Rotational impact orientation effects traumatic brain injury severity, a biomimetic study.

Rotational impacts on the head involve complex interactions among brain tissue, cerebrospinal fluid (CSF), and the skull, making the underlying biomechanics difficult to investigate experimentally. This study utilized a transparent biomimetic head surrogate together with a high-speed imaging system with two-dimensional digital image correlation (2D-DIC) to visualize and quantify brain motion during rotational impacts. The experimental results provide direct visualization demonstrating that rotational impacts produce substantial relative motion between the brain and the skull. The resulting sliding at the brain-skull interface may increase mechanical interaction over large regions of the brain surface. Horizontal impacts were associated with the greatest relative brain motion, whereas sagittal impacts generated the highest principal strains, particularly compressive strains, indicating that impact orientation influences the biomechanical response of the brain. The results further indicate that skull geometry appears to be an important factor influencing brain motion, together with the mechanical interaction between the brain, the CSF surrogate, and the skull. These experimental measurements provide quantitative data that improve the understanding of rotational traumatic brain injury biomechanics.