The effect of neck stiffness on the response of a surrogate head due to blunt trauma in judo

Acute subdural hematomas can result from blunt trauma due to unbraced backwards falls in judo. This study investigated the response of a surrogate head subjected to blunt trauma from experimental backwards falls. The head was constrained by a Hybrid III surrogate neck (stiff condition) and by a novel surrogate neck (less stiff condition) attached to a simplified surrogate torso. A DTS 6DX Pro sensor was used to record linear acceleration and angular rate data and has been reported at the head’s centre of gravity. Peak angular acceleration values of ~9600 - 11000 rad/s2 and ~1500 - 1800 rad/s2 were recorded for the novel surrogate neck and the Hybrid III surrogate neck, respectively. The novel surrogate neck predicted acute subdural haematomas through bridging vein rupture when considering threshold values. The study indicates that angular kinematics of the head in the sagittal plane could be significantly underestimated when constrained by an overly stiff surrogate neck, such as the Hybrid III surrogate neck.