Bicycle injuries in children: Prevention

INTRODUCTION — Bicycles were first marketed in the United States during the 1830s but were too expensive for most people to buy. With the advent of the "safety bicycle" in the 1880s, bicycles became affordable, and bicycling became a national pastime. The Sports and Fitness Industry Association estimates that approximately 11 million children age 6 to 17 years rode a bicycle at least once during 2018 [1]. Although regular bicycle riding (ie, ≥25 times per year) among children age 6 to 17 years declined between 2014 and 2018, bicycles continue to result in more childhood injuries than any other consumer product except the automobile [1-4].

This topic review will describe the epidemiology of bicycle injuries, review strategies for prevention of bicycle injuries in children, and define the clinician's role in bicycle safety. General principles of injury prevention are discussed separately. (See "Pediatric injury prevention: Epidemiology, history, and application".)

DEFINITION — The term "pedal cycle" is defined by the International Classification of Diseases [5] as any road transport vehicle operated solely by pedals. A pedal cycle includes a bicycle, unicycle, or tricycle. Toys that a child straddles and propels with their feet are not pedal cycles and will not be discussed in this topic review.

A pedal cyclist is any person riding on a pedal cycle or riding in an attachment to such a vehicle. Although pedal cycle is the common language used in injury surveillance and reporting, the word "bicycle" will be used in this report unless specified otherwise.

SCOPE OF THE PROBLEM

Epidemiology — According to the Centers for Disease Control and Prevention, in 2020, there were 136,765 nonfatal bicycle-associated injuries in children age 0 to 19 years in the United States [6]. Children between the ages of 5 and 14 years are at the highest risk for bicycle injury [2,7,8].

Bicycle injuries in children typically are caused by falls or collision with a fixed or moving object. Serious injuries and fatalities are usually caused by collisions with motor vehicles [9-11]. Bicycle riding accounts for approximately 6 percent of fatal injuries and 5 percent of nonfatal injuries sustained during transportation to or from school [12].

In 2020, there were 102 bicycle-associated deaths among children age 0 to 19 years in the United States [13]. Children between 10 and 14 years of age have the highest death rate [8,9,14]. Most bicycle-related deaths (87 percent) occur in males [15].

Among children younger than 14 years of age, most bicycle fatalities are associated with the bicyclist's behavior (eg, not following the rules of the road: riding against the flow of traffic, riding into the street without stopping, etc) [16].

Types of injuries — Bicycle-related soft-tissue injuries, fractures, abdominal injury, and traumatic brain injury are common causes of emergency department visits and hospitalizations in children [17-19]. In a review of 5420 emergency department visits for bicycle-related facial trauma in children and adolescents (72 percent males), lacerations (63 percent), abrasions/contusions (27 percent), and fractures (7 percent) were most common [19]. Lacerations and abrasions were more common in children younger than 11 years, whereas fractures were more common in older children.

Traumatic brain injury is the leading cause of death and long-term disability in bicycle crashes [10,20-22]. In 2018, 14,403 children ≤17 years of age were treated in emergency departments in the United States for nonfatal bicycle-related traumatic brain injuries [8]. Nonfatal bicycle-related traumatic brain injuries were most common among children age 10 to 14 years. The rate of nonfatal bicycle-related traumatic brain injury in children ≤17 years of age decreased between 2009 and 2019 (from 38.2 to 19.6 per 100,000 population).

In addition to head injuries, injuries to the musculoskeletal system and internal organs are important causes of bicycle-related morbidity [2]. In 1997, handlebar injuries to the abdominal or pelvic organs led to the hospitalization of an estimated 1147 subjects ≤19 years of age [23].

Young children who ride in bicycle-mounted seats are also at risk for injury [7]. Feet, legs, or clothing can get caught in the spokes of the bicycle wheel [24,25]. In addition, the added weight may make it more difficult for caregivers to control the bicycle or stop in time [26]. When falls occur, children in bicycle-mounted seats are exposed to adult-level forces of speed [27].

Bike trailers are hitched and towed behind the caregiver and should not be used by infants. Likewise, the "trail-a-bike," which converts an adult bicycle into a three-wheel tandem, should not be used by children younger than three years of age. Both products reduce the impact of forces from collisions related to height. However, injury data have not been studied, and these items have other safety issues related to product failure [28].

Risk factors — Age between 10 and 15 years and male sex are associated with increased bicycle injury mortality [9,14,29]. Other factors associated with bicycle injury in children and adolescents, described in observational studies, include nondaylight riding (eg, at dawn, dusk, or night), more frequent riding (eg, >3 hours per week), riding on the road, riding on the sidewalk, and riding in rural areas [30-36]. Some studies identify using the bicycle for play rather than transportation as a risk factor for bicycle injury, but the association is inconsistent [31-33].

PREVENTION OF BICYCLE-RELATED INJURIES — As with most other injury prevention programs, research continues to support a combination or layering of multiple interventions as the best approach in increasing bicycle safety [37-40]. (See "Pediatric injury prevention: Epidemiology, history, and application", section on 'Principles of injury prevention and control'.)

Bicycle helmets — Wearing a helmet is the first rule of bicycle safety.

Effectiveness — Head injuries account for the majority of bicycle-related deaths and hospital admissions. Multiple observational studies have shown that the use of a bicycle helmet reduces the risk of brain injury [41-50]. In a meta-analysis of 55 observational studies of police- or hospital-verified bicycle injuries in adults and children, bicycle helmets reduced head injury by 48 percent (95% CI 41-54 percent), serious head injury by 60 percent (95% CI 54-65 percent), traumatic brain injury by 53 percent (95% CI 39-64 percent), face injury by 23 percent (95% CI 12-33 percent), and death or serious injury by 34 percent (95% CI 21-46 percent) [51]. Helmets appear to be more effective in single bicycle crashes than in crashes with motor vehicles.

In a subsequent retrospective study, among adult patients involved in a bicycle crash, helmet use was associated with reduced risk of head fracture (7 versus 14 percent) and head soft tissue injury (11 versus 15 percent) [52].

Bicycle helmet use — Bicycle helmet use has increased significantly with the advent of bicycle helmet laws [53-58] and strict enforcement of the legislation [59]. (See 'Legislation and programs to increase use' below.)

Survey data indicate bicycle helmet use is also influenced by caregiver rules, caregiver helmet use, and the age and attitudes of the children [60-62]. In a telephone survey, injury prevention counseling was associated with an increase in "always wearing a helmet" in 5- to 14-year-olds (58 versus 44 percent in those who did not receive counseling) [63].

Even if they have a helmet, many children do not wear it every time they ride [64]. Caregivers and children provide different reasons for lack of helmet use. Reasons provided by caregivers include lack of knowledge [65,66] and cost of the helmet [67,68]. Reasons provided by children include that they don't own a helmet [34], helmets are uncool and not used by their friends [69], helmets are uncomfortable [34,70] or inconvenient [60], and that helmets are not needed (eg, for casual riding, in contrast to sport or race bicycling) [39,71].

Although it is increasing, helmet use among teenagers is particularly low. In the 2015 Youth Risk Behavior Survey, among the 68 percent of high school students who reported riding a bicycle in the previous 12 months, 81 percent reported that they rarely or never wore a helmet [72]. The prevalence of never or rarely wearing a helmet declined from 96 to 81 percent between 1991 and 2015 [72]. In another survey, only 3 percent of 14- to 15-year-olds reported helmet use, whereas 80 percent of 12- to 13-year-olds reported wearing helmets when they were younger [60]. Because of these dismal findings, the American Academy of Pediatrics and other groups (eg, the National Safe Kids Campaign) have called for increased efforts to promote bicycle helmet usage among children and adolescents [73].

Helmet specifications — The United States Consumer Product Safety Commission (CPSC) has established federal safety standards for all bicycle helmets sold in the United States [74]. These standards replace the voluntary standards established by the American National Standards Institute (ANSI), the Snell Memorial Foundation, and the American Society for Testing and Materials (ASTM). Helmets that meet the CPSC standards have a CPSC sticker on the inside liner. Improvements in helmet design have led to the manufacture of rounder, more compact bike helmets with more foam and fewer air vents [75]. Bicycle helmets certified by the ASTM and/or the Snell Memorial Foundation that meet the current standards also may be used [76]. Multisport helmets, designed to be worn for several wheeled recreational activities including bicycling, must be certified to meet the CPSC standard for bicycle helmets.

In addition, helmets that have been in a crash in which the head has hit a hard surface or in which a fall has resulted in marks on the shell should be discarded immediately [73]. Helmets older than five years should be replaced due to possible product deterioration.

Helmet fit — It is important that the helmet fit correctly and be worn in the proper position. In a study of helmet fit and risk of head injury, children who wore poorly fitting helmets had nearly two times the risk of head injury in a crash compared with children who wore properly fitted helmets [77]. In addition, children who wore the helmet tipped posteriorly had a 52 percent increase in the risk of head injury during a crash compared with children who wore the helmet centered on their heads [77].

Children and caregivers may benefit from review of proper helmet fit and positioning. In one study of children aged 4 to 18 years presenting for a health maintenance visit, 96 percent of children and adolescents wore helmets that were either in unsatisfactory condition or did not fit properly [78].

To help caregivers properly fit their children's helmets, the Bicycle Helmet Safety Institute developed the following guidelines:

●The helmet should rest just above the eyebrows and not slide around on the head (figure 1). Use the foam pads to raise or lower the helmet or pad the side space if necessary.

●The straps of the helmet should be adjusted to form a Y just under the ear of the child.

●The chin strap should be snug enough to pull down on the helmet when the child opens the mouth wide.

In addition, Safe Kids Worldwide created a video demonstrating these guidelines [79].

Legislation and programs to increase use — Bicycle safety programs include legislation, awareness (education), and giveaway programs to increase the use of bicycle helmets. Of the three, legislation has achieved the greatest increase in bicycle helmet use [40,54,55,80]. Bicycle helmet legislation also is associated with reduced head injuries. In a meta-analysis of 21 observational studies, mandatory bicycle helmet legislation was associated with a 20 percent reduction in head injuries (95% CI 13-27 percent) and a 55 percent reduction in serious head injuries (95% CI 8-78 percent) [81]. State-specific information about bicycle helmet laws is available from the Insurance Institute for Highway Safety [82].

Awareness or education programs in the school and/or community [83-87] and by clinicians [68,88] have also led to increases in the use of bicycle helmets. A systematic review of nonlegislative interventions for the promotion of helmet wearing by children found an increase in observed helmet wearing after educational programs, particularly those that were community based and provided free helmets [86].

Giveaway programs, although initially successful, have not been found to have a sustained effect in increasing the use of bicycle helmets [59,89]. In one giveaway program, researchers recommended a co-pay as to increase the number of helmets available to give to low-income children [90].

Bicycle paths — Because the majority of serious bicycle injuries and fatalities are usually caused by collisions with motor vehicles [9,10], it makes sense to try to separate young recreational cyclists from motor vehicle traffic [91,92]. Researchers in the Netherlands and Germany attribute a dramatic reduction in both pedestrian and bicycle injuries to improvements in infrastructure, which included bike paths and improved street markings [93]. Although the benefits of bicycle lanes and bicycle paths have yet to be proven conclusively, evidence suggests that an increase in dedicated bike lanes increases the number of cyclists, which in turn reduces the number of bicycle injuries due to greater visibility and awareness [94-96].

CLINICIAN'S ROLE — Health care providers play an important role in increasing the use of bicycle helmets [73]. However, only 33 to 44 percent of caregivers [39,65] and 22 percent of children [97] surveyed report receiving bicycle safety counseling from their child's health care provider. Pediatric health care providers should encourage parents and caregivers to require children to wear bicycle helmets as soon as they begin riding and to model wearing a helmet themselves [73,98].

In addition, as advocates for children, clinicians can encourage state and local legislation requiring bicycle helmet use for all children.

Anticipatory guidance — The anticipatory guidance for prevention of bicycle injuries varies according to the age of the child.

Children <1 year — Caregivers with infants should be cautioned against the use of bicycle-mounted child seats [99]. The American Academy of Pediatrics (AAP) recommends that no child younger than one year of age ride as a passenger on a bicycle restraining seat [100]. In addition, it is unsafe to use infant carriers, such as backpacks and front packs, to transport infants on bicycles [101].

Children 1 to 5 years — Caregivers should be counseled about injury prevention if they choose to use bicycle-mounted carriers. The carrier should be securely mounted and should have a spoke guard to protect the child's hands and feet; the seat should have a high back and a shoulder harness and lap belt that would adequately support a sleeping child; the child should never be left alone in the bicycle carrier [101]. Mounted-carrier riding becomes less safe as the child approaches the age of four years and their weight makes the bicycle unstable and difficult to handle [101]. Bicycle-towed trailers are a safer alternative to bicycle-mounted child seats [24]. The trailer provides greater stability, is out of reach of the spokes, and is lower to the ground in the event of a fall. All child passengers should wear an appropriately sized and properly fastened helmet (figure 1) [100].

A child should not be allowed to ride a tricycle or bicycle until they are developmentally ready [102]. In general, children younger than three years do not have the cognitive or physical ability to both pedal and steer. According to the United States Consumer Product Safety Commission's Age Determination Guidelines, a tricycle should have wheels that are 12 to 13 inches in diameter [103]. Three-year-old children may be able to use a small bicycle with training wheels, but because children of this age cannot yet use hand brakes, the bicycle should have foot brakes [103].

Training wheels can facilitate the transition from tricycle to bicycle.

The first bicycle should be of an appropriate size for the child. Caregivers should be discouraged from buying a "bigger bicycle" with the hopes a child will grow into it. To fit properly, a child should be able to sit on the seat and put the balls of both feet on the ground while holding the handlebars. To prevent straddle injuries, the child should have a one-inch clearance between the bar and the crotch when they straddle the bicycle and have both feet on the ground [104]. (See "Straddle injuries in children: Evaluation and management".)

By five years of age, most children have the balance and coordination to ride bicycles with training wheels and foot brakes [103]. However, they do not understand the risks of riding in areas with cars and should be taught to ride only in areas away from motorists (eg, parks or playgrounds) [105]. Basic bicycle skills include learning how to use the brakes to stop and how to look left, right, and left again. Children should also practice the quick shoulder check by glancing behind while proceeding forward in a straight line. Once the basics are mastered, caregivers should instruct young children to ride on the sidewalk, avoid the street, and only to ride when accompanied by an adult.

Children 6 to 12 years — By the age of six years, most children are able to ride a bicycle without training wheels and have developed some understanding of the consequences of riding in areas shared by cars and pedestrians [103]. Foot brakes on bicycles should be used until the child has developed the motor coordination to use hand brakes (usually by six years of age) [106]. As for younger children, the bicycle should be of an appropriate size for the child. To fit properly, a child should be able to sit on the seat and put the balls of both feet on the ground while holding the handlebars. The purchase of bicycle that the child can "grow into" should be discouraged. The Injury Prevention Program (TIPP) of the AAP provides information to help caregivers teach young children bicycle safety.

School-age children have the motor skills to become accomplished bike riders. However, children in this age group may lack concentration or engage in high-risk behavior and should be reminded to obey all traffic laws [107]. The AAP offers the following bicycle safety recommendations for children in this age [108]:

●Learn the rules of the road

•Ride with traffic

•Stop and look both ways before entering the street

•Stop at all intersections, marked and unmarked

•Before turning, use hand signals and look all ways

●Ride in single file and use bicycle lanes whenever possible

●Avoid all trick and double riding (children should never ride on the handlebars or the crossbar [24])

●Do not ride at dusk or after dark

●Do not wear loose-fitting clothing; wear shoes and tie the laces when riding

●Do not wear earbuds while riding

●Place objects in a backpack or a basket

The National Highway and Traffic Safety Administration has added that electronic devices are a distraction and should be avoided while riding a bicycle [109].

Adolescents — Adolescents, who are at increased risk of bicycle injury and death, should be encouraged to wear bicycle helmets every time they ride. In addition, they should follow the bicycle safety recommendations listed above.

RESOURCES — The following web resources may be helpful to pediatric health care providers in counseling their patients and patients' families about bicycle safety:

●American Academy of Pediatrics: Healthy Children: Bicycle Helmets: What every parent should know

●American Academy of Pediatrics: Bicycle Safety: Myths and Facts

●Kids and Bicycle Safety

●Safe Kids Worldwide: Bike Safety Tips

●Bicycle Helmet Safety Institute

●Pedestrian and Bicycle Information Center

●National Center for Safe Routes to School

●Consumer Product Safety Commission – Bicycles

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or email these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient education" and the keyword[s] of interest.)

●Beyond the Basics topics (see "Patient education: Head injury in children and adolescents (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Epidemiology – Children between the ages of 5 and 14 years are at the highest risk for bicycle injury. Head injuries account for the majority of bicycle-related deaths and hospital admissions. (See 'Epidemiology' above.)

●Bicycle helmets – Bicycle helmets reduce the risk of head, brain, and severe brain injuries for bicyclists of all ages and should be encouraged for bicycle riders and passengers of all ages, on every occasion that they ride a bicycle. (See 'Bicycle helmets' above.)

Only bicycle helmets that meet United States Consumer Product Safety Commission standards should be used; helmets that have been involved in a crash should be discarded. Bicycle helmets should fit properly and be worn in the proper position (figure 1). (See 'Helmet specifications' above and 'Helmet fit' above.)

●Anticipatory guidance – The anticipatory guidance for prevention of bicycle injuries varies according to the age of the child. (See 'Anticipatory guidance' above.)

•Children younger than one year should not ride in bicycle-mounted carriers or trailers.

•When used, mounted carriers should be securely mounted and should have a spoke guard and seats with a high back, shoulder harness, and lap belt. The use of mounted carriers should be discouraged as the child approaches four years of age since the weight of the child makes the bicycle unstable and difficult to handle.

•For child passengers, bicycle trailers are a safer alternative to bicycle-mounted carriers. Children who ride in bicycle trailers should wear a helmet.

•Children younger than three years do not have the developmental skills necessary to ride a tricycle.

•Children aged four to five usually can ride a bicycle with training wheels and foot-operated brakes; they should not ride in traffic and must be supervised at all times.

•Children aged six and older usually can ride a bicycle without training wheels and operate hand brakes; they begin to develop the skills necessary to ride in areas with pedestrians and traffic; children should not be permitted to ride in traffic until they have demonstrated that they can control the bicycle, understand and follow the rules of the road, and exercise good judgment. The age of attainment of these skills is different for different children.

•Adolescents, who are at increased risk of bicycle injury and death, should be encouraged to wear bicycle helmets and avoid the use of electronics every time they ride.