title: Head impact accelerations for brain strain-related responses in contact sports: a model-based investigation.
abstract: Both linear [Formula: see text] and rotational [Formula: see text] accelerations contribute to head impacts on the field in contact sports; however, they are often isolated in injury studies. It is critical to evaluate the feasibility of estimating brain responses using isolated instead of full degrees-of-freedom (DOFs) accelerations. In this study, we investigated the sensitivities of regional brain strain-related responses to resultant [Formula: see text] and [Formula: see text] as well as the relative contributions of these acceleration components to the responses via random sampling and linear regression using parameterized, triangulated head impacts with kinematic variable values based on on-field measurements. Two independently established and validated finite element models of the human head were employed to evaluate model-consistency and dependency in results: the Dartmouth Head Injury Model and Simulated Injury Monitor. For the majority of the brain, volume-weighted regional peak strain, strain rate, and von Mises stress accumulated from the simulation significantly correlated with the product of the magnitude and duration of [Formula: see text], or effectively, the rotational velocity, but not to [Formula: see text]. Responses from [Formula: see text]-only were comparable to the full-DOF counterparts especially when normalized by injury-causing thresholds (e.g., volume fractions of large differences virtually diminished (i.e., [Formula: see text]1 %) at typical difference percentage levels of 1-4 % on average). These model-consistent results support the inclusion of both rotational acceleration magnitude and duration into kinematics-based injury metrics and demonstrate the feasibility of estimating strain-related responses from isolated [Formula: see text] for analyses of strain-induced injury relevant to contact sports without significant loss of accuracy, especially for the cerebrum.
authors.affiliation: Thayer School of Engineering, Dartmouth College, Hanover, NH, 03755, USA, Songbai.Ji@Dartmouth.edu.
authors.forename: Songbai
authors.initials: S
authors.lastname: Ji
authors.forename: Wei
authors.initials: W
authors.lastname: Zhao
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Li
authors.forename: Thomas W
authors.initials: TW
authors.lastname: McAllister
mesh_terms: D000054:Acceleration; D001265:Athletic Injuries / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology*; D001930:Brain Injuries / Q000503:physiopathology*; D006257:Head; D006801:Humans; D016014:Linear Models; D008954:Models, Biological; D013177:Sports; D013997:Time Factors