Initial analysis of archived non-human primate frontal and rear impact data from the biodynamics data resource

ABSTRACT

Objective: The research objective was to conduct an initial analysis of non-human primate (NHP) data from frontal and rear impact events archived in the Biodynamics Data Resource (BDR) records of the Naval Biodynamics Laboratory (NBDL). These rare data, collected between 1973 and 1989, will inform the safety community of upper-end tolerance limits of NHP and may be related to severe crash scenarios.

Methods: Data from frontal and rear acceleration tests to 93 macaque NHP were examined. Each NHP was fully torso restrained, whereas the head–neck complex was unrestrained. Each NHP underwent between 1 and 21 total runs; 2 total runs was most common—a low-level run and then a high-level run. Following each impact exposure, the NHP was evaluated using a series of medical examinations. Now part of the legacy collection in the BDR, these evaluations were used to assess NHP exposures to be in one of 3 categories: noninjurious, injurious, or fatal. Using reported peak sled acceleration values, data were amenable to survival analysis statistical methodology to derive injury probability curves (IPCs). IPCs were derived for injury and fatality outcomes.

Results: Fatal injuries for both frontal and rear impacts were mostly at the cranio-vertebral junction. In addition to hemorrhage, fatal frontal and rear impact tests both produced predominantly atlanto-occipital dislocations, with and without spinal cord transection. After exclusions, IPCs were derived for frontal and rear impact for both (1) fatal outcome and (2) injurious outcome (any injury including fatal injury). For frontal impact, 53 NHP qualified with 5, 25, and 50% risk for fatality at 89, 105, and 114 peak sled Gs, respectively, and for injurious outcome at 70, 92, and 106 Gs, respectively. For rear impact, 34 NHP qualified with 5, 25, and 50% risk for fatality at 96, 122, 138 peak sled Gs, respectively, and for injurious outcome at 75, 99, and 115 Gs, respectively.

Conclusions: The majority of injuries were at the cranio-vertebral junction, indicating that the inertial head mass caused a tensile loading mechanism to the cervical spine. These data may be used in conjunction with finite element modeling to estimate risks to the human population. The most direct application in the automotive environment could be to the well-restrained child. The N_ij neck injury criteria, currently based on data from piglet studies, could also benefit because the NHP is a more accurate human surrogate. These types of tests are likely to never be repeated and will form an upper bound of tolerance information valuable to safety system designers.

KEYWORDS:

• Neck injury
• impact responses
• front impact
• rear impact
• injury risk curve

Disclosure statement

The animals involved in this study were maintained and used in accordance with the regulatory guidance at the time of research, including the Animal Welfare Act of 1970, the “Guide for Care and Use of Laboratory Animals” prepared by the Committee on Care and Use of Laboratory Animals of the Institute of Laboratory Animal Resources, National Research Council. In compliance with the DoD Directive (DODD) 3216.1, “Use of Animals in DoD Programs,” the Naval Biodynamics Laboratory (NBDL) was approved by the American Association for Accreditation of Laboratory Animal Care (AAALAC). The last animal work was conducted at NBDL in 1989.

Additional information

Funding

This study was supported by Defense Health funding from the Office of the Assistant Secretary of Defense for Health Affairs (DHA) through the U.S. Army Medical Research and Materiel Command (USAMRMC) Broad Agency Announcement under the Joint Program Committees (JPC-5 and JPC-6) and Award No. W81XWH-16-1-0010. This study was also supported with resources and use of facilities at the Zablocki VA Medical Center, Milwaukee, Wisconsin.