Citation

Broglio SP, Lapointe AP, O'Connor KL, McCrea M. J. Neurotrauma 2017; 34(19): 2675-2683.

Affiliation

Medical College of Wisconsin, Neurosurgery, Milwaukee, Wisconsin, United States ; mmccrea@mcw.edu.

Copyright

(Copyright © 2017, Mary Ann Liebert Publishers)

DOI

10.1089/neu.2016.4767

PMID

28381134

Abstract

Concussions is a heterogeneous injury occurring throughout a range of impact magnitudes. Consequently, research focusing on a single or set of variables at the time of injury to understand concussive biomechanics has been thwarted by low injury prediction sensitivity. The current study examined the role of Impact Density in estimating concussive injury risk. Head impact data were collected across seven high school football seasons with the Head Impact Telemetry System (HIT System). Over the study period, 29 concussions were included for data analysis. The linear acceleration of the concussive impact was matched to a control athlete, along with impacts in the 24 hours prior. Linear and rotational acceleration for the 19 impacts leading into the final event and the cumulative accelerations over time were evaluated. Analyses indicated no difference in impact counts within the final 24 hours, or impact magnitudes for linear and rotational acceleration among the final 20 impacts (p's >0.05). A novel metric, Impact Density, was calculated from the final 20 impacts by summing the acceleration magnitude divided by time from the previous impact. Analyses indicated the concussed athletes incurred a significantly higher linear (Concussed: 255.4g/s(SEM=40.1), Controls:145.4g/s(SEM=23.8), p=0.016) and rotational (Concussed:10311.3 rad/s/s/s(SEM=1883.7), Controls:6083.8 rad/s/s/s(SEM=1115.9), p=0.029) Impact Density than the control athletes. Similar to other investigations, there was no difference in individual linear or rotational impact magnitude in the 20 impacts prior to and including the injury. However, the measure of Impact Density revealed differences between the concussed and control athletes. These data suggest that the biomechanical threshold for concussion fluctuates downwardly with a greater impact magnitude and number with a return to pre-impact levels with time, suggesting physiological vulnerability to repeated head impacts. The current results highlight that time between impacts, not just impact magnitude influences risk for concussion.

Keywords: American football

Language: en

Keywords

IN VIVO STUDIES; MODELS OF INJURY; PEDIATRIC BRAIN INJURY