Association Between Conventional Bicycle Helmet Use and Facial Injuries After Bicycle Crashes.

Importance: Bicycling is an increasingly common activity in the United States that is often associated with fall injuries to the head and face. Although helmets lessen head injury, their role in reducing facial injuries is less clear; therefore, it is important to understand the protective capacity for the face in current helmet design. Objective: To estimate the conventional bicycle helmet's association with the rate of facial injury after bicycle crashes. Design, Setting, and Participants: This retrospective cohort study accessed records from January 1, 2010, to December 31, 2014, from the National Trauma Databank, which collects data from emergency departments in US hospitals. Each record pertained to 1 emergency department admission for a bicycle crash. The National Trauma Databank registry data are collected and recorded by incident, which is equivalent to an injury-related hospital admission. All injuries involving patients aged 18 to 65 years for whom data on helmet use and injury were available were included. Statistical analysis was conducted from July 19 to October 17, 2016. Exposures: Helmeted and nonhelmeted bicycle crashes. Main Outcomes and Measures: Head and facial injuries among helmeted and nonhelmeted bicycle crashes. Results: A total of 85 187 facial injuries met inclusion criteria (patient age 18-65 years, availability of helmet use status, and type of injury). Demographic information on bicycle riders was frequently unavailable. Among all injuries, fractures to the head (11.6% [9854]) and face (11.3% [9589]) occurred at similar rates. Helmets reduced head fractures by 52% (from 14.0% [7623] to 7.3% [2231]) and head soft-tissue injuries by 30% (from 15.0% [8151] to 10.9% [3358]), but had lower rates in protecting against facial injuries. While reducing facial injuries overall, the amount of protection with helmet use varied with facial location of the injury. Reduction in facial fractures was 35% (95% CI, 31%-39%) for upper face, 28% (95% CI, 23%-32%) for mid face, and 21% (95% CI, 15%-26%) for the lower face. Helmets were less protective against facial soft-tissue injuries, with a reduction of 33% (95% CI, 30%-36%) in the upper face, 21% (95% CI, 16%-26%) in the mid face, and 2% (95% CI, 0%-6%) in the lower face. Conclusions and Relevance: Although bicycle helmets provide some protection against facial injuries after bicycle crashes, the level of protection depends on the proximity of the injury to the helmeted head. The lower face is particularly vulnerable to injury despite helmet use.