Measuring the Influence of Neck Compliance on Brain Tissue Strain

The aim of this study was to determine if a change in neck compliance would influence the risk of sustaining a TBI by quantifying its effects on maximum principal strain in the brain. This was done by impacting a Hybrid III headform with a 16.6 kg impactor arm at 5.5 m·s. Three different Hybrid III neckforms were used: 1) one 50 percentile male neck – standard neck; 2) one 50 percentile male neck plus 30 per cent compliance – soft neck; 3) one 50 percentile male neck minus 30 per cent compliance – stiff neck. The kinematic data obtained was then used to drive a finite element model developed by University College Dublin. The results showed that neck compliance did not have a significant effect on maximum principle strains in the white matter, grey matter and brain stem. The stiff neck, however, generated higher strain levels in the cerebellum than the medium and soft neck conditions. A comparison to proposed mild TBI thresholds revealed that collisions happening at 5 m·s can disrupt the axons in the white and grey matter.