Head Impact Exposure Sustained by Football Players on Days of Diagnosed Concussion

Abstract

Purpose This study compares the frequency and severity of head impacts sustained by football players on days with and without diagnosed concussion and to identify the sensitivity and specificity of single impact severity measures to diagnosed injury. Methods 1,208 players from eight collegiate and six high school football teams wore instrumented helmets to measure head impacts during all team sessions, of which 95 players were diagnosed with concussion. Eight players sustained two injuries and one three, providing 105 injury cases. Measures of head kinematics (peak linear and rotational acceleration, Gadd Severity Index (GSI), Head Injury Criteria (HIC15), change in head velocity (Δv)) and the number of head impacts sustained by individual players were compared between days with and without diagnosed concussion. Receiver operator characteristic curves were generated to evaluate the sensitivity and specificity of each kinematic measure to diagnosed concussion using only those impacts that directly preceded diagnosis. Results Players sustained a higher frequency of impacts and impacts with more severe kinematic properties on days of diagnosed concussion than on days without diagnosed concussion. Forty-five injury cases were immediately diagnosed following head impact. For these cases, peak linear acceleration and HIC15 were most sensitive to immediately diagnosed concussion (AUC = 0.983). Peak rotational acceleration was less sensitive to diagnosed injury than all other kinematic measures (p = 0.01) which are derived from linear acceleration (peak linear, HIC15, GSI, and Δv). Conclusions Players sustain more impacts and impacts of higher severity on days of diagnosed concussion than on days without diagnosed concussion. Additionally, of historical measures of impact severity, those associated with peak linear acceleration are the best predictors of immediately diagnosed concussion.

The Mechanics of Traumatic Brain Injury: A Review of What We Know and What We Need to Know for Reducing Its Societal Burden

“…The most widely used monitoring technology (head impact telemetry system, or HITS) allows investigators to record the estimated exposures in an American football game [225]. As of this writing, nearly 2 Â 10 6 exposures have been recorded with this technology, and over 200 concussion events are contained in this data set [226][227][228]. New recording technologies are under active development, especially as the advantages of microelectronic fabrication technologies make these sensors smaller, less expensive, and potentially more widely available.…”

The Influence of Head Impact Threshold for Reporting Data in Contact and Collision Sports: Systematic Review and Original Data Analysis

“…Based on the differences observed in this study, at the 14.4g threshold there could have been as many as 42% of the impacts recorded not being reported. As a result, studies 7,8,[12][13][14][15]20, 27, 33, 94, 107, 115, 119 using impact thresholds above 10g may have removed 2,100 to 206,573 impacts (see Table 2). At the 30g impact threshold it can be estimated that 80 to 85% of impacts were not reported.…”

Can helmet design reduce the risk of concussion in football?

“…Head impact exposure data (severity, frequency, and impact location) were collected for all games and practices that the players participated in, and were paired with clinical data provided by team physicians (diagnosis of concussion). 2,3 Players were equipped with either a Riddell VSR4 or Riddell Revolution helmet (Fig. 1).…”