Prediction of Cervical Spine Injury Risk for the 6-Year-Old Child in Frontal Crashes

Abstract

This article presents a series of 49 km/h sled tests using the Hybrid III 6-year-old dummy in a high-back booster, a low-back booster, and a three-point belt. Although a 10-year review at a level I trauma center showed that noncontact cervical spine injuries are rare in correctly restrained booster-age children, dummy neck loads exceeded published injury thresholds in all tests. The dummy underwent extreme neck flexion during the test, causing full-face contact with the dummy's chest. These dummy kinematics were compared to the kinematics of a 12-year-old cadaver tested in a similar impact environment. The cadaver test showed neck flexion, but also significant thoracic spinal flexion which was nonexistent in the dummy. This comparison was expanded using MADYMO simulations in which the thoracic spinal stiffness of the dummy model was decreased to give a more biofidelic kinematic response. We conclude that the stiff thoracic spine of the dummy results in high neck forces and moments that are not representative of the true injury potential.

Patterns of severe injury in pediatric car crash victims: Crash Injury Research Engineering Network database

“…However, a safety device must prevent injuries encountered in the real world to be effective. This extrapolation from the laboratory to the real world is not always accurate, which is nicely elucidated in a study by Sherwood et al [4]. Injury tolerance studies in the laboratory on properly restrained children showed a remarkably high number of cervical spine injuries, yet these types of injuries are rarely encountered in the clinical setting.…”

“…Consequently, a vast amount of resources has been directed toward prevention and intervention strategies. Child crash test dummies have often been used for this purpose, providing an in vitro model by which to examine crash injury characteristics [4]. However, these models are limited in their ability to account for the wide spectrum of shapes and sizes in the pediatric population.…”

“…A potential alteration (eg, airbag) must be tested, typically by using crash test dummies to assess safety innovation and injury tolerance, to prove that it reduces injury. These in vitro models are limited by the variability in pediatric sizes and shapes and, combined with a developing skeleton, are significant obstacles for an effective injury tolerance model [4]. The Crash Injury Research Engineering Network (CIREN) can supplement the knowledge gained from laboratory crash dummy testing [5].…”

Biomechanical Impact Response of the Human Chin and Manubrium

“…These differences were attributed to a lack of spinal flexibility in the ATD. Sherwood et al 15 used modeling to compare the kinematics of a 12YO PMHS with the Hybrid III 6YO child ATD. It was shown that spinal motion is quite different in ATD and PMHS, and increasing thoracic spine flexibility generally improves biofidelity.…”

Mechanics of the Pediatric Thoracic Spine and its Role in the Kinematics of the Head in Automotive Frontal Impacts

“…There is also evidence of the lack of biofidelity of the spine of the Hybrid III 6YO that causes a questionable prediction of the trajectory of the pediatric head and unreliable neck loads Seacrist et al, 2010;Sherwood et al, 2003). These biofidelity issues have been attributed to the rigid thoracic spine of the ATD and it is envisioned that future models of pediatric occupants (either physical or computational) will consider some degree of deformation of the thoracic spine.…”