The wearing of a standard-approved motorcycle helmet has been the most significant step in reducing fatal and serious injury among motorcyclists worldwide. Mandatory helmet use for motorcyclists is now in place in many parts of the world. Nevertheless, some researchers have observed a high percentage and duration of hospitalisations in helmet-protected motorcyclists with the long-term outcome considerably influenced by head injury severity. The objective of this study was to investigate head and neck injuries sustained by helmeted motorcyclists in real world crashes and define the circumstances which result in injury.

Data were collected by in-depth crash investigations of motorcyclist crashes in NSW, Australia. The crash investigations included inspections of the accident scene, the crash involved motorcycle and the helmet. Where possible, detailed helmet examination including helmet disassembly was performed to identify all crash related damage. The type of damage, damage location and damage severity on the helmets were recorded. The major head and neck injury types sustained by these helmeted riders were analysed for crash and helmet damage related factors which influenced the incidence of injury.

Due to the recruitment procedures used, participants in this study were biased towards lower severity head injuries. A head injury was sustained in 23.9% of cases but serious (AIS 3+) head injury was sustained in only 2.3%. There was neck injury in 9.1% of cases but no serious (AIS 3+) neck injuries. The main head and neck injury types by frequency were superficial injury (13.6%), “diffuse” type brain injury (13.6%), facial/dental fracture (4.5%) and cervical spine fracture (4.5%).

Helmet damage was observed in the majority of cases (86.4%) suggesting successful injury prevention in many instances. A high proportion of observed impact damage was to the front of the helmet (78.5% of cases), particularly the chin bar and visor of full-face helmets. Impact damage associated with a predominantly tangential force onto the head was more common than radially directed force damage.

Superficial head injury and facial/dental fractures was significantly more common (p < 0.01) in riders who were wearing open face helmets, where the face and chin are exposed to direct impact, compared to full face protected riders. There were significantly more cervical spine fractures in cases with damage indicative of a radially directed force (p = 0.036) than where damage indicated a tangentially applied force. The circumstances resulting in “diffuse” brain injuries could not be clearly defined by the data in this study due to the small number of riders with this injury.

The results highlight potential areas for improving the head and neck protection offered to motorcyclists including extending the required region of coverage, particularly to the face, and through mitigating the effect of tangential impacts on the helmet. Given the high frequency of diffuse intracranial injury even in lower severity head injury cases, assessment of helmet effectiveness should use performance criteria reflecting the mechanisms of this type of injury.