Slide 1: Opening Slide.

Slide 2: There has been much attention on frontal crashes over the past
20 years, and this has yielded great success in the safety of child
occupants. Two decades of frontal impact sled testing, CRS-to-vehicle
interface engineering and CRS development has made rear and forward
facing child restraint one of the most effective safety systems for
their target age group. There has been recent attention on side impacts,
with extensive focus on adults. I note however, that the development of
the 5th female side impact dummy SID IIs has brought an ATD roughly the
same size as a 50th percentile 12 year old into the crash test
environment. Focus on children under 12 has been limited to CRS-based
research and regulatory programs. NHTSA proposed and withdrew a side
impact sled test more recently. Despite this, 42% of fatalities of rear
seat occupants age 0 --8 were in side impacts.

Slide 3: If I was a vehicle designer who desires information to help
them design a safety system for the side impact involved belt restrained
occupant, the data available to me would be somewhat limited. I would
have at my disposal, information on Fatality risk for the struck vs. the
center position in the rear seat, but this would be for all restraint
conditions -- from the rear facing infant to the belt-restrained teen. I
would have some information on injury risk. But the design engineer
would not have any information regarding injury MECHANISM in side
impact.

Slide 4: Thus, the goal of this research project is to provide such
information. That is, we want to delineate injury mechanisms for
belt-restrained children involved in side impact crashes. We're hopeful
the results of this research will prove useful to the OEM / Supplier
community, and help develop safety systems that better project children.

Slide 5: Thus, the goal of this research project is to provide such
information. That is, we want to delineate injury mechanisms for
belt-restrained children involved in side impact crashes. We're hopeful
the results of this research will prove useful to the OEM / Supplier
community, and help develop safety systems that better project children.

Slide 6: We employed a CIREN-like interdisciplinary case review team
consisting of physicians, engineers, crash investigation specialists,
and database analysts. We met 3x per month, often just before our
regular monthly case CIREN case review. At each meeting we reviewed 2 to
3 cases, and we kept this up for 8 months. We retrospectively drew our
cases from the CIREN and PCPS databases. Each case was presented in a
manner similar to the CIREN model. We BIOTab'd all AIS 2+ injuries, and
we recorded occupant to vehicle contact points in a graphical manner
I'll describe shortly. Thus, we employed a method of reviewing the cases
in our study sample a little at a time, allowing a paced review of a
fairly large sample of cases that met a very specific inclusion
criteria.

Slide 7: Here are our inclusion criteria. 63 cases met the inclusion
criteria, 17 were eliminated due to quality control issues, leaving 46
cases.

Slide 8: Vehicles carrying the case occupants were overwhelmingly
passenger cars followed by equal numbers of sport utility vehicles (SUV)
(9%) and Minivans (9%). The vehicles that struck the case occupant's
vehicle, or the struck object, were largely passenger cars (32%) or
SUV's (24%), followed by pickup trucks (17%), narrow objects such as a
tree or pole (11%), large trucks (9%), and minivans (7%). Delta V
averaged 26.5 km/h (standard deviation 12.4) but was often considered
unreliable due to frequent impacts to the rear suspension.

Slide 8: More crashes were to the right side of the vehicle than the
left. Nearly all crashes could be categorized between pure lateral and
30 degrees forward of pure lateral, and no crashes occurred rearward of
pure lateral. Delta V averaged 26.5 km/h (standard deviation 12.4) but
was often considered unreliable due to frequent impacts to the rear
suspension.

Slide 9: We reasoned that an occupant's height was the best available
metric for grouping occupants of different sizes. Using the Centers for
Disease Control Growth Charts, we height bins for the 50th percentile 4
to 8 year old, 9 to 12 year old, and 13 to 15 year. The bins were as
follows: 4 to 8 year old: 104 to 131 cm, 9 to 12 year old: 132 to 152
cm, and 13 to 15 year old: 153 to 172 cm. For 5 cases, the occupant's
height was unknown, so in those cases the subject's age was used.
Fifty-four percent of subjects fell within the size range of a 4 to 8
year old, with the remaining cases nearly split between the 9 to 12 year
old (26%) and 13 to 15 year old (20%). Subject injury severity spanned
the spectrum of the AIS scale; 100% of subjects had an AIS 2 or greater
injury (as expected because AIS2+ was an inclusion criteria), 66 % had
injuries that met or exceeded AIS 3, and 30% had injuries that met or
exceeded AIS 4.

Slide 10: The head was the most frequently injured body region
regardless of seat position. (Figure 6) On the nearside, head injuries
including concussions were 33% of all injuries, and even larger
percentages were observed in the center (60%) and farside (56%)
positions. However, with concussions removed, the head injuries dropped
significantly, ranging from 18% on the nearside to 50% in the center.
The abdomen was the second-most frequently injured body region, with
injury percentages of 18% on the nearside, 10% in the center, and 39% on
the farside. Face, thorax, upper extremity, and pelvis injuries were
each approximately 8% to 11% of injuries.

Slide 11: Focusing on intracranial head injuries and skull fractures
only, an altered state of consciousness (Loss of Consciousness, Amnesia,
or Concussion) was the most frequent head injury (16 total) with 10
injuries on the nearside, 4 injuries in the center and 2 injuries on the
farside. (Figure 7) Hematoma or hemorrhage between brain and skull,
typically subdural, was the second most frequent head injury type (9
total) and occurred most frequently on the nearside (7 total). Almost as
frequent was skull fracture at 7 injuries total, with 3 on the nearside
and 2 each on the center and farside. Remaining primary tissue damage
injuries include 4 cases of cerebral contusion and 2 cases of diffuse
axonal injury (DAI). Secondary injuries include two cases of edema, and
one case of ischemic brain injury.

Slide 12: On the nearside, the most frequent injury contact points were
the door and intruding object, each consisting of 30% of all contacts;
the second most frequent contact point was either the B, C or D pillars.
The remaining 20% of head injuries were divided evenly between the
window or were simply unknown. In the center position, the door and
other occupant were both the most frequent head contact point, each at
29% of contacts. The second most frequent contacts points were equally
the pillar, the window, and unknown points within the vehicle, each at
14% of head contact points in the center position. In the farside
position, 50% of the contacts were to other occupants, followed by 33%
contacting the some point on the seat in front of the occupant,
including the headrest or seatback frame. The contact point was unknown
in 17% of head contacts.

Slide 13: To illustrate our methods, let us review one head injury case.
This case was a 9 year old female in the 2^nd^ row right position in a
right side impact crash.

Slide 14: The occupant's injuries were as follows: Right Small Subdural
Cerebrum Hematoma/Hemorrhage, AIS 4, a lower base (basilar) skull
fracture , AIS 3, and a right posterior minor scalp laceration, AIS 1.
All head injuries were associated with the right side window frame.

Slide 15: This is a picture of the right side interior where the head
contact occurred.

Slide 16: To geometrically quantify the location of occupant contacts
within the vehicle, we developed an unbiased method of localizing
occupant-to-vehicle contact points on a generic mock-up drawing of a
vehicle door interior. Occupant contact points were identified by crash
investigator's marking tape or by CRT determination. Quantifying
occupant contact points from vehicle photographs was a challenging task.
Vehicle interior pictures were taken from a variety of angles, and no
specific landmark is consistently available in each picture to be used
to as reference to geometrically locate an occupant contact on a generic
vehicle interior mockup drawing.

Slide 17: Thus, a method was developed whereby several blinded research
analysts visually interpreted the location of the occupant contact mark
in the vehicle picture. Then the analyst marks that same point on the
vehicle mockup drawing. Custom software was developed using Visual Basic
in Excel (Microsoft, Inc. Redmond, WA) to give consistent instructions
to analysts and to automate the data collection process. Researchers not
affiliated with this project were recruited as analysts for this task,
so that no bias was introduced by the CRT team. The same mockup drawing
was utilized for second and third row occupants.

Slide 18: In addition to head injuries, abdominal injuries to farside
occupants were also prevalent.

Slide 19: Our dataset included 5 cases of farside abdominal injury, with
one fatality. To demonstrate the injury mechanism in these cases, we
have selected one exemplar case to show. This is a 13 year old male
subject who was tall for his age. He was seated in the 2^nd^ row right
seating position, which is on the farside. He was restrained by the 3-pt
belt, and his maximum AIS was 3.

Slide 20: The case vehicle was a 1997 Plymouth Neon and the striking
vehicle was an Aerostar minivan.

Slide 21: This was an intersection crash.

Slide 22: Damage to the case vehicle was to the passenger compartment
and left rear quarter panel. Again, the case occupant is seated on the
right rear. The delta V in this crash was unknown, but the damage is
moderate.

Slide 23: This is the case occupant's seating position, which is absent
of deformation.

Slide 24: There were two other occupants in this crash, both with minor
injuries.

Slide 25: Our case occupant received relatively significant abdominal
injuries.

Slide 26: In conclusion, we applied a CIREN-model to retrospective case
review of belted children in side impacts. We also successfully applied
the BioTab injury coding scheme, retrospectively. We developed a method
for occupant contact localization from photographs to facilitate head
injury prediction. Head injuries were the most common in our dataset.
The most frequent contact points is the rear 1/3 of the door, from the
window sill extending ½ way up the window glass. We also noted
significant abdominal injuries in farside crashes, which should prompt
us to consider and test novel farside restraint concepts.

Slide 27: For our future work, we plan to compare our crash
investigation dataset with the PCPS Surveillance data. Further, there
has been a significant effort around the globe to look at Farside adult
injuries, and we intend to compare our findings with the adult farside
injury group. Given that we found head injury protection as a most
significant problem, we hope to conduct some headform testing on vehicle
interior, and also consider expanded door coverage from curtain airbags.

Slide 28: We're grateful to funding members of the Center for Child
Injury Prevention Studies for providing financial support for this work.
We're grateful to NHTSA and State Farm for supporting the data gathering
that made this research possible.