Improving Bicycle and Motorcycle Helmet Design to Prevent Traumatic Brain Injury: A Review

Traumatic brain injury (TBI) from bicycle and motorcycle-related accidents continues to be a major medical and financial burden in the United States. The complex management and debilitating consequences of TBI demand greater attention to its prevention, of which much relies on helmet use and structure. Conventional helmets today rely on an expanded polystyrene (EPS)-liner, which works to mitigate the linear acceleration experienced by the brain during impact. However, recent evidence suggests that it is not the linear acceleration but the rotational acceleration of the impact that most contribute to TBI development. This has led to the development of novel helmet designs that aim to mitigate rotational kinematics in addition to linear kinematics. The objective of this study was to overview limitations in current helmet design and discuss two of the most well-studied novel prototypes: WaveCels and Multi-Directional Impact Protection Systems (MIPS). Though both ultimately reduce the rotational acceleration of injury, they differ in mechanism and efficacy. Given the importance of helmet structure in the prevention of TBI, we find that more work is needed directly comparing these and other new designs