Do bicycle safety helmets reduce severity of head injury in real crashes?

doi:10.1016/0001-4575(87)90002-9

Accident Analysis & Prevention

Volume 19, Issue 3, June 1987, Pages 183-190

https://doi.org/10.1016/0001-4575(87)90002-9 Get rights and content

Abstract

In the past, evaluation of helmet efficacy has been based on laboratory tests of limited relevance to real crashes. In the present study 894 South Australian bicycling enthusiasts returned mail questionnaires about their most recent bicycle crash and their helmet use at the time. 197 bicyclists reported a crash within the past five years in which they had struck their head or helmet. Helmet status at the time of the crash was reported as: no helmet used (n = 75), hairnet-style helmet (n = 69), hard-shell with soft or no liner (n = 37), or hard-shell helmet with stiff liner (n = 16). Analysis of the crude, unadjusted data showed a statistically significant association between helmet use and reduced severity of head injury. The association persisted after adjustment for age and sex of rider, and severity of crash forces. Using an unpublished method developed by Somers, it was estimated that the risk of death from head injury was considerably reduced for helmeted relative to unhelmeted bicyclists, depending on helmet type.

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Cited by (87)

Recent bicycle helmet designs and directions for future research: A comprehensive review from material and structural mechanics aspects
2022, International Journal of Impact Engineering
Cycling becomes more and more popular for recreation, exercising and commuting in many countries. Despite the popularity of cycling, it often comes with high level of risk. Conventional bicycle helmets, with expanded polystyrene foam (EPS) liners, can effectively mitigate impact by linear acceleration. However, there has been an urgent call for further improvement in bicycle helmets, as rotational acceleration has been found to be more dominant in severe head injuries. Recent advancements in manufacturing technologies have enabled various novel conceptual ideas and designs of bicycle helmets, which are previously deemed impracticable due to complexities in structures and materials, to become feasible. There are various bicycle helmet designs in terms of structures and materials used in both the helmet shell and liner, targeting at reducing both linear and rotational acceleration. Moreover, inspired by biological structures in nature, bio-inspired structures have been developed rapidly with excellent energy absorption capacity. As a piece of protective equipment, Bicycle helmet is a representative example where researchers are attempting to apply bio-inspired structures. The objective of the paper is to review the development of bicycle helmets and recent exploration for improvement. This includes the history of bicycle helmets, current test standards, designs of conventional bicycle helmets and the latest research (e.g. material replacement and novel structures), as well as application of bio-inspired structures to helmets. This review also identifies the limitations of current designs and standards, and challenges for future investigations.
Cyclist aerodynamics through time: Better, faster, stronger
2021, Journal of Wind Engineering and Industrial Aerodynamics
Citation Excerpt :
Two examples were the pneumatic helmet by Wannson (Fig. 22a) and the leather helmet by Di Lello, patented in France with the number 343187 (Fig. 22b): both helmets were designed in 1904. Later, helmets made with strips of leather, also called hairnets (Fig. 23a) spread among cyclists, however the protection offered by this leather helmet was later revealed to be poor (Dorsch et al., 1987; Heijmans and Mallon, 2011). Nevertheless, hairnets were commonly used until the 1980s.
The last decades have seen an increasing interest in cycling aerodynamics, with the design of more aerodynamic bicycles and wearable equipment such as helmets and skinsuits and the development and application of new cyclist positions. Moreover, a better understanding of the flow topology around a cyclist and of the aerodynamic interaction between cyclists and other cyclists and nearby vehicles has been gained. However, some knowledge – albeit mainly empirical – of the impact of aerodynamics on cycling performance was already known in late 1800s and early 1900s; as shown by the design of recumbent bicycles and aerodynamic fairings, the adoption of dropped cyclist positions and the organization of drafting races. The goal of this paper is to demonstrate the evolution of aerodynamic knowledge in cycling from the early days to the most recent state-of-the-art to efficiently drive future studies. Therefore, this paper provides a comprehensive review of the history and state-of-the-art in cyclist aerodynamics, focused on three aspects: (i) cycling flow topology and the wind influence; (ii) the aerodynamics of a single cyclist and his/her wearable components; and (iii) the aerodynamic interaction between a cyclist and other cyclists or nearby vehicles. Finally, some future perspectives about cyclist aerodynamics are provided.
Bicycle helmets work when it matters the most
2017, American Journal of Surgery
Citation Excerpt :
The comparison group in the study by Thompson et al was controls and had no head injury at all, whereas in our study we compared the severity of head injury with patients who had some form of intracranial bleed. The study by Dorsch et al14 demonstrated a similar benefit; however, their study relied on identification of subjects retrospectively by questionnaire and did not validate the injuries using medical records. Some studies have suggested that benefit from bicycle helmet use may actually arise from a resulting change in riding behavior and not from the helmet use itself.15
Helmets are known to reduce the incidence of traumatic brain injury (TBI) after bicycle-related accidents. The aim of this study was to assess the association of helmets with severity of TBI and facial fractures after bicycle-related accidents.
We performed an analysis of the 2012 National Trauma Data Bank abstracted information of all patients with an intracranial hemorrhage after bicycle-related accidents. Regression analysis was also performed.
A total of 6,267 patients were included. About 25.1% (n = 1,573) of bicycle riders were helmeted. Overall, 52.4% (n = 3,284) of the patients had severe TBI, and the mortality rate was 2.8% (n = 176). Helmeted bicycle riders had 51% reduced odds of severe TBI (odds ratio [OR] .49, 95% confidence interval [CI] .43 to .55, P < .001) and 44% reduced odds of mortality (OR .56, 95% CI .34 to .78, P = .010). Helmet use also reduced the odds of facial fractures by 31% (OR .69, 95% CI .58 to .81, P < .001).
Bicycle helmet use provides protection against severe TBI, reduces facial fractures, and saves lives even after sustaining an intracranial hemorrhage.
Long term bicycle related head injury trends for New South Wales, Australia following mandatory helmet legislation
2013, Accident Analysis and Prevention
Citation Excerpt :
Moreover, when considering the biomechanical helmet padding system protecting the head, Newtonian laws of physics dictate that an impact force via the helmet to the head during a reasonable velocity crash (50–60 km/h or less) must reduce the magnitude of the blunt force imposed onto the rider's head, and thus the severity of the head injury. This is a given physical fact that can be readily proven both experimentally and from in-depth real world crash investigations (Dorsch et al., 1987; Benz et al., 1993; McIntosh et al., 1998, 2010; Pang et al., 2009; Haworth et al., 2010; McIntosh and Patton, 2012). Thus, given that helmets dampen the impact force and subsequent injury severity, it is expected that evidence of helmets reducing head injuries would be evident in hospital admissions data and bicycle population surveys.
Since the 1991 enactment of mandatory helmet legislation (MHL) for cyclists in New South Wales (NSW), Australia, there has been extensive debate as to its effect on head injury rates at a population level. Many previous studies have focused on the impact of MHL around the time of enactment, while little has been done to examine the ongoing effects. We aimed to extend prior work by investigating long-term trends in cyclist head and arm injuries over the period 1991–2010. The counts of cyclists hospitalised with head or arm injuries were jointly modelled with log-linear regression. The simultaneous modelling of related injury mechanisms avoids the need for actual exposure data and accounts for the effects of changes in the cycling environment, cycling behaviour and general safety improvements. Models were run separately with population counts, bicycle imports, the average weekday counts of cyclists in Sydney CBD and cycling estimates from survey data as proxy exposures. Overall, arm injuries were higher than head injuries throughout the study period, consistent with previous post-MHL observations. The trends in the two injury groups also significantly diverged, such that the gap between rates increased with time. The results suggest that the initial observed benefit of MHL has been maintained over the ensuing decades. There is a notable additional safety benefit after 2006 that is associated with an increase in cycling infrastructure spending. This implies that the effect of MHL is ongoing and progress in cycling safety in NSW has and will continue to benefit from focusing on broader issues such as increasing cycling infrastructure.
The determinants of bicycle helmet use: Evidence from Germany
2011, Accident Analysis and Prevention
Previous research has shown that the risks of serious injury or death from bicycling can be mitigated by the decision to wear a helmet. Drawing on a nationwide household survey conducted in 2008 in Germany, this analysis investigates the determinants of voluntary helmet use through a combination of descriptive analyses and econometric methods, the latter relying on variants of the probit- and heteroskedastic probit model. Confirming results uncovered elsewhere in the literature, we find that household demographics, residential location, and riding patterns are significant correlates of helmet use. Contrasting with other studies, however, we also find that women are significantly less likely to use a helmet than men, a discrepancy that holds over most of the adult life-cycle. The paper concludes by highlighting the scope for designing strategic information campaigns to promote helmet use.
Bicycle-related head injury: A study of 86 cases
2004, Accident Analysis and Prevention
Citation Excerpt :
However, the authorities recently launched a promotion campaign and helmet use has also been promoted in media and sports events. The protective effect of bicycle helmets has been demonstrated in numerous epidemiological studies (Dorsch et al., 1987; Maimaris et al., 1994; McDermott et al., 1993; Thomas et al., 1994; Thompson et al., 1989). Other authors, however, have outlined that the currently used helmets are still susceptible to improvement (Ching et al., 1997; Gilchrist and Mills, 1996; McIntosh et al., 1995; Williams, 1991).
Within the framework of a bicycle helmet research program, we have set up a database of bicycle accident victims, containing both accident and clinical data. The database consists of a consecutive series of 86 victims of bicycle accidents who underwent a neurosurgical intervention in our hospital between 1990 and 2000. Data were obtained from police files, medical records, computed tomography head scans and a patient questionnaire. In only three victims, the wearing of a helmet was documented. In this study, the head injuries are analysed and the relation between the different types of head injuries and outcome is assessed.
Forty-four accidents were collisions with a motor vehicle and 42 accidents were falls. Most impacts occurred at the side (57%) or at the front (27%) of the head. The most frequent injuries were skull fractures (86%) and cerebral contusions (73%). Age was negatively correlated with outcome (P=0.0002) and positively correlated with the number (P=0.00002) and volume (P=0.00005) of contusions and the presence of subdural haematomas (P=0.0004). The injuries with the strongest negative effect on outcome were: subarachnoid haemorrhage (P=0.000001), multiple (P=0.000005) or large (P=0.0007) contusions, subdural haematoma (P=0.001) and brain swelling (P=0.002). A significant coexistence of these four injuries was found. We hypothesise that in many patients the contusions may have been the primary injuries of this complex and should therefore be considered as a main injury determining outcome in this study. We believe that such findings may support a rational approach to optimising pedal cyclist head protection.

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^☆: A previous version of this paper was presented at the 28th Annual Conference of the American Association for Automotive Medicine in October 1984.

^§: Present Address: The Ageing Project, 229 Marion Road, Marleston, S.A. 5033, Australia.

^†: Present Address: Department of Community Medicine, University of Adelaide, G.P.O. Box 498, Adelaide, S.A., 5001, Australia.

^#: Present Address: Epidemiology Branch, S.A. Health Commission, G.P.O. Box 1313, Adelaide, S.A., 5001, Australia.

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Accident Analysis & Prevention

Abstract

References (22)

The probability of death score: an improvement of the injury severity score

Accid. Anal. & Prev.

Fatal traffic accidents in Brisbane from 1935 to 1964

Med. J. Aust.

Helmet attenuation of the head response in oblique impacts to the ground

Bicycle helmets: Which one?

Bicycling Magazine (US)

Safety helmets for pedal cyclists—a pilot study amongst children

The Abbreviated Injury Scale 1980 Revision

A Study of Bicycle/Motor Vehicle Accidents: Identification of Problem Types and Countermeasure Approaches

Fatal injuries to bicyclists: the experience of Dade County, Florida

J. Trauma

Helmets for use by bicycle riders

The mechanics of brain injuries

Br. Med. Bull.

Cited by (87)

Recent bicycle helmet designs and directions for future research: A comprehensive review from material and structural mechanics aspects

Cyclist aerodynamics through time: Better, faster, stronger

Bicycle helmets work when it matters the most

Long term bicycle related head injury trends for New South Wales, Australia following mandatory helmet legislation

The determinants of bicycle helmet use: Evidence from Germany

Bicycle-related head injury: A study of 86 cases

Do bicycle safety helmets reduce severity of head injury in real crashes?☆

Abstract

Accid. Anal. & Prev.

Med. J. Aust.

Helmet attenuation of the head response in oblique impacts to the ground

Bicycle helmets: Which one?

Bicycling Magazine (US)

Safety helmets for pedal cyclists—a pilot study amongst children

The Abbreviated Injury Scale 1980 Revision

A Study of Bicycle/Motor Vehicle Accidents: Identification of Problem Types and Countermeasure Approaches

Fatal injuries to bicyclists: the experience of Dade County, Florida

J. Trauma

Helmets for use by bicycle riders

The mechanics of brain injuries

Br. Med. Bull.