available in color online only.

A. Kaul et al.
J Neurosurg Spine Volume 25 • December 2016758
ferential positioning of the HANS device to investigate its
efcacy across different styles of auto racing, such as the
more reclined (45°) position used by IndyCar and Formula
1 drivers and the upright (30°) position used in NASCAR.
The HANS device signicantly reduced tension and shear
forces on the neck in both seating positions (Table 1).
In 2002, Gideon et al. also investigated the effects of
variable crash deceleration time histories on resultant
neck tension during automobile crashes with and without
the use of the HANS device.6 To simulate a life-threaten-
ing crash energy level, all trials used a 40-mph crash ve-
locity at a 36° right front angle barrier impact. The forces
measured on the ATDs during crash testing included neck
tension and compression, head acceleration, and chest ac-
celeration; Injury Assessment Reference Values (IARVs)
were used to judge injury potential associated with dum-
my measurements. The HANS device was found to ef-
fectively reduce the neck tension to less than 225 lbs of
force, well below the IARV criterion of 900 lbs used to
assess injury for all types of deceleration time histories.
These studies provided validation for the effectiveness of
the HANS device, showing an 80% reduction in exion-
distraction force on the head and neck compa red wit h con-
trols (Table 1). Following the death of Formula 1 driver
Aryton Senna in 1994, DaimlerChrysler investigated sled
testing with the HANS device, concluding that the device
was both efcacious and safe.7–9 With the cooperation of
DaimlerChrysler, the second-generation HANS device
FIG. 3. Comparison using an ATD with and without the HANS device. The results of a simulated head-on crash at 40 mph us-
ing the Mercedes Benz ATD simulation. A: Without the HANS device, a large amount of neck tension is exhibited on the test
dummy. B: With the HANS device, the neck and head are kept closer to the torso by distributing loads across the shoulders and
chest of the driver. Photograph courtesy of Dr. Robert Hubbard. Figure is available in color online only.
FIG. 4. Force diagrams demonstrating typical results from frontal crash test with and without HANS. The guidelines as developed
by GM and the SAE indicate that the threshold values to prevent head and neck injury should not exceed 740 lbs axial neck ten-
sion, 700 lbs forward shear, and 900 lbs compression, and that chest compression should not exceed 51 mm (Hubbard et al.). This
testing was conducted by GM to simulate a 45-mph crash at a 45° seat back angle to model the reclined position as seen in Indy-
Car and Formula 1 racing. Without the HANS device, the neck load values all exceed the injury thresholds, with neck axial tension
and shear at 1122 lbs and 752 lbs, respectively. With the HANS device all load values are significantly below thresholds, with neck
axial tension and shear at 210 lbs and axial compression at 290 lbs. Reprinted with permission from Hubbard RP, Begeman PC,
Downing JR: Biomechanical Evaluation and Driver Experience with the Head and Neck Support. SAE Technical Paper, 1994.

Preventing craniovertebral junction injuries: the HANS device
J Neurosurg Spine Volume 25 • December 2016 759
was created.7 The adoption rate for the HANS device by
race car drivers remained poor, however, because even
with research and testing indicating their potential safety
benet, marketing and awareness of these devices lagged
behind for nearly 5 years.25, 27 This delay continued until
2001 when, during his nal lap of the Daytona 500, Dale
Earnhardt Sr. was involved in a fatal collision. Root-cause
analysis of his death determined that his car decelerated
so rapidly that he suffered a fatal CVJ injury.
The passing of Earnhardt was one of the most tragic
events in modern motor sports. His fatal crash on Feb-
ruary 18, 2001, was extensively investigated. Earnhardt’s
No. 3 car was making the fourth turn of his last lap when
his left rear bumper made contact with the No. 40 car,
causing him to yaw counterclockwise toward the center
of the track. A corrective sharp turn back to the right sent
him up the racing surface into the path of the No. 36 car,
which made unavoidable impact with Earnhardt’s passen-
ger door area just before he made angled contact with the
side wall.
Analyses of the crash component velocity vectors dem-
onstrated that Earnhardt’s car had an impact velocity in
excess of 150 mph and experienced a total deceleration of
43–44 mph in a period of 0.08 seconds, with the equiva-
lent forces of 45–50g.22 Injury causation analysis likened
the velocity change due to the crash to that of a parked car
being struck head on by a similar car traveling 75 mph.3
The nal cause of death was found to be a fatal CVJ in-
jury with an associated basilar ring fracture; however, the
mechanism of fracture was heavily debated. The ofcial
NASCAR crash report explai ned that impact to the occipi-
tal scalp in conjunction with the tension and torsion stress
to the base of the skull resulted in the fracture, and addi-
tional consultation by Dr. Barry Myers described a “whip”
mechanism resulting from the differential restraint of the
torso and head, leading to a lethal exion-distraction in-
j u r y.22
Earnhardt’s crash marked a turning point for the adop-
tion of head and neck restraint systems, with NASCAR
mandating the use of these restraint systems in cars in
2001. The creation of the head and neck restraint speci-
cations by auto racing’s nonprot quality assurance
company, the SFI Foundation, Inc. (SFI) (specica-
tion 38.1; www. sfoundation.com/wp-content/pdfs/specs/
Spec_38.1_031615.pdf), should have heralded the arrival
of many new neck restraint devices. However, by 2004
only 2 of these were certied, including the long-stand-
ing HANS device. The Fédération Internationale de
l’Automobile (FIA) mandated the use of the third-genera-
tion HANS device for Formula 1 racing in 2003 (Fig. 5).
By 2007, more than 40 sanctioning bodies required the
use of SFI-certied devices.25
TABLE 1. Testing data results from the frontal impact crash sled testing of the HANS device as conducted by GM*
Neck Support Condition Sled Velocity Change,
Seat Back Angle Neck Forward
Shear Load (lbs) Neck Axial
Load (lbs) Total Neck Stretch
Load (lbs) Chest
Compression (mm)
Tolerance thresholds† 698 765–900‡ 698 51
No neck support 45 mph, 30° seat 617 806 1011 25
45 mph, 45° seat 752 1122 1352 36
With neck support 45 mph, 30° seat 151 0–270 151 25
45 mph, 45° seat 210 210–290 296 8
* Front-impact tests were per formed using the ATD and conducted at 45 mph at 30° and 45° seat angles, designed to model Formula 1 seating positions. The tests
were performed both with and without the HANS device, with loads measured. Modied with permission from Hubbard RP, Begeman PC, Downing JR: Biomechanical
Evaluation and Driver Experience with the Head and Neck Support. SAE Technical Paper, 1994.
† Tolerance threshold values as determined by GM and the SAE for maximum allowed loads to prevent injury to the head and neck.
‡ Axial loads are measured as extension (positive) and compression (negative). Extension loads are indicative of distractive injuries. Compression loads are caused by
the head pushing down on the neck due to the restraint provided by the HANS device.
FIG. 5. More recent HANS devices. A: The third-generation HANS device is now fully composite. The device is lighter in weight
and signicantly less bulky. The device can now be readily modied to meet the individual specications for drivers as well as the
general requirements for a different racing series (regarding positioning of the helmet in relation to the device). B: The HANS de-
vice as used in CART racing required a more reclined position. C: The HANS device as used in NASCAR required a more upright
driving position. Photographs courtesy of Dr. Robert Hubbard. Figure is available in color online only.

A. Kaul et al.
J Neurosurg Spine Volume 25 • December 2016760
According to clinical literature, basilar skull ring frac-
tures occur from distraction or compressive forces.15,28
Compression ring fractures occur from a vertical fall from
a height or direct impact to the top of the head and are
often associated with fatal downward displacement of the
posterior fossa, brainstem, and vascular structures. Flex-
ion-distraction ring fractures and atlantooccipital disloca-
tion occur when forces applied to the head are sufcient
to cause suture diastasis during acceleration experienced
by the head and torso, which is often fatal as well.1,2, 12, 23,31
Pollanen et al. evaluated a series of 8 fatal basilar skull
fractures and found that fractures of the petrous portion
of temporal bones will often involve laceration of the in-
ternal carotid arteries, leading to massive hemorrhage.21
These fractures can involve the middle ear as well and
create a carotid–middle ear stula leading to rapid exsan-
guination.21, 30
The grave prognosis of these high-velocity sports in-
juries from atlantooccipital dissociation, fatal vascular
injuries, and concurrent basilar skull ring fractures ne-
cessitated further investigation into prevention and safety.
Trammell and Hubbard explored medical and technical
outcomes of the HANS device in Championship Auto
Racing Team (CART) series racing.27 They found that
in 2000 and 2001, there were 28 incidents involving 33
drivers using the HANS device, with 0 fatalities, 0 cer-
vical fractures or dislocations, 1 minor head injury, and
8 drivers with minor neck complaints.27 In comparison,
between 1985 and 1999 there were a total of 146 different
injuries to drivers, 11 of which (7.5%) involved the cervi-
cal spi ne, resulting in 2 fatalit ies.20 Trammell and Hubbard
compared 2 crashes experienced by a single driver—one
in which the HANS device was implemented and another
in which it was not. The crash in which the HANS device
had been used had a higher rear-impact acceleration (100g
vs 66g) and a velocity change from 44 to 22 mph, but the
driver sustained a lower-grade concussion without any
neck symptoms or soft-tissue injury.
Traumatic brain injury (TBI) is another major source
of death from trauma. Studies using Indy Racing League
(IRL) data showed a dramatic increase in risk of TBI with
collision accelerations in excess of 50g.29 An analysis of
NASCAR data showed that increased head acceleration
provided a good correlation with injury severity according
to the Abbreviated Injury Scale (AIS), ranging from loss
of consciousness to hemorrhage to fatal skull fracture.24
These studies have not directly examined the benets of
the HANS device, but it may be interesting to investigate
what effect the reduced loads on the head and neck of the
driver would have on the overall AIS severity.
In the US alone, 42,000 trafc fatalities and 6.1 million
trafc accidents occur each year. Meanwhile, NASCAR
drivers averaged 220 crashes per year over 9 years from
2001 to 2009. Based on this ratio, there should have been
15 deaths since 2001; however, there have been none re-
ported.10
Conclusions
The HANS device, with an 80% reduction in exion-
distraction vectors, has led to dramatic declines in fatal
CVJ injuries. Critical understanding of the biomechani-
cal forces at the CVJ led to the invention of the HANS
and other similar CVJ-stabilizing devices, revolutionizing
safety in high-speed racing. Initial adoption of HANS de-
vices was low due to a lack of community awareness of
the injuries involved. The tragic death of Dale Earnhardt
Sr. had a lasting cultural impact on auto racing because
it was a turning point for the adoption of HANS devices.
Since requirements mandating the use of head and neck
support devices were put in place in 2001, there have been
no reported fatalities due to CVJ injuries.
Acknowledgments
This study was done as a retrospective review of neurosurgical
and Society of Automotive Engineers (SAE) literature. We thank
NASCAR, CART, SAE, Dr. Robert Hubbard, Mr. Tom Gideon,
Dr. Stephen Olvey, Dr. Terry Trammell, Dr. John Hopkins, and all
of their associates for vital contributions to the manuscript. Crash
sled test data were provided by Dr. Robert Hubbard and Mr. Tom
Gideon.
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Disclosures
Dr. Steinmetz is a consultant for Stryker Spine, Biomet, DePuy
Synthes, and Intellirod. He also receives royalties from Biomet.
Author Contributions
Conception and design: all authors. Acquisition of data: Smith,
Kaul, Abbas. Analysis and interpretation of data: Smith, Kaul,
Abbas, Steinmetz. Drafting the article: Smith, Kaul, Abbas,
Steinmetz.
Supplemental Information
Videos
Video 1. https://vimeo.com /159214496.
Correspondence
Gabriel Smith, Department of Neurosurgery, University Hospi-
tals, Case Medical Center, 11100 Euclid Ave., Hanna House 5th
Fl., Cleveland, OH 44106. email: gabriel.smith@uhhospitals.org.