Comparison of Brain Strain Magnitudes Calculated Using Head Tracking Impact Parameters and Body Tracking Impact Parameters Obtained from 2D Video

Abstract

Relying on signs and symptoms of head injury outcomes has shown to be unreliable in capturing the vulnerabilities associated with brain trauma (Karton & Hoshizaki, 2018). To accommodate the subjectivity of self-reported symptoms, data collection using sensor monitoring and video analysis combined with event reconstruction are used to objectively measure trauma exposure (Tator, 2013; Scorza & Cole, 2019; Hoshizaki et al., 2014). Athletes are instrumented with wireless sensors designed to measure head kinematics during play. However, these systems have not been widely adopted as they are expensive, face challenges with angular acceleration measures, and often require video confirmation to remove false positives. Video analysis of head impacts, in conjunction with physical event reconstruction and finite element (FE) modeling, is also used to calculate tissue level strain. This data collection method requires specialized equipment and expertise. Effective management of head trauma in sport requires an objective, accessible, and quantifiable tool that addresses the limitations associated with current measurement systems. The purpose of this research was to determine if a simplified version of video analysis and event reconstruction using impact characteristics (velocity, location, mass, and compliance) obtained from body tracking could yield similar measures of brain strain magnitude to the standard head tracking method. Ice hockey impacts (x36) that varied in terms of competition level, event type and maximum principal strain (MPS) were chosen for analysis. 2D videos of previously completed head reconstructions were reanalyzed and each event was reconstructed again in the laboratory using impact parameters obtained from body tracking. MPS values were calculated using finite element (FE) modeling and compared to the MPS values from events that were reconstructed using impact parameters obtained from head tracking. The relationship between head and body tracking MPS data and level of agreement between MPS categories were also assessed. Overall, a significant difference was observed between MPS magnitudes obtained using impact parameters from body and head tracking data from 2D video. When analyzed by event type, only shoulder and glass events demonstrated significant differences in MPS magnitudes. A strong linear relationship was depicted between the two data collection methods and moderate level of agreement between MPS categories was observed, demonstrating that impact characteristics obtained from body tracking and 2D video can be used to measure brain tissue strain.