Handlebar Grip Related Injury Prevention (GRIP) Study: Are Exposed Metal Handlebar Ends a Risk Factor for Injury?
Condition: Injuries; Trauma; Wounds and Injuries; Children; Child
MeSH terms: Wounds and Injuries
Study type: Observational

Summary: 
      Cycling injuries are the 3rd most common mechanism of injury in 7-13 year olds[1]. Bicycle
      injuries have remained one of the commonest causes of paediatric abdominal trauma for over 60
      years[2,3]. 15% of child cyclist injuries involve impact with a handlebar; two-thirds of
      those are abdominal injuries[4]. Handlebar impact is now the commonest mechanism of major
      paediatric abdominal injury[3]. Serious handlebar injuries often occur after apparently minor
      falls; they are not unique to riders performing stunts[5].

      One small study found that the metal handlebar ends were often exposed on bikes of children
      sustaining severe abdominal injuries[6]. Most European safety standards do not test grip
      durability[7-10]. Day-to-day use can damage rubber grips, exposing the underlying metal
      handlebar tube.

      This feasibility study aims to test the research methods that will be used in a subsequent
      nationwide multicentre study. The main study will investigate the association between
      injuries and handlebar grip condition.

      Children attending study hospitals with any bicycle or kick scooter injury will be invited to
      participate. Parents of injured children will be invited to complete questionnaires regarding
      circumstances surrounding the injury and condition of the handlebar ends on the bike or
      scooter involved. Clinical information regarding the injury will also be collected. The
      handlebar end condition will be compared between children sustaining a handlebar end injury
      [Cases] and riders whose injury did not involve the handlebar [Controls].

      If exposed handlebar ends are more prevalent amongst riders with handlebar end injuries,
      injury prevention strategies can focus on methods to prevent damage occurring to grips
      through day-to-day use. If no such association is found, prevention strategies can be focused
      elsewhere, such as on design of effective protective clothing.

      Data collection for this feasibility study will occur between March 2015 and September 2015.

      The Chief Investigator, Mr. Andrew Neilson, funds the feasibility study.
    

Detailed description: 
      Injuries are the most common cause of death of children aged 1-14 years in the European
      Union[11]. In the United States cyclist injuries are the 3rd most common mechanism of injury
      in 7-13 year olds, after motor vehicle collisions (MVC) and falls[1]. Bicycle injuries have
      remained one of the most common causes of paediatric abdominal trauma for over 60 years[2,3].
      The vast majority (95-98%) of child cyclists admitted due to abdominal trauma are over 5
      years old[2,3]. As with most mechanisms of injury, boys are injured more frequently than
      girls. Around three quarters of injured child cyclists are boys[12].

      In a recent UK study, handlebar end impact was the mechanism that most frequently resulted in
      major intra-abdominal trauma in children. Impact with a handlebar end was implicated in 29%
      of cases. This was ahead of falls (20%), pedestrians (8%) and MVC occupants (8%)[3]. A study
      conducted in Australia found 15% of child cyclist injuries involved impact with a handlebar,
      and 10% of all child cyclist injuries were abdominal handlebar injuries[4]. A study in
      Philadelphia found that 8% of all paediatric bicycle-related trauma admissions involved
      handlebars impacting the abdomen resulting in an injury with an Abbreviated Injury Scale
      (AIS) score of 2 or greater[13].

      The majority of handlebar injury case series reported in the literature relate to children's
      abdominal injuries. The peak incidence occurs between 6 and 14 years of age[4]. However,
      adults can also sustain serious handlebar related injuries[14-16] and 36% of all handlebar
      injured patients sustain only extra-abdominal injuries[4]. It is not just pedal cyclists who
      are at risk of these injuries. Incidents also involve non-motorized kick scooters, moto-cross
      bikes, motorbikes and quad bikes[3,4].

      Crash investigations have found that serious handlebar injuries often occur after apparently
      minor incidents; they are not unique to riders performing stunts or those riding BMX
      bikes[5,6]. There is a typical sequence of events common to many of these handlebar
      injuries[5]. The child loses control of the bike and begins to fall. The front wheel rotates
      through 90 degrees so that it is perpendicular to the child's body. The child continues to
      fall forwards, landing on the upturned handlebar end.

      Children's bikes and scooters often have damaged rubber grips with exposed metal handlebar
      ends. This occurs through day-to-day use. Each time the child drops their bike or scooter on
      its side, the handlebar end contacts the ground. When it does so, the metal tube inside the
      rubber grip cuts into that rubber. With time, a circle is cut from the rubber end, exposing
      the metal pipe within.

      Handlebar end injuries can occur both when the handlebar ends are exposed and when they are
      intact. Two studies from the 1990s have looked at the condition of the handlebar end
      implicated in such injuries[5,6].

      Acton et al published a series of 21 patients who reported handlebar impact as the cause of
      their injuries. Re-interview found that metal handlebar ends were exposed on bikes of all 10
      children who sustained a major abdominal injury, whilst exposed handlebar ends were present
      on only one bike of 8 respondents with minor abdominal injuries[6].

      Winston et al included detailed analysis on 4 riders who sustained serious abdominal injuries
      due to landing on a handlebar end. They found that these serious injuries occurred in 3
      riders despite the presence of protective rubber covering on the handlebar ends. The rider
      who impacted an exposed metal handlebar end, however, had a particularly serious injury. He
      was a 6-year-old boy who sustained a life threatening liver laceration[5].

      Identifying if there is an association between the condition of handlebar grips and the
      likelihood of sustaining an injury is the ultimate aim of the main GRIP study. This
      feasibility study aims to test the intended methodology prior to rolling out a nationwide
      multicentre study. The feasibility study will allow power calculations to be performed for
      the nationwide study. The primary outcome of the nationwide study will address whether
      children falling onto exposed metal handlebar ends are at a greater risk of sustaining an
      injury than those who fall onto handlebars with intact rubber grips. A sub-study will explore
      whether there is any relationship between injury severity and grip condition.

      Our clinical experience tells us that serious handlebar injuries do occur even when handlebar
      grips are intact. The investigators also know through anecdotes that some riders fall onto
      their handlebar ends and never attend hospital because no injury or only a minor injury is
      sustained. The cases presenting to tertiary paediatric units represent the 'tip of the
      iceberg'. A study to accurately identify the number of children who fall onto a handlebar but
      do not present to hospital is unlikely to be feasible. This is why the investigators have
      designed a case-controlled study.

      If the nationwide multicentre GRIP study rejects the null hypothesis, then the investigators
      can focus on passive injury prevention strategies relating to handlebar ends. There are two
      aspects that could easily be addressed by safety standards. Grip durability and grip end
      minimum diameter. Improved durability should reduce the number of bikes or scooters in
      circulation with exposed metal handlebar ends. Larger diameter ends distribute any end-on
      impact over a larger surface area and hence reduce the pressure exerted on the point of
      contact.

      Currently only one of the many applicable European safety standards includes a drop test of
      handlebar grip durability[9]. This standard for BMX bikes was introduced in 2012. However,
      the drop test has not been included in the more recently published standard for Bicycles for
      Young Children[10].

      A minimum grip diameter requirement has been included in the standard for Bicycles for Young
      Children. It specifies that handlebars shall be fitted with handlebar grips, and that such
      grips shall be of resilient material and shall have an enlarged and covered end not less than
      40mm in diameter[10]. That standard applies only to bikes suitable for children up to around
      5 years of age. There is no such minimum handlebar end diameter requirement applied to
      bicycles ridden by children over 5 years of age, or to kick scooters. These standards simply
      require the handlebar to be fitted with handgrips or end plugs[7-9].

      If, however, the nationwide multicentre GRIP study accepts the null hypothesis, the
      investigators can focus handlebar-related injury prevention on more complex mechanical
      solutions such as steering limiters or compressible handlebar ends, and on design of
      effective protective clothing. Some of the secondary outcomes the investigators propose
      addressing will be useful if it is found that exposed handlebar ends are not a risk factor
      for this injury mechanism.
    

Observational model: Case-Control
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Children attending either one of two tertiary paediatric hospital emergency departments and
        paediatric surgical units in the United Kingdom.
      
Keywords: Bike; Bicycle; Scooter; Handlebar