No abstract

It has been suggested that contouring the landing area of a terrain park jump, by increasing the landing slope with increasing horizontal distance from the takeoff ramp of a jump, would reduce the likelihood of injury. In theory, this limits the component of center-of-mass velocity that is normal to the snow surface at contact. In published works that recommend this jump design, velocity normal to the snow surface at contact is converted into an equivalent height above the ground, referred to as equivalent fall height (EFH). The purpose of the current research is to evaluate the injury mitigation potential of a landing surface that limits EFH. An instrumented 50th-percentile male Hybrid III anthropomorphic test device (ATD) fitted with snowboarding equipment was used to determine the head accelerations, cervical spine loads, and lumbar spine loads associated with landing on a snow surface in backward rotated configurations. For these tests, the ATD was suspended above a hard-packed, snow-filled box, rotated backwards, and allowed to fall onto the snow. The ATD fall distance and backward rotation were varied in order to adjust the EFH (range: 0.23 to 1.52 m) and torso to snow angle at impact (range: 0 to 92°). The peak resultant linear and angular head accelerations, peak cervical spine load, and peak lumbar spine load were determined for each trial and compared to the loads associated with severe injuries from the biomechanical engineering literature. Full sets of data were recorded for thirteen test trials. The peak resultant linear and angular head accelerations were well below the levels associated with severe brain injury. For eight of the tests, the cervical spine compression exceeded the average compression known to create severe injuries [Nightingale, R. W., McElhaney, J. H., Richardson, W. J. and Myers, B. S., “Dynamic Responses of the Head and Cervical Spine to Axial Impact Loading,” J. Biomech., Vol. 29, 1996, pp. 307–318; Maiman, D. J., Sances, A. Jr., Myklebust, J. B., Larson, S. J., Houterman, C., Chilbert, M., and El-Ghatit, A. Z., “Compression Injuries of the Cervical Spine: A Biomechanical Analysis,” Neurosurgery, Vol. 13, 1983, pp. 254–260]. All of the tests produced cervical spine flexion moments above those associated with cervical spine failure found in the literature. There was no correlation between cervical spine compression and EFH (R2 = 0.03), but there was a significant correlation with torso to snow surface angle at landing (R2 = 0.90). Results of the present study indicate that the likelihood of severe brain injury was low for all impacts within the EFHs examined. Despite this, even low EFHs can produce cervical spine loads well above the levels associated with severe cervical spine injury; these results support the findings of Dressler et al. [Dressler, D., Richards, D., Bates, E., Van Toen, C. and Cripton, P., “Head and Neck Injury Potential With and Without Helmets During Head-First Impacts on Snow,” Skiing Trauma Safety, 19th Volume, STP 1553, R. Johnson, J. Shealy, R. Greenwald and I. Scher, Eds., ASTM International, West Conshohocken, PA, 2012, pp. 235–249], who used a partial ATD without rotational kinematics. Furthermore, the lack of relationship between EFH and the metrics related to severe neck injury in the testing suggest that landing configuration is more important than EFH in determining injury likelihood of cervical spine from a backward rotated, unsuccessful jump landing.

Ice hockey body checks involving direct shoulder-to-head contact frequently result in head injury. In the current study, we examined the effect of shoulder pad style on the likelihood of head injury from a shoulder-to-head check. Shoulder-to-head body checks were simulated by swinging a modified Hybrid-III anthropomorphic test device (ATD) with and without shoulder pads into a stationary Hybrid-III ATD at 21 km/h. Tests were conducted with three different styles of shoulder pads (traditional, integrated and tethered) and without shoulder pads for the purpose of control. Head response kinematics for the stationary ATD were measured. Compared to the case of no shoulder pads, the three different pad styles significantly (p < 0.05) reduced peak resultant linear head accelerations of the stationary ATD by 35-56%. The integrated shoulder pads reduced linear head accelerations by an additional 18-21% beyond the other two styles of shoulder pads. The data presented here suggest that shoulder pads can be designed to help protect the head of the struck player in a shoulder-to-head check.

Crash testing and validation of Military vehicles has not to date, accounted for the Soldier gear burden. Actual loads imparted onto the occupant in a representative Military vehicle crash test environment have been limited and do not reflect what an occupant would actually see in this type of an event. The US Army Soldier encumbered with his gear poses a challenge in restraint system design that is not typical in the automotive world. The weight of the gear encumbrance may have a significant effect on how the restraint system performs and protects the occupant during a frontal event. Other system level complications to Military vehicle interiors are secondary impact surfaces, such as instrument panels, ammunition cans and weaponry which provide a path for off-loading the energy generated by the occupant and gear combination. The energy absorption of these surfaces however, is not ideal in current Military vehicle designs and may result in injury or death. The goal of this study was to investigate gear and accelerative pulses as they relate to the restraints and occupant interaction. Data from this study will be used for further restraint development. To limit experimental variation a fixed steel seat structure was utilized throughout the entire testing series. It is hypothesized that determining these effects will lead to a restraint system design that can be optimized to provide restraint for the whole range of occupant sizes and gear variations. Further reductions in occupant injury are achieved by properly tuning the surrounding trim, air bags and cargo contact surfaces. Results of this study indicate the inclusion of the soldier gear may increase the likelihood of occupant excursion and injury. Variation in accelerative pulses resulted in lower injury values and occupant displacements.

Head and neck injuries sustained during water skiing and wakeboarding occur as a result of falls in water and collisions with obstacles, equipment, or people. Though water sports helmets are designed to reduce injury likelihood from head impacts with hard objects, some believe that helmets increase head and neck injury rates for falls into water (with no impact to a solid object). The effect of water sports helmets on head kinematics and neck loads during simulated falls into water was evaluated using a custom-made pendulum system with a Hybrid-III anthropometric testing device. Two water entry configurations were evaluated: head-first and pelvis-first water impacts with a water entry speed of 8.8 ± 0.1 m/s. Head and neck injury metrics were compared to injury assessment reference values and the likelihoods of brain injury were determined from head kinematics. Water sport helmets did not increase the likelihood of mild traumatic brain injury compared to a non-helmeted condition for both water entry configurations. Though helmets did increase injury metrics (such as head acceleration, HIC, and cervical spine compression) in some test configurations, the metrics remained below injury assessment reference values and the likelihoods of injury remained below 1%. Using the effective drag coefficients, the lowest water impact speed needed to produce cervical spine injury was estimated to be 15 m/s. The testing does not support the supposition that water sports helmets increase the likelihood of head or neck injury in a typical fall into water during water sports.