Head injury patterns in helmeted and non-helmeted cyclists admitted to a London Major Trauma Centre with serious head injury

Background Cycle use across London and the UK has increased considerably over the last 10 years. With this there has been an increased interest in cycle safety and injury prevention. Head injuries are an important cause of mortality and morbidity in cyclists. This study aimed to ascertain the frequency of different head injury types in cyclists and whether wearing a bicycle helmet affords protection against specific types of head injury. Methods A retrospective observational study of all cyclists older than 16 years admitted to a London Major Trauma Centre between 1st January 2011 and 31st December 2015 was completed. A cohort of patients who had serious head injury was identified (n = 129). Of these, data on helmet use was available for 97. Comparison was made between type of injury frequency in helmeted and non-helmeted cyclists within this group of patients who suffered serious head injury. Results Helmet use was shown to be protective against intracranial injury in general (OR 0.2, CI 0.07-0.55, p = 0.002). A protective effect against subdural haematoma was demonstrated (OR 0.14, CI 0.03-0.72, p = 0.02). Wearing a helmet was also protective against skull fractures (OR 0.12, CI 0.04-0.39, p<0.0001) but not any other specific extracranial injuries. This suggests that bicycle helmets are protective against those injuries caused by direct impact to the head. Further research is required to clarify their role against injuries caused by shearing forces. Conclusions In a largely urban environment, the use of cycle helmets appears to be protective for certain types of serious intra and extracranial head injuries. This may help to inform future helmet design.