Mechanisms of Head and Neck Injuries Sustained by Helmeted Motorcyclists in Fatal Real-World Crashes: Analysis of 47 In-Depth Cases

Evaluation of full-face, open-face, and airbag-equipped helmets for facial impact protection

OBJECTIVE

Two-wheeler riders frequently sustain injuries to the head and face in real-world crashes, including traumatic brain injury, basilar skull fracture, and facial fracture. Different types of helmets exist today, which are recognized as preventing head injuries in general; however, their efficacy and limitations in facial impact protection are underexplored. Biofidelic surrogate test devices and assessment criteria are lacking in current helmet standards. This study addresses these gaps by applying a new, more biofidelic test method to evaluate conventional full-face helmets and a novel airbag-equipped helmet design. Ultimately, this study aims to contribute to better helmet design and testing standards.

METHODS

Facial impact tests at two locations, mid-face and lower face, were conducted with a complete THOR dummy. Forces applied to the face and at the junction of the head and neck were measured. Brain strain was predicted by a finite element head model taking both linear and rotational head kinematics as input. Four helmet types were evaluated: full-face motorcycle and bike helmets, a novel design called a face airbag (an inflatable structure integrated into an open-face motorcycle helmet), and an open-face motorcycle helmet. The unpaired, two-sided student's t-test was performed between the open-face helmet and the others, which featured face-protective designs.

RESULTS

A substantial reduction in brain strain and facial forces was found with the full-face motorcycle helmet and face airbag. Upper neck tensile forces increased slightly with both full-face motorcycle (14.4%, p >.05) and bike helmets (21.7%, p =.039). The full-face bike helmet reduced the brain strain and facial forces for lower-face impacts, but not for mid-face impacts. The motorcycle helmet reduced mid-face impact forces while slightly increasing forces in the lower face.

SIGNIFICANCE OF RESULTS

The chin guards of full-face helmets and the face airbag protect by reducing facial load and brain strain for lower face impact; however, the full-face helmets' influence on neck tension and increased risk for basilar skull fracture need further investigation. The motorcycle helmet's visor re-directed mid-face impact forces to the forehead and lower face via the helmet's upper rim and chin guard: a thus-far undescribed protective mechanism. Given the significance of the visor for facial protection, an impact test procedure should be included in helmet standards, and the use of helmet visors promoted. A simplified, yet biofidelic, facial impact test method should be included in future helmet standards to ensure a minimum level of protection performance.

Investigation into the Trampoline Dynamic Characteristics and Analysis of Double Bounce Vibrations

Double bounce is an unusual and potentially very hazardous phenomenon that most trampoline users may have experienced, yet few would have really understood how and why it occurs. This paper provides an in-depth investigation into the double bounce. Firstly, the static and dynamic characteristics of a recreational trampoline are analysed theoretically and verified through experiments. Then, based on the developed trampoline dynamic model, double bounce simulation is conducted with two medicine balls released with different time delays. Through simulation, the process of double bounce is presented in detail, which comprehensively reveals how energy is transferred between users during double bounce. Furthermore, the effect of release time delay on double bounce is also presented. Finally, we conducted an experiment which produced similar results to the simulation and validated the reliability of the trampoline dynamic model and double bounce theoretical analysis.

The Pattern of Injuries Among Motorcyclists in Fatal Road Traffic Accidents: An Autopsy-Based Study

INTRODUCTION

In recent years, there has been a significant increase in mortality among motorcyclists, which warrants a need to analyze the epidemiology and pattern of injuries among road users in Malaysia. Hence, prioritizing road safety in the government policy by implementing targeted actions is justified to reduce injury and fatality.

MATERIALS AND METHODS

Cases of road accident deaths in motorcyclists received by UKM Medical Centre were studied over a period of 10 years, that is, between 2010 and 2019. This study was based on forensic autopsy records database and forensic autopsy.

RESULTS

The most affected age group by road fatalities were young men. The most common injuries were intracranial hemorrhage (74%), thoracic hemorrhage (73%), and lung laceration (85.7%). About 39 (31%) fatally injured riders were positive for illicit drug and/or alcohol.

CONCLUSIONS

This study showed that men in the third decade of life are the major victims of motorcycle fatalities. Hence, urgent measures are necessary to establish road safety policy to reduce such fatalities.

Relationship between head and neck injuries and helmet use in fatal motorcycle and moped crashes in Denmark

Motorcycle- and moped crashes are prevalent in motorised societies and carry a significant risk of serious injury. Whereas helmet use has reduced the frequency and severity of head injuries, the association between helmet use and neck injury risk is less clear. In the present retrospective study, we examined the relationship between helmet use and various types of head and neck injuries resulting from fatal motorcycle and moped crashes during a 20-year period. Eighty-three cases were included of whom 56 were analysed in detail based on their confirmed use/non-use of helmet. Intracranial haemorrhage was the most common finding, followed by CNS disruption and skull fracture. There was a significantly lower prevalence of skull vault fractures and epidural haemorrhage in the helmeted cases. Injuries to the brainstem and cervical spine fracture/dislocation were more common in the helmeted cases, although this was likely a function of higher speeds among motorcycle riders rather than an effect of helmet use per se. Further investigation of these findings require additional detailed information regarding the nature and severity of the crash, as well as helmet use and type, in order to assess non-confounded associations with the anatomical distribution, type and severity of observed head and neck injuries.

The effects of topology and relative density of lattice liners on traumatic brain injury mitigation

This paper evaluates the effects of topology and relative density of helmet lattice liners on mitigating Traumatic Brain Injury (TBI). Finite Element (FE) models of new lattice liners with prismatic and tetrahedral topologies were developed. A typical frontal head impact in motorcycle accidents was simulated, and linear and rotational accelerations of the head were recorded. A high-fidelity FE model of TBI was loaded with the accelerations to predict the brain response during the accident. The results show that prismatic lattices have better performance in preventing TBI than tetrahedral lattices and EPS that is typically used in helmets. Moreover, varying the cell size through the thickness of the liner improves its performance, but this effect was marginal. The relative density also has a significant effect, with lattices with lower relative densities providing better protection. Across different lattices studied here, the prismatic lattice with a relative density of 6% had the best performance and reduced the peak linear and rotational accelerations, Head Injury Criterion (HIC), brain strain and strain rate by 48%, 37%, 49%, 32% and 65% respectively, compared to the EPS liner. These results can be used to guide the design of lattice helmet liners for better mitigation of TBI.

A retrospective analysis of the relationship between facial injury and mild traumatic brain injury

BACKGROUND/AIMS

The association between facial injury characteristics and mild traumatic brain injury (mTBI) is unclear. The aim of this study was to determine the association between facial injury characteristics and mTBI.

METHODS

A retrospective review utilizing patients' medical records at the Universiti Kebangsaan Malaysia Medical Centre (UKMMC), Kuala Lumpur, Malaysia, was performed. Records of subjects with a history of facial trauma from 1 April 2012 to 31 December 2012 were selected. Various levels and surgical speciality records were reviewed to ascertain the diagnoses of facial injuries and mTBI.

RESULTS

A total of 348 medical records with the diagnosis of facial injuries were included. The prevalence of mTBI among these patients was 41.4% (95% CI 36.2-46.6). The majority of the patients with mTBI were in the age group of 18-25 years old. Patients with or without facial lacerations that were located on the lower face had a significant association with mTBI, P=.001, compared to other types of soft tissue injury. In addition, a statistically significant association was observed between facial fractures occurring to the middle face and mTBI, P=.018. Pearson chi-square test also showed statistically significant association between the severity of facial injuries and mTBI, P=.018.

CONCLUSIONS

Mild traumatic brain injury should be suspected in patients with facial injuries and particularly those with lower face lacerations, midface fractures, moderate to severe facial injury and presence of multiple injuries.