MECHANISM OF INJURY AND POST-CONCUSSION SYMPTOMS IN ADOLESCENT SOCCER PLAYERS
Authors: Wang Henry H. , Bunt Stephen C. , Zynda Aaron J. , Hicks Cason , Vargas Bert , Bell Kathleen , Cullum Munro 
Published: March 2019

Background: In contact sports such as soccer, a variety of mechanisms exist in which a sport-related concussion (SRC) may be sustained. This includes striking the ball with the head, whether unintentional or in the act of heading, striking the ground, and hitting other players’ bodies or heads. There are limited data examining whether different mechanisms of injury have an effect on post-concussion symptoms. The purpose of this study was to explore the relationship between concussion injury mechanism and symptom clusters in adolescent soccer players. Methods: Data were collected from subjects enrolled in the North Texas Concussion Network Registry (ConTex). Subjects were included if they were age 12-18 and diagnosed with a SRC while playing soccer. Upon clinical visit, subjects completed a self-reported symptom evaluation and relevant medical and concussion history. Symptoms were divided into three clusters: physical, cognitive, and emotional. A symptom count for each cluster was calculated along with a sum of reported symptom level. These values were compared to injury mechanism (collision with another player’s body, ground, ball, etc.) using one-way ANCOVA which controlled for differences in body mass index (BMI). For analyses in which BMI had no main effect, the covariate was removed from the model and ANOVA was performed. For analyses with significant Levene’s values, a Kruskal-Wallis H Test was used to verify the main effect of the independent variable. Pairwise comparisons with Bonferroni correction were used to analyze the data. Results: A total of 169 (57 male, 112 female) subjects met inclusion criteria. The mean age of the group was 13.9 years (range: 12-18). Of all the subjects, 42 (24.9%) experienced a collision with another player, 20 (11.8%) experienced a head-to-head collision, 49 (29.0%) were struck in the head by the ball unintentionally, 47 (27.8%) hit their heads on the ground, and 11 (6.5%) were intentionally heading the ball. Mechanism of injury had a significant effect on Physical Cluster Symptom count (p=.005), Cognitive Cluster Symptom count (p=.004), and Emotional Cluster Symptom count (p=.003) and Emotional Symptom sum (p=.013). Hitting the head to the ground was associated with a higher Physical Cluster Symptom count (p=.015), Cognitive Cluster Symptom count (p=.004), and Emotional Cluster Symptom count (p=.002) and Emotional Cluster Symptom sum (p=.009) than unintentional ball strikes. Additionally, hitting the ground resulted in a higher Emotional Cluster Symptom count than hitting another player’s body (p=.017). No other effects of mechanism on symptoms were seen. Conclusions: These findings suggest that there is a significant effect for some injury mechanisms and symptom clusters in adolescent soccer players. In this sample, a greater number of physical, cognitive, and emotional symptoms as well as a greater sum of emotional symptoms were reported by subjects who hit their head on the ground than subjects who experienced other mechanisms of injury such as being incidentally struck by the ball or colliding with another player. The outcomes of this analysis encourage the consideration of mechanism of injury when evaluating symptoms for SRC in soccer.