A Comparison of Maxillofacial and Head Injuries Following Electric Scooter and Bicycle Accidents

Background: The prevalence of maxillofacial and head injuries associated with electric scooters (e-scooter, ES) has risen in concordance with its popularity.

Purpose: The purpose of this study was to compare maxillofacial and head injury location, type, and severity related to ES and bicycle accidents and to identify factors contributing to injury severity.

Study design, setting, sample: The authors implemented a multicenter retrospective cohort study in Seattle, Washington, and enrolled a sample of ES riders and bicyclists who sustained maxillofacial injuries between September 2020 and September 2022. The exclusion criteria included nonmotorized scooters, motorized bicycles, injuries with other operators, or vehicles, and pre-evaluation deaths.

Predictor variable: The predictor variable was vehicle type, bicycle or ES.

Outcome variables: The outcome variables included maxillofacial injury location, distinguished by horizontal facial thirds and injury type, defined as hard or soft tissue. Associated head injury types were also reported as hard (calvaria) or soft (scalp) tissue injuries. The severity of these injuries was quantified using both the injury severity score and the face and head abbreviated injury scale.

Covariates: Demographic, injury, and treatment-related variables were collected.

Analyses: Bivariate, multivariate, and regression statistics were computed. Statistical significance was P < .05.

Results: The final sample was composed of 205 total subjects, of which 52 (25.4%) were in the ES group and 153 (74.6%) in the bicycle group. Isolated midface injuries were the most common hard tissue location in the ES (15.4%) and bicycle (29.4%) groups. The most common soft tissue injury location included the upper face and midface in the ES group (19.2%) and the midface in the bicycle group (22.9%). Both hard and soft tissue head injuries were more prevalent in the ES group (P < .0002 and P < .0001). Moreover, intracranial injuries were seen in 36.5% of ES subjects compared to 9.8% bicycle subjects (P < .0001). Between the two groups there was no difference in maxillofacial injury severity, but head injuries were more severe in the ES group (P < .0002). Using regression analysis, drug use was found to have a significant impact on the mean injury severity score (P < .002) and helmet use did not have significant impact on face or head injury severity.

Conclusion: Maxillofacial injury location, type, and severity are comparable among ES and bicycles. However, ES riders are at greater risk of severe head injuries compared to bicycles, and riding while intoxicated has the greatest effect on injury severity.