Traumatic brain injury is a leading cause of global death and disability.
Clinically relevant large animal models are a vital tool for understanding the
biomechanics of injury, providing validation data for computation models, and
advancing clinical translation of laboratory findings. It is well-established
that large angular accelerations of the head can cause TBI, but the effect of
head impact on the extent and severity of brain pathology remains unclear.
Clinically, most TBIs occur with direct head impact, as opposed to inertial
injuries where the head is accelerated without direct impact. There are
currently no active large animal models of impact TBI. Sheep may provide a
valuable model for studying TBI biomechanics, with relatively large brains that
are similar in structure to that of humans. The aim of this project is to
develop an ovine model of impact TBI to study the relationships between impact
mechanics and brain pathology. An elastic energy impact injury device has been
developed to apply scalable head impacts to rapidly rotate the head without
causing hard tissue damage. A motion constraint device has been developed to
limit the head motion to a single plane of rotation. The apparatus has been
tested using deceased animals to assess the controllability of impact
velocities, the repeatability of head kinematics, and the dynamic response of
the head to impact. Impact velocities are effectively controlled by modulating
the elastic energy stored in the impact piston. The resulting head kinematics
are somewhat variable, and are influenced by impact location, time-dependent
postmortem tissue changes, and specimen head and neck physiology. Model
development will continue, and in vivo testing will be conducted to assess the
brain pathology following impacts of varying severity.
