Bicycle-related head injury: a study of 86 cases

Bicycle injuries: A systematic review for forensic evaluation

Bicycles are employed as means of transportation across various age groups, from young students to the elderly, for work, education, health, and leisure trips. Despite not achieving high speeds, bicyclists remain vulnerable to severe and even fatal injuries when they are involved in traffic accidents. Although the rising awareness of ecological issues and traffic law enforcement mean that cyclists are increasingly susceptible to road traffic crashes and injuries. Injuries resulting from a traffic accident involving cyclists can show distinct and specific characteristics depending on the manner of occurrence. The aim of this study is to provide a systematic review of the literature on injuries sustained in cyclists involved in road accidents describing and analysing elements useful for forensic assessment. The literature search was performed using PubMed, Scopus, and Web of Science from January 1970 to March 2023. Eligible studies have investigated issues of interest to forensic medicine about traffic accidents involving bicycles. A total of 128 studies satisfied the inclusion criteria and were categorized and analyzed according to the anatomical regions of the body affected (head, neck, thoraco-abdominal, and limb injuries), and the assessment of lesions in reconstruction of the bicycle accident was examined and discussed. This review highlights that injuries resulting from a traffic accident involving cyclists can show distinct and specific characteristics depending on the manner of occurrence and the energy levels involved in the crash. The assessment of injuries offers valuable insights that integrated with circumstantial and engineering data perform the reconstruction of accident dynamics.

A Review of Cyclist Head Injury, Impact Characteristics and the Implications for Helmet Assessment Methods

Head injuries are common for cyclists involved in collisions. Such collision scenarios result in a range of injuries, with different head impact speeds, angles, locations, or surfaces. A clear understanding of these collision characteristics is vital to design high fidelity test methods for evaluating the performance of helmets. We review literature detailing real-world cyclist collision scenarios and report on these key characteristics. Our review shows that helmeted cyclists have a considerable reduction in skull fracture and focal brain pathologies compared to non-helmeted cyclists, as well as a reduction in all brain pathologies. The considerable reduction in focal head pathologies is likely to be due to helmet standards mandating thresholds of linear acceleration. The less considerable reduction in diffuse brain injuries is likely to be due to the lack of monitoring head rotation in test methods. We performed a novel meta-analysis of the location of 1809 head impacts from ten studies. Most studies showed that the side and front regions are frequently impacted, with one large, contemporary study highlighting a high proportion of occipital impacts. Helmets frequently had impact locations low down near the rim line. The face is not well protected by most conventional bicycle helmets. Several papers determine head impact speed and angle from in-depth reconstructions and computer simulations. They report head impact speeds from 5 to 16 m/s, with a concentration around 5 to 8 m/s and higher speeds when there was another vehicle involved in the collision. Reported angles range from 10° to 80° to the normal, and are concentrated around 30°-50°. Our review also shows that in nearly 80% of the cases, the head impact is reported to be against a flat surface. This review highlights current gaps in data, and calls for more research and data to better inform improvements in testing methods of standards and rating schemes and raise helmet safety.

Age effects on the mechanical behavior of human cerebral bridging veins

BACKGROUND

It is well established that the probability of occurrence of acute subdural hematomas in traumatic situations increases with age, since the main cause of such hematomas is the mechanical failure of cerebral blood vessels known as bridging veins. This research aims to determine whether there is an effect of age on the mechanical properties of these cerebral vessels, because previous reported studies were conflicting.

METHODS

This study used mechanical tests blue of cerebral bridging veins from post-mortem human subjects. In particular, a series of in vitro tensile tests were performed on a balanced sample of bridging veins from different human subjects.

FINDINGS

The mechanical parameters measured from the tests were analyzed by means of regression analysis looking for age related effects. The results show that there is a significant effect on both the ultimate strength, maximum stress and strain that the specimens can withstand. The quantitative analysis shows reductions of nearly 50% in ultimate stress, and almost 35% in ultimate strain.

INTERPRETATION

Mechanical deterioration of the mechanical strength of cerebral blood vessels seems to be a major factor involved in the increase of frequency of acute subdural hematoma in elderly people in a wide range of life-threatening traumatic situations.

Evaluating the effect of drunk driving on fatal injuries among vulnerable road users in Taiwan: a population-based study

Background

Most studies have focused on injuries sustained by intoxicated drivers themselves, but few have examined the effect of drunk driving on injury outcomes among VRUs (vulnerable road users) in developing countries. This study aims to evaluate the effect of drunk driving on fatal injuries among VRUs (pedestrians, cyclists, or motorcyclists).

Methods

The data were extracted from the National Taiwan Traffic Crash Dataset from January 1, 2011, to December 31, 2019. Crashes involving one motorized vehicle and one VRU were considered. This study examines the effect of drunk driving by estimating multivariate logistic regression models of fatal injuries among VRUs after controlling for other variables.

Results

Among 1,416,168 casualties, the fatality rate of VRUs involved in drunk driving was higher than that of general road users (2.1% vs. 0.6%). Drunk driving was a significant risk factor for fatal injuries among VRUs. Other risk factors for fatal injuries among VRUs included VRU age ≥ 65 years (adjusted odds ratio [AOR]: 5.24, 95% confidence interval [CI]: 5.53–6.07), a nighttime accident (AOR: 4.52, 95% CI: 4.22–4.84), and being hit by a heavy-duty vehicle (AOR: 2.83, 95% CI: 2.26–3.55). Subgroup analyses revealed a linear relationship between driver blood alcohol concentration (BAC) and the risk of fatal injury among motorcyclists. Motorcyclists exhibited the highest fatality rate when they had a BAC ≤ 0.03% (AOR: 3.54, 95% CI: 3.08–4.08).

Conclusion

Drunk driving was associated with a higher risk of fatality for all VRUs. The risk of fatal injury among motorcyclists was linearly related to the BAC of the drunk drivers. Injuries were more severe for intoxicated motorcyclists, even those with BAC ≤ 0.03%, which is within the legal limit.

Analyzing Safety Concerns of (e-) Bikes and Cycling Behaviors at Intersections in Urban Area

Extensive effort has been devoted to examining the causal relationship between contributing factors and injury severities. Given the important role of riders’ behaviors in traffic conflicts, this paper aims to analyze the causal effects of traffic conflicts resulting from riders’ behaviors at intersections. The authors collected video data on 152 traffic conflicts caused by riders’ dangerous behaviors in Jiangning District, China. This paper proposes a Bayesian-structural equation modeling (BSEM) approach. Based on the obtained BSEM path coefficient diagram, the factor loadings and path coefficients are analyzed to unveil the potential influence of factors, including personal features, dangerous behavior tendency, temporal and spatial characteristics of dangerous behavior, and the external environment. The results show that compared to human factors, environmental factors have a less direct impact on the severity of traffic conflicts; instead, they have an indirect positive impact on traffic conflicts by affecting behaviors. That is, if riders judge that road conditions are not suitable to conduct dangerous behaviors, they become more cautious in view of current road conditions and time revenue. Furthermore, dangerous cycling behaviors that continue to encroach on the time and space of motorized vehicles are prone to be more dangerous. The dangerous behaviors that continuously encroach on the time and space of motor vehicles (e.g., disobeying traffic signals and riding in a motorway) are significant predictors of serious conflicts. Considering the heterogeneity of riding behavior, these findings could be applied to develop effective education and intervention programs for preventing riders’ high-risk behaviors and improving the traffic environment.

Subdural and epidural hematoma occurrence in relation to the head impact site: An autopsy study

Blunt head injury is a major public health and socioeconomic problem causing death and disability particularly among the young population throughout the world. The purpose of the present study was to evaluate if the impact site is correlated with the subdural and epidural hematoma occurrence. A retrospective analysis of consecutive autopsy cases submitted to our Department during a 5-year period was performed. The basic criterion for inclusion in the study was death due to blunt head injury. The recorded variables included the circumstances of death, the existence, and location of head injuries, the primary impact site, age, gender, and toxicological results. A total number of 683 fatal head injury cases was recorded, with most of them being male (74.1%). In 424 cases (62.1%) fatal head injuries were due to road traffic accidents. Fall (from height or on the ground) was the cause of death in 220 (32.2%) cases followed by inflicted impact-assault in 26 (3.8%) cases. A subdural hematoma was found more frequently (26.9%) than epidural (5.0%). Epidural hematomas were found only under the primary impact site, whereas subdural hematomas were coup, contrecoup, or bilateral. An epidural hematoma was found to be almost 5 times more frequent in cases in which a subdural hematoma was present. A higher proportion of subdural, as well as epidural hematoma, was found when the site of impact was the temporal region, followed by the parietal one. Sex did not exert any influence on the probability of subdural and epidural hematoma, whereas for age, a 10% increase in the probability of subdural hematoma occurrence was observed with 10-year age increase.

A Machine Learning Approach to Investigate the Uncertainty of Tissue-Level Injury Metrics for Cerebral Contusion

Controlled cortical impact (CCI) on porcine brain is often utilized to investigate the pathophysiology and functional outcome of focal traumatic brain injury (TBI), such as cerebral contusion (CC). Using a finite element (FE) model of the porcine brain, the localized brain strain and strain rate resulting from CCI can be computed and compared to the experimentally assessed cortical lesion. This way, tissue-level injury metrics and corresponding thresholds specific for CC can be established. However, the variability and uncertainty associated with the CCI experimental parameters contribute to the uncertainty of the provoked cortical lesion and, in turn, of the predicted injury metrics. Uncertainty quantification via probabilistic methods (Monte Carlo simulation, MCS) requires a large number of FE simulations, which results in a time-consuming process. Following the recent success of machine learning (ML) in TBI biomechanical modeling, we developed an artificial neural network as surrogate of the FE porcine brain model to predict the brain strain and the strain rate in a computationally efficient way. We assessed the effect of several experimental and modeling parameters on four FE-derived CC injury metrics (maximum principal strain, maximum principal strain rate, product of maximum principal strain and strain rate, and maximum shear strain). Next, we compared the in silico brain mechanical response with cortical damage data from in vivo CCI experiments on pig brains to evaluate the predictive performance of the CC injury metrics. Our ML surrogate was capable of rapidly predicting the outcome of the FE porcine brain undergoing CCI. The now computationally efficient MCS showed that depth and velocity of indentation were the most influential parameters for the strain and the strain rate-based injury metrics, respectively. The sensitivity analysis and comparison with the cortical damage experimental data indicate a better performance of maximum principal strain and maximum shear strain as tissue-level injury metrics for CC. These results provide guidelines to optimize the design of CCI tests and bring new insights to the understanding of the mechanical response of brain tissue to focal traumatic brain injury. Our findings also highlight the potential of using ML for computationally efficient TBI biomechanics investigations.

Investigation of tissue level tolerance for cerebral contusion in a controlled cortical impact porcine model

OBJECTIVE

Cerebral contusions (CC) represent a frequent lesion in traumatic brain injury, with potential morbidity from mass effect and tissue loss. Better understanding of the mechanical etiology will help to improve head protection. The goal of this study is to investigate the threshold for mechanical impact parameters to induce CC in an in vivo porcine controlled cortical impact model.

METHODS

Thirty-four adult male pigs underwent craniotomy and controlled cortical impact with a hemispherical tip on intact dura under general anesthesia. Peak impact depth varied between 1.1 and 12.6 mm, and impact velocity between 0.4 and 2.2 m/s while the dwell time was kept at 200 ms. Two days following impact, the animals underwent magnetic resonance (MR) imaging of the brain, and were subsequently sacrificed for brain extraction. CC damage was investigated by magnetic resonance imaging and histology.

RESULTS

All animals recovered from the impact without overt neurological deficit. Provoked injuries were histologically confirmed to be CC. Decreasing probability of cortical damage and white matter edema volume was observed with decreasing impact depth and velocity. No CC could be demonstrated below a product of impact depth and velocity of 0.8 mm*m/s, whereas the probability for CC was one third below 15 mm*m/s. The threshold for CC development as estimated from the current series of experiments, was situated at an impact depth of 2.0 mm and impact velocity of 0.4 m/s.

CONCLUSION

Mechanical thresholds for CC development could be explored in the current porcine controlled cortical impact model. Findings will be used to further refine a cerebral contusion porcine model with volumetric histology data in light of future finite element cerebral contusion validation studies.

Estimated and underreported parameters in report based vehicle-bicycle accident reconstructions have a significant influence

This study aimed to reconstruct four real life vehicle-bicycle collisions and evaluates the reconstruction parameters that affect the outcome of head injuries in report based accident reconstructions. A computational model of a car was developed in the multibody software MADYMO (MAthematical DYnamic MOdeling) and was used together with a validated bicycle model and the MADYMO 50 percentile pedestrian model. The accidents were reconstructed through an optimal fit method, based on kinematic and medical information. After the reconstruction, a parametric study on cyclists' movement and accident conditions was performed on the different cases. The velocity of the car and the angle of impact were found to significantly affect the accident outcome. This was demonstrated in terms of head injury criteria such as the Head Injury Criterion (HIC), the peak linear and peak angular velocity and acceleration. It was shown that the severity of the injury increases exponentially with increasing collision velocities. Additionally, the bicycle's parameters; crank rotation, handlebar angle and seat position revealed a large heterogeneity in the results. The maximum alteration between the lowest and highest HIC-value found for a complete crank rotation was a 416 % difference. For a handlebar rotation up to 100° or seat height alteration of maximum 34 cm, this value was respectively 169 % and 294 %. These high percentages of change indicate the need for cycling phase information for case-specific vehicle-bicycle accident reconstructions.

To helmet or not to helmet: a global perspective on the bicycle compulsory protective helmet law

Child injury from bike accidents is a significant component of morbidity, mortality and health expenditure in many countries. Universal use of bicycle helmets by children could prevent between 135 and 155 deaths, and between 39,000 and 45,000 head injuries annually. Surprisingly, epidemiologic data indicate a worldwide low prevalence of helmet use. A global view on the law on the compulsory use of safety helmets involving 58 different countries is provided in order to bring this critical debate back to the table. A broad search using "bicycle-related injuries," "bicycle helmet," "bicycle helmet legislation" and "compulsory bicycle helmet law by countries" was performed in order to identify and select the most pertinent information on the issue as well as all the information available on bicycle helmet law by countries. The papers identified permitted us to assess the main topics related to the use of bicycle helmets discussed over the years which are still relevant and without consensus even today, as well as alphabetically enlist the approach of 58 countries to the compulsory helmet law. Our review on the many faces of the bicycle helmet use (pros and cons), personal aspects, head injuries, legislation, promotion, socioeconomic influence, and finally a global view on the law on the compulsory use of safety helmets allowed us to bring here many suggestions and a few conclusions, mainly because "to helmet or not to helmet" should not be a question anymore. A universal consensus on their compulsory use has to be achieved in order to improve children's safety.

Prediction of subdural haematoma based on a detailed numerical model of the cerebral bridging veins

Traumatic brain injury is one of the major causes of death and disability in the world. One of the most frequent and deadly injury resulted from a head trauma is acute subdural haematoma (ASDH), which consists on the rupture of a bridging vein (BV). Given the importance of this type of injury, it is necessary to correctly assess thresholds and damage criteria, which is difficult to perform on human cadavers or animals, due to ethical and economical issues. Finite element (FE) models are a very good and cost-effective alternative. Once properly validated, a finite element head model (FEHM) becomes a valuable tool, that can be used in the development of head protective gear as a design tool and in the reconstruction of head traumas by predicting brain injuries under impact conditions. The YEt Another Head Model (YEAHM) is one example of a FE model that can be used to assist/replace the experimental tests. In this study, the bridging veins model from YEAHM was improved and validated by comparing its results with others reported in literature and estimating the success rate. At the end, it was developed a pressurised tubular shaped FE model of BVs, considering the blood pressure in cerebral veins. Results showed a maximum success rate of 90%, which in comparison with other FE models available in the literature, presents an equal or even better ASDH prediction success rate.

Collagen fibre orientation in human bridging veins

Bridging veins (BVs) drain the blood from the cerebral cortex into dural sinuses. BVs have one end attached to the brain and the other to the superior sagittal sinus (SSS), which is attached to the skull. Relative movement between these two structures can cause BV to rupture producing acute subdural haematoma, a head injury with a mortality rate between 30 and 90%. A clear understanding of the BVs microstructure is required to increase the biofidelity of BV models when simulating head impacts. Twelve fresh BV samples draining in the superior sagittal sinus (SSS) from a single human cadaver were cut open along their length and placed on an inverted multiphoton microscope. To ensure that the BVs were aligned with the axial direction an in-house built, uniaxial tension set-up was used. Two scans were performed per sample. Before the first scan, a minor displacement was applied to align the tissue; then, a second scan was taken applying 50% strain. Each BV was scanned for a length of 5 mm starting from the drainage site into the SSS. Imaging was performed on a Zeiss LSM780 microscope with an 25[Formula: see text] water immersion objective (NA 0.8), coupled to a tunable MaiTai DS (Spectraphysics) pulsed laser with the wavelength set at 850 nm. Second harmonic and fluorescence signals were captured in forward and backward direction on binary GaAsP (BiG) detectors and stored as four colour Z-stacks. Prior to the calculation of the local orientations, acquired Z-stacks were denoised and enhanced to highlight fibrillar structures from the background. Then, for each Z-plane of the stack, the ImageJ plugin OrientationJ was used to extract the local 2D orientations of the fibres based on structure tensors. Two kinds of collagen architectures were seen. The most common (8[Formula: see text]12 samples) was single layered and had a uniform distribution of collagen. The less common (4[Formula: see text]12 samples) had 2 layers and 7 to 34 times thicker collagen bundles on the outer layer. Fibre angle analysis showed that collagen was oriented mainly along the axial direction of the vessel. The von Mises fittings showed that in order to describe the fibre distribution 3 components were needed with mean angles [Formula: see text] at [Formula: see text] 0.35, 0.21, [Formula: see text] 0.02 rad or [Formula: see text] 20.2[Formula: see text], 12.1[Formula: see text], [Formula: see text] 1.2[Formula: see text] relative to the vessel's axial direction which was also the horizontal scan direction.

Bicycling-related concussions leading to postconcussion syndrome in adults

Background

Concussions among adult bicyclists are common, but little is known about the long-term effects of the consequences of these concussions such as postconcussion syndrome (PCS) including its occurrence, clinical features and recovery potential. Indeed, our study is the first to examine PCS due to bicycling in any age group.

Objectives

We examined patient demographics, concussion mechanisms and persistent symptoms as factors leading to PCS in adults and the potential for recovery.

Methods

We conducted a retrospective chart review of 28 patients age 18 or older who sustained a concussion while bicycling and were referred to the Canadian Concussion Centre for management of PCS.

Results

Eighteen patients (64.3%) fell from their bicycles due to loss of control, attempts to avoid a crash or collision with an object. Eight patients (28.6%) were struck by a motor vehicle, and two patients (7.1%) were injured by collision with another bicycle. The mean duration of PCS was 23.7 months and at the time of the last follow-up, 23 (82.1%) patients had failed to recover completely. Patients with one or more previous concussions had a significantly longer duration of PCS (p=0.042). Bicycling concussions resulted in a greater mean duration of PCS (23.7 months) than a comparison group of patients with PCS due to collision sports (16.1 months) (p=0.07).

Conclusion

Adults who sustain bicycling-related concussions and develop PCS often have long-lasting symptoms; greater attention should be given to prevention strategies such as improved bicycling infrastructure and safer bicycling practices to reduce concussions in adult bicyclists.

Differences in Impact Performance of Bicycle Helmets During Oblique Impacts

Cycling is a leading cause of sport-related head injuries in the U.S. Although bicycle helmets must comply with standards limiting head acceleration in severe impacts, helmets are not evaluated under more common, concussive-level impacts, and limited data are available indicating which helmets offer superior protection. Further, standards evaluate normal impacts, while real-world cyclist head impacts are oblique-involving normal and tangential velocities. The objective of this study was to investigate differences in protective capabilities of ten helmet models under common real-world accident conditions. Oblique impacts were evaluated through drop tests onto an angled anvil at common cyclist head impact velocities and locations. Linear and rotational accelerations were evaluated and related to concussion risk, which was then correlated with design parameters. Significant differences were observed in linear and rotational accelerations between models, producing concussion risks spanning >50% within single impact configurations. Risk differences were more attributable to linear acceleration, as rotational varied less between models. At the temporal location, shell thickness, vent configuration, and radius of curvature were found to influence helmet effective stiffness. This should be optimized to reduce impact kinematics. At the frontal, helmet rim location, liner thickness tapered off for some helmets, likely due to lack of standards testing at this location. This is a frequently impacted location for cyclists, suggesting that the standards testable area should be expanded to include the rim. These results can inform manufacturers, standards bodies, and consumers alike, aiding the development of improved bicycle helmet safety.

Bicycle-related traumatic injury hospitalizations: six years descriptive analysis in Qatar

Background:

Bicycle riding is a widely practiced mode of transportation, commuting, competition, fitness and recreation. We aimed to describe the incidence, risk factors and outcomes of Bicycle-Related Traumatic Injury (BRTI) in a Middle Eastern country.

Methods:

Data were extracted from a prospectively collected trauma registry over a period of six years (2010- 2015) from the national trauma center. Demographics and clinical characteristics of patients, and outcomes were analyzed.

Results:

There were 150 patients with a mean age of 27.2±16.6 years, 98% were males, 86.6% were hit by a car and 8.7% died. The average annual incidence of BRTIs was 1.3 per 100,000 populations. The mean Glasgow Coma Score (GCS) and injury severity score (ISS) were12.7±4.0 and 13.6±9.8; respectively. Almost one-third of cases had an ISS of 9-15. The most commonly injured region was the head (47%) followed by a lower extremity (30%), chest (25%), upper extremity (21.3%), spine (20.7%), abdomen (18.7%) and (7%) pelvis.

Conclusions:

BRTI is relatively uncommon in Qatar; however, it is characterized by a distinct epidemiology with a considerable mortality. Young male nationals, recreational cyclists and expatriate young commuter cyclists comprise the majority of victims and should be the focus of primary prevention efforts. Complementary prevention should aim at enforcing helmet laws to reduce fatal head injuries, and educating motorists of safer practices around cyclists.

Do equestrian helmets prevent concussion? A retrospective analysis of head injuries and helmet damage from real-world equestrian accidents

OBJECTIVES

To collect and analyse helmets from real-world equestrian accidents. To record reported head injuries associated with those accidents. To compare damage to helmets certified to different standards and the injuries associated with them.

METHODS

Two hundred sixteen equestrian helmets were collected in total. One hundred seventy-six helmets from amateur jockeys were collected via accident helmet return schemes in the UK and USA, while 40 helmets from professional jockeys were collected by The Irish Turf Club. All helmet damage was measured, and associated head injury was recorded.

RESULTS

Eighty-eight percent (189) of equestrian fall accidents returned an injury report of which 70% (139) reported a head injury. Fifty-four percent (75) of head injury cases had associated helmet damage while 46% had no helmet damage. Reported head injuries consisted of 91% (126) concussion, 4% (6) skull fractures, 1 (0.7%) subdural hematoma, 1 (0.7%) cerebral edema and 5 (3.6%) diffuse axonal injury (DAI). It is also shown that helmets certified to the most severe standard are overrepresented in this undamaged group (p <0.001).

CONCLUSIONS

It is clear that despite jockeys wearing a helmet, large proportions of concussion injuries still occur in the event of a jockey sustaining a fall. However, the data suggest it is likely that helmets reduce the severity of head injury as the occurrence of skull fracture is low. The proportion of undamaged helmets with an associated head injury suggests that many helmets may be too stiff relative to the surface they are impacting to reduce the risk of traumatic brain injury (TBI). It may be possible to improve helmet designs and certification tests to reduce the risk of head injury in low-severity impacts.

Bicycle-related injuries among children treated in US emergency departments, 2006-2015

OBJECTIVE

One of the leading causes of non-fatal injury among children is bicycling. Past studies indicate that helmets are protective against bicycle-related injuries and involvement of motor vehicles is associated with severe injuries, but research utilizing a nationally representative data set for this population and focusing on these risk factors does not exist. The objective of this study was to describe the epidemiology of bicycle-related injuries among children treated in hospital emergency departments (EDs) in the United States (US).

METHODS

A retrospective analysis was conducted with data from the National Electronic Injury Surveillance System for children 5-17 years of age who were treated in US EDs from 2006 through 2015 for a bicycle-related injury. Helmet use and motor vehicle involvement were two variables that were created and coded using keyword searches of the case narratives. Rates of injuries over time were described. Multivariate logistic regression along with 95% confidence intervals (CIs) were used to contrast types of injuries sustained among injured helmet users with non-users.

RESULTS

An estimated 2 219 742 (95% CI: 1 871 120-2 568 363) children 5-17 years of age were treated in US EDs for bicycle-related injuries over the 10-year study period, an average of 608 injuries per day. Most injuries (45.7%) involved children 10-14 years of age. The rate of bicycle-related injuries significantly decreased from 447.4 per 100 000 children in 2006 to 321.1 per 100 000 children in 2015 (P < 0.001). Helmet use at the time of injury was significantly associated with lower likelihood of head and neck injuries (OR: 0.52 [95% CI: 0.40-0.59]) and hospitalizations (OR: 0.71 [95% CI: 0.54-0.94]), but there was no significant change in the rate of injury among helmet users over the study period (P = 0.224). Motor vehicle involvement increased the odds of bicycle-related traumatic brain injuries (TBIs) (OR: 1.98 [95% CI: 1.49-2.64]) as well as injury-related hospitalizations (OR: 4.04 [95% CI: 3.33-4.89]).

CONCLUSIONS

Despite decreasing injury rates, bicycling remains an important source of injury for children. Helmet use has demonstrated significant protective effects for TBIs, head and neck injuries, and hospitalizations. Motor vehicle involvement increased the risk of hospitalization. More efforts are needed to promote use of helmets and to reduce the possibility of bicycle-motor vehicle collisions to prevent bicycle-related injuries among children.

Fatal Transorbital Intracranial Penetrating Injury Due to a Bicycle Brake Handle

Transorbital intracranial injuries are uncommon and mostly accidental in nature. These injuries are usually associated with high mortality. The key to preventing this mortality involves an early diagnosis of intracranial injuries and immediate and appropriate management. Any delay can pose a serious risk to the patient's life. A case of a 55-year-old man who had experienced an accidental self-fall while riding a bicycle is presented. Initially, he was treated at a primary health center. He was referred to the tertiary care institute due to unavailability of ancillary investigation at the primary health center. He was declared dead on arrival at the casualty in the tertiary institute. On autopsy, it was observed that the injury above the right side of the upper eyelid was penetrating the right side roof of the orbit and the right cerebral cortex and brainstem. The highlighting feature of the case is that, despite the fatal penetrating brain injury, the eyeball did not sustain any major injury.

Comparison of traffic-injury related hospitalisation between bicyclists and motorcyclists in Taiwan

OBJECTIVES

Bicyclists and motorcyclists contribute substantially to the morbidity and mortality rates of road crash casualties. The objective of the study was to investigate the crash characteristics of bicyclist and motorcyclist casualties presented to hospitals in Taiwan resulting from crashes.

METHODS

By using linked data from The National Traffic Crash Dataset and the National Health Insurance Database between 2003 and 2012, logistic regression models were used to examine the determinants of hospitalisation among motorcyclist and bicyclist casualties. The examined variables include demographic characteristics, road and weather conditions, and vehicle characteristics.

RESULTS

A total of 1,998,606 two-wheelers were enrolled in the study, of whom 216,600 were hospitalised: 203,623 were motorcyclists and 12,964 were bicyclists. Bicyclists were more likely to be hospitalised than motorcyclists were (14.0% vs. 10.7%). The pooled logistic regression model shows that bicyclists had higher odds of hospitalisation than motorcyclists (adjusted odds ratio [AOR] = 1.11, 95% confident interval [CI] = 1.08-1.14). In the motorcyclist and bicyclist models, helmet non-use appears to be a determinant of hospitalisation for motorcyclists (AOR = 1.14, CI = 1.12-1.16), although insignificant for cyclists (AOR = 1.03, CI = 0.94-1.12). Other important determinants of hospitalisation for motorcyclists and cyclists include female riders, elderly riders, rural roadways, unlicensed riding (for motorcyclists only), curved roadways, defective roadways, alcohol consumption (only for motorcyclists), and single-vehicle crashes (for motorcyclists only).

CONCLUSIONS

The result that bicyclists had an increased probability of being hospitalised than motorcyclists is particularly noteworthy, because there have recently been much more users of bikesharing systems in metropolitan cities where cycle helmets are not provided. We further found that helmet non-use was also a risk factor for motorcyclists, but insignificant for cyclists, possibly due to lower helmet utilization rates among bicyclists. Our findings regarding the increased hospitalisation percentage emphasize the importance of helmet use.

Features of fatal injuries in older cyclists in vehicle-bicycle accidents in Japan

OBJECTIVE

The purpose of this study was to identify and better understand the features of fatal injuries in cyclists aged 75 years and over involved in collisions with either hood- or van-type vehicles.

METHODS

This study investigated the fatal injuries of cyclists aged 75 years old and over by analyzing accident data. We focused on the body regions to which the fatal injury occurred using vehicle-bicycle accident data from the Institute for Traffic Accident Research and Data Analysis (ITARDA) in Japan. Using data from 2009 to 2013, we examined the frequency of fatally injured body region by gender, age, and actual vehicle travel speed. We investigated any significant differences in distributions of fatal injuries by body region for cyclists aged 75 years and over using chi-square tests to compare with cyclists in other age groups. We also investigated the cause of fatal head injuries, such as impact with a road surface or vehicle.

RESULTS

The results indicated that head injuries were the most common cause of fatalities among the study group. At low vehicle travel speeds for both hood- and van-type vehicles, fatalities were most likely to be the result of head impacts against the road surface. The percentage of fatalities following hip injuries was significantly higher for cyclists aged 75 years and over than for those aged 65-74 or 13-59 in impacts with hood-type vehicles. It was also higher for women than men in the over-75 age group in impacts with these vehicles.

CONCLUSIONS

For cyclists aged 75 years and over, wearing a helmet may be helpful to prevent head injuries in vehicle-to-cyclist accidents. It may also be helpful to introduce some safety measures to prevent hip injuries, given the higher level of fatalities following hip injury among all cyclists aged 75 and over, particularly women.

Sport-Related Traumatic Brain Injury with and without Helmets in Children

BACKGROUND

Soccer, bicycling, and horseback riding are sports most commonly associated with traumatic brain injury (TBI) in Germany. The latter 2 sports activities are commonly practiced with helmets, and data on helmet use and usefulness vary widely.

METHODS

On Ethics Committee approval, a retrospective analysis was performed for patients age 5-17 between January 2009 and August 2014 based on a diagnosis of TBI, using the electronic patient file for 2 university hospital locations. Descriptive data analysis and multivariate and univariate logistic regression were used to calculate odds ratios (ORs).

RESULTS

A total of 380 children were identified, including 162 females (42.6%) and 218 males (57.4%), with a mean age of 11.9 ± 3.8 years. Activities included bicycling (n = 64), horseback riding (n = 19), and soccer (n = 16). Helmet use was documented in 26 patients (14 cyclists, 12 riders), and nonuse was documented in 20 (all cyclists). Compared with not wearing a helmet, wearing a helmet was associated with a trend toward lower odds of loss of consciousness (OR, 0.7; 95% confidence interval [CI], 0.18-2.52). A cohort of 251 patients with non-sports-related TBI (NSTBI) served as a control group for further analyses. Compared with the NSTBI group, the odds of amnesia were 2.9 times greater (95% CI, 1.1-21.6) in the patients with a riding-related TBI and 4.8 times greater (95% CI, 0.3-239) in those with a cycling-related TBI, and the odds of epidural hematoma were 2.2 times greater (95% CI, 0.4-12.3) in those with a cycling-related TBI and 4.9 times greater (95% CI, 0.5-50.4) greater in those with a soccer-related TBI.

CONCLUSIONS

We gained important epidemiologic data on pediatric TBI in our region. Despite the descriptive nature of the data, a trend toward reduced odds of loss of consciousness was seen in the helmet wearers. Nevertheless, serious injury can occur despite helmet use.

Bicycle-Related Crashes in Hong Kong: Is it Possible to Reduce Mortality and Severe Injury in the Metropolitan Area?

Background

Cycling is not the primary mode of commuter transport in Hong Kong, yet cyclists are exposed to a high risk of injury and fatality in road crashes. It is essential to identify the significant factors contributing to severe injury among cyclists in Hong Kong.

Aim

To evaluate the effects of significant factors, including demographics, temporal distribution, cyclist behavior, road conditions, and weather, on the risk of severe and life-threatening injury among cyclists in road crashes in Hong Kong.

Method

The study was nested on a database known as Road Casualty Information System (RoCIS) which is a linked database between police traffic accident investigations reports and hospital injury records. A total of 682 victims were identified during the study period from 1 January 2004 to 31 December 2006. In particular, injured body part, demographics, helmet use, alcohol intoxication, weather conditions, road type and geometry, and collision characteristics of 682 trauma patients were the attributing variables of concern. The primary outcome measure was the injury severity of trauma patients which was classified into three levels: slight injury [Injury severity Scale (ISS) </=8], severe injury (ISS >/=9), and life-threatening injury (ISS >/=25). A multinomial logit regression model was established to evaluate the significance of factors contributing to severe and life-threatening injuries among cyclists in road crashes.

Results

The results indicated that middle-aged and elderly (35-54, RRR=2.48; and 55 or above, RRR=4.39) casualties and favourable weather conditions (2.56) significantly increased the risk of severe injury among cyclists. The presence of severe head injury (RRR=509.24), severe trunk injury (RRR=79.24), and the involvement of motor vehicles (RRR=27.18) substantially increased the risk of life-threatening injury to cyclists.

Conclusions

Middle-aged casualties, the presence of head injuries, and the involvement of motor vehicles all increase the risk of more severe injury in bicycle-related crashes. Safety education and countermeasures should target at middle-aged and elderly cyclists and discourage cycling on the motorway.

A population-based case-control study of hospitalisation due to head injuries among bicyclists and motorcyclists in Taiwan

INTRODUCTION

According to official statistics in Taiwan, the main body region of injury causing bicyclist deaths is the head, and bicyclists are 2.6 times more likely to be fatally injured than motorcyclists. There is currently a national helmet law for motorcyclists but not for bicyclists.

OBJECTIVES

The primary aim of this study was to determine whether bicyclist casualties have higher odds of head-related hospitalisation than motorcyclists. This study also aims to investigate the determinants of head injury-related hospitalisation among bicyclists and motorcyclists.

METHODS

Using linked data from the National Traffic Accident Dataset and the National Health Insurance Research Database for the period 2003-2012, this study investigates the crash characteristics of bicyclist and motorcyclist casualties presenting to hospitals due to motor vehicle crashes. Head injury-related hospitalisation was used as the study outcome for both road users to evaluate whether various factors (eg, human attributes, road and weather conditions, vehicle characteristics) are related to hospital admission of those who sustained serious injuries.

RESULTS

Among 1 239 474 bicyclist and motorcyclist casualties, the proportion of bicyclists hospitalised for head injuries was higher than that of motorcyclists (10.0% vs 6.5%). However, the multiple logistic regression model shows that, after adjustment of this result for other factors such as helmet use, bicyclists were 18% significantly less likely to be hospitalised for head injuries than motorcyclists (AOR 0.82, 95% CI 0.79 to 0.85). Other important determinants of head injury-related hospitalisation for bicyclists and motorcyclists include female riders, elderly riders, crashes occurring in rural areas, moped riders, riding unhelmeted, intoxicated bicyclists and motorcyclists, unlicensed motorcyclists, dusk and dawn conditions and single-vehicle crashes.

CONCLUSIONS

Our finding underscores the importance of helmet use in reducing hospitalisation due to head injuries among bicyclists while current helmet use is relatively low.

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.

A Test Bed to Examine Helmet Fit and Retention and Biomechanical Measures of Head and Neck Injury in Simulated Impact

Conventional wisdom and the language in international helmet testing and certification standards suggest that appropriate helmet fit and retention during an impact are important factors in protecting the helmet wearer from impact-induced injury. This manuscript aims to investigate impact-induced injury mechanisms in different helmet fit scenarios through analysis of simulated helmeted impacts with an anthropometric test device (ATD), an array of headform acceleration transducers and neck force/moment transducers, a dual high speed camera system, and helmet-fit force sensors developed in our research group based on Bragg gratings in optical fiber. To simulate impacts, an instrumented headform and flexible neck fall along a linear guide rail onto an anvil. The test bed allows simulation of head impact at speeds up to 8.3 m/s, onto impact surfaces that are both flat and angled. The headform is fit with a crash helmet and several fit scenarios can be simulated by making context specific adjustments to the helmet position index and/or helmet size. To quantify helmet retention, the movement of the helmet on the head is quantified using post-hoc image analysis. To quantify head and neck injury potential, biomechanical measures based on headform acceleration and neck force/moment are measured. These biomechanical measures, through comparison with established human tolerance curves, can estimate the risk of severe life threatening and/or mild diffuse brain injury and osteoligamentous neck injury. To our knowledge, the presented test-bed is the first developed specifically to assess biomechanical effects on head and neck injury relative to helmet fit and retention.

Estimated total costs from non-fatal and fatal bicycle crashes in the USA: 1997–2013

Introduction

Emergency department visits and hospital admissions resulting from adult bicycle trauma have increased dramatically. Annual medical costs and work losses of these incidents last were estimated for 2005 and quality-of-life losses for 2000.

Methods

We estimated costs associated with adult bicycle injuries in the USA using 1997–2013 non-fatal incidence data from the National Electronic Injury Surveillance System with cost estimates from the Consumer Product Safety Commission's Injury Cost Model, and 1999–2013 fatal incidence data from the National Vital Statistics System costed by similar methods.

Results

Approximately 3.8 million non-fatal adult bicycle injuries were reported during the study period and 9839 deaths. In 2010 dollars, estimated adult bicycle injury costs totalled $24.4 billion in 2013. Estimated injury costs per mile bicycled fell from $2.85 in 2001 to $2.35 in 2009. From 1999 to 2013, total estimated costs were $209 billion due to non-fatal bicycle injuries and $28 billion due to fatal injuries. Inflation-free annual costs in the study period increased by 137% for non-fatal injuries and 23% for fatal injuries. The share of non-fatal costs associated with injuries to riders age 45 and older increased by 1.6% (95% CI 1.4% to 1.9%) annually. The proportion of costs due to incidents that occurred on a street or highway steadily increased by 0.8% (95% CI 0.4% to 1.3%) annually.

Conclusions

Inflation-free costs per case associated with non-fatal bicycle injuries are increasing. The growth in costs is especially associated with rising ridership, riders 45 and older, and street/highway crashes.

Characteristics of bicycle crashes in an adolescent population in Flanders (Belgium)

INTRODUCTION

In regions where transportation is mainly motorized, air pollution and traffic congestion are rife. Active transportation such as cycling might be a solution but safety is a major concern. An efficient science based safety policy is needed. The aim of this paper is to analyze in depth the bicycle crash causes and characteristics in an adolescent population (14-18 yr).

METHODS

By using questionnaires for self-reported bicycle crashes, bicycle crash data were collected from insurance companies (January 2014-June 2015) and from schools (November 2013-March 2014). Six bicycle crash causes were predefined and possible differences between schools and insurance companies were analyzed.

RESULTS

Eighty-six school and 78 insurance registered crashes were analyzed. "Distraction of the cyclist" and "third party crossing a bicycle path failing to see the cyclist" are the main causes of bicycle crashes (both 29%). Bad (maintained) infrastructure accounted for 21% of the crash causes. Bicycle crashes reported at insurance companies needed significantly more medical attention and led to high absenteeism (57% at least one day of absenteeism). Only 21% of the bicycle crashes reported at insurance companies were also reported in the official police database.

CONCLUSION

The human factor was the main cause accounting for 79% of the crashes. Bicycle crashes involving a car accounted for 42% and single bicycle crashes accounted for 31% of the total number of crashes. From the bicycle crashes registered at insurance companies 21% was also registered in official police statistics. A combination of information, education and changing the bicycle specific environment might reduce the consequences of human errors more efficiently.

Cyclists fatalities: Forensic remarks regarding 335 cases

A retrospective study was carried out on post-mortem examination data regarding 335 cyclists involved in fatal accidents along the period 1983-2012. The following variables were considered: temporal data (year, month, day of the week and hour of the day), circumstances of the accident, vehicles involved, victims' features (sex, age), pathological and toxicological findings, cause of death. Most victims were male (77.62%), with a mean age of 58 years. In most cases vehicles other than only bicycles were involved, more frequently cars, followed by heavy motor vehicles. Head was the most frequently body region involved in lethal injuries (65.37%); low extremities were the body district most frequently involved in non-lethal injuries (63.9%). This study confirmed the importance of using helmet; head protection should be a priority for bikers.

Comparative Outcomes of Traumatic Brain Injury from Biking Accidents With or Without Helmet Use

OBJECTIVE

To determine if health outcomes and demographics differ according to helmet status between persons with cycling-related traumatic brain injuries (TBI).

METHODS

This is a retrospective study of 128 patients admitted to the Montreal General Hospital following a TBI that occurred while cycling from 2007-2011. Information was collected from the Quebec trauma registry and the coroner's office in cases of death from cycling accidents. The independent variables collected were socio-demographic, helmet status, clinical and neurological patient information. The dependent variables evaluated were length of stay (LOS), extended Glasgow outcome scale (GOS-E), injury severity scale (ISS), discharge destination and death.

RESULTS

25% of cyclists wore a helmet. The helmet group was older, more likely to be university educated, married and retired. Unemployment, longer intensive care unit (ICU) stay, severe intracranial bleeding and neurosurgical interventions were more common in the no helmet group. There was no significant association between the severity of the TBI, ISS scores, GOS-E or death and helmet wearing. The median age of the subjects who died was higher than those who survived.

CONCLUSION

Cyclists without helmets were younger, less educated, single and unemployed. They had more severe TBIs on imaging, longer LOS in ICU and more neurosurgical interventions. Elderly cyclists admitted to the hospital appear to be at higher risk of dying in the event of a TBI.

The analysis of influence of individual and environmental factors on 2-wheeled users' injuries

OBJECTIVE

Powered 2-wheeled motor vehicles (PTWs) are one of the most vulnerable categories of road users. Bearing that fact in mind, we have researched the effects of individual and environmental factors on the severity and type of injuries of PTW users. The aim was to recognize the circumstances that cause these accidents and take some preventive actions that would improve the level of road safety for PTWs.

METHODS

In the period from 2001 to 2010, an analysis of 139 road accidents involving PTWs was made by the Faculty of Transport and Traffic Engineering in Belgrade. The effects of both individual (age, gender, etc.) and environmental factors (place of an accident, time of day, etc.) on the cause of accidents and severity and type of injuries of PTWs are reported in this article. Analyses of these effects were conducted using logistic regression, chi-square tests, and Pearson's correlation.

RESULTS

Factors such as categories of road users, pavement conditions, place of accident, age, and time of day have a statistically significant effect on PTW injuries, whereas other factors (gender, road type; that is, straight or curvy) do not. The article also defines the interdependence of the occurrence of particular injuries at certain speeds. The results show that if PTW users died of a head injury, these were usually concurrent with chest injuries, injuries to internal organs, and limb injuries.

CONCLUSIONS

It has been shown that there is a high degree of influence of individual factors on the occurrence of accidents involving 2-wheelers (PTWs/bicycles) but with no statistically significant relation. Establishing the existence of such conditionalities enables identifying and defining factors that have an impact on the occurrence of traffic accidents involving bicyclists or PTWs. Such a link between individual factors and the occurrence of accidents makes it possible for system managers to take appropriate actions aimed at certain categories of 2-wheelers in order to reduce casualties in a particular area. The analysis showed that most of the road factors do not have a statistically significant effect on either category of 2-wheeler. Namely, the logistic regression analysis showed that there is a statistically significant effect of the place of accident on the occurrence of accidents involving bicyclists.

Trauma injuries sustained by cyclists

The aim of this article is to review the pertinent literature and to analyse our own data on facial trauma related to bicycling and mountain-biking. This article focuses on the mechanisms and the variety of bicycle related injuries and addresses the advantages of wearing protection clothes.

Within the world of bicycling, the popularity of mountain-biking has increased the most dramatically. The main risk factors for the growing number of bicycle-related injuries are not wearing a helmet, age, male sex, unsafe riding techniques and intoxication. Bikers most commonly collide or fall in daily traffic whereas mountain-bikers get hurt whilst descending. The most common types of injury apart from superficial lesions are dentoalveolar trauma and facial fractures. Wearing protective clothing such as a helmet is demonstrably beneficial and so we suggest that the obligatory use of protective wear should be introduced. For a better insight into overall cycling-related trauma further research will be required.

The protective effect of a helmet in three bicycle accidents--A finite element study

There is some controversy regarding the effectiveness of helmets in preventing head injuries among cyclists. Epidemiological, experimental and computer simulation studies have suggested that helmets do indeed have a protective effect, whereas other studies based on epidemiological data have argued that there is no evidence that the helmet protects the brain. The objective of this study was to evaluate the protective effect of a helmet in single bicycle accident reconstructions using detailed finite element simulations. Strain in the brain tissue, which is associated with brain injuries, was reduced by up to 43% for the accident cases studied when a helmet was included. This resulted in a reduction of the risk of concussion of up to 54%. The stress to the skull bone went from fracture level of 80 MPa down to 13-16 MPa when a helmet was included and the skull fracture risk was reduced by up to 98% based on linear acceleration. Even with a 10% increased riding velocity for the helmeted impacts, to take into account possible increased risk taking, the risk of concussion was still reduced by up to 46% when compared with the unhelmeted impacts with original velocity. The results of this study show that the brain injury risk and risk of skull fracture could have been reduced in these three cases if a helmet had been worn.

Injury patterns and features of cycling fatalities in South Australia

There has been an increase in cycling in Australia. This means that more cyclists are at risk of injuries, which account for a proportion of transport-related fatalities. In this study, all cyclist fatalities from 2002 to 2013 in South Australia where post-mortem examinations were performed were investigated. There were 42 deaths representing 3% of the total road fatalities over the same time. Of this total number of cases, 13 deaths (31%) involved collapse (mostly natural causes from an underlying medical condition) and 29 (69%) resulted from trauma. There were no cases of hyperthermia. Of the decedents 95% were male, and the mean age at death was 47 years. Fatal incidents were more likely to occur during April and November, and on a Monday. However, statistical analysis was not possible due to the small number of cases. Fatalities (traumatic and collapse) predominantly occurred whilst the cyclist was riding (86%). The majority of riding fatalities were as a result of collision with vehicles (81%). Drugs (including alcohol) were detected in two (15%) of the 13 cases of the collapses, and in seven (26%) of the 27 trauma cases tested. In trauma cases, death was most often due to multiple injuries. The most frequent area for injury was the head (found in 90% of traumatic deaths). Despite the increasing numbers of cyclists on South Australian roads over the last decade, death rates have trended downwards suggesting that road safety campaigns and the provision of more dedicated bicycle lanes have had a positive outcome.

The effect of the Swedish bicycle helmet law for children: an interrupted time series study

BACKGROUND

Previous population-based research has shown that bicycle helmet laws can reduce head injury rates among cyclists. According to deterrence theory, such laws are mainly effective if there is a high likelihood of being apprehended. In this study, we investigated the effect of the Swedish helmet law for children under the age of 15, a population that cannot be fined.

METHOD

An interrupted time series design was used. Monthly inpatient data on injured cyclists from 1998-2012, stratified by age (0-14, 15+), sex, and injury diagnosis, was obtained from the National Patient Register. The main outcome measure was the proportion of head injury admissions per month. Intervention effect estimates were obtained using generalized autoregressive moving average (GARMA) models. Pre-legislation trend and seasonality was adjusted for, and differences-in-differences estimation was obtained using adults as a non-equivalent control group.

RESULTS

There was a statistically significant intervention effect among male children, where the proportion of head injuries dropped by 7.8 percentage points. There was no evidence of an intervention effect on the proportion of head injuries among female children.

CONCLUSION

According to hospital admission data, the bicycle helmet law appears to have had an effect only on male children.

PRACTICAL APPLICATIONS

This study, while quasi-experimental and thus not strictly generalizable, can contribute to increased knowledge regarding the effects of bicycle helmet laws.

Adult headform impact tests of three Japanese child bicycle helmets into a vehicle

The head is the body region that most frequently incurs fatal and serious injuries of cyclists in collisions against vehicles. Many research studies investigated helmet effectiveness in preventing head injuries using accident data. In this study, the impact attenuation characteristics of three Japanese child bicycle helmets were examined experimentally in impact tests into a concrete surface and a vehicle. A pedestrian adult headform with and without a Japanese child bicycle helmet was dropped onto a concrete surface and then propelled into a vehicle at 35 km/h in various locations such as the bonnet, roof header, windshield and A-pillar. Accelerations were measured and head injury criterion (HIC) calculated. In the drop tests using the adult headform onto a concrete surface from the height of 1.5m, the HIC for a headform without a child helmet was 6325, and was reduced by around 80% when a child helmet was fitted to the headform. In the impact tests, where the headform was fired into the vehicle at 35 km/h at various locations on a car, the computed acceleration based HIC varied depending on the vehicle impact locations. The HIC was reduced by 10-38% for impacts headforms with a child helmet when the impact was onto a bonnet-top and roof header although the HIC was already less than 1000 in impacts with the headform without a child helmet. Similarly, for impacts into the windshield (where a cyclist's head is most frequently impacted), the HIC using the adult headform without a child helmet was 122; whereas when the adult headform was used with a child helmet, a higher HIC value of more than 850 was recorded. But again, the HIC values are below 1000. In impacts into the A-pillar, the HIC was 4816 for a headform without a child helmet and was reduced by 18-38% for a headform with a child helmet depending on the type of Japanese child helmet used. The tests demonstrated that Japanese child helmets are effective in reducing accelerations and HIC in a drop test using an adult headform onto a relatively rigid hard surface, i.e., simulating a road surface or concrete path. However, when the impact tests are into softer surfaces, the child helmet's capacity to decrease accelerations is accordingly reduced. Impacts into the windshield, while below the critical HIC value of 1000, indicated higher HIC values for a headform with a child helmet compared to an adult headform without a child helmet. The unpredictable nature of the results indicates further research work is required to assess how representative the stiffness of an adult headform is when compared to an actual head.

A study of bicyclist kinematics and injuries based on reconstruction of passenger car-bicycle accident in China

Like pedestrians, bicyclists are vulnerable road users, representing a population with a high risk of fatal and severe injuries in traffic accidents as they are unprotected during vehicle collisions. The objective of this study is to investigate the kinematics response of bicyclists and the correlation of the injury severity with vehicle impact speed. Twenty-four car-bicyclist cases with detailed information were selected for accident reconstruction using mathematical models, which was implemented in the MADYMO program. The dynamic response of bicyclists in the typical impact configuration and the correlation of head impact conditions were analyzed and discussed with respect to the head impact speed, time of head impact and impact angle of bicyclists to vehicle impact speed. Furthermore, the injury distribution of bicyclists and the risk of head injuries and fractures of lower limbs were investigated in terms of vehicle impact speed. The results indicate that wrap-around distance (WAD), head impact speed, time of head impact, head impact angle, and throw-out distance (TOD) of the bicyclists have a strong relationship with vehicle impact speed. The vehicle impact speed corresponding to a 50% probability of head AIS 2+ injuries, head AIS 3+ injuries, and lower limb fracture risk for bicyclists is 53.8km/h, 58.9km/h, and 41.2km/h, respectively. A higher vehicle impact speed produces a higher injury risk to bicyclist. The results could provide background knowledge for the establishment or modification of pedestrian regulations considering bicyclist protection as well as being helpful for developing safety measures and protection devices for bicyclists.

Bicycle helmets are highly effective at preventing head injury during head impact: head-form accelerations and injury criteria for helmeted and unhelmeted impacts

Cycling is a popular form of recreation and method of commuting with clear health benefits. However, cycling is not without risk. In Canada, cycling injuries are more common than in any other summer sport; and according to the US National Highway and Traffic Safety Administration, 52,000 cyclists were injured in the US in 2010. Head injuries account for approximately two-thirds of hospital admissions and three-quarters of fatal injuries among injured cyclists. In many jurisdictions and across all age levels, helmets have been adopted to mitigate risk of serious head injuries among cyclists and the majority of epidemiological literature suggests that helmets effectively reduce risk of injury. Critics have raised questions over the actual efficacy of helmets by pointing to weaknesses in existing helmet epidemiology including selection bias and lack of appropriate control for the type of impact sustained by the cyclist and the severity of the head impact. These criticisms demonstrate the difficulty in conducting epidemiology studies that will be regarded as definitive and the need for complementary biomechanical studies where confounding factors can be adequately controlled. In the bicycle helmet context, there is a paucity of biomechanical data comparing helmeted to unhelmeted head impacts and, to our knowledge, there is no data of this type available with contemporary helmets. In this research, our objective was to perform biomechanical testing of paired helmeted and unhelmeted head impacts using a validated anthropomorphic test headform and a range of drop heights between 0.5m and 3.0m, while measuring headform acceleration and Head Injury Criterion (HIC). In the 2m (6.3m/s) drops, the middle of our drop height range, the helmet reduced peak accelerations from 824g (unhelmeted) to 181g (helmeted) and HIC was reduced from 9667 (unhelmeted) to 1250 (helmeted). At realistic impact speeds of 5.4m/s (1.5m drop) and 6.3m/s (2.0m drop), bicycle helmets changed the probability of severe brain injury from extremely likely (99.9% risk at both 5.4 and 6.3m/s) to unlikely (9.3% and 30.6% risk at 1.5m and 2.0m drops respectively). These biomechanical results for acceleration and HIC, and the corresponding results for reduced risk of severe brain injury show that contemporary bicycle helmets are highly effective at reducing head injury metrics and the risk for severe brain injury in head impacts characteristic of bicycle crashes.

Structural and mechanical characterisation of bridging veins: A review

Bridging veins drain the venous blood from the cerebral cortex into the superior sagittal sinus (SSS) and doing so they bridge the subdural space. Despite their importance in head impact biomechanics, little is known about their properties with respect to histology, morphology and mechanical behaviour. Knowledge of these characteristics is essential for creating a biofidelic finite element model to study the biomechanics of head impact, ultimately leading to the improved design of protective devices by setting up tolerance criteria. This paper presents a comprehensive review of the state-of-the-art knowledge on bridging veins. Tolerance criteria to prevent head injury through impact have been set by a number of research groups, either directly through impact experiments or by means of finite element (FE) simulations. Current state-of-the-art FE head models still lack a biofidelic representation of the bridging veins. To achieve this, a thorough insight into their nature and behaviour is required. Therefore, an overview of the general morphology and histology is provided here, showing the clearly heterogeneous nature of the bridging vein complex, with its three different layers and distinct morphological and histological changes at the region of outflow into the superior sagittal sinus. Apart from a complex morphology, bridging veins also exhibit complex mechanical behaviour, being nonlinear, viscoelastic and prone to damage. Existing material models capable of capturing these properties, as well as methods for experimental characterisation, are discussed. Future work required in bridging vein research is firstly to achieve consensus on aspects regarding morphology and histology, especially in the outflow cuff segment. Secondly, the advised material models need to be populated with realistic parameters through biaxial mechanical experiments adapted to the dimensions of the bridging vein samples. Finally, updating the existing finite element head models with these parameters will render them truly biofidelic, allowing the establishment of accurate tolerance criteria and, ultimately, better head protection devices.

Perception of safety of cyclists in Dublin City

In recent years, cycling has been recognized and is being promoted as a sustainable mode of travel. The perception of cycling as an unsafe mode of travel is a significant obstacle in increasing the mode share of bicycles in a city. Hence, it is important to identify and analyze the factors which influence the safety experiences of the cyclists in an urban signalized multi-modal transportation network. Previous researches in the area of perceived safety of cyclists primarily considered the influence of network infrastructure and operation specific variables and are often limited to specific locations within the network. This study explores the factors that are expected to be important in influencing the perception of safety among cyclists but were never studied in the past. These factors include the safety behavior of existing cyclists, the users of other travel modes and their attitude toward cyclists, facilities and network infrastructures applicable to cycling as well as to other modes in all parts of an urban transportation network. A survey of existing cyclists in Dublin City was conducted to gain an insight into the different aspects related to the safety experience of cyclists. Ordered Logistic Regression (OLR) and Principal Component Analysis (PCA) were used in the analysis of survey responses. This study has revealed that respondents perceive cycling as less safe than driving in Dublin City. The new findings have shown that the compliance of cyclists with the rules of the road increase their safety experience, while the reckless and careless attitudes of drivers are exceptionally detrimental to their perceived safety. The policy implications of the results of analysis are discussed with the intention of building on the reputation of cycling as a viable mode of transportation among all network users.

Structural brain injury in sports-related concussion

Object

Sports-related concussions (SRCs) represent a significant and growing public health concern. The vast majority of SRCs produce mild symptoms that resolve within 1–2 weeks and are not associated with imaging-documented changes. On occasion, however, structural brain injury occurs, and neurosurgical management and intervention is appropriate.

Methods

A literature review was performed to address the epidemiology of SRC with a targeted focus on structural brain injury in the last half decade. MEDLINE and PubMed databases were searched to identify all studies pertaining to structural head injury in sports-related head injuries.

Results

The literature review yielded a variety of case reports, several small series, and no prospective cohort studies.

Conclusions

The authors conclude that reliable incidence and prevalence data related to structural brain injuries in SRC cannot be offered at present. A prospective registry collecting incidence, management, and follow-up data after structural brain injuries in the setting of SRC would be of great benefit to the neurosurgical community.

Bicycle-related injuries requiring hospitalization in the United Arab Emirates

OBJECTIVES

To study the anatomical distribution, severity, and outcome of bicycle-related injuries requiring hospitalization in Al-Ain city, United Arab Emirates in order to improve preventive measures.

METHODS

All patients with bicycle-related injuries who were admitted to Al-Ain Hospital or who died after arrival were studied. Data were prospectively collected over a period of six years (October 2001-October 2007). Demography of patients, Glasgow Coma Scale (GCS), Injury Severity Score (ISS), hospital stay, and mortality were analysed.

RESULTS

There were 130 patients (126 males). Mean (SD) age was 27.1 (14.5) years. 17.7% were United Arab Emirates (UAE) nationals. None of the patients was wearing a helmet. The percentage of UAE nationals of less than 15 years old was significantly higher (65.2%) than non-UAE nationals (14.3%) (p<0.0001, Fisher's Exact Test). The most common mechanism of injury for UAE nationals was falling from a bicycle (73.7%) whilst for non-UAE nationals was hitting a moving vehicle (66.7%). 96 (73.9%) patients had head and face injuries whilst 91 patients (70%) had extremity injuries. On arrival to the hospital, the median (range) ISS was 4 (1-41) and the median (range) GCS was 15 (3-15). The median (range) of total hospital stay was 4 (1-95) days. 17 patients (13.1%) were admitted to the Intensive Care Unit. Two patients died because of head injury (overall mortality was 1.5%).

CONCLUSIONS

The majority of hospitalized injured cyclists in our study were low income adults using cycling as a cheap transportation method. Compulsory helmet use by bicycle riders and subsidising helmet cost should be adopted so as to reduce morbidity and mortality of bicycle-related injuries.