Scientific Journal Articles
on Bike Safety and Helmets
Summary: Here are references to a few of the many medical and scientific journal articles on the Web about helmets and bicycle safety. Most of them let you see the abstract summary for free, but ask you to pay for the full article. In some cases the abstract is all you need. The first listing is a unique summary of everything available on intervention strategies.
Systematic Review of Childhood Injury Prevention Interventions available on the Harborview Web page. Summarizes the problem and evaluates intervention methods.
Many of the articles below are from the Journal of the American Medical Association. They change the URL's from time to time and we may have missed a new one. If the links do not work, this search for helmet articles on the JAMA site should find most of them.
The Big One: The New England Journal of Medicine article describing the Thompson and Rivara studies documenting the effectiveness of bicycle helmets. There are references at the bottom to other medical journal articles. This article is the authoritative source most often quoted on the potential for injury reduction by wearing a helmet.
Effectiveness of bicycle safety helmets in preventing head injuries. A case-control study is a second study from the same team.
Bicycle-associated head injuries and deaths in the United States from 1984 through 1988. How many are preventable?
Use of Alcohol as a Risk Factor for Bicycling Injury
Elevated Blood Alcohol and Risk of Injury Among Bicyclists
Caloric Imbalance and Public Health Policy. This 1999 article discussed obesity and exercise, a prime reason for promoting bicycle use, opening with a statement that obesity had become an epidemic.
Alcohol and Motor Vehicle-Related Deaths of Children as Passengers, Pedestrians, and Bicyclists
Unpowered Scooter-Related Injuries--United States, 1998-2000. (You have to page forward in this .pdf file to find the article.)
A Study of the Effectiveness of Bicycle Safety Helmets Among Children in Skaraborg County, Sweden
(1991) Ekman, R and Welander, G. - Karolinska Institute, Department of Social Medicine, Kronan Health Center and Skaraborg County Council, Department of Health Promotion, Sit Olafsgatan 46, S-52135 Fallioping, Sweden
Helmet legislation effectiveness in three NY counties - Dr Douglas R. Puder et. al. of the Department of Pediatrics, Nyack Hospital, Nyack NY
November, 1999, issue of the American Journal of Public Health.
Risk Factors for Injuries from in-Line Skating and the Effectiveness of Safety Gear
Bicycle helmet use by children. Evaluation of a community-wide helmet campaign.
Profile of Pediatric Bicycle Injuries from the Southern Medical Journal. "Bicycle injuries accounted for 18% of all pediatric trauma alert patients. The mean age of injured children was 10 years, and 79% were males. Bicycle-motor vehicle collisions caused 84% of injuries. Only 3 children (1.4%) wore bicycle helmets. Resulting injuries included external wounds (86%), head injuries (47%), fractures (29%), and internal organs (9%). Six children died. You have to register with Medscape to read the article, but it's free.
Bicycle Injury Hospitalisations and Deaths in Western Australia - 1981-1995. An Australian Government publication showing that "There was a decrease in the proportion of head injuries from almost half in 1981-1983 to just over a third in 1993-1995..."
Attitudes to cycle helmet usage. A Swedish National Road and Transport Research Institute study on why Swedes and others do or do not wear helmets. Concludes: "...we know fairly well what reasons are given for and against helmet usage but there is a lack of studies with a more theoretical analysis of the relationship between different arguments, e.g. whether certain arguments are more important than others."
Bicycle helmets: it's time to use them. This review of an editorial in a 2000 issue of British Medical Journal appears on Health Behavior News Service. It reports that serious head injuries among cyclists of all ages had fallen due to increased helmet use.
Impact of mandatory helmet legislation on bicycle-related head injuries in children: a population-based study.
Macpherson AK, To TM, Macarthur C, Chipman ML, Wright JG, Parkin PC.
Pediatrics 2002; 110(5):e60. Examines the effect of helmet laws on the rate of head injuries in four Canadian provinces. The bicycle-related head injury rate declined significantly (45% reduction) in provinces where legislation had been adopted compared with provinces and territories that did not adopt legislation (27% reduction).
(Copyright © 2002 American Academy of Pediatrics)
Children's bicycle helmet use and injuries in Hillsborough County, Florida before and after helmet legislation
K D Liller et al. Explored the changes in children's bicycle helmet use and motor vehicle bicycle related injuries in Hillsborough County, Florida before and after passage of the state bicycle helmet law. The results show a significant increase in bicycle helmet use among children, ages 5–13, in the post-law years compared with the pre-law years. Also, there has been a significant decline in the rates of bicycle related motor vehicle injuries among children in the post-law years compared with the pre-law years. Although there have been complementary educational and outreach activities in the county to support helmet use, it appears that the greatest increase in use occurred after the passage of the helmet law.
Bicycle Helmet Assessment During Well Visits Reveals Severe Shortcomings in Condition and Fit Gregory W. Parkinson, MD, FAAP and Kelly E. Hike, BA, Falmouth Pediatric Associates, Falmouth, MA. PEDIATRICS Vol. 112 No. 2 August 2003, pp. 320-323. Results. Eighty-four percent (395/473) of eligible families participated. A total of 479 participants were assessed. Eighty-eight percent of participants (419/478) owned a helmet. Reported helmet use "always" or "almost always" was 73% for bicycling (317/434), 69% for in-line skating (193/279), 58% for scootering (179/310), and 50% for skateboarding (79/158). Compared with younger children, teenagers were less likely to wear helmets for all activities. Complete pass rate for every aspect of condition and fit was 4% (20/478, 95% confidence interval: 3–6). The pass rate when the parent alone fit the helmet was 0% (0/52). Three individual aspects of fit were most problematic: 1) helmet ‘resting position’ too high on the forehead (pass rate 249/479; 52%), 2) improper strap position (pass rate 157/476; 33%), and 3) excessive movement of the helmet from front to back of the head (pass rate 247/479; 52%). Mean time for questionnaire completion was 4 (standard deviation: ±1) minutes, and 7 (standard deviation: ±3) minutes for helmet assessment. Conclusions. Ninety-six percent of children and adolescents wore helmets in inadequate condition and/or with inadequate fit. This occurred despite a high acceptance of helmet use by this population.
Legislation for the compulsory wearing of cycle helmets a report of the British Medical Association's Board of Science and Education. November 2004. The BMA examined the evidence and recommended in 2004 that the UK adopt a mandatory helmet law for both children and adults. They had previously recognized the benefits of helmet use but had feared that a helmet law might reduce cycling.
The rationale for promotion of bicycle helmet legislation for children up to 18 years (Israel) an article reviewing the evidence showing the effectiveness of helmets and setting out reasons why Israel should adopt legislation requiring them.
School Helmet Programs Produce Behavioral Change. This review of an article in the March, 2003 issue of Health Promotion Practice appears on Health Behavior News Service. The study was supported by the Washington State Traffic Safety Commission. It showed that kids exposed to helmet promotion programs in fourth grade showed more helmet safety awareness a year later and said on questionnaires that they wear helmets more. Almost half said they know how to fall in a way that prevents injury, a very bad sign.
Rational Approach to Pedal Cyclist Head Protection (and other titles) Doctoral thesis by Bart Depreitere. Date also used for articles in various journals and magazines. Analyzed head injuries of 86 pedal cyclists. Performed 12 mathematical accident recontructions (DADS-software) to estimate impact severity. Second phase was an impact study with ten human cadavers, showing longer energy pulses did more brain damage. A series of 81 impact tests on human skulls showed that energy response varied and suggested that a helmet filtering out skull base vibration could reduce some injuries. The author hopes that with more knowledge of brain injury better bicycle helmets will be possible. "In a limited series of impact tests on helmeted cadavers, it was found that helmets do not unequivocally reduce the head’s rotational acceleration and even may lead to increased accelerations. Helmets did not perform well either with respect to filtering out the frequencies (skull natural frequencies < 1500 Hz) at which the skull base vibration was most pronounced. In a third series of performance tests it was assessed whether helmets could prevent contact between the impactor and the temporal area in lateral impacts on helmeted cadavers. The helmets that did not cover the temporal area failed to protect it against such contacts and in one of these tests a skull fracture was produced." More of this analysis is available from various journal sites locatable by Googling.
Inequalities in cycle helmet use: cross sectional survey in schools in deprived areas of Nottingham. This UK study showed that helmet use in low income areas increased in response to a free helmet program.
Alcohol Intake and the Pattern of Trauma in Young Adults and Working Aged People Admitted After Trauma. This 2004 study in Finland demonstrates a link between alcohol and bicycle crashes in that country.
Head first: Bicycle-helmet use and our children’s safety This Canadian article reviews Canadian injury and helmet use stats, as well as the effect of mandatory helmet laws. The authors conclude that legislation is called for in the remaining provinces who do not have laws.
The Cochrane Collaboration and Bicycle Helmets. This one is a rant from the May, 2005 issue of Accident Analysis & Prevention about the Thompson, Rivara and Thompson study that leads off this list. The author, Aussie W. J. Curnow, feels that the data is stale and that helmets have changed. He says hard shell helmets are "rare" (they must not have skate-style, downhill racing or BMX helmets in Australia) and that the protection of soft shells has not been proven. He has lots of other complaints too, none of which we consider valid. On top of that, it cost us $30 to read it. But you can read the abstract for free.
And here is the rebuttal, for another $30, from two authors in Canada.
These articles illustrate the problem with publishing your material in a journal--the information is buried behind expensive walls.
Incidence and risk factors of severe traumatic brain injury resulting from road accidents: A population-based study. This French study found that the head injury fatality rate increased from 20% in childhood to 71% over 75-year-old. Compared to restrained car occupants, the odds ratio for having a severe head injury was 18.1 for un-helmeted motorcyclists, 9.2 for pedestrians, 6.4 for un-helmeted cyclists, 3.9 for unrestrained car occupants and 2.8 for helmeted motorcyclists. Even after adjustment for several severity factors, male gender and age above 55 were both risk factors. The authors advocated prevention programs to improve head protection. $30 for the download.
Lights Out: Can contact sports lower your intelligence? This article appeared in Discover Magazine. Although not a peer-reviewed journal article, it is available to the public for free, and is a very interesting source of info on concussion levels and mechanisms.
Bicycle safety helmet legislation and bicycle-related non-fatal injuries in California by Brian Ho-Yin Lee, Joseph L. Schofer and Frank S. Koppelman. Accident Analysis & Prevention, Volume 37, Issue 1 , January 2005, Pages 93-102. Compared developments in injury rates in California after adoption of helmet legislation covering kids. Adult rates did not change, while traumatic brain injuries among child riders went down 18%. We have a lot of questions about the data and the assumptions of this study. Available online for $30.
Research sponsored by the NFL Players Association developed a lot of good info on concussion. Here is another Neurosurgery article from that data concluding that "dementia-related syndromes may be initiated by repetitive cerebral concussions in professional football players."
Skid Tests on a Select Group of Bicycle Helmets
to Determine Their Head-Neck Protective Characteristics by Voigt Hodgson of Wayne State University. A study published by the Michigan Department of Public Health in 1991. Hard shell, micro shell and no-shell helmets were impacted into slanted concrete. Helmets with shells slid better, resulting in lower linear g's to the headform (your brain). "Test results predict that hard and micro-shell helmets provide about equal protection from cervical spine injury. The hard and micro-shell helmets tended to slide rather than hang up on impact with concrete. This sliding tendency was the mechanism that reduced the potential for neck injury." This is part of the scientific justification for our Rounder, Smoother, Safer slogan.
Chin strap forces in bicycle helmets. A study by Torbjorn Andersson of the Swedish National Testing & Research Institute. Published in the International Journal of Injury Control and Safety Promotion, Vol. 2, Issue 1 March 1995, pp 1-11. DOI: 10.1080/09298349508945743. Measured forces on bike helmet chin straps during impacts on asphalt. Tested with hard shell, no shell and a ribbed helmet with large vents. The test dummy was suspended from the ceiling impacted by a chunk of asphalt. Chin strap forces differed appreciably. "The shell helmets did not grip the asphalt layer at all and did not rotate, which implies that the headform did not rotate either. The non-shell helmets gripped the asphalt layer
in each impact, rotated and transferred this rotation to the headform." This is part of the scientific justification for our Rounder, Smoother, Safer slogan.
The influence of reduced friction on head injury metrics in helmeted head impacts. An article on what a slippery helmet means when you crash, going beyond earlier publications to assess the likelihood of injury using rotational forces as the criterion. Appeared in Traffic Injury Prevention, Volume 9, Issue 5 October 2008 , pages 483 - 488. DOI: 10.1080/15389580802272427.
The article explores the possibility that in some cases reducing surface friction of a helmet in a crash could increase head injury risk. The goal of was "to demonstrate that reducing friction on the surface of a helmet decreases the rotational acceleration of the head in some scenarios and increases it in other scenarios and to discuss the implications for helmet design." The authors conclude that "The theoretical considerations presented here could be interpreted
into a design criterion as follows: friction should be
reduced for each point on the helmet surface until the cone defined
by the friction angle and the surface normal at that point no
longer includes the center of gravity of the head-helmet system.
Reducing friction beyond this point is not costly in an averaged
sense but neither is it beneficial. It is worth emphasizing that
this study has shown that substantial improvements in helmet
performance can result from a reduction in the coefficient of
friction and these findings are supported by other studies (Aare
and Halldin, 2003). Furthermore, we argue that while friction may be beneficial in a particular impact, in an averaged sense it is never beneficial and may be quite costly." This article has implications for our rounder, smoother, safer theme, and supports our views.
Protective Effect of Different Types of Bicycle Helmets. A Norwegian study by Kari Schroder Hansen et al published in 2003 in Traffic Injury Prevention comparing injury rates in hard shell and "foam" helmets. The authors concluded that "The use of hard shell helmets reduced the risk of getting injuries to the head. Children less than nine years old that used foam helmets had an increased risk of getting face injuries. All bicyclists should be recommended to use hard shell bicycle helmets while cycling." We have not seen the study and don't understand the conclusions.
Skull Study Proves Bike Helmets Work. Original study by Dr. Chris A. Sloffer, a neurosurgical resident at the University of Illinois College of Medicine, in Peoria, et al. This report of the study says they dropped water-filled child skulls in helmets and the skulls did not fracture. A real head-scratcher, since reducing brain injury is the goal, and fractured skulls don't have much to do with that.
This Cochrane Collaboration study found that helmet legislation "appears to be effective in increasing helmet use and decreasing head injury rates in the populations for which it is implemented. However, there are very few high quality evaluative studies that measure these outcomes, and none that reported data on possible declines in bicycle use."
This abstract of a German meeting paper is titled Specific patterns of bicycle accident injuries - An analysis of correlation between level of head trauma and trauma mechanism. Although not a journal article, it was presented in 2004 to a Joint Meeting of the Ungarischen Gesellschaft für Neurochirurgie and the Deutsche Gesellschaft für Neurochirurgie. The authors noted that cyclists with and without helmets had about the same head injuries, and concluded that helmets were not working. Although it is difficult to tell from just the abstract, their conclusion seemed to miss the point. For helmeted riders to be included in their data the cyclist had to be head-injured despite wearing a helmet. But there is no indication of any effort to determine how many cyclists had not been included in their study because the helmet prevented their injury, and there is no indication that they knew how hard a blow the helmeted and unhelmeted riders had suffered. So bare-headed riders injured in lesser impacts were compared with helmeted riders probably injured in much harder impacts after the helmet's protection had been used up, impacts where a bare-headed rider would have perhaps died and not been included in a clinical study. We count this one in the ranks of papers written to prove a point that the authors had already decided on.
Demographic, socioeconomic, and attitudinal associations with children's cycle-helmet use in the absence of legislation and article that concludes using self-reported data from school kids that attitudes are probably the most important determinant of helmet wearing. We have not seen the whole article and can't imagine how the result could have been different. But we never put any stock in child studies using self-reported data anyway, since the kids tell you whatever they think they should be telling you.
Awareness of the bicycle helmet law in North Carolina reports on a study using a written survey that found that the majority of those returning the survey said they were aware that North Carolina has a helmet law.
An Outstanding Science Fair Project: J. Raleigh Burt produced a 2005 science project called Dangerous Decision: The Consideration for Helmet Use At Any Speed". He convincingly demonstrates that a simple fall from a bicycle at zero forward speed can cause a head injury, and further concludes that helmets meeting current standards are likely to prevent it. The project won awards at two Colorado state-level science fairs. You can read about it and download a full copy of the paper.
Children Should Wear Helmets While Ice-Skating: A Comparison of Skating-Related Injuries. An article comparing head injuries in skateboarding, roller skating, inline skating and ice skating that appeared in the July, 2004 edition of Pediatrics. The authors found similar head injury patterns and recommended that ice skaters wear helmets.
Trends in pediatric and adult bicycling deaths before and after passage of a bicycle helmet law. An article about Ontario death rates after a helmet law was passed. Appeared inPEDIATRICS Vol. 122 No. 3 September 2008, pp. 605-610 (doi:10.1542/peds.2007-1776) The article examines bicycle-related mortality rates in Ontario, Canada, before and after helmelt legislation. "For bicyclists 1 to 15 years of age, the average number of deaths per year decreased 52%, the mortality rate per 100000 person-years decreased 55%, and the time series analysis demonstrated a significant reduction in deaths after legislation." But for bicyclists 16 and over, there was no significant change. "These findings support promotion of helmet use, enforcement of the existing law, and extension of the law to adult bicyclists."
The influence of reduced friction on head injury metrics in helmeted head impacts. An article on what a slippery helmet means when you crash, going beyond earlier publications to assess the likelihood of injury using rotational forces as the criterion. Appeared in Traffic Injury Prevention, Volume 9, Issue 5 October 2008 , pages 483 - 488. DOI: 10.1080/15389580802272427.
The article explores the possibility that in some cases reducing surface friction of a helmet in a crash could increase head injury risk. The goal of was "to demonstrate that reducing friction on the surface of a helmet decreases the rotational acceleration of the head in some scenarios and increases it in other scenarios and to discuss the implications for helmet design." The authors conclude that "The theoretical considerations presented here could be interpreted
into a design criterion as follows: friction should be
reduced for each point on the helmet surface until the cone defined
by the friction angle and the surface normal at that point no
longer includes the center of gravity of the head-helmet system.
Reducing friction beyond this point is not costly in an averaged
sense but neither is it beneficial. It is worth emphasizing that
this study has shown that substantial improvements in helmet
performance can result from a reduction in the coefficient of
friction and these findings are supported by other studies (Aare
and Halldin, 2003). Furthermore, we argue that while friction may be beneficial in a particular impact, in an averaged sense it is never beneficial and may be quite costly." This article has implications for our rounder, smoother, safer theme, and supports our views.
Bicycle-Related Injuries Among Children and Adolescents in the United States.
Mehan TJ, Gardner R, Smith GA, McKenzie LB. Clin Pediatr 2008; ePub(ePub): ePub.
DOI: 10.1177/0009922808324952
Describes the epidemiology of US bicycle-related injuries among children and adolescents 18 years and younger. Analyzes NEISS data for patients seen in emergency rooms 1990 to 2005 who were injured while operating a bicycle. During the study period an estimated 6,228,700 individuals 18 years and younger were treated for bicycle-related injuries. Children with head injuries were more than 3 (relative risk, 3.63) times as likely to require hospitalization and were almost 6 (relative risk, 5.77) times more likely to have their injuries result in death. The authors concluded that the large number of bicycle-related injuries indicates that prevention of these injuries should remain an important area of bicycle safety research and practice.
Bicycle Helmet Design. A paper by Mills and Gilchrist that appeared in Proceedings of the Institution of Mechanical Engineers. The authors, from the University of Birmingham in the UK, used finite element analysis to analyze theoretical oblique impacts of helmeted heads, concluding that "thicker foam liners of lower compressive yield stress can protect the head against linear acceleration in 150 J impacts. The peak rotational acceleration of the head was shown to be only slightly affected by the friction coefficient on the road and, in general, to be insufficient to cause serious diffuse brain injuries." When conclusions reached by finite element analysis disagree with studies conducted in physical labs, as the second finding does, the usual cause is the inadequacy of brain models.
Informaworld.com search for helmet articles. We found many interesting journal articles with this search.
Science Direct has many more helmet articles, mostly available at about $30 each. They include articles on motorcycle helmet design and materials, bicycle helmet usage and finite element testing, and a range of article about other types of helmets. This search brought up hundreds of articles, not all of them directly relevant.
This page was last revised on: October 8, 2009.
Contact us.
|
|