Effect of helmet use on maxillofacial injuries due to bicycle and scooter accidents: a systematic literature review and meta-analysis

Maxillofacial injury is a common injury resulting from bicycle (including e-bike) and scooter accidents. With 80,000 admissions to emergency departments in 2019, bicycle accidents account for more than half of all trafficrelated emergency department visits in the Netherlands. The United States reports approximately 130,000 injuries and 1000 fatalities related to cycling annually. This systematic review and meta-analysis was performed to examine the protective effect of helmets against maxillofacial injuries resulting from bicycle and scooter (including e-bike and e-scooter) accidents. After a systematic literature search, 14 studies were found to be eligible for this systematic review. Of these, 11 were included in the meta-analysis. None of the included studies focused on vehicles with motors (e-bikes and e-scooters); all focused only on non-motorized vehicles. All included studies were non-randomized, which could have led to bias in the pooled results. Data from the included studies were tested for heterogeneity using the binary random-effects model (DerSimonian-Laird method), and the odds ratio for the occurrence of maxillofacial injury in cyclists wearing a helmet versus those not wearing a helmet was calculated by randomeffects meta-analysis. Patients who had worn a helmet suffered significantly fewer maxillofacial injuries than patients who had not, in bicycle accidents (odds ratio 0.682). In conclusion, wearing a helmet has a significant protective effect against maxillofacial injury, indicating the need for strict helmet legislation.