Effectiveness of bicycle helmets in preventing head injury in children: case-control study.

OBJECTIVE--To examine the risk of injury to the head and the effect of wearing helmets in bicycle accidents among children. DESIGN--Case-control study by questionnaire completed by the children and their carers. SETTING--Two large children''s hospitals in Brisbane, Australia. SUBJECT--445 children presenting with bicycle related injuries during 15 April 1991 to 30 June 1992. The cases comprised 102 children who had sustained injury to the upper head including the skull, forehead and scalp or loss of consciousness. The controls were 278 cyclists presenting with injuries other than to the head or face. A further 65 children with injuries to the face were considered as an extra comparison group. MAIN OUTCOME MEASURES--Cause and type of injury, wearing of helmet. RESULTS--Most children (230) were injured after losing control and falling from their bicycle. Only 31 had contact with another moving vehicle. Children with head injury were significantly more likely to have made contact with a moving vehicle than control children (19 (19%) v 12 (4%), P < 0.001). Head injuries were more likely to occur on paved surfaces than on grass, gravel, or dirt. Wearing a helmet reduced the risk of head injury by 63% (95% confidence interval 34% to 80%) and of loss of consciousness by 86% (62% to 95%). CONCLUSIONS--The risk of head injury in bicycle accidents is reduced among children wearing a helmet. Current helmet design maximises protection in the type of accident most commonly occurring in this study. Legislation enforcing helmet use among children should be considered.     

Nonuse of bicycle helmets and risk of fatal head injury: a proportional mortality, case�Ccontrol study

Background:

The effectiveness of helmets at preventing cycling fatalities, a leading cause of death among young adults worldwide, is controversial, and safety regulations for cycling vary by jurisdiction. We sought to determine whether nonuse of helmets is associated with an increased risk of fatal head injury.

Methods:

We used a case–control design involving 129 fatalities using data from a coroner’s review of cycling deaths in Ontario, Canada, between 2006 and 2010. We defined cases as cyclists who died as a result of head injuries; we defined controls as cyclists who died as a result of other injuries. The exposure variable was nonuse of a bicycle helmet.

Results:

Not wearing a helmet while cycling was associated with an increased risk of dying as a result of sustaining a head injury (adjusted odds ratio [OR] 3.1, 95% confidence interval [CI] 1.3–7.3). We saw the same relationship when we excluded people younger than 18 years from the analysis (adjusted OR 3.5, 95% CI 1.4–8.5) and when we used a more stringent case definition (i.e., only a head injury with no other substantial injuries; adjusted OR 3.6, 95% CI 1.2–10.2).

Interpretation:

Not wearing a helmet while cycling is associated with an increased risk of sustaining a fatal head injury. Policy changes and educational programs that increase the use of helmets while cycling may prevent deaths.One cyclist dies in Canada each week, and cycling fatalities account for more than 2% of traffic fatalities, a leading cause of death in young adults.¹ Cycling safety regulations vary by jurisdiction, and controversy remains about the effectiveness of safety measures such as helmets. There is strong evidence that helmets prevent nonfatal head injuries,² but very limited evidence exists related to fatal head injuries. A meta-analysis of case–control studies showed a protective effect of helmets against head injuries, but it was based on just 4 case fatalities in which helmets were not worn.³ Another large study involving 1710 cycling collisions found a trend toward a protective effect of helmets, but included only 14 fatalities.⁴ The existing literature leaves open the possibility that helmets prevent nonfatal head injuries, but not fatal ones.We sought to determine whether cycling without a helmet was associated with an increased risk of sustaining a fatal head injury.     

Bicycle accidents in childhood.

The results of a 10 year study of bicycle fatalities and an eight year study of serious non-fatalities are reported for urban Brisbane (population 1,000,000). There were 845 serious non-fatal bicycle accidents and 46 fatalities during the study. Boys were involved in 86% of accidents. Boys have an accident rate of 134.21 per 100,000 population at risk and a fatality rate of 5.06 per 100,000 at risk. Serious bicycle accidents have increased by 50% in this decade; but considering fatal cases alone, no secular trend was evident over the 10 year period of the study. This suggests that an increase in the overall rate of bicycle accidents has been in part compensated by less serious injuries. In 70% of fatalities children had head injuries, and 87% of fatalities followed a collision between a cyclist and a motor vehicle or a train. Bicycle accidents on the roads most commonly occur to boys aged between 12 and 14 years on a straight road at "mid-block" between 3 and 5 pm in clear weather conditions and in daylight. It is concluded that injuries and fatalities after bicycle accidents can be reduced by protecting children''s heads, separating child cyclists from other road traffic, or educating and training both cyclists and other road users in safe behaviour. The compulsory use of helmets and the restriction of access to the roads by child cyclists to reduce injuries are, however, still controversial in many areas.     

Helmet use improves outcomes after motorcycle accidents.

To determine the effects of motorcycle helmet use on the outcome of patients admitted to a Level I trauma center, we studied patient outcomes and demographic and epidemiologic variables of 474 patients injured in motorcycle collisions and treated at such a center over a 45-month period. Of those involved in a motorcycle collision, 50% were not wearing a helmet, 23% were wearing a helmet, and in 27% helmet use was unknown. Those who were wearing a helmet had fewer and less severe head and facial injuries, required fewer days on a ventilator, and sustained no serious neck injuries; fewer patients who wore helmets were discharged with disability, and hospital charges were lower. These data support the need for both increased public education regarding helmet use and mandatory helmet use legislation.     

A computational study of the EN 1078 impact test for bicycle helmets using a realistic subject-specific finite element head model

Abstract

In the present study, the free fall impact test in accordance with the EN1078 standard for certification of bicycle helmets is replicated using numerical simulations. The impact scenario is simulated using an experimentally validated, patient-specific head model equipped with and without a bicycle helmet. Head accelerations and intracranial biomechanical injury metrics during the impacts are recorded. It is demonstrated that wearing the bicycle helmet during the impact reduces biomechanical injury metrics, with the biggest reduction seen in the metric for skull fracture.     

Vehicle safety

To help reduce the number of deaths and injuries caused by vehicle accidents on Canadian roads, the CMA has for several years made recommendations on a wide range of vehicle safety standards. Since the 1960s the association has urged the provinces to enact mandatory seatbelt legislation, although it was not until 1976 that the first two provinces (Ontario and Quebec) did so. The CMA believes that the nonuse of restraint systems should be considered contributory negligence in the event of an accident producing injury to vehicle occupants. It has urged governments to approve and promote appropriate child restraint systems and to require the legislated provision of suitable and standardized tether anchorage. To increase the conspicuousness of motor vehicles the association has advocated the introduction of daytime running lights in all new vehicles. In 1965 the CMA recommended that motorcyclists wear approved helmets; indeed, it believes that there is no medical reason that would justify exemption from wearing a helmet. The CMA has also made several recommendations on safety standards for mopeds, all-terrain vehicles, minivans and light trucks and has encouraged its provincial divisions to form highway safety committees. As well as recognizing the importance of appropriate and enforced vehicle safety standards in reducing the rates of death and injury, the CMA has recommended and supported legislation aimed at decreasing the incidence of drinking and driving (Can Med Assoc J 1985; 133:806A).     

Morbidity and mortality of car occupants: comparative survey over 24 months.

The severity of injuries sustained by 2577 car occupants in road traffic accidents in the catchment area of one district accident service during February 1982 to January 1984 inclusive was assessed using the injury severity score system. In the first 12 months the mean injury severity score for front seat occupants injured in a road traffic accident was 4.94 and in the second 12 month period, after the implementation of the seat belt law, the mean injury severity score of all injured front seat occupants was 2.80. These figures indicated a reduction in injury severity of front seat occupants of 53.4% on the previous 12 month figures. The severity of injury sustained by unbelted front seat occupants and back seat passengers showed no significant change over the two years. The number of front seat occupants killed or sustaining serious injuries (injury severity score greater than 12) showed a reduction of 54% in the 12 months beginning February 1983. Front seat occupants requiring admission for injuries sustained showed a decline of 42% in the 12 months after the introduction of the seat belt law, and deaths among front seat occupants fell by 27% compared with the previous 12 months. After the implementation of seat belt legislation those front seat occupants killed or sustaining serious injuries included a significantly higher proportion of victims who were not wearing their seat belts or showed positive evidence of alcohol intake at the time of the accident. This series suggests that the incidence of serious injury or deaths among front seat occupants of cars has decreased substantially since the seat belt law became effective on 31 January 1983.     

Bicycle-related injuries: a survey in a pediatric emergency department.

The number of bicycle-related injuries has risen significantly with the increased popularity of bicycle riding in Canada. The risk of injury is highest among children. To assess the magnitude of the problem and to identify the contributing factors we used a questionnaire, injury reports and patient charts to survey bicycle-related injuries among children brought to the emergency department of the Children''s Hospital of Eastern Ontario, Ottawa, between May 1 and Sept. 30, 1988. The questionnaire was completed for 517 (91%) of the 568 children; 70% were boys, and the mean age was 9.4 years. Only 2% of the patients had been wearing a helmet at the time of injury, although 13% claimed to own one for cycling. Over 60% of the accidents were attributable to carelessness or poor bicycle control; mechanical failure and environmental hazards were minor factors. Over 80% of the injuries occurred within a kilometre of the child''s home. Of the 97 children admitted to hospital 49% had head and skull injuries and 40% had limb fractures. Bicycle-related injuries represented 14.8% of all nonwinter (Apr. 1 to Oct. 31) trauma admissions among children 5 years or older. Our results further document bicycle-related injuries as an important childhood problem and underscore the need for improved safety measures.     

Causes of fatal childhood accidents involving head injury in northern region, 1979-86.

OBJECTIVE--To examine the causes and circumstances surrounding fatal accidents involving head injuries in children in the Northern region. DESIGN--Retrospective review of the hospital case notes, necropsy reports, and records of the coroners'' inquests. SETTING--Northern Regional Health Authority. PATIENTS--All 255 children aged less than 16 years who died with a head injury during 1979-86. MAIN OUTCOME MEASURES--Cause of injury and circumstances of accident according to reports of inquests; injury severity score; number of fatal accidents and mortality per 100,000 children in 10 groups of local authority wards ranked according to their score on the overall deprivation index; and distance of site of accident from child''s home. RESULTS--Of the 255 children who died after a head injury, 136 (53%) children were playing at the time of the accident. 195 (76%) children sustained the head injury in road traffic accidents, 135 as pedestrians, 35 as cyclists, and 25 as passengers in a vehicle. In 120 accidents in child pedestrians the primary cause of accident was the unsafe behaviour of the child. 172 (67%) accidents occurred within one to two km of the child''s home and 153 (63%) between 3 pm and 9 pm. The mortality was significantly related to social deprivation; excluding eight children injured while on holiday in the region, 15-fold decrease in mortality was recorded between the local authority wards that ranked highest on the overall deprivation index and those that ranked lowest (14.0/100,000 children, group 10 v 0.9/100,000, group 1 respectively, p less than 0.00001). CONCLUSIONS--The finding that most accidents occurred in children living in deprived areas who were playing unsupervised near their home suggests that childhood mortality might be appreciably reduced if children at play were protected from traffic, particularly in socially deprived areas.     

Simulation-based assessment for construction helmets

In recent years, there has been a concerted effort for greater job safety in all industries. Personnel protective equipment (PPE) has been developed to help mitigate the risk of injury to humans that might be exposed to hazardous situations. The human head is the most vulnerable to impact as a moderate magnitude can cause serious injury or death. That is why industries have required the use of an industrial hard hat or helmet. There have only been a few articles published to date that are focused on the risk of head injury when wearing an industrial helmet. A full understanding of the effectiveness of construction helmets on reducing injury is lacking. This paper presents a simulation-based method to determine the threshold at which a human will sustain injury when wearing a construction helmet and assesses the risk of injury for wearers of construction helmets or hard hats. Advanced finite element, or FE, models were developed to study the impact on construction helmets. The FE model consists of two parts: the helmet and the human models. The human model consists of a brain, enclosed by a skull and an outer layer of skin. The level and probability of injury to the head was determined using both the head injury criterion (HIC) and tolerance limits set by Deck and Willinger. The HIC has been widely used to assess the likelihood of head injury in vehicles. The tolerance levels proposed by Deck and Willinger are more suited for finite element models but lack wide-scale validation. Different cases of impact were studied using LSTC's LS-DYNA.     

Effectiveness of helmets in skiers and snowboarders: case-control and case crossover study

Objective To determine the effect of helmets on the risk of head and neck injuries in skiers and snowboarders.Design Matched case-control and case crossover study.Setting 19 ski areas in Quebec, Canada, November 2001 to April 2002.Participants 1082 skiers and snowboarders (cases) with head and neck injuries reported by the ski patrol and 3295 skiers and snowboarders (controls) with non-head or non-neck injuries matched to cases at each hill.Main outcome measures Estimates of matched odds ratios for the effect of helmet use on the risk of any head or neck injury and for people requiring evacuation by ambulance.Results The adjusted odds ratio for helmet use in participants with any head injury was 0.71 (95% confidence interval 0.55 to 0.92), indicating a 29% reduction in the risk of head injury. For participants who required evacuation by ambulance for head injuries, the adjusted odds ratio for helmet use was 0.44 (0.24 to 0.81). Similar results occurred with the case crossover design (odds ratio 0.43, 0.09 to 1.83). The adjusted odds ratio for helmet use for participants with any neck injury was 0.62 (0.33 to 1.19) and for participants who required evacuation by ambulance for neck injuries it was 1.29 (0.41 to 4.04).Conclusions Helmets protect skiers and snowboarders against head injuries. We cannot rule out the possibility of an increased risk of neck injury with helmet use, but the estimates on which this assumption is based are imprecise.     

Finite element modelling of equestrian helmet impacts exposes the need to address rotational kinematics in future helmet designs

Jockey head injuries, especially concussions, are common in horse racing. Current helmets do help to reduce the severity and incidences of head injury, but the high concussion incidence rates suggest that there may be scope to improve the performance of equestrian helmets. Finite element simulations in ABAQUS/Explicit were used to model a realistic helmet model during standard helmeted rigid headform impacts and helmeted head model University College Dublin Brain Trauma Model (UCDBTM) impacts.

Current helmet standards for impact determine helmet performance based solely on linear acceleration. Brain injury-related values (stress and strain) from the UCDBTM showed that a performance improvement based on linear acceleration does not imply the same improvement in head injury-related brain tissue loads. It is recommended that angular kinematics be considered in future equestrian helmet standards, as angular acceleration was seen to correlate with stress and strain in the brain.     

Accidents involving off-road motor vehicles in a northern community.

The increasing number of accidents associated with off-road motor vehicles used for recreational purposes prompted this prospective study. During 1985 the records of victims of all motor vehicle accidents who were seen at the Hudson Bay Union Hospital, Hudson Bay, Sask., were studied; patients involved in on-road vehicle accidents were included for comparison. Emphasis was placed on age, vehicle type, mechanism of accident, injury severity and the use of safety features. Almost half of the victims of off-road vehicle accidents were under 16 years of age. The poor adherence to government legislation and manufacturer recommendations was evident in the number of people who did not wear helmets or use headlights.     

A system for quantifying the cooling effectiveness of bicycle helmets

This article describes the design and development of a system that is capable of quantifying the thermal comfort of bicycle helmets. The motivation for the development of the system stems from the desire both to increase helmet use and to provide the designer with a quantitative method of evaluating the thermal comfort of a helmet. The system consists of a heated mannequin head form, a heated reference sphere, a small wind tunnel, and a data acquisition system. Both the head form and the reference sphere were instrumented with thermocouples. The system is capable of simulating riding speeds ranging from 4.5-15.5 m/s. A cooling effectiveness, C1, that is independent of both ambient conditions and wind velocity is defined as a measure of how well the helmet ventilates as compared to the reference sphere. The system was validated by testing six commercially available bicycle helmets manufactured between approximately 1992 and 1998.     

The effect of helmets on the risk of head and neck injuries among skiers and snowboarders: a meta-analysis

Background

The prevention of head injuries in alpine activities has focused on helmets. However, no systematic review has examined the effect of helmets on head and neck injuries among skiers and snowboarders.

Methods

We searched electronic databases, conference proceedings and reference lists using a combination of the key words “head injury or head trauma,” “helmet” and “skiing or snowboarding.” We included studies that used a control group; compared skiers or snowboarders with and without helmets; and measured at least one objectively quantified outcome (e.g., head injury, and neck or cervical injury).

Results

We included 10 case–control, 1 case–control/case-crossover and 1 cohort study in our analysis. The pooled odds ratio (OR) indicated that skiers and snowboarders with a helmet were significantly less likely than those without a helmet to have a head injury (OR 0.65, 95% confidence interval [CI] 0.55–0.79). The result was similar for studies that used controls without an injury (OR 0.61, 95% CI 0.36–0.92), those that used controls with an injury other than a head or neck injury (OR 0.63, 95% CI 0.52–0.80) and studies that included children under the age of 13 years (OR 0.41, 95% CI 0.27–0.59). Helmets were not associated with an increased risk of neck injury (OR 0.89, 95% CI 0.72–1.09).

Interpretation

Our findings show that helmets reduce the risk of head injury among skiers and snowboarders with no evidence of an increased risk of neck injury.Skiing and snowboarding are popular winter activities.¹ Estimates from numerous countries indicate that head injuries account for 9% to 19%, and neck injuries for 1% to 4%, of all injuries reported by ski patrols and emergency departments.^2–11 Rates of head and neck injuries have been reported between 0.09 and 0.46 per 1000 outings.¹² Head and neck injuries are disproportionately represented in cases of severe trauma, and traumatic brain injury is the leading cause of death and serious injury among skiers and snow-boarders.¹³ As far back as 1983, Oh and Schmid recommended mandatory helmet use for children while skiing.¹⁴Many studies of the relation between helmet use and head injuries among skiers and snowboarders have found a protective effect.^15–24 It has been suggested that the use of helmets may increase the risk of neck injury in a crash or fall.²⁵ This may be more evident among children because they have a greater head:body ratio than adults, and the additional size and weight of the helmet may increase the risk of neck injury in an otherwise routine fall.²⁶ We conducted a systematic review of the effect of helmets on head and neck injuries among skiers and snowboarders.     

Effect of alternating G loads on the activities of a human operator wearing a protective helmet

Specific types of operator activity make it necessary to wear a helmet protecting the head against various physical factors. Wearing a heavy helmet for a long time may affect the quality of operator activity when the operator is exposed to alternating G loads. Studies have been performed using a dynamic model of a vehicle subjected to considerable alternating G loads. Crash test dummies have been used to test a system protecting the cervical region of the spinal column. The effects of accelerations, vibrations, and the time of wearing helmets with different weights on the functional state and operator performance have been studied. Data on the effects of helmet weight on some physiological, psychological, and biomechanical reactions of human operators are reported. Some relationships have been found that have practical implications for the functional improvement of the operator component of vehicle operation.     

The Epidemiology and Prevention of Traffic Accidents Involving Child Pedestrians

A study of 713 motor vehicle accidents involving 749 children in the city of Vancouver is reported. A control group of 110 children who did not have accidents was included in the concurrent study. Factors investigated were the driver, the vehicle, the weather, the time of day, the day of week, the month, the width of roadway, the location of the accident, the child''s age, sex, personality, school record, and family background, the type of injury, and the ambulance and hospital service received. Boys were more commonly involved than girls, and most accidents occurred in the 3 to 7 year age group. Head injuries prevailed in the younger age groups and decreased steadily with the age of the child. Specific epidemic areas in the city were identified and selective enforcement was suggested as a possible countermeasure. Hospital records seldom provided a detailed history of the events leading up to the accident. In order to apply the preventive techniques of education and enforcement it was suggested that in each pedestrian traffic accident the driver should be required to accompany the victim to the site of medical care.     

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.     

Head impact exposure in collegiate football players

In American football, impacts to the helmet and the resulting head accelerations are the primary cause of concussion injury and potentially chronic brain injury. The purpose of this study was to quantify exposures to impacts to the head (frequency, location and magnitude) for individual collegiate football players and to investigate differences in head impact exposure by player position. A total of 314 players were enrolled at three institutions and 286,636 head impacts were recorded over three seasons. The 95th percentile peak linear and rotational acceleration and HITsp (a composite severity measure) were 62.7g, 4378rad/s(2) and 32.6, respectively. These exposure measures as well as the frequency of impacts varied significantly by player position and by helmet impact location. Running backs (RB) and quarter backs (QB) received the greatest magnitude head impacts, while defensive line (DL), offensive line (OL) and line backers (LB) received the most frequent head impacts (more than twice as many than any other position). Impacts to the top of the helmet had the lowest peak rotational acceleration (2387rad/s(2)), but the greatest peak linear acceleration (72.4g), and were the least frequent of all locations (13.7%) among all positions. OL and QB had the highest (49.2%) and the lowest (23.7%) frequency, respectively, of front impacts. QB received the greatest magnitude (70.8g and 5428rad/s(2)) and the most frequent (44% and 38.9%) impacts to the back of the helmet. This study quantified head impact exposure in collegiate football, providing data that is critical to advancing the understanding of the biomechanics of concussive injuries and sub-concussive head impacts.     

A survey of koala road kills in New South Wales.

Between 1984 and 1990, 75 koalas (Phascolarctos cinereus) from the central northern coast of New South Wales (Australia) were presented for necropsy due to motor vehicle accidents. The koalas consisted of 44 males and 31 females. Fifty one of these were between 2 and 7 yr (39 males and 12 females). The greater proportion of koalas, especially males, were struck by vehicles between June and December. The main injuries detected were head injuries (44), hemoperitoneum (16), limb injuries (16), hemothorax (15) and spinal injuries (7). Nine koalas were not dead at the time of the accident but died later following complications from the trauma. Twelve koalas had evidence of underlying disease at the time of accident. Ten of these had either conjunctivitis, cystitis, prostatitis, periovarian cysts, endometritis or a combination of the diseases. All 10 koalas still had good body condition. It is suggested that healthy young to middle-aged males are particularly prone to vehicular accidents during the mating period. This has implications for the management of local koala populations.