ON-ROAD VERSUS OFF-ROAD MOTORCYCLE ACCIDENTS IN …scripties.umcg.eldoc.ub.rug.nl/FILES/root/... · Injury profiles of on-road versus off-road motorcycle accidents in Western Australia

Injury profiles of on-road versus off-road motorcycle accidents in Western Australia Steven J.G. Leeuwerke P a g e | II

ON-ROAD VERSUS OFF-ROAD

MOTORCYCLE ACCIDENTS IN

WESTERN AUSTRALIA

Steven J.G. Leeuwerke Master’s thesis Medicine

Student number: s1727044

Period: September 2013 – April 2014

Institutions and supervisors:

Department of Orthopaedic and Trauma Surgery of the Royal Perth Hospital, Western Australia Professor René Zellweger, MD, FRACS, FACS

Doctor Manimaran Sinnathamby, MBBS

University Medical Centre Groningen, Groningen, the Netherlands Miss Inge H.F. Reininga, PhD

Doctor Roeland H. den Boer, MD

Injury profiles of on-road versus off-road motorcycle accidents in Western Australia Steven J.G. Leeuwerke P a g e | I

Foreword After months of hard work, the end result is finally there: a comprehensive report on 180

cases of motorcycle accidents that were reviewed or admitted by the trauma team in the Royal

Perth Hospital (RPH) between 18 September 2013 and 5 March 2014. Up to 50% of all

motorcycle accidents have been reported to occur off-road and yet, most literature and

prevention campaigns are targeted solely at on-road motorcyclists. The primary aim was

therefore to assess the injury severity, injury profiles and outcomes in terms of health and

return to work three months after the accident in off-road motorcyclists compared to on-road

motorcyclists, in order to emphasise the need for action towards reducing trauma in this

group. This thesis, which is part of an ongoing project, is one of the final stages in becoming a

doctor and has been a wonderful experience for me. However, it has not been without

challenges and I would like to thank all who played a role in this project, in particular the

following persons.

First of all, I would like to thank my local supervisors, Professor René Zellweger and Doctor

Manimaran Sinnathamby. Prof., you have been supportive in many ways and have

encouraged me from the start to make the most of my stay here. You have a strong, unique

personality and have challenged me to think critically about a variety of subjects. For me

personally, my stay has been a success and I hope the feeling is mutual. Maran, you have

given me the freedom to explore my own ideas and were available when needed to steer me in

the right direction. Thank you for allowing me to take responsibility of the project and to fully

experience what it means to do a scientific research project. Also, I would like to thank

Maxine Burrell and the people from Medical Records in RPH, who have put effort in making

part of the data available in time, which was a successful challenge in the end. Further thanks

go to Katrin Zellweger, for casting a critical eye on my writing and providing important

suggestions towards improvement.

Secondly, I would like to thank my supervisors in the Netherlands, especially Ms. Inge

Reininga who has been an invaluable help with constructive comments and her expertise on

statistical analyses. Inge, you drove the necessary reshaping of this thesis to make it a

comprehensive whole and you have put a lot of effort into helping me understand how to

analyse the data. It all makes more sense now! Further, I would like to thank Doctor Roeland

den Boer, who was available at the start for advice with the content of the study.

Lastly, but most importantly, I would like to thank all patients that participated in this study,

not only by taking the time to answer all the questions with patience, but also by providing

insight in your passion for motorcycling and willingness to share graphic material of your

motorcycles, injuries and equipment. Your input has been an inspiration and at least one other

project has sprouted from your suggestions.

Enjoy the read and do not hesitate to contact me for questions or critical notes on the content!

Kind regards,

Steven Leeuwerke

Final year medical student at the Rijksuniversity Groningen, the Netherlands

E: [email protected]

mailto:[email protected]

Injury profiles of on-road versus off-road motorcycle accidents in Western Australia Steven J.G. Leeuwerke P a g e | II

Summary

Introduction Roughly 15,500 serious injuries and over 200 deaths occur on Australian roads annually

following motorcycle accidents, which equals to approximately 26% of all serious road

trauma. While the incidence of off-road motorcycle trauma is gradually increasing and up to

50% of all motorcycle accidents have been reported to occur off-road, preventive strategies

have almost been solely aimed at on-road motorcyclists. Earlier literature suggests differences

between both groups in terms of risk factors, injury severity, injury profiles and the use and

effect of motorcycle clothing, but results remain inconclusive. Further, differences in health

outcomes and return to work have not been investigated previously.

Objective This study primarily aimed to compare on-road and off-road motorcyclists with respect to

injury severity, injury profiles, the use and effect of motorcycle clothing and outcomes in

terms of physical and emotional health, as well as return to work. Secondary objectives

included a comparison of rider demographics and contributing factors to both the cause and

severity of an accident.

Methods

A prospective cohort study was undertaken at a level 1 trauma centre of Royal Perth Hospital,

Western Australia, collecting data from interviews and medical records. All motorcycle

accidents (two-wheeled and all-terrain vehicles) that were reviewed by trauma surgery during

a 6 month period ending on the 5th

of March 2014 were approached for inclusion.

Results There were no significant differences between on-road (n=108, 60.0%) and off-road (n=72,

40.0%) motorcyclists in terms of injury severity, hospital length of stay and discharge location

(home or rehabilitation facility). Injury profiles were similar between both groups, with the

exception of soft tissue injuries, which occurred more frequently in on-road motorcyclists (on-

road n=93, 89.4% versus off-road n=52, 74.3%; p=0.01). Only motorcycle clothing with body

armour was found to be significantly protective against soft tissue injuries. A protective effect

of gloves was not found. Although protective, the use of motorcycle clothing was low with

only 6.5% of on-road and 15.3% of off-road motorcyclists wearing full equipment with body

armour imbedded in all parts. Physical and emotional health outcomes three months after the

accident were generally worse in on-road motorcyclists. Return to work was overall low with

46.7% of patients unable to return to partial or full-time employment three months after the

accident. Return to work was not significantly different between both groups.

Conclusion Off-road motorcyclists sustain equally severe injuries with mostly similar injury profiles and

form a significant group of trauma. These findings emphasise the implications of off-road

motorcycling trauma to patient and society and reinforce the need to take action to reduce

trauma in this group of motorcyclists. Further research is needed to formulate ways to

effectively implement new injury prevention strategies specifically targeted at off-road

motorcyclists.

Key terms: motorcycle accidents, off-road motorcycles, motorcycle clothing, health

outcomes, return to work.

Injury profiles of on-road versus off-road motorcycle accidents in Western Australia Steven J.G. Leeuwerke P a g e | III

Samenvatting

Introductie Jaarlijks vinden er ruim 15,000 ernstige en meer dan 200 fatale motorongevallen plaats op

Australische wegen en vormen daarmee ongeveer 26% van alle ernstige verkeersongevallen.

Hoewel de incidentie van off-road ongevallen gestaag toeneemt en tot wel 50% van alle

motorongevallen off-road plaatsvinden, zijn preventie campagnes tot nu toe vrijwel

uitsluitend gericht op on-road motorrijders. Eerdere literatuur suggereert verschillen tussen

on-road en off-road motorrijders betreft risicofactoren, letsel ernst, letsel profielen en het

gebruik en effect van motorkleding, maar resultaten zijn tot nu toe niet eenduidig. Verschillen

in gezondheidsuitkomsten en werk hervatting na het ongeval zijn niet eerder onderzocht.

Doel Het primaire doel was het vergelijken van on-road en off-road motorrijders op het gebied van

letsel ernst, letsel profielen, het gebruik en effect van motorkleding, fysieke en emotionele

gezondheidsuitkomsten en werk hervatting drie maanden na het ongeval. Secondaire doelen

waren onder meer het vergelijken van demografische gegevens en bijdragende factoren in

zowel de oorzaak en de ernst van het ongeval.

Methoden Dit prospectieve cohort onderzoek verzamelde gegevens afkomstig uit interviews en

medische dossiers in het Royal Perth Hospital, West Australië, een level 1 trauma centrum.

Alle motorongevallen (twee-wielers en all-terrain voertuigen) die werden beoordeeld door het

trauma team binnen een periode van 6 maanden (t/m 5 maart 2014), werden benaderd voor

deelname.

Resultaten Er werden geen significante verschillen gevonden tussen on-road (n=108, 60.0%) en off-road

(n=72, 40.0%) motorrijders op het gebied van letsel ernst, ziekenhuisverblijf of ontslag locatie

(huis of rehabilitatie centrum). Letsel profielen waren vergelijkbaar tussen beide groepen, met

uitzondering van weke delen letsels, welke vaker voorkwamen in on-road motorrijders (on-

road n=93, 89.4% versus off-road n=52, 74.3%; p=0.01). Motorkleding met body armour

bleek significant te beschermen tegen weke delen letsels. Er werd geen beschermend effect

gevonden van handschoenen. Het gebruik van motorkleding was infrequent, slechts 6.5% on-

road en 15.3% off-road motorrijders droegen een complete uitrusting met body armour.

Fysieke en emotionele gezondheidsuitkomsten waren slechter in on-road motorrijders drie

maanden na het ongeval. Werkhervatting was laag, 46.7% van alle patiënten was niet in staat

om het werk gedeeltelijk of volledig te hervatten. Er waren geen significante verschillen in

werkhervatting tussen on-road en off-road motorrijders.

Conclusie

Off-road motorrijders lopen letsels op van gelijke ernst en tonen grotendeels gelijke letsel

profielen en vormen daarmee een belangrijke groep trauma patiënten. De resultaten

benadrukken de gevolgen van off-road ongevallen voor zowel de patiënt en de maatschappij

en de noodzaak om trauma in deze groep motorrijders te verminderen. Toekomstig onderzoek

gericht op de invoer van preventie stragieën zijn

Sleutelwoorden: motorongevallen, off-road motorrijders, motorkleding,

gezondheidsuitkomsten, werkhervatting.

Injury profiles of on-road versus off-road motorcycle accidents in Western Australia Steven J.G. Leeuwerke P a g e | IV

Definitions and abbreviations

1. Definitions used by the WHO ICD-10[1]

Motorcycle: a motorcycle is a two-wheeled motor vehicle with one or two riding saddles and

sometimes with a third wheel for the support of a sidecar. The sidecar is considered part of the

motorcycle. A motorcycle rider is any person riding on a motorcycle or in a sidecar or trailer

attached to such a vehicle.

All-terrain vehicle (ATV): a special all-terrain vehicle is a motor vehicle of special design

to enable it to negotiate rough or soft terrain or snow. Examples of special design are high

construction, special wheels and tyres, tracks, and support on a cushion of air.

Traffic accident: a traffic accident is any vehicle accident occurring on the public highway

[i.e. originating on, terminating on, or involving a vehicle partially on the highway]. A vehicle

accident is assumed to have occurred on the public highway unless another place is specified,

except in the case of accidents involving only off-road motor vehicles, which are classified as

non-traffic accidents unless the contrary is stated.

Public highway or street: a public highway [trafficway] or street is the entire width between

property lines (or other boundary lines) of land open to the public as a matter of right or

custom for purposes of moving persons or property from one place to another. A roadway is

that part of the public highway designed, improved and customarily used for vehicular traffic.

Non-traffic accident: a non-traffic accident is any vehicle accident that occurs entirely in any

place other than a public highway.

2. Definitions used in the present study

Motorcycle: two wheeled motor vehicles and ATVs (as per WHO ICD-10 definition)

Motorcycle accident: any fall or collision whilst riding on a motorcycle as motorcycle rider

or passenger.

On-road: as per WHO ICD-10 definition of a traffic accident, or if involving an off-road

motorcycle on a public highway or street.

Off-road: as per WHO ICD-10 definition of a non-traffic accident, or if occurring on an

unsealed road.

Abbreviations:

ATV All-terrain vehicle

BA Body armour

ED Emergency Department

ICD-10 International Classification of Diseases version 10

ICU Intensive Care Unit

ISS Injury Severity Score

LOS Length of stay

MCA Motorcycle accident

RPH Royal Perth Hospital

TBI Traumatic Brain Injury

WA Western Australia

WHO World Health Organisation

Injury profiles of on-road versus off-road motorcycle accidents in Western Australia Steven J.G. Leeuwerke P a g e | V

List of figures and tables

Box 1 – Criteria for ED to involve trauma surgery in the line of care (Appendix I – page 35).

Box 2 – WHO ICD-10 definitions for motorcycles (page 9).

Figure 1 – Details of 36 excluded patients (Appendix I – page 35).

Figure 2 – A motorcycle handlebar penetrating the left thigh (page 18).

Figure 3 – Anterior-posterior view of a traumatic amputation of the thumb (page 18).

Figure 4 – Off-road impaling injury with a branch (page 18).

Table 1 – Demographics and admission details (page 12).

Table 2 – Rider characteristics (page 13).

Table 3 – Mechanism of injury by crash type (page 14).

Table 4 – Injury profiles of on-road and off-road motorcyclists (page 16).

Table 5 – Frequency of motorcycle clothing that was worn and owned, but not worn in on-

road and off-road motorcyclists (page 20).

Table 6 – Risk of not wearing any motorcycle clothing compared to wearing motorcycle

clothing with or without body armour (reference) (page 20).

Table 7a – Physical outcomes three months after the accident (page 22).

Table 7b – Physical outcomes three months after the accident between on-road and off-road

motorcyclists (reference), adjusted for possible confounders (age, gender, impact

speed, crash type and ISS) (page 23).

Table 8a – Emotional outcomes three months after the accident (page 24).

Table 8b – Emotional outcomes three months after the accident between on-road and off-road

motorcyclists (reference), adjusted for possible confounders (age, gender, impact

speed, crash type and ISS) (page 24).

Injury profiles of on-road versus off-road motorcycle accidents in Western Australia Steven J.G. Leeuwerke P a g e | VI

Contents FOREWORD ............................................................................................................................. I

SUMMARY/SAMENVATTING .....................................................................................II, III

DEFINITIONS AND ABBREVIATIONS ........................................................................... IV

LIST OF FIGURES AND TABLES ...................................................................................... V

CONTENTS .................................................................................................................... VI, VII

1. INTRODUCTION .................................................................................................... page 1-7

1.1 – Background ................................................................................................................... 1-6 1.1.1 – Definitions and classification systems in motorcycling ................................................. 1

1.1.2 – Popularity of motorcycling in Australia ......................................................................... 1

1.1.3 – Injury and mortality rates ........................................................................................... 1, 2

1.1.4 – Injury profiles ................................................................................................................. 2

1.1.5 – Burden to patient and society ..................................................................................... 2, 3

1.1.6 – Who gets hurt: contributing factors to the cause and mechanism of injury ............... 3, 4

1.1.7 – Who gets hurt: contributing factors to the severity and outcome of injury .................... 5

1.1.8 – On-road versus off-road motorcycle accidents .......................................................... 5, 6

1.2. – Study objectives ............................................................................................................ 6, 7 1.2.1 – Aim of this study ....................................................................................................... 6, 7

1.2.2 – Hypotheses .................................................................................................................... 7

2. METHODS ............................................................................................................. page 8-10

2.1 – Setting ............................................................................................................................... 8

2.2 – Study design ................................................................................................................. 8-10 2.2.1 – Definitions ...................................................................................................................... 8

2.2.2 – Study population, case identification and sample size ............................................... 8, 9

2.2.3 – Data collection and study variables .......................................................................... 9, 10

2.3 – Ethics approval ............................................................................................................... 10

2.4 – Statistical analyses .......................................................................................................... 10

3. RESULTS .............................................................................................................. page 11-24

3.1 – Study population ............................................................................................................. 11

3.2 – Demographics and injury severity ................................................................................. 11

3.3 – Rider characteristics, accident cause and mechanism ............................................. 12-15 3.3.1 – Rider characteristics ............................................................................................... 12, 13

3.3.2 – Cause and mechanism ............................................................................................. 13-15

3.4 – Injury profiles ............................................................................................................ 15-17 3.4.1 – Traumatic brain and neurological injuries ................................................................... 15

3.4.2 – Internal injuries ............................................................................................................ 15

3.4.3 – Fractures ................................................................................................................. 15, 17

3.4.4 – Soft tissue injuries ........................................................................................................ 17

3.5 – Motorcycle clothing ................................................................................................... 17-21 3.5.1 – Frequency of use ..................................................................................................... 17-19

3.5.2 – Effectiveness in preventing injury ........................................................................... 19-21

3.6 – Outcomes three months after the accident ............................................................... 21-24 3.6.1 – Demographics ............................................................................................................... 21

3.6.2 – Physical health ......................................................................................................... 21-23

3.6.3 – Emotional health .......................................................................................................... 23

Injury profiles of on-road versus off-road motorcycle accidents in Western Australia Steven J.G. Leeuwerke P a g e | VII

3.6.4 – Return to work and financial loss ................................................................................. 24

4. DISCUSSION ....................................................................................................... page 25-29

4.1 – Rider characteristics, accident cause and mechanism ............................................ 25, 26

4.2 – Injury severity and injury profiles ........................................................................... 26, 27

4.3 – Motorcycle clothing ........................................................................................................ 27

4.4 – Outcomes three months after the accident .................................................................... 28

4.5 – Recommendations .......................................................................................................... 29

4.6 – Strengths and limitations ............................................................................................... 29

5. CONCLUSION .......................................................................................................... page 30

REFERENCES .................................................................................................................. 31-34

APPENDICES ........................................................................................................................ 35

Injury profiles of on-road versus off-road motorcycle accidents in Western Australia Steven J.G. Leeuwerke P a g e | 1

1. Introduction

1.1 Background

1.1.1 Definitions and classification systems in motorcycling

Motorcycles are engine-powered machines used primarily for recreation and transportation.

Various vehicles may be regarded as motorcycles and the literature is subject to inconsistently

used terminology. Whereas some studies use the term ‘motorcycle’ to indicate only one

specific type of motorcycles (e.g. street bikes), in others this term also includes other

motorcycle types, such as quad bikes and dirt bikes. Two commonly used definitions to

classify motorcycles more accurately are ‘powered two-wheelers’ and ‘All-terrain vehicles’

(ATVs). However, although these definitions differentiate between the general build of the

motorcycle (e.g. frame and number of wheels), this does not take into account the intended

location of use of the motorcycle. This is important, as rider characteristics and the

environment in which in is ridden may influence the risk of having an motorcycle accident

(MCA), as well as the injury severity and injury profile of persons victim to such accidents.

Arguably the best method to define motorcycles and MCAs may be the classification system

used by the World Health Organisation (WHO), the International Classification of Diseases

(ICD), which is revised on a regular basis. The latest version, the ICD 2010 (ICD-10),

classifies motorcycles separately into two-wheeled motorcycles and ATVs and further

separates them into ‘traffic’ and ‘non-traffic’ accidents. Traffic accidents refer to accidents

occurring on public highways or streets, which are defined by the ICD-10 as ‘the entire width

between property lines (or other boundary lines) of land open to the public as a matter of right

or custom for purposes of moving persons or property from one place to another’, which is in

most definitions largely consistent with the term ‘on-road’. Non-traffic accidents are defined

as ‘any vehicle accident that occurs entirely in any place other than a public highway’ and is

in most definitions largely consistent with the term ‘off-road’.

The definitions used in this study deviate slightly from the definitions used by the

ICD-10 and are discussed in detail in the methods section, paragraph 2.2.1. The terminology

in this chapter is subject to the differences in terminology throughout the literature and is

specified where possible.

1.1.2 Popularity of motorcycling in Australia

The popularity of motorcycling as a method of recreation and transportation has steadily

increased in Australia over the years. With 115,488 new motorcycles (including scooters) sold

in 2012 of which over half (53.1%) were intended for off-road use, an overall increase in sales

of 5.4% compared to 2011 was observed [2]. This seems consistent with the average annual

increase in motorcycle registrations of 6.8% and 5.8% from 2002 to 2008 and 2008 to 2013

respectively [3,4], which is much higher than the increase in registrations of other road

vehicles [5]. Furthermore, whereas motorcycles comprised 3.7% of all road vehicle

registrations in 2008, this percentage had grown to 4.3% in 2013 [3]. These trends predict a

continuing increase in the use of both on-road and off-road motorcycles, with an associated

increase in future motorcycle trauma.

1.1.3 Injury and mortality rates

Although motorcyclists represent a relatively small proportion of all Australian road users,

Injury profiles of on-road versus off-road motorcycle accidents in Western Australia

Steven J.G. Leeuwerke P a g e | 2

they show the highest morbidity and mortality rates due to crashes [5-7]. From 2008 to 2009,

14,493 hospital admissions due to serious motorcycle injuries were recorded in Australia,

which accounted for 26.3% of all hospital admissions for serious injuries following traffic

accidents during that year [7]. In 2012, 224 MCA associated deaths were recorded [8]. The

fact that motorcyclists are a vulnerable group of road users becomes even more evident when

comparing injury and death rates per 100,000 registered vehicles and per distance travelled.

Compared to other road users, motorcyclists show a 10-fold higher injury rate and a 5- to 6-

fold higher death rate per 100,000 registered vehicles [4,5,7]. Per distance travelled,

motorcyclists show an approximately 41-fold higher rate of serious injury and a 30- to 34-fold

higher death rate compared with car occupants [5,9]. Furthermore, although the death rate per

distance travelled has decreased for car occupants over the last decade, for motorcyclists it has

not [5], despite an average decrease in the number of deaths per 10,000 registered

motorcycles [8]. Although motorcyclists account for less than 1% of the distance travelled of

all Australian road users, the proportion of deaths due to MCAs is increasing and was near

15% of all road fatalities in 2007 [5]. Similar trends are observed in the United Kingdom

(UK) and Europe, where motorcyclists comprise less than 1% of all road users (UK) [10], but

account for 14% and 16% of all traffic fatalities respectively [10,11]. The fact that

motorcyclists are much more exposed compared to most other road users, may explain the

higher risk of serious and fatal injuries observed in motorcyclists.

1.1.4 Injury profiles

The type and severity of sustained injuries following a MCA (and any other accident) are

related to the impact force that is inflicted upon the body. The impact force is roughly

determined by the mass (kilograms) times the deceleration of the crashing object (meters per

second), the latter of which is determined by the change in velocity over a certain time period.

Both deceleration and mass are directly proportional with the impact force. In other words, a

large and rapid decrease in velocity and a high mass result in a high impact force. Effective

measures to prolong the deceleration time and subsequently decrease the impact force have

been implemented in cars for decades and include seatbelts, airbags and crumple zones. The

absence of such measures due to the difficulty to implement them on motorcycles may

explain the high morbidity and mortality observed in motorcyclists.

Because MCAs usually involve a significant impact force, many MCAs result in

multi-trauma patients with multiple injured body regions [12] (up to 88% in major trauma

patients [13]). Injured body regions most commonly involving the extremities [12,14],

followed by the head or neck and chest in non-fatal accidents [12,14-16]. In patients admitted

to trauma units, over 95% of patients sustained one or more fractures [15], which most

commonly involves the lower extremity [12,14-16]. Of these, the tibia, followed by the femur

[15], foot and patella are most frequently involved and have shown to have a large impact on

disability, economic costs and return to work [12]. Fatal accidents predominantly occur in on-

road motorcyclists (94%) [16] and are mainly the result of the head injuries [12,16], followed

by internal thoracic and abdominal injuries [12]. With roughly 26% of all hospital admissions

due to serious injuries following traffic accidents consisting of motorcyclists [7], the potential

burden to both patient and society are considerable.

1.1.5 Burden to patient and society

By 2020, traffic accidents are expected to be the third leading cause of long-term disability

and impairment worldwide [17]. With MCAs accounting for roughly 26% of all traffic

accidents that result in serious injury and hospital admission [7], both short- and long-term



disability rates are likely to be high in motorcyclists. Recently, a large study investigating

functional outcomes of MCA victims in eight European countries, reported that 46.4% of

patients was expected to experience some functional limitation as a result of their injuries at

least one year after hospital discharge [14]. The most common injuries involved the lower and

upper extremity, accounting for 26 and 21% of the total number of injuries respectively. The

expected long-term disability rates for these body regions were high at 80 and 47%

respectively. A more dated study looking at MCA victims that received compensation for

disability during that year (57.6%), reported that 68% had a mechanical impairment of a limb

and 80% were reported to have disfiguring impairments [18]. Disability mostly involved

problems with locomotion and dexterity at work.

Not only the burden to the patient, but also the burden to society is an important

consideration. As stated earlier, motorcyclists are prone to more severe injuries compared to

most other road users and may subsequently require more surgical procedures, require a

prolonged length of stay in hospitals and specialised rehabilitation centers and record a longer

absence from work, all of which have a financial impact on both the patient and society.

When looking at this more closely, the costs of MCAs to society are considerable. An

American study looking into the costs of medical care and lost productivity following fatal

and non-fatal traffic accidents, found that motorcyclists account for 12% (12 billion USD) of

all costs due to traffic accidents in 2005 [19]. Although motor vehicle accidents had the

largest share in cost (70 billion USD), motorcyclists showed disproportionally higher costs

with respect to their injury incidence [19]. An earlier American study investigating the costs

of motor vehicle accidents showed that the majority (74%) of these costs are paid by society

through insurance and taxes [20]. These are strong indicators that MCAs are a considerable

burden to both the patient and society in terms of disability, lost working days, productivity

and (ongoing) health care costs.

1.1.6 Who gets hurt: contributing factors to the cause and mechanism of injury

Age and sex

Most frequently involved in MCAs are young males [12,21,22], especially motorcyclists in

their twenties [11,21]. Young motorcyclists are more often inexperienced [22], which has

been related to the risk of a MCA [12,23]. Furthermore, they have been shown to be more

likely to engage in risk/taking behaviour, such as dangerous driving and breaking the law (e.g.

speeding, drink-riding, not wearing a helmet) [12]. Despite the higher risk of MCAs in young

motorcyclists, another peak is reported in motorcyclists in their forties and fifties [12,21,22].

It has been suggested that this is related to decreased physical resiliency and slower reaction

times [21,22].

A disturbing note is the increasing number of children involved in MCAs, especially

off-road. Between 2009 and 2010, 10.2% and 30.3% of reported MCAs occurred in persons

under the age of 15 and 25 respectively [24]. Another study even found that 56% of off-road

MCAs occurred in children under the age of 12, and 8% of children were only 5 years old or

even younger [25]. Bevan et al. reported a similar distribution and showed an annual increase

of juvenile MCAs with almost 10% during the study period (2000 to 2004) [26]. Multiple

studies show that off-road MCAs in children are associated with significant morbidity and

mortality [25-28] and disability rates up to 24% following head injuries [27,29,30]. The large

number of juvenile motorcyclists may in part be explained by the absence of minimum age

requirements, obligatory licensing or obligatory registering of motorcycles when riding on

private lands [13].



Inexperience and training

Although inexperienced motorcyclists show an increased risk of being involved in a MCA

[12], a significant lower risk of MCAs in trained motorcyclists versus untrained motorcyclists

has not been clearly demonstrated [12,31]. A recent Cochrane review concluded that no clear

statements could be made as to the effect of motorcycle training on crash, injury or offence

rates, due to the poor quality of the studies currently available [32]. A possible explanation for

the absence of clear evidence that motorcycle training has any influence on MCA rates may

be that not experience, but rather age is the main determinant for the risk of a MCA due to the

higher occurrence of risk taking behaviour in young motorcyclists, as was stated earlier [12].

Another possible explanation is that motorcyclists adapt their riding behaviour because of

increased confidence in their operating skills following motorcycle training [12].

Single- and multi vehicle accidents

As explained in paragraph 1.1.4, the type and severity of sustained injuries following a MCA

are related to the impact force that is inflicted upon the body. Keeping this in mind, one may

understand how sudden loss of velocity (e.g. due to hitting a moving or static solid object)

results in a short deceleration time and subsequently, a high impact force. It is therefore not

surprising that collisions are reported to result in a greater injury severity [6,22]. Cassell et al.

reported that 58% of all fatal accidents were attributable to collisions with other road users,

and 12% to collisions with fixed objects [16]. In collisions with cars at intersections, the car

driver is usually responsible for the accident [22]. This has been found to be attributable to

drivers not seeing the motorcycle either due to the shape and colour of the motorcycle or

having a strong set to only see other cars [22]. Although most MCAs are single vehicle

accidents [6,33], a considerable proportion of accidents involves other vehicles and a

significant proportion of single vehicle MCAs result from swerving to avoid impact with

another vehicle [12].

Intoxication

Intoxication with alcohol and/or drugs is a widely accepted risk factor for traffic accidents and

is associated with decreased riding skills [22]. Especially amongst motorcyclists, the rate of

alcohol use is high [12]. Further, fatal accidents involving alcohol occur more frequently in

motorcyclists than in drivers of any other motor vehicles [12,22]. Alcohol use is associated

with speeding, lower rates of helmet use [34] and more severe head injuries in both helmeted

and unhelmeted patients, likely due to increased susceptibility to haemorrhagic shock [12].

The use of other drugs, such as cannabis and cocaine, has been reported to be higher in

motorcyclists as well [12]. It has been suggested that intoxicated riding occurs more

frequently in off-road motorcyclists than in on-road motorcyclists [35].

Environmental factors: road conditions and weather

Both road conditions and weather may be a causative contributor in a small proportion of

MCAs. While most fatal and non-fatal traffic accidents occur on dry, sealed roads [35], loss

of surface grip, which is influenced by wet roads, road markings, loose materials, potholes,

and surface irregularities, seem to be the main causative contributors [22]. Further, many

motorcyclists lose control in curves [22] and roadside objects such as crash barriers and

guardrails have been shown to increase mortality rates [6]. Weather does not appear to be an

important contributing factor in the majority of MCAs, likely due to the fact that motorcycling

is mainly a recreational activity reserved for favourable weather conditions [22]. When used

for transportation, motorcyclists may switch to alternative transport options during bad

weather [22].



1.1.7 Who gets hurt: contributing factors to the severity and outcome of injury

Speeding

Not only is it more difficult to remain in control of the motorcycle at high speeds due to faster

required reaction times and may therefore be a causative factor in an accident, higher speeds

also contribute to the impact force and subsequently the injury severity of a MCA (paragraph

1.1.4). Indeed, higher impact speeds have been associated with more severe injuries in

motorcyclists [6,12]. Speeding is reported to account for almost two thirds of fatal MCAs

involved in single vehicle accidents [12], possibly due to a reported reduction in helmet

effectiveness at high speeds [6,12]. Not only excessive speed, but also the appropriate speed

for the traffic conditions in which in is ridden is an important consideration [12].

Protective equipment

In most countries including Australia, the use of a helmet is mandatory. Helmets reduce the

risk of injury by absorbing the impact force through an energy absorbent liner and resisting

penetration of sharp objects through a hard outer shell [36]. Their protective benefit is well

established and a reduction of head injury and mortality by 42 and 69% respectively is

reported in the literature [37]. Nonetheless, some controversy remained because of observed

cervical spine injuries in helmeted MCA patients [12]. It was thought that the added head

mass might increase the chance of hyper-flexion or -extension during a MCA. Most of these

studies, however, had limitations in their designs and their findings have been contradicted by

many other studies that did not find such a relationship [12]. Controversially, a protective

effect of helmets on cervical spine injuries has also been reported [38]. Despite their

irrefutably proven benefit, helmet compliance remains an issue in a small group of MCAs and

it has been suggested that the rate of helmet non-compliance is higher in off-road MCAs

[26,39].

Additional protective equipment, such as special motorcycle jackets, pants, boots and

gloves, may also decrease the risk of injury following an accident. An additional protective

effect against the weather has been argued, which may decrease the risk of an accident by

minimizing distraction and discomfort from the weather [40]. The use of protective equipment

other than helmets is optional and not bounded by Australian law. Many variations in clothing

material, thickness and the presence and location of additional body armour exist,

complicating the assessment of their protective properties. Few studies have looked into the

effect of protective equipment on injury prevention. A recent study by de Rome et al. showed

a significant reduction in soft tissue damage, in particular open wounds, when wearing

protective equipment during a MCA [41]. A protective effect on fractures, however, could not

be demonstrated. Nonetheless, motorcyclists wearing protective equipment spent less time in

hospital and reported less severe pain scores, impairment and disability two months after the

accident.

1.1.8 On-road versus off-road motorcycle accidents

As stated in the beginning of this chapter, on-road and off-road motorcyclists may differ with

respect to rider characteristics, risk factors, injury severity and injury profiles following a

MCA. The focus has mainly been on on-road motorcyclists, despite the fact that more than

half of all motorcycles sold in Australia are intended for off-road use [2] and the proportion of

MCAs occurring in off-road locations have been reported to be 24 to 50% in adults or adults

and children combined [13,16,24,33,39,42] and as high as 89% in children ≤16 years [26].

Furthermore, multiple studies show that the incidence of off-road MCAs is increasing [13,24-

26,28,39,43-45]. To the authors knowledge, only three studies have reported on differences



between on-road and off-road motorcyclists with respect to injury severity and injury profiles

[13,16,42]. Cassell et al., comparing both fatal and non-fatal on-road and off-road MCAs,

found that although most on-road fatalities are the result of a collision with another road user

(49%) or fixed object (25%), off-road fatalities were more frequently caused by non-collision

accidents (67%) [16]. Injury profiles in fatal accidents were similar between on-road and off-

road MCAs and most commonly involved head injuries, followed by thoracic injuries.

Further, no differences in injury profiles between both groups were found in non-fatal

injuries, with fractures being the most common type of injury followed by open wounds. For

severe cases, injury profiles were similar as well with the most common type of injury being

fractures, followed by internal organ injuries, intracranial injuries and injury to the nerve and

spinal cord. On-road motorcyclists, however, involved generally more severe injuries in terms

of hospital length of stay. Mikocka-Walus et al., looking exclusively at major trauma patients,

found comparable results [13]. They found that on-road motorcyclists were more commonly

admitted to rehabilitation facilities, had longer admission lengths and longer stays in Intensive

Care Units (ICU) [13]. Further, the incidence of serious head and extremity injuries was

higher in on-road motorcyclists. In both on-road and off-road motorcyclists, thoracic injuries

were the most common type of injury [13]. Grange et al., investigating crashed motorcyclists

in a level 1 trauma centre and an Emergency Department (ED) in California, reported no

significant differences in injury severity between on-road and off-road motorcyclists in terms

of Injury Severity Scores (ISS), admission rates and admission to ICUs [42]. They did find

differences in injury profiles, with the incidence of blunt chest, abdominal and skin trauma

being higher in on-road motorcyclists. Further, on-road motorcyclists were more likely to

require transfusions and die from their injuries [42].

With regards to risk factors, all three studies found that off-road motorcyclists are

generally younger [13,16,42]. Bevan et al. investigated ED presentations and trauma

admissions related to motorcycling in paediatric patients (≤16 years) and found that only 72%

of patients in which helmet-wearing status was recorded were wearing a helmet [26]. The

high non-compliance of helmet use in off-road motorcyclists has been reported previously and

higher rates of alcohol and/or drug use in off-road motorcyclists have been reported as well

[39].

To date, the only data on the differences between on-road and off-road MCAs with

respect to injury severity and injury profiles comes from three studies that report partially

conflicting results [13,16,42]. As all of these studies were retrospective studies based on

hospital codings, the recording of less severe injuries such as soft tissue injuries were likely

underreported or were not reported at all. None of these studies have adjusted the found

differences for possible confounding factors such as impact speed and worn motorcycle

clothing. More research is needed to provide a more detailed insight into the differences

between both groups.

1.2 Study objectives

1.2.1 Aim of this study

Western Australia (WA) is the largest state of Australia and encompasses a large area of rural

and remote regions. Of all Australian states, WA has shown the largest increase in motorcycle

registrations (47.8% from 2008 to 2013) [3]. Further, WA has been reported to have the

second smallest average annual decrease in fatal MCAs from 2003 to 2012 [8] and the

number of seriously injured people following MCAs keeps increasing [46]. Royal Perth

Hospital (RPH) houses the only level 1 trauma centre in the state and subsequently receives

near 80% of all major (motorcycling) trauma. The experience of local doctors is that off-road



motorcycling is a increasingly popular recreational activity in WA and that a high proportion

of all MCAs occur off-road. Many of these accidents are of at least equal severity compared

to on-road MCAs and often no protective equipment is worn. As stated earlier, previous

studies investigating differences between on-road and off-road MCAs with respect to injury

severity and injury profiles remain partly inconclusive and the impact speed and use of

motorcycle clothing in this group of motorcyclists remains uninvestigated. Furthermore,

although there have been studies reporting on disability rates following MCAs [14,18], these

focused on on-road motorcyclists and a comparison with on-road motorcyclists has not been

made. More research is needed to supplement the existing literature and to emphasise the

implications of off-road motorcycle trauma on both patient and society, so that new

prevention campaigns specifically targeted at off-road motorcyclists may be implemented.

The primary aim of this study was therefore to compare on-road and off-road motorcyclists

with respect to:

1. injury severity and injury profiles;

2. the use of motorcycle clothing and their effect on injury prevention;

3. outcomes in terms of physical and emotional health, as well as return to work three

months after the accident.

Secondary study objectives included a comparison of rider demographics and contributing

factors to both the cause and severity of the injury, including intoxication, (impact) speed and

environmental factors.

1.2.2 Hypotheses

For primary study objectives, the following hypotheses were formulated and tested:

1. Injury profiles and injury prevention

H0: off-road motorcycle accidents are of equal severity compared to on-road

motorcyclists following an accident, measured using ISS and hospital length of stay

H0: off-road motorcyclists show similar injury profiles compared to on-road

motorcyclists following an accident.

2. Use of protective equipment and their effect on injury prevention

H0: the use of motorcycle clothing is similar in on-road and off-road motorcyclists that

are involved in an accident.

H0: motorcycle clothing in on-road and off-road motorcyclists is equally protective.

3. Outcome

H0: off-road motorcyclists show similar outcomes in terms of physical health,

emotional health and return to work three months after the accident compared to on-

road motorcyclists following an accident.

H0: off-road motorcyclists show similar return to work rates three months after the

accident compared to on-road motorcyclists following an accident.



2. Methods

2.1 Setting

The Royal Perth Hospital (RPH) is a level 1 major trauma service provider and includes a

specialised trauma centre with a 30-bed capacity and four high acuity beds. RPH provides

care for an area of approximately 2.5 million km2 and 2.2 million people [6]. As the only level

1 trauma centre in the state, RPH receives approximately 80% of all major trauma cases in

WA [47]. MCAs account for 8% of all trauma cases admitted to RPH, which translates into

roughly 400 RPH admissions following MCAs annually [48]. All (acute) trauma cases that

are presented to RPH are admitted to the Emergency Department (ED), where the initial

resuscitation, diagnostic investigations and treatment take place. The decision to involve the

trauma team is predominantly based on the physical signs, mechanism and anatomical area of

injury of the patient (appendix I – box 1). From the ED, trauma patients may be admitted

under trauma surgery, orthopaedics, plastic surgery, spinal surgery or other specialties.

2.2 Study design

2.2.1 Definitions

The definitions used in this study were based on the WHO ICD-10 definitions and were

adapted to include a slightly different range of motorcycles and road locations. In this study,

the term ‘motorcycle’ was used to indicate both two-wheeled motor vehicles and ATVs,

which were defined in concordance with the WHO ICD-10 definitions (box 2) [1] and

included street bikes, dirt bikes, scooters, mopeds, motorized bicycles, quad bikes and buggies

respectively. A MCA was defined as any fall or collision whilst riding on a motorcycle as

motorcycle rider or passenger. The accident was considered to have occurred ‘on-road’ if it

fulfilled the criteria of a traffic accident or involved an off-road motorcycle that was ridden on

a public highway or street. The accident was considered to occur ‘off-road’, if the accident

occurred anywhere else or occurred on an unsealed road.

Injury severity was assessed using the Injury Severity Score (ISS), an internationally accepted

tool to grade injury severity in trauma patients. In concordance with the classification used by

the American College of Surgeons [49], injury severity was further classified based on ISS

score into minor (ISS 1 – 9), moderate (10 – 15), severe (ISS 16 – 24) and very severe (>24)

trauma. Trauma was considered ‘major’ in case of an ISS of 16 or greater.

Motorcyclists were considered to wear full equipment if all worn parts were

specifically designed for motorcycling and included at least a helmet, a jacket or impact

protector, pants, boots and gloves. The use of neck braces, shin guards/knee pads and kidney

belts were considered to be additional protective equipment. Equipment was considered to

contain body armour if this included multiple reinforcements over physically vulnerable areas

(e.g. foam pads over shoulders or elbows, Kevlar lining in pants). Although potentially

protective, the use of equipment not designed for motorcycling (e.g. steel-capped work boots)

was not considered to be protective equipment in this study.

2.2.2 Study population, case identification and sample size

A prospective cohort design was chosen for this study. Over a six month period (September

2013 to March 2014), all MCA cases that were reviewed or admitted by the trauma team were

considered to be eligible for this study. Eligible cases were identified from the hospital’s



patient management system (iSOFT Clinical Manager) and were approached by the student-

investigator for participation in the study. Patients deficient of the English language or with an

altered consciousness throughout admission (Glasgow Coma Scale <15) were excluded from

the study, as were MCAs that did not involve a review of the trauma team or resulted from an

(alleged) assault whilst on the motorbike. Written informed consent was obtained with

additional parental consent in case of under aged patients (<18 years). The sample size was

estimated at 100 – 150 patients, based on findings of an earlier RPH study [6] and annual

statistics on the number of MCAs in RPH [48].

2.2.3 Data collection and study variables

Data collection was separated into three occasions. First, a structured questionnaire-based

interview was conducted during admission, capturing data on demographics, substance use,

cause and mechanism of injury, use of protective equipment and details about the motorcycle

and riding behaviour. Secondly, the medical record of eligible patients was audited, capturing

data on admission and discharge details, accident location, sustained injuries and

management. Unconfirmed injuries were excluded from the analyses. ISS scores were

provided by a trained research nurse. Third, in a subgroup of patients, a structured

questionnaire-based follow-up interview was conducted over the telephone three months after

the accident, comprising of questions regarding the physical, emotional, social and

occupational impact of the accident. Time restrictions prevented completing the follow-up

interview in all patients.

Data from the questionnaire and the medical record were compared and conjoined into

a single database. Details on impact speed and riding while intoxicated were collected from

both the questionnaire and the medical record to increase accuracy. Discrepancies were

Box 2 – WHO ICD-10

1 definitions for motorcycles [49].

Motorcycle:

A motorcycle is a two-wheeled motor vehicle with one or two riding saddles and sometimes with a third wheel for

the support of a sidecar. The sidecar is considered part of the motorcycle. A motorcycle rider is any person riding

on a motorcycle or in a sidecar or trailer attached to such a vehicle.

All-terrain vehicle:

A special all-terrain vehicle is a motor vehicle of special design to enable it to negotiate rough or soft terrain or

snow. Examples of special design are high construction, special wheels and tyres, tracks, and support on a cushion

of air.

Traffic accident:

A traffic accident is any vehicle accident occurring on the public highway [i.e. originating on, terminating on, or

involving a vehicle partially on the highway]. A vehicle accident is assumed to have occurred on the public

highway unless another place is specified, except in the case of accidents involving only off-road motor vehicles,

which are classified as non-traffic accidents unless the contrary is stated.

Public highway or street:

A public highway [trafficway] or street is the entire width between property lines (or other boundary lines) of land

open to the public as a matter of right or custom for purposes of moving persons or property from one place to

another. A roadway is that part of the public highway designed, improved and customarily used for vehicular

traffic.

Non-traffic accident:

A non-traffic accident is any vehicle accident that occurs entirely in any place other than a public highway.

1 World Health Organisation, International Classification of Diseases version 10.



resolved by finding evidence to support the data (e.g. measured blood ethanol level), or were

marked unknown when the accuracy of the data remained questionable. For variables that

involved an estimation (e.g. impact speed, years of riding experience), a mean value was

calculated if estimations were within a reasonable range (e.g. ± 20 km/h for impact speed).

2.2 Ethics approval

Ethics approval for this study was obtained from the Royal Perth Hospital Human Research

Ethics Committee prior to commencement of this study. All included images were used with

the consent of the patients.

2.3 Statistical analyses

Data were analysed using IBM SPSS Statistics for Windows (version 21.0 Armonk, NY: IBM

Corp). Descriptive statistics generally included frequency with percent distribution for

binomial data. Quantitative data were assessed for normality using plots and the Shapiro-Wilk

test and were presented as mean with standard deviation for normally distributed data or

median with range for non-normally distributed data. Inferential statistics were performed

using Fisher’s exact test for binomial data and the Pearson’s Chi-squared test for trends for

categorical data. Binomial and categorical quantitative data were tested using the T-test and

Mann-Whitney U test for normally distributed data and ANOVA and Kruskall-Wallis test for

non-normally distributed data respectively. Single injuries were categorized by injury type

and were analysed as binomial data (injury present or absent) in two steps. First, potential

differences in the incidence of injury between on-road and off-road motorcyclists were

identified using Fisher’s exact test. Secondly, a multivariate logistic regression model was

calculated, adjusting for possible confounders. Theoretical confounders included age, gender,

impact speed, crash type (single versus multiple vehicle accident) and motorcycle clothing

and were selected using univariate logistic regression models using a broad alpha (≤0.30).

Identified confounders were then entered into the final model (forward method) using the

likelihood ratio. The protective effect of motorcycle clothing and outcomes were analysed in a

similar manner, with potential confounders that were taken into account being age, gender,

impact speed, crash type and ISS. Multivariate logistic regression models were presented as

regression coefficient with odds ratio (OR) and 95% confidence interval (95% CI). All

inferential analyses used two-tailed significance levels of p≤0.05.



3. Results

3.1 Study population

A total of 247 MCA cases were identified during the study period, of which 222 met the

inclusion criteria. Of the 222 patients eligible for participation, 180 (81.1%) patients agreed to

be interviewed and were included in the study (details of excluded patients are presented in

Appendix I – figure 1). The medical records of 174 (96.7%) patients were available for audit,

in the remaining six cases data from the questionnaire was used exclusively. In addition, a

total of 101 (56.1%) patients were approached three months after the accident to partake in

the follow-up interview. Of these, 89 (88.1%) patients completed the interview, 10 (9.9%)

patients could not be reached and 2 (2.0%) patients refused participation.

3.2 Demographics and injury severity

Of the total of 180 accidents, 108 (60.0%) accidents occurred on-road and 72 (40.0%)

accidents occurred off-road. Patients were predominantly male (n=160, 88.9%) with ages

ranging from 14 to 84 years (median 30.5 years) (Table 1). Most patients were single (n=80,

44.4%), followed by married (n=46, 25.6%), defacto (n=22.2, 40.0%) and divorced or

separated (n=14, 7.8%). The majority of patients were admitted under trauma surgery (n=100,

55.6%) or orthopedic surgery (n=53, 29.4%). Other admitting specialties included spinal

surgery, plastic surgery, burns, neurosurgery, maxillofacial surgery and urology. Injury

severity varied greatly among motorcyclists and ISS ranged from 1 to 38 (median ISS 9.0).

Most patients were considered minor traumas (n=104, 57.8%) and 27 (15%) patients were

considered major traumas (ISS > 15). Overall, including re-admissions a total of 1358 RPH

admission days were recorded (median length of stay (LOS) 5.0 days, range 1 – 76 days).

Twelve patients required admission to an Intensive Care Unit (ICU) (median LOS 3.0 days,

range 1 – 9 days). Ninety-nine (55.0%) patients required injury management by means of one

or more surgical interventions (minor interventions such as suturing small lacerations were

considered conservative management). Most patients were discharged home following

admission (n=127, 70.6%), a smaller proportion required rehabilitation in a specialised center

(n=37, 20.6%) or were discharged to another hospital (n=15, 8.3%). Patients spent a total of

850 days in rehabilitation centers, ranging from 4 to 86 days (median LOS 17.0 days). An

additional 114 days were spent in other hospitals (median LOS 5.0 days, range 1 – 30 days).

When comparing on-road and off-road MCAs, off-road motorcyclists were generally

younger than on-road motorcyclists (p≤0.001) (Table 1). Injury severity (ISS) did not differ

significantly between both groups (p=0.26), nor was the proportion of motorcyclists in each

trauma category significantly different (p=0.64). The proportion of major trauma cases (ISS

category severe and very severe) were statistically similar for on-road and off-road MCAs

(on-road n=18, 16.7% versus off-road n=9, 12.5%; p=0.53). LOS between on-road and off-

road motorcyclists did not differ significantly for RPH (p=0.65), ICU (p=0.37), rehabilitation

facilities (p=0.37) or other hospitals (p=0.46). The proportion of patients that required

surgical intervention was related to injury severity (p=0.05), but did not differ between both

groups (p=1.00). Statistically similar proportions of patients were discharged home (p=1.00),

to a rehabilitation facility (p=1.00) or to another hospital (p=1.00).



Table 1 – Demographics and admission details.

Total n=180 (100.0%)

On-road

n=108 (60.0%) Off-road

n=72 (40.0%) P-value

Age

Sex Male

Female

Marital status

Single

Defacto

Married

Divorced/separated

LOSa

RPH

ICU

Rehabilitation

Other hospital

Discharge locationb

Home

Rehabilitation

Other hospital

Injury severity

ISS

Minor (1– 9)

Moderate (10 – 15)

Severe (16 – 24)

Very severe (>24)

Management Conservative

Surgical

30.5 (14 – 84)

160 (88.9%)

20 (11.1%)

80 (44.4%)

40 (22.2%)

46 (25.6%)

14 (7.8%)

5.0 (1 – 76)

3.0 (1 – 9)

17.0 (4 – 86)

5.0 (1 – 30)

127 (70.6%)

37 (20.6%)

15 (8.3%)

9.0 (1 – 38)

104 (57.8%)

49 (22.7%)

19 (10.6%)

8 (4.4%)

81 (45.0%)

99 (55.0%)

34.5 (14 – 84)

94 (87.0%)

14 (13.0%)

47 (43.5%)

25 (23.2%)

26 (24.1%)

10 (9.3%)

5.0 (1 – 76)

4.0 (1 – 9)

16.5 (4 – 86)

4.0 (1 – 30)

77 (71.3%)

22 (20.4%)

9 (8.3%)

9.0 (1 – 38)

64 (59.3%)

26 (24.1%)

13 (12.0%)

5 (4.6%)

49 (45.4%)

59 (54.6%)

26.5 (14 – 64)

66 (91.7%)

6 (8.3%)

33 (45.8%)

15 (20.8%)

20 (27.8%)

4 (5.6%)

4.0 (1 – 48)

2.5 (2 – 4)

17.0 (4 – 73)

6.0 (3 – 20)

50 (69.4%)

15 (20.8%)

6 (8.3%)

9.0 (1 – 30)

40 (55.6%)

23 (31.9%)

6 (8.3%)

3 (4.2%)

32 (44.4%)

40 (55.6%)

≤0.001

0.47

0.77

0.65

0.37

0.53

0.46

1.00

1.00

1.00

0.26

0.64

1.00

a, b In 7 patients, a provisional length of stay (LOS) was used; (one patient was still an in-patient

in RPH and six patients were an in-patient in a rehabilitation center). The discharge

location was unknown in these patients.

Data are presented as frequency (%) and median (range).

3.3 Rider characteristics, accident cause and mechanism

3.3.1 Rider characteristics

Overall, 160 (88.9%) two-wheeled motorcycles and 20 (11.1%) ATVs were involved in a

MCA. Thirty-four (18.9%) patients crashed a motorcycle other than their own and nine

(5.0%) were passengers (Table 2). The majority of accidents occurred in the metropolitan area

(n=114, 63.3%). Eighty-eight (81.5%) of on-road MCAs occurred with street bikes, the

remainder involved scooters (n=10, 9.3 %) and mopeds (n=4, 3.7%). Six (5.6%) patients rode

a dirt bike on-road. Off-road MCAs mainly involved dirt bikes (n=50, 69.4%) and quad bikes

(n=18, 25.0%). Two (2.8%) patients rode a buggy and one (1.4%) patient rode his scooter off-

road. The majority of patients used their motorcycle exclusively for recreation (n=99, 55.0%)

or for both recreation and transportation or for work (n=57, 31.7%). Over half (n=96, 53.3%)

of all patients had been riding motorcycles (on-road and/or off-road, gaps of time in which

was not ridden not taken into account) for at least 10 years and most rode at least once a

month (n=129, 71.7%) or once a week (n=112, 62.2%). A considerable number of patients

that rode their own motorcycle had used it for less than a year (n=72, 40.0%). Many patients

had a previous MCA (including minor ones, n=128, 71.1%) and 57 (31.7%) patients had been



hospitalized before following a MCA.

When comparing on-road and off-road motorcyclists, statistically similar proportions

of patients were passengers in both groups (0.74) (Table 2). Riders of off-road motorcycles

more often rode on a motorcycle that was not their own (p=0.03). While on-road accidents

predominantly occurred in the metropolitan area (n=85, 78.7%), more than half of all off-road

MCAs occurred in a rural or remote area (n=38, 52.8%; p≤0.001). On-road motorcyclists

were more likely to ride at least once a week (p≤0.001) and also tended to ride at least once a

month more often (p=0.07). On-road motorcycles were more often used for both recreation

and transportation or work, whereas off-road motorcycles were mainly used for recreation

only (p≤0.001). There were no significant differences in riding experience (p=0.70). Although

off-road motorcyclists tended to have had a previous MCA more often (p=0.07), the

proportion of patients that had been hospitalized before was not statistically different

(p=0.19).

Table 2 – Rider characteristics.

Total n=180 (100.0%)

On-road

n=108 (60.0%) Off-road

n=72 (40.0%) P-value

Passenger

Not own motorcycle

Accident location Metro

Rural or remote

Regular rider ≥ once a week

≥ once a month

Motorcycle use

Recreation

Transportation/work

Both

Experience (years)

<1

1 to 4

5 to 9

≥10

Started riding motorcycle

of MCA (years)a

<1

1 to 2

2+

Previous MCA

Previous hospitalisation

9 (5.0%)

27 (15.0%)

114 (63.3%)

55 (30.6%)

162 (90.0%)

129 (71.7%)

99 (55.0%)

15 (8.3%)

57 (31.7%)

12 (6.7%)

40 (22.2%)

26 (14.4%)

96 (53.3%)

72 (40.0%)

34 (18.9%)

25 (13.9%)

128 (71.1%)

57 (31.7%)

6 (5.6%)

11 (10.2%)

85 (78.7%)

17 (15.7%)

77 (71.3%)

82 (75.9%)

38 (35.2%)

13 (12.0%)

52 (48.1%)

6 (5.6%)

22 (20.4%)

16 (14.8%)

61 (56.5%)

44 (40.7%)

22 (20.4%)

17 (15.7%)

71 (65.7%)

30 (27.8%)

3 (4.2%)

16 (22.2%)

29 (40.3%)

38 (52.8%)

35 (48.6%)

47 (65.3%)

61 (84.7%)

2 (2.8%)

5 (6.9%)

6 (8.3%)

18 (25.0%)

10 (13.9%)

35 (48.6%)

28 (38.9%)

12 (16.7%)

8 (11.1%)

57 (79.2%)

27 (37.5%)

0.74

0.03

≤0.001

≤0.001 0.07

≤0.001

0.70

0.81

0.07

0.19

a Motorcycle accident (MCA)

Data are presented as frequency (%) and median (range).

3.3.2 Cause and mechanism

The majority of accidents were single vehicle accidents (n=119, 66.1%), in both on-road

(n=58, 53.7%) and off-road MCAs (n=61, 84.7%) (Table 3). The most common crash

mechanisms in on-road motorcyclists were collisions with other road users (n=43, 39.8%),

followed by losing control over the motorcycle (n=21, 19.4%) and hitting an object (n=17,

15.7%). Collisions with other road users mainly involved cars (n=37, 34.3%), another 9

(8.3%) accidents were caused in an attempt to evade a collision with another road user. The



most common reason for losing control over the motorcycle in this group were sliding out in

or overshooting a bend (n=12, 57.1%) and brakes locking up (n=6, 28.6%). Hit objects

involved mainly kerbs or road islands (n=10, 58.8%). Off-road MCAs were most frequently

caused by losing control over the motorcycle (n=28, 38.9%), followed by riding into an

unexpected drop or ditch (n=13, 18.1%) and hitting an object (n=11, 15.3%). Losing control

over the motorcycle in this group was mainly caused following a jump or wheel stand (n=10,

35.7%), sliding out in or overshooting a corner (n=9, 32.1%) and due to a bumpy or slippery

surface (n=8, 28.6%). Hit objects mainly included rocks (n=9, 81.8%).

Table 3 – Mechanism of injury by crash type.

Total

n=180 (100.0%)

On-road

n=108 (60.0%)

Off-road

n=72 (40.0%) P-value

Single vehicle Swerved to avoid road user

Lost control

While turning a corner

While performing a trick

Irregular surface/slid out

Brakes locked

Rode into a drop/ditch

Collision with object

Other/unspecified

119 (66.1%)

9 (5.0%)

49 (27.2%)

21 (42.9%)

11 (22.5%)

10 (20.4%)

7 (14.3%)

14 (7.8%)

28 (15.6%)

19 (10.6%)

58 (53.7%)

9 (8.3%)

21 (19.4%)

12 (57.1%)

1 (4.8%)

2 (9.5%)

6 (28.6%)

1 (0.9%)

17 (15.7%)

10 (9.3%)

61 (84.7%)

0

28 (38.9%)

9 (32.1%)

10 (35.7%)

8 (28.6%)

1 (3.6%)

13 (18.1%)

11 (15.3%)

9 (12.5%)

≤0.001

0.01

≤0.001

0.78

≤0.001

0.01

0.16

≤0.001

0.93

0.49

Multiple-vehicle

Collision with car

Collision with motorcycle

Other/unspecified

54 (30.0%)

41 (22.8%)

8 (4.4%)

5 (2.8%)

43 (39.8%)

37 (34.3%)

1 (0.9%)

5 (4.6%)

11 (15.3%)

4 (5.6%)

7 (9.7%)

0

≤0.001

≤0.001

0.01

0.06

Unknown 7 (3.9%) 7 (6.5%) 0 0.03

Other contributors

Speed

Substance use

Alcohol

Drugs

Weather

Road conditions

63 (35.0%)

46 (25.6%)

41 (22.8%)

7 (3.9%)

7 (3.9%)

55 (30.6%)

28 (25.9%)

25 (23.2%)

21 (19.4%)

5 (4.6%)

4 (3.7%)

18 (16.7%)

35 (48.6%)

21 (29.2%)

20 (27.8%)

2 (2.8%)

3 (4.2%)

37 (51.4%)

≤0.001

0.39

0.21

0.42

0.69

≤0.001

Data are presented as frequency with percent distribution.

When looking at other factors that had an influence in the occurrence of the crash, 63

(35.0%) patients indicated that speed was a contributor, regardless of riding above or below

the speed limit (for on-road motorcyclists) (Table 3). Forty-six (25.6%) patients admitted to

alcohol (n=41, 22.8%) or drug use (n=7, 3.9%) prior to the accident. Two (1.1%) patients

were under the influence of both alcohol and drugs. Ingested drugs included amphetamines,

cannabis and methadone. A small number of patients (n=7, 3.9%) stated that the weather was

a contributing factor in the accident, due to being hit by (a gust of) wind (n=4, 57.1%) or

being blinded by the sun (n=3, 42.9%). Road conditions were reported to be a contributing

factor in the crash in at least 55 (30.6%) patients. In 12 (6.7%) patients, a malfunction of the

motorcycle caused or contributed to the crash (e.g. damaged brake or accelerator cable, blown

tire).

Although the majority of MCAs were single vehicle accidents in both on-road and off-

road motorcyclists, on-road MCAs involved relatively more often other vehicles (p≤0.001)

(Table 3). However, while on-road motorcyclists were more likely to collide with a car



(p≤0.001), off-road motorcyclists were more likely to collide with another motorcycle

(p=0.01). Crash type had no significant influence on ISS (p=0.91) or RPH LOS (p=0.59),

although single vehicle accidents recorded a significantly longer stay in rehabilitation

facilities (single vehicle median LOS 20.0, range 4 – 73 days, multi vehicle median LOS 10.0,

range 6 – 45 days; p=0.03). Speed was more often a contributor in off-road motorcyclists than

in on-road motorcyclists (p=0.01), although overall the impact speed did not differ

significantly between on-road and off-road motorcyclists (on-road median 60.0, range 0 – 210

km/h versus off-road median 60.0, range 6 – 130 km/h; p=0.26). Alcohol and drug use prior

to the accident were statistically similar in on-road and off-road motorcyclists (p=0.39).

Compared with on-road MCAs, in off-road MCAs the road condition was more frequently of

influence (p≤0.001).

3.4 Injury profiles

3.4.1 Traumatic brain and neurological injuries

A total of 11 (6.3%) patients sustained a traumatic brain injury (TBI) (Table 4). TBI types

included subarachnoid bleeding (n=4, 36.4%), diffuse axonal injury (n=3, 27.3%) and intra

cerebral hemorrhage (n=2, 18.2%). TBI patients frequently sustained multiple TBI types.

Neurological injuries were relatively rare (n=3, 1.7%) and consisted of a brachial plexus

injury, unspecified canal compression and one paraplegia (off-road MCA).

Although a slightly higher proportion of on-road motorcyclists sustained TBIs (n=7,

6.7% versus n=4, 5.7%), this difference was not statistically significant (p=1.00) (Table 4).

When adjusting for possible confounders (age, gender, impact speed, crash type, protective

equipment), the incidence of TBI tended to be higher in on-road motorcyclists (p=0.09).

Speed was also shown to be a significant contributor to the incidence of TBI (regression

coefficient 0.02, OR 1.0, 95% CI 1.0 – 1.0; p≤0.001).

3.4.2 Internal injuries

A total of 49 (28.2%) patients sustained an injury to one or multiple internal organs, which

most frequently involved the thoracic region (n=37, 73.5%) (Table 4). The majority of

thoracic injuries involved pulmonary injuries (n=34, 94.4%), which mainly consisted of

(haemo)pneumothoraces (n=25, 73.5%). Abdominal injuries comprised 38.8% of all patients

with internal injuries and most commonly involved the spleen (n=7, 36.8%) and liver (n=6,

31.6%) (mostly lacerations). Vascular injuries were relatively rare (n=2, 4.1%) and involved a

laceration to the cubital fossa artery and a bilateral common iliac artery dissection. One

patient sustained a penetrating injury to the left thigh, which missed the femoral and deep

femoral artery only by a few centimeters (Figure 2).

The incidence of internal thoracic (p=1.00), abdominal (p=0.62) or any internal

injuries (p=0.73) was statistically similar between on-road and off-road motorcyclists (Table

4). When adjusting for possible confounders (age, gender, impact speed, crash type, protective

equipment), still no differences were found between both groups (p=0.96, 0.52 and 0.34

respectively).

3.4.3 Fractures

Fractures were the second most common type of injuries, with 138 (79.3%) patients

sustaining one or more fractures (Table 4). Fractures mainly involved the thoracic region

(n=56, 32.2%), followed by the lower (n=48, 26.6%) and upper extremity (n=37, 21.3%) and


Table 4 – Injury profiles of on-road and off-road motorcyclists.

Total n=174 (100.0%)

On-road n=104 (59.8%)

Off-road n=70 (40.2%)

P-value

Traumatic Brain Injuries (TBI)a 11 (6.3%) 7 (6.7%) 4 (5.7%) 1.00

Spinal cord or nerve injuries 3 (1.7%) 2 (1.9%) 1 (1.4%) 1.00

Internal injuries Thoracic

Cardiac

Pulmonary

Abdominal

Hepatic

Splenic

Pancreatic

Intestinal

Kidney/urinary tract

Vascular

49 (28.2%)

36 (73.5%)

3 (8.3%)

34 (94.4%)

19 (38.8%)

6 (31.6%)

7 (36.8%)

1 (5.3%)

3 (15.8%)

7 (36.8%)

2 (4.1%)

28 (26.9%)

22 (78.6%)

1 (4.6%)

21 (95.5%)

10 (35.7%)

4 (40.0%%)

4 (40.0%%)

0

3 (30.0%)

2 (20.0%)

2 (7.1%)

21 (30.0%)

14 (66.7%)

2 (14.3%)

13 (92.9%)

9 (42.9%)

2 (22.2%)

3 (33.3%)

1 (11.1%)

0

5 (55.6%)

0

0.73

1.00

0.57

0.85

0.62

1.00

1.00

0.40

0.27

0.12

0.51

Fractures

Head

Skull and facial

Spine

Cervical

Thoracic

Lumbar

Thoracic

Clavicular

Scapular

Ribs

Upper extremity

Humerus

Radius/ulna

(Meta-) carpals/phalanges

Pelvic

Lower extremity

Femur

Tibia/fibula

(Meta-) tarsals/phalanges

138 (79.3%)

13 (9.4%)

35 (25.4%)

7 (20.0%)

19 (13.8%)

17 (12.3%)

56 (32.2%)

22 (39.3%)

17 (30.4%)

39 (69.6%)

37 (21.3%)

6 (16.2%)

20 (54.1%)

20 (54.1%)

23 (16.7%)

48 (27.6%)

16 (33.3%)

25 (52.1%)

17 (35.4%)

80 (76.9%)

6 (7.5%)

18 (17.3%)

5 (27.8%)

8 (44.4%)

10 (55.6%)

35 (33.7%)

12 (34.3%)

10 (28.6%)

25 (71.4%)

27 (26.0%)

5 (18.5%)

14 (51.9%)

15 (55.6%)

12 (15.0%)

32 (30.8%)

11 (34.4%)

15 (46.9%)

12 (37.5%)

58 (82.9%)

7 (12.1%)

17 (24.3%)

2 (11.8%)

11 (64.7%)

7 (41.2%)

21 (33.0%)

12 (57.1%)

7 (33.3%)

14 (66.7%)

10 (14.3%)

1 (10.0%)

6 (60.0%)

5 (50.0%)

11 (19.0%)

16 (22.9%)

5 (31.3%)

10 (62.5%)

5 (31.3%)

0.45

0.38

0.34

0.70

0.12

1.00

0.74

0.65

1.00

0.58

0.09

0.40

0.47

0.16

0.50

0.30

0.60

1.00

0.44

Soft tissue injuriesb

Ligament injuries

Degloving injuries

145 (83.3%)

6 (4.1%)

3 (2.1%)

93 (89.4%)

2 (2.2%)

2 (2.2%)

52 (74.3%)

4 (7.7%)

1 (1.9%)

0.01 0.22

1.00

a Excluding mild TBI (i.e. concussions) due to the inconsistent recording of this type of injury.

b Including abrasions, burns, hematomas and lacerations

Data presented as frequency with percent distribution. Specific injuries were presented as proportion of the total

number of injuries in that category, due to patients sustaining multiple injuries frequencies do not add up.



spine (n=35, 20.1%). Pelvic and skull or facial fractures were slightly less common (n=23,

13.2% and n=13, 7.5% respectively). Thoracic fractures mainly involved rib fractures (n=39,

69.6%), followed by clavicular fractures (n=22, 39.3%). A slightly smaller proportion of

patients sustained a scapular fracture (n=17, 30.4%). Lower extremity fractures mainly

involved a tibial or fibular fracture (n=25, 52.1%). Upper extremity fractures most frequently

involved radial/ulnar and (meta)carpal fractures (both n=20, 54.1%). Spinal fractures mainly

involved fractures of the thoracic (n=19, 54.3%) and lumbar spine (n=17, 48.6%). A smaller

proportion involved cervical spine fractures (n=7, 20.0%). Additionally, 3 (1.7%) patients

sustained amputations (all on-road), which involved a traumatic amputation of a phalanx

(Figure 3), a traumatic amputation of the leg and an open tibial/fibial fracture combined with

a degloving injury which required surgical amputation of the lower leg.

No significant differences were observed in the occurrence of fractures between on-

road and off-road motorcyclists, although there was a tendency for on-road motorcyclists to

sustain more upper extremity fractures (p=0.09) (Table 4). When adjusting for possible

confounders (age, gender, impact speed, crash type, protective equipment), no differences

between both groups were found with respect to skull or facial fractures (p=0.32), spinal

fractures (p=0.26), thoracic fractures (p=0.29), upper extremity (p=0.13) or lower extremity

fractures (p=0.23). The incidence of upper extremity fractures was higher in multi vehicle

accidents (regression coefficient 1.1, OR 3.1, 95% CI 1.4 – 6.8; p=0.01) and was related to

impact speed, although not statistically significantly (p=0.06).

3.3.4 Soft tissue injuries

Soft tissue injuries (including abrasions, (full thickness) burns, lacerations and hematomas)

were the most common type of injury with 145 (83.3%) patients sustaining one or multiple

soft tissue injuries in at least one body region (Table 4). Most of these injuries were caused by

friction of the skin against the impact surface. A small proportion of accidents was caused by

other mechanisms such as penetrating injuries (Figure 4). The body regions that most

commonly sustained soft tissue injuries were the legs (n=107, 73.8%) and thorax, abdomen or

back (n=104, 71.7%), followed by the hands and wrists (n=59, 40.7%), the head and neck

(n=46, 31.7%) and feet and ankles (n=35, 24.1%). Ligament and degloving injuries occurred

relatively infrequent (n=6, 3.4% and n=3, 1.7% respectively).

Compared to on-road motorcyclists, a lower incidence of soft tissue injuries to any

body region (p≤0.001) was seen in off-road motorcyclists (Table 4). When adjusting for

possible confounders (age, gender, impact speed, crash type, protective equipment), the

incidence of soft tissue injuries to any body region were statistically similar between on-road

and off-road motorcyclists (p=0.24). The occurrence of soft tissue injuries was related to

speed (regression coefficient 0.03, OR 1.0, 95% CI 1.0 – 1.0) and multi vehicle accidents

(regression coefficient 2.0, OR 7.0, 95% CI 1.5 – 33.1).

3.4 Motorcycle clothing

3.4.1 Frequency of use

Overall, only a minority of patients wore full protective equipment at the time of the accident

(n=24, 13.3%) and even less patients had body armour imbedded in all parts of clothing

(n=18, 10.0% of total) (Table 5). Helmets were the most common type of motorcycle clothing

worn (n=156, 86.7%), followed by gloves (n=90, 50.0%), jackets or impact protectors (n=67,

37.2%), boots (n=65, 36.1%) and pants (n=51, 28.3%). A considerable proportion of patients

owned, but did not wear (parts of) motorcycle clothing at the time of the accident (full


Figure 2 – A near-miss: this multi vehicle accident

(on-road) resulted in the motorbike’s handlebar

penetrating the left thigh, barely missing the

femoral and deep femoral artery. From left to right:

A. the handlebar entered the left medial thigh in

anterior-posterior direction and is penetrating the

skin and quadriceps muscle. B. the entry wound

after extraction of the handlebar. C. the wound

after debridement. Visible are the left femoral and

deep femoral artery which was missed a few

centimetres. D. a vacuum dressing was applied,

with negative pressure on the wound surface to

promote healing. The wound was closed by a few

days later . E. the handlebar after extraction from

the wound.

Figure 3 – Anterior-posterior (AP) and lateral view

of the left hand following a motorcycle versus car

(on-road) at 80 km/h. The x-ray clearly shows a

traumatic amputation of the left thumb. An avulsion

fracture of the left ulnar styloid process can also be

seen.

Figure 4 – this patient lost control over his dirt

bike after hitting a rock and subsequently swerved

into a bush, impaling his right hip on a branch

equipment n=3, 1.7%; jacket/impact protector n=45, 25.0%; pants n=30, 16.7%; boots n=26,

14.4% and gloves n=40, 22.2%).

When comparing any motorcycle clothing (with and without body armour) worn

between on-road and off-road motorcyclists, off-road motorcyclists wore full equipment

(p=0.02), pants (≤0.001) and boots (≤0.001) significantly more often than on-road

motorcyclists did (Table 5). Only 7 (6.5%) on-road and 11 (15.3%) off-road motorcyclists

wore full equipment with body armour embedded in all parts. Controversially, off-road

motorcyclists less frequently wore helmets (off-road n=56, 77.8% versus on-road n=100,

92.6%; p=0.01). The use of any jackets/impact protectors and any gloves was similar in both

groups (p=0.27 and 0.65 respectively). There were relatively more off-road motorcyclists that

owned, but did not wear full equipment (any) or a helmet, but neither of these differences

were statistically significant (p=0.06 and 0.07 respectively). On-road motorcyclists owned,

but did not wear gloves significantly more often than did off-road motorcyclists (p≤0.001),

although off-road motorcyclists tended to own, but not wear gloves with body armour more

frequently (p=0.09). The main reasons for patients not wearing motorcycle clothing that they

owned were: too much effort to put it on or only going for a short ride (n=40, 44.0%), too hot

(n=18, 19.9%), inconvenient (n=8, 8.8%), did not expect to ride (n=6, 6.6%), lost/lend out



(n=3, 3.3%) or other/unspecified (n=15, 16.5%). Fifty-five (30.6%) patients expressed a

regret not to have worn more motorcycle clothing (on-road n=33, 30.6% versus off-road

n=22, 30.6%; p=1.00).

Additional protection that was worn exclusively by off-road motorcyclists included

neck braces (n=8, 11.1%) and knee pads or shin guards (n=15, 20.8%) (Table 5). A small

number of patients owned, but did not wear a neck brace (n=4, 5.6%) or knee pads/shin

guards (n=7, 9.7%) at the time of the accident. Kidney belts were mostly worn by off-road

motorcyclists (off-road n=9, 12.5% versus on-road n=1, 0.9%; p=0.05), although statistically

similar proportion of patients owned, but did not wear a kidney belt (on-road n=5, 4.6%

versus off-road n=5, 6.9%; p=0.52).

3.4.2 Effectiveness in preventing injuries

Full equipment

When adjusting for possible confounders (age, gender, impact speed, crash type), patients not

wearing full equipment did not sustain significantly more internal injuries than did patients

that were wearing full equipment with full or partial body armour (p=0.38), but tended to

sustain less fractures (p=0.06) and soft tissue injuries (p=0.08) in any body region (Table 6).

Helmets

Patients that did not wear a helmet were more at risk of TBI (regression coefficient 2.4, OR

11.3, 95% CI 1.9 – 69.3; p=0.04), facial or skull fractures (regression coefficient 1.9, OR 6.4,

95% CI 1.8 – 22.6; p=0.01) and facial soft tissue injuries (regression coefficient 1.3, OR 3.6

1.2 – 11.2; p=0.03) compared with those that did wear a helmet (Table 6).

Jackets/impact protectors

Jackets without body armour were not shown to be protective against thoracic and abdominal

internal injuries (p=0.46), thoracic fractures (p=0.28) or soft tissue injuries in that body area

(including the back and arms) (p=0.53) (Table 6). Although jackets and impact protectors

with body armour were also not protective against thoracic and abdominal internal injuries

(p=0.74) or thoracic fractures (p=0.48), they were protective against soft tissue injuries in that

body region (regression coefficient 1.5, OR 4.3, 95% CI 2.0 – 9.1; p≤0.001).

Pants

Pants without body armour were not shown to be protective against lower extremity fractures

(femoral, tibial or fibular) (p=0.22) or soft tissue injuries in that body region (p=0.61) (Table

6). Pants with body armour were shown to be protective against soft tissue injuries of the

lower extremity (regression coefficient 1.2, OR 3.2, 95% CI 1.4 – 7.5; p=0.01), but also did

not protect against lower extremity fractures (p=0.22).

Boots

Although boots were not shown to protect against lower extremity fractures (tibial, fibial or

and (meta-)tarsal) (p=0.65), they did protect against soft tissue injuries of the ankle and feet

(regression coefficient 2.7, OR 14.9, 95% CI 3.1 – 70.9; p≤0.001) (Table 6).

Gloves

Gloves without body armour were not shown to protect against (meta-)carpal and phalangeal

fractures (p=0.55), nor protected against soft tissue injuries of the hands (p=0.10) (Table 6).

Further, gloves with body armour were also not found to protect against fractures (p=0.10) or

soft tissue injuries (p=0.10). Speed was identified as a risk factor for both (meta-)carpal and


Table 5 – Frequency of motorcycle clothing that was worn and not worn in on-road and off-road motorcyclists.

Total (n=180, 100%) Worn Not worn

On-road (n=108, 60.0%) Worn Not worn

Off-road (n=72, 40.0%) Worn Not worn

P-value

Worn Not worn

Full equipment (any)

With full BA

Helmet

Jacket/impact protector (any)

With BA

Pants (any)

With BA

Boots

Gloves (any)

With BA

24 (13.3%) 3 (1.7%)

18 (75.0%) 2 (66.7%)

156 (86.7%) 16 (8.9%)

67 (37.2%) 45 (25.0%)

59 (88.1%) 38 (84.4%)

51 (28.3%) 30 (16.7%)

41 (80.4%) 24 (80.0%)

65 (36.1%) 26 (14.4%)

90 (50.0%) 40 (22.2%)

69 (76.7%) 28 (70.0%)

9 (8.3%) 0

7 (77.8%) 0

100 (92.6%) 6 (5.6%)

44 (40.7%) 32 (29.6%)

36 (81.8%) 26 (81.3%)

15 (13.9%) 20 (18.5%

14 (93.3%) 15 (75.0%)

25 (23.1%) 15 (13.9%)

52 (48.1%) 32 (29.6%)

41 (78.9%) 21 (65.6%)

15 (20.8%) 3 (4.2%)

11 (73.3%) 2 (66.7%)

56 (77.8%) 10 (13.9%)

23 (31.9%) 13 (18.1%)

23 (100.0%) 12 (92.3%)

36 (50.0%) 10 (13.9%)

27 (75.0%) 9 (90.0%)

40 (55.6%) 11 (15.3%)

38 (52.8%) 8 (11.1%)

28 (73.7%) 7 (87.5%)

0.02 0.06

0.07 0.16

0.01 0.07

0.27 0.08

0.87 0.27

≤0.001 0.54

≤0.001 0.83

≤0.001 0.83

0.65 ≤0.001

0.75 0.09

Data are presented as frequency with percent distribution. With and without body armour distributions are presented as proportion of any protective equipment of that type.

Table 6 – Risk of not wearing any motorcycle clothing compared to wearing motorcycle clothing with or without body armour (BA, reference) in sustaining internal injuries,

fractures and soft tissue injuries in the corresponding body region, adjusting for possible confounders (age, gender, impact speed and crash type).

Protection worn (reference) Regression

coefficient

Internal injuries

Adj. OR (95% CI)

P-value Regression

coefficient

Fractures

Adj. OR (95% CI) P-value Regression

coefficient

Soft tissue injuries Adj. OR (95% CI)

P-value

Full equipment without BA or partial

Full equipment with BA

Helmet

Jacket without BA

Jacket with BA or impact protector

Pants without BA

Pants with BA

Boots

Gloves without BA

Gloves with BA

n/s

n/s

2.4

n/s

n/s

-

-

-

-

-

n/s

n/s

11.3 (1.9 – 69.3)

n/s

n/s

-

-

-

-

-

0.38

0.38

0.01

0.46

0.74

-

-

-

-

-

n/s

n/s

1.9

n/s

n/s

n/s

n/s

n/s

n/s

n/s

n/s

n/s

6.4 (1.8 – 22.6)

n/s

n/s

n/s

n/s

n/s

n/s

n/s

0.06

0.06

≤0.001

0.28

0.48

0.22

0.22

0.06

0.55

0.10

n/s

n/s

1.3

n/s

1.5

n/s

1.2

2.7

n/s

n/s

n/s

n/s

3.6 (1.2 – 11.2)

n/s

4.3 (2.0 – 9.1)

n/s

3.2 (1.4 – 7.5)

14.9 (3.1 – 70.9)

n/s

n/s

0.08

0.08

0.03 0.53

≤0.001 0.61

0.01

≤0.001 0.10

0.10

Data are presented as regression coefficient and odds ratio (OR) with 95% confidence interval (CI), comparing wearing protective equipment (reference) with wearing no

protection.


phalangeal fractures (regression coefficient 0.02, OR 1.0, 95% CI 1.0 – 1.0; p=0.01) and soft

tissue injuries of the hands (regression coefficient 0.01, OR 1.0, (95% CI 1.0 – 1.0; p=0.03).

Although multi vehicle accidents were shown to be a risk factor for soft tissue injuries

(regression coefficient 0.01, OR 3.7, 95% CI 1.8 – 7.8; p≤0.001), crash type was not of

statistical significant influence for fractures (p=0.11).

3.5 Outcomes three months after the accident

3.5.1 Demographics

Eighty-seven (48.3%) of the total of 180 included patients that reached 3 months after the

accident within the study period completed the follow-up interview. Of these, 51 (58.6%)

accidents occurred on-road and 36 (41.4%) accidents occurred off-road. Patients were

predominantly male (n=76, 87.4%) with ages ranging from 14 to 68 years (median 30.0

years). Most patients were single (n=38, 43.7%), followed by married (n=23, 26.4%), defacto

(n=18, 20.7%) or divorced or separated (n=8, 9.2%).

Although off-road motorcyclists tended to be younger, this difference was not

significant (off-road median 27.5, range 14 – 53 years versus on-road median 34.0, range 14 –

68 years; p=0.064). Injury severity was not significantly different between on-road and off-

road motorcyclists (on-road median ISS 9.00, range 1 – 38 versus off-road median ISS 9.50,

range 1 – 29; p=0.597). Impact speed was statistically similar between both groups (p=0.74).

3.5.2 Physical health

Overall, 66 (75.9%) patients reported to be in good to excellent general health three months

after the accident, although 58 (66.7%) patients indicated to be in a worse condition compared

to the situation prior to the accident (Table 7a). Twenty-two (25.3%) patients indicated no

health change and in 7 (8.0%) patients health was even improved, because they felt stronger

or fitter due to increased exercise (n=2, 28.6%), losing weight (n=2, 28.6%), getting life back

on track (n=2, 28.6%) or stopped smoking (n=1, 14.3%). Most patients still experienced

problems during daily activities (n=55, 63.2%), mostly minor in nature (n=47, 85.5%). A

minority of patients experienced many problems (n=8, 14.6%). Pain or discomfort during rest

or activities was reported in 63 (72.4%) patients. Increased fatigue compared to the situation

prior to the accidents was reported in 35 (40.2%) patients, mostly throughout the day (n=20,

57.1%) or after light or heavy activities (n=15, 42.9%). Thirty-nine (44.8%) patients reported

to have (almost) completely recovered, 25 (28.7%) to have recovered for a great part and 23

(26.4%) patients felt they had only recovered a bit or not recovered at all.

Compared with on-road motorcyclists, off-road motorcyclists generally reported to be

in better general health (p=0.02), reported better health compared to the situation prior to the

accident (p=0.05), reported less often problems with daily activities (p≤0.001) and reported

overall a better recovery (p≤0.001) (Table 7a). Off-road motorcyclists also tended to report

pain less frequently and reported less frequently an increase in fatigue, although these

difference did not reach statistical significance (p=0.06 and 0.08 respectively). When

adjusting for possible confounders (age, gender, impact speed, crash type and ISS), on-road

motorcyclists still showed a higher risk of reporting daily problems (regression coefficient

1.9, OR 6.6, 95% CI 1.9 – 14.5; p≤0.001) (Table 7b). ISS also was a risk factor for daily

problems (regression coefficient 0.1, OR 1.1, 95% CI 1.0 – 1.3; p=0.02). Speed tended to be a

risk factor for daily problems, but this did not reach statistical significance (p=0.09). Reported

pain was not significantly different between on-road and off-road motorcyclists after adjusting

(p=0.35), but was related to age (regression coefficient 0.1, OR 1.1, 95% CI 1.0 – 1.1;



p=0.01) and ISS (regression coefficient 0.1, OR 1.1, 95% CI 1.0 – 1.3; p=0.03). Patients

involved in multi vehicle accidents reported pain more frequently (regression coefficient 1.5,

OR 4.7, 95% CI 1.1 – 19.9; p=0.04). Risk factors for increased fatigue were multi vehicle

accidents (regression coefficient 1.8, OR 5.9, 95% CI 2.0 – 17.2; p≤0.001) and still tended to

occur more frequently in on-road motorcyclists after adjusting, although this difference did

not reach statistical significance (p=0.06). Increased fatigue tended to occur more frequently

in patients with a higher ISS, but this difference did not reach statistical significance (0.06).

After adjusting, reported recovery still tended to be better in off-road motorcyclists, although

not statistically significantly (p=0.09). Soft tissue injuries, the only injury category that

occurred statistically significantly more frequently in on-road motorcyclists, did not occur

more frequently in patients that more frequently reported worse general health (p=0.10),

worse health compared to the situation before the accident (p=0.95), problems with daily

activities (p=0.58), pain (p=0.76) or worse recovery (p=0.89).

Table 7a – Physical outcomes three months after the accident

Total

n=87 (100%)

On-road

n=51 (58.6%)

Off-road

n=36 (41.4%) P-value

General health

Very poor – fair

Good – excellent

Compared with

health before

accident Worse

Unchanged

Improved

Daily problems

Paina

Increased fatigue All the time

During activities

Recovered Not at all or a bit

For a great part or

(Almost) completely

21 (24.1%)

66 (75.9%)

58 (66.7%)

22 (25.3%)

7 (8.0%)

55 (63.2%)

63 (72.4%)

35 (40.2%)

20 (57.1%)

15 (42.9%)

23 (26.4%)

25 (28.7%)

39 (44.8%)

17 (33.3%)

34 (66.7%)

38 (74.5%)

8 (15.7%)

5 (9.8%)

40 (78.4%)

41 (80.4%)

25 (49.0%)

15 (60.0%)

10 (40.0%)

18 (35.3%)

19 (37.3%)

14 (27.5%)

4 (11.1%)

17 (47.2%)

20 (55.6%)

14 (38.9%)

2 (5.6%)

15 (41.7%)

22 (61.1%)

10 (27.8%)

5 (50.0%)

5 (50.0%)

5 (13.9%)

6 (16.7%)

25 (69.4%)

0.02

0.05

≤0.001 0.06

0.08

0.12

≤0.001

a in rest or during activities.

Data are presented as proportion with percent distribution.

Table 7b – Physical outcomes three months after the accident between on-road and off-road

motorcyclists (reference), adjusted for possible confounders (age, gender, impact speed,

crash type and ISS).

Present/absent

Regression

coefficient

Adj. OR (95% CI) P-value

Daily problems

Pain

Increased fatigue

Recovereda

1.9

n/s

n/s

n/s

6.6 (1.9 – 14.5)

n/s

n/s

n/s

≤0.001

0.35

0.06

0.09

a not at all or a bit (reference) or for a great part/ (almost) completely

Data are presented as regression coefficient and odds ratio (OR) with 95% confidence

interval (95% CI), comparing on-road motorcyclists with off-road motorcyclists (reference).



3.5.3 Emotional health

Overall, 63 (72.4%) patients reported to be in good to excellent emotional health three months

after the accident (Table 8a). Forty-six (52.9%) patients still experienced emotional feelings

about the accident, 25 (28.7%) still felt very emotional. This was mainly due to the

consequences of the accident and included frustration, anger or sadness about physical

limitations and stress or sadness due to financial consequences. Fifty-five (63.2%) patients

still thought a lot about the accident and 17 (19.5%) patients experienced flashbacks (n=13,

14.9%) or nightmares (n=4, 4.6%) at some point following the accident.

Although the number of off-road motorcyclists that still thought about the accident

was statistically similar to the number of on-road motorcyclists (p=0.26), on-road

motorcyclists were more likely to still experience emotional feelings about the accident

p=0.01) (Table 8a). The occurrences of nightmares or flashbacks were statistically similar in

both groups (0.11). When adjusting for possible confounders (age, gender, impact speed,

crash type and ISS), no differences were found between on-road and off-road motorcyclists

for thinking about the accident (p=0.14) (Table 8b). Still feeling emotional about the accident

remained occurring significantly more often in on-road motorcyclists after adjusting

(regression coefficient 1.3, OR 3.7, 95% CI 1.3 – 10.0; p=0.01) and was also related to ISS

(regression coefficient 0.1, OR 1.1, 95% CI 1.0 – 1.2; p=0.01). Patients involved in multi

vehicle accidents also tended to feel emotional about the accident more frequently after

adjusting, but this difference did not reach statistical significance (p=0.07). While nightmares

or flashbacks tended to occur more frequently in on-road motorcyclists as well after adjusting,

this difference did not reach statistical significance (p=0.06). Nightmares of flashbacks were

reported more frequently in younger patients (regression coefficient -0.1, OR 0.9, 95% CI 0.9

– 1.0; p=0.04).

Table 8a – Emotional outcomes three months after the accident.

Total

n=87 (100%)

On-road

n=51 (58.6%)

Off-road

n=36 (41.4%) P-value

General emotional health

Very poor – fair

Good – excellent

Think about accident

Emotional about accident a bit emotional

very emotional

Nightmares or flashbacksa

24 (27.6%)

63 (72.4%)

55 (63.2%)

46 (52.9%)

21 (45.7%)

25 (54.3%)

17 (19.5%)

18 (35.3%)

33 (64.7%)

35 (68.6%)

34 (66.7%)

16 (47.1%)

18 (52.9%)

13 (25.5%)

6 (16.7%)

30 (83.3%)

20 (55.6%)

12 (33.3%)

5 (41.7%)

7 (58.3%)

4 (11.1%)

0.09

0.26

≤0.001

0.01

0.11

a at any point during or after admission

Data are presented as frequency with percent distribution.

Table 8b – Emotional outcomes three months after the accident between on-road and off-road motorcyclists

(reference), adjusted for possible confounders (age, gender, impact speed, crash type and ISS).

Present/absent

Regression

coefficient

Adj. OR (95% CI) P-value

Think about the accident

Emotional about the accident

Nightmares or flashbacks

n/s

1.3

n/s

n/s

3.7 (1.3 – 10.0)

n/s

0.14

0.01

0.06

Data are presented as regression coefficient and odds ratio (OR) with 95% confidence interval

(95% CI), comparing on-road motorcyclists with off-road motorcyclists (reference).



3.5.4 Return to work and financial loss

A total of 75 (86.2%) patients were employed prior to the accident and had recorded a total of

677 weeks of absence until three months after the accidents. Of these, thirty-five (46.7%)

patients were unable to return to full or partial employment within three months after the

accident. Most employed patients lost income (n=53, 70.7%), with most patients losing more

than 2000 AUD per month (<500 AUD n=2, 2.7%; 500-1000 AUD n=2, 2.7%; 1000-2000

n=12, 16.0%; >2000 n=36, 48.0%). Multiple patients lost over 10.000 AUD per month.

Return to work was similar between on-road and off-road motorcyclists (on-road

n=25, 49.0% versus off-road n=15, 41.7%; p=0.65), as was lost income (p=0.58). Return to

work was associated with ISS (returned median ISS 5.00 (1 – 29) versus not returned median

ISS 11.0 (1 – 38); p≤0.001).



4. Discussion

The primary objective of this study was to investigate the differences between on-road and

off-road MCAs with respect to injury severity, injury profiles, and the impact on perceived

health status three months after the accident. The aim was to increase awareness on the

gravity of off-road motorcycle trauma and to provide suggestions towards trauma prevention

in this group of patients.

4.1 Rider characteristics, accident cause and mechanism

Although the primary aim was not to compare on-road and off-road MCAs with respect to

cause, mechanism or risk factors, some interesting differences were found. A considerable

proportion of off-road motorcyclists rode on someone else’s motorcycle in the present study

(22.2%) which was significantly more often than on-road motorcyclists. Further, 40.0% of all

patients that had an accident on their own motorcycle had ridden this specific motorcycle for

less than a year. Only 6.3% of all motorcyclists had been riding motorcycles for less than a

year. Although no conclusions on risk factors for having an accident can be drawn from the

present study due to the absence of motorcyclists that did not have an accident, this may

suggest that unfamiliarity with the motorcycle may be a risk factor for having an accident,

which would be in keeping with previous literature [50].

While similar proportions of off-road MCAs were single vehicle accidents, the

proportion of single vehicle MCAs in on-road accidents was considerably higher than

previously reported by Cassell et al. (39.8% versus 53.7% in the present study) [16]. The

observed difference may be explained by the fact that 26.8% of accidents in their study were

unspecified (versus 3.9% in the present study). Although off-road motorcyclists still more

often involved single vehicle accidents than on-road motorcyclists, they were more likely to

collide with other motorcyclists, a finding that is supported by Cassell et al. [16].

Losing control in a corner, which has previously been identified as a risk factor for

MCAs [22], also caused a considerable number of on-road and off-road MCAs in the current

study (11.7%), often in combination with speed. Road conditions in general were much more

often an accident contributor in off-road motorcyclists than in on-road motorcyclists, as may

be expected due to the differences in terrain. However, an alarming proportion of off-road

accidents were caused by riding into an unexpected drop or ditch, which stresses the

importance of knowledge about the terrain in which in is ridden. Rider education through

general campaigns or local motorcycling clubs may be an effective way of achieving this.

When looking at preventable causes or contributors to the accident, an alarming

proportion of patients (25.6%) were found to have consumed alcohol or drugs prior to the

accident. Although comparison is difficult because of differences in definitions, other studies

also found intoxication to be of influence to the crash in a considerable number of accidents.

Cunningham et al. found that 6% of all accidents in their study were solely caused by alcohol

or drug intoxication and Steinhardt et al. reported that up to 53% and 40% of off-road and on-

road motorcyclists respectively had used alcohol 24 hours before the accident [6,39].

Although Steinhardt et al. found illicit drug use to be higher in off-road motorcyclists, the

results from the present study did not show a significant difference between both groups. With

the true number of accidents influenced by substance use probably lying somewhere in the

middle, it remains a completely preventable cause of a considerable number of accidents and

should remain an important focus for injury prevention in both on-road and off-road

motorcyclists. Another important finding was the higher contribution of speed in off-road

MCAs (off-road 48.6% versus on-road 25.9%). Although it has been suggested that off-road



motorcyclists usually ride at lower speeds [16,42], the present study did not find significant

differences in impact speed between both groups. This is surprising, given the fact that off-

road motorcyclists usually ride in much rougher terrain and it is more difficult to stay in

control at high speeds in such conditions. This suggest that misappropriate speeds for the

condition in which in is ridden is a bigger factor off-road than it is on-road and may be related

to risk-taking behaviour, which has been found to occur more frequently in younger people

[12]. Indeed, off-road motorcyclists were found to be younger than on-road motorcyclists in

the present study, which is consistent with earlier findings [13,16,42]. Although

misappropriate speed for conditions in which in is ridden has been related to a higher risk of

multiple vehicle collisions [12], this effect has not been reported previously in off-road

motorcyclists. Another completely preventable cause were motorcycle malfunctions, which

contributed to or caused 6.7% of all accidents.

A considerable proportion of patients had been involved in previous MCAs (71.1%)

and many had been hospitalized before due to a MCA before (31.7%). Because the present

study did not differentiate between the location where the previous accidents had occurred,

some on-road motorcyclists also rode an off-road motorcycle (and vice versa) and some

accidents occurred during racing, conclusions on the risk for off-road motorcyclists to crash

compared to on-road motorcyclists could not be drawn. Nonetheless, off-road motorcyclists

still tended to have been involved in an accident before more frequently than on-road

motorcyclists. Although no difference in previous hospitalization was found between both

groups, Meuleners et al. found that off-road motorcyclists have a higher risk of hospitalization

compared to on-road motorcyclists in patients presenting to the ED [33]. In contrast, Grange

et al. found no differences in the proportion of patients that were admitted between both

groups [42]. With accurate data on the number of off-road motorcyclists that have an accident

in relation to the exposure and distance travelled being absent, the relative accident rate

between on-road and off-road motorcyclists remains unclear.

4.2 Injury severity and injury profiles

Most importantly, no significant differences between on-road and off-road motorcyclists were

found in terms of ISS, hospital length of stay (including ICU and rehabilitation facilities) or

discharge location. These results contradict the findings from Cassell et al. and Mikocka-

Walus et al., who both found a shorter hospital length of stay in off-road motorcyclists

[13,16]. Further, Mikocka-Walus et al. found that off-road motorcyclists had a lower ISS, a

shorter ICU stay and were more likely to be discharged home, whereas on-road motorcyclists

were more likely to be discharged to a rehabilitation facility [13]. Although Grange et al. also

did not detect a significant difference in ISS between both groups, there was a tendency for

on-road motorcyclists to have a higher ISS. The observed differences with the present study

may reflect local differences and are likely unrelated to the fact that the patient population in

the present study tended to include more severely injured patients, as the study of Mikocka-

Walus et al. focused on major trauma patients.

Injury profiles were not statistically significantly different between on-road and off-

road motorcyclists with the exception of soft tissue injuries, which were overall the most

common type of injuries (83.3%). The higher incidence of soft tissue injuries in on-road

motorcyclists is consistent with the findings of Grange et al. and is likely to be related to the

higher proportion of off-road motorcyclists that wore motorcycle clothing. Indeed, when

adjusting for possible confounders (including motorcycle clothing), the difference between

both groups disappeared. Although all traumatic amputations occurred in on-road

motorcyclists, no statistically significant differences were found between on-road and off-road

motorcyclists due to the low incidence of this injury type. Similar incidences between both



groups have been reported by Cassell et al. [16]. Although also not statistically significant, the

incidence of TBIs tended to be higher in on-road motorcyclists after adjusting, despite the

higher proportion of off-road motorcyclists that did not wear a helmet, as did the incidence of

upper extremity fractures, which was shown to be related to multi vehicle accidents. Overall,

the incidence of TBI, nerve or spinal cord injuries was relatively low compared to other

studies [14,15,42], but was consistent with the findings of Cassell et al. [16]. Fractures were

the second most common injury with 79.3% of patients sustaining one or more fractures.

Thoracic fractures were the most common (32.2%), followed by lower extremity (27.6%),

spinal (25.4%) and upper extremity fractures (21.3%). Ankarath et al., who reported injury

profiles in a similar fashion, found similar incidences of internal injuries, although they

reported a higher incidence of fractures (94.3%) and a lower incidence of spinal fractures

(10.4% versus 25.4% in the present study) [15]. The present study also found a higher

proportion of cervical spine fractures compared with other studies (20.0% versus

approximately 10%) [14,15]. Although not entirely comparable due to the different

classification systems, Mikocka-Walus found similar injury profiles with thoracic injuries

being the most common, followed by lower extremity injuries [13]. However, they found that

on-road motorcyclists sustained upper extremity, lower extremity and head injuries

significantly more often than off-road motorcyclists [13]. As discussed, the present study also

found that on-road motorcyclists tended to sustain upper extremity fractures and TBIs more

frequently, although this difference did not reach statistical significance.

4.3 Motorcycle clothing

Due to relatively low incidences of certain injury categories, the protective effect of

motorcycle clothing was analyzed for on-road and off-road motorcyclists combined. Overall,

no protective effect of motorcycle clothing was shown in preventing internal injuries or

fractures, with the exception of helmets. Although the incidence of lower extremity fractures

was lower when boots were worn, this effect was not statistically significant. However, with

the exception of gloves, all motorcycle clothing with body armour imbedded in it was shown

to protect significantly against soft tissue injuries, whereas clothing without body armour had

no significant effect on the incidence of soft tissue injuries. These findings are largely

consistent with findings of de Rome et al., with the exception of gloves which were found to

protect in their study [41]. Although the present study did not separate between any soft tissue

injuries and open wounds, the results from this study also suggest an effect of motorcycling

clothing with or without body armour in preventing open wounds [41].

Despite the observed protective effect, only 13.3% of all patients wore full protective

equipment during the accident of which only 75.0% had body armour embedded in all parts of

the equipment. Off-road motorcyclists wore full protective equipment considerably more

often than did on-road motorcyclists (20.8% versus 8.3% of on-road motorcyclists), which

may be related to a general higher anticipation of having an accident in off-road

motorcyclists. Although most patients did not own full equipment, a considerable proportion

of patients owned, but did not wear (all) motorcycle clothing during the accident, for which

the main reasons were that it was too much effort to put on, they were only going for a short

ride or that it was too hot. Helmet use was considerably lower in off-road motorcyclists

(77.8% versus 92.6% in on-road motorcyclists), which supports earlier literature [26,39]. This

is concerning, especially considering that impact speed was found to be similar in on-road and

off-road motorcyclists, in contrast to what has been thought previously. Helmets have been

found to be less effective in preventing fatal head injuries at higher speeds [12], although this

may be due to differences in road characteristics [6]. Controversially, on-road motorcyclists

tended to sustain TBIs more often when adjusting for helmet use and speed.



4.4 Outcomes three months after the accident

Overall, many patients reported worse health than before the accident (66.7%), problems with

daily activities (63.2%) and pain (72.4%) and a considerable proportion of patients reported

no recovery or only to have recovered a bit (26.4%). Fatigue was also very common (40.2%

of patients) and most of these patients felt tired throughout the day (57.1%). Many patients

felt emotional about the accident (52.9%) and a considerable proportion of patients reported

inconvenience or distress by flashbacks or nightmares (19.5%). The financial burden for the

patient was high as well, with 70.7% of patients losing income, of which almost half (48.0%)

lost more than 2000 AUD each month. With approximately half (50.6%) of all patients that

were followed up being single or divorced/separated men, who are likely to be the sole

breadwinner in their household, the financial impact on patients was likely high. A substantial

proportion (46.7%) were not able to return to partial or full employment three months after

the accident and were therefore at risk of losing their job. Although employees can not be

dismissed due to temporary absence or illness under Australian law, after 3 months this right

expires [51]. Not only may this have a big influence on patient’s personal situation, it may

also be a financial burden to society in terms of unemployment benefits, which add up to the

societal costs for hospital admission and treatment. Further, earlier research has shown that

most long-term disability following MCAs involve problems with locomotion or dexterity at

work, which seems to be in keeping with the large proportion of patients reporting increase

fatigue. Earlier findings of de Rome et al. 2012, although limited to on-road MCAs, support

the findings that MCAs have a big influence on the patient. They reported that less than half

of all patients were riding pain free 6 months after the accident, that 8% reporting some

extend of disability and 13% still had not returned to the work role they occupied before the

accident [52]. They also found that patients that wore motorcycle clothing had a generally

better health outcome compared with patients that had not [52].

Although no differences between on-road and off-road motorcyclists were seen with

respect to return to work and lost income, off-road motorcyclists showed better physical and

emotional outcomes three months after the accident. This is surprising, when considering that

both groups sustained equally severe injuries and similar injury profiles were seen with the

exception of soft tissue injuries. When looking at motorcycle clothing, de Rome et al. showed

lower rates of hospitalization in patients wearing motorcycle clothing [41] and implied that

the potential reduction in soft tissue injuries may reduce complications such as opportunistic

infections, scarring and disability, which has been found to result in a high rate of impairment

[18,41]. Indeed, in a separate publication the same authors found better health outcomes in

protected patients [52]. Although soft tissue injuries in the present study were not related to

physical outcomes, it must be noted that these were not quantified or assessed based on

extend and severity and this might have influenced the results. Keeping this in mind, a lower

proportion of on-road motorcyclists wore motorcycle clothing, which may partly explain the

observed difference. Not only did on-road motorcyclists report worse physical health, they

also felt more frequently emotional (e.g. frustrated, sad) about the accident than did off-road

motorcyclists. As patients that were involved in a multi vehicle accidents were found to feel

emotional about the accident more frequently than patients involved in single vehicle

accidents, the observed difference may in part be explained by the person at fault in these

accidents. It has been found that collisions with cars at intersections are generally the fault of

the car driver [22], which may lead to patients feeling more often frustrated about the

situation than when the accident was caused by themselves or no one was at fault.



4.5 Recommendations

Although preventive campaigns have been successfully implemented for on-road

motorcyclists and have reduced the number of accidents in this group [13], similar campaigns

for off-road motorcyclists are generally lacking. This should change, considering the high

proportion of off-road motorcyclists that sustain serious trauma. Some important issues were

raised by the present study, including high proportions of patients with substance use prior to

the accident in both groups, the relatively big contribution of speed in off-road accidents and

the high incidence of off-road accidents due to riding into an unexpected drop or ditch. These

issues may be addressed by educating riders on the importance of knowledge of the terrain.

Other interventions to reduce trauma in off-road motorcyclists have been suggested, including

age restrictions, special licensing, skills and risk awareness courses and mentoring schemes

for novice riders [16]. Although the most effective way to reduce to morbidity and mortality

due to MCAs is to prevent accidents from happening, another important consideration is

altering the outcome. Motorcycle clothing has shown to reduce the incidence of soft tissue

injuries and may improve patient outcome and costs, especially in accidents of relatively low

severity [52]. Although off-road motorcyclists were shown to wear motorcycle clothing more

frequently than on-road motorcyclists, the majority of patients did not wear full protective

clothing and this remains an important issue to be addressed. Another important consideration

is the encouragement and enforcement of helmet use in off-road motorcyclists, as a

considerable proportion of off-road motorcyclists did not wear a helmet. Future research

should focus on formulating ways to effectively implement new injury prevention strategies

specifically targeted at off-road motorcyclists, in order to reduce the burden of trauma to both

patient and society in this specific group of riders.

4.6 Strengths and limitations

A strength of this study was the combined prospective cohort design and retrospective audit,

which allowed a very detailed collection of patient demographics, accident details and

outcome three months after the accident. Further, by collecting possible sensitive data from

two sources, the accuracy of the data was maximized. Nonetheless, several limitations must

be addressed. The most important limitation was the relatively small sample size, which may

have compromised the detection of statistically significant differences between on-road and

off-road motorcyclists for some variables. Previous studies comparing both groups generally

used larger sample sizes and the fact that no differences in injury severity were found may be

attributable to this. Therefore, the results of this study should be interpreted with some

caution. Another obvious limitation was the possible selection bias towards more severely

injured patients, as this study only included patients that were reviewed or admitted by the

trauma team. Lastly, despite the effort to maximize accuracy of the data, the data were subject

to the willingness of the patient to answer the questions. Although every effort was taken to

increase the accuracy of possible sensitive subjects such as substance, the data was limited by

the honesty of the patients and the limited availability of objective measures such as a routine

blood alcohol level. Nonetheless, this study provided some important insights into the

characteristics of accidents in both on-road and off-road motorcyclists and reported some

findings that have not been found previously.



4. Conclusion

The results from this study showed no significant differences in injury severity between on-

road and off-road motorcyclists in terms of ISS, hospital length of stay or discharge location.

Injury profiles were similar between both groups, with the exception of soft tissue injuries

which were higher in on-road motorcyclists. This higher incidence is likely related to the

lower rate of motorcycle clothing worn in this group. Although off-road motorcyclists

generally wore more protective equipment, a relatively low proportion of patients in both

groups wore full motorcycle equipment. Only motorcycle clothing with body armour was

shown to protect against soft tissue injuries and helmets were the only form of protection that

protected significantly against internal (traumatic brain) injuries and fractures. The effect of

motorcycle clothing on internal injuries has not previously been reported. This is the first

study to compare outcomes of on-road and off-road motorcyclists and showed that despite

similar injury severity and largely similar injury profiles, on-road motorcyclists reported

worse physical and emotional health outcomes three months after the accident. Nonetheless,

return to work was similar in on-road and off-road motorcyclists and was generally low with

nearly half of previously employed patients unable to return to partial or full employment

three months after the accident. The financial impact for patient and society are likely be

considerable. These findings emphasise the implications of off-road motorcycling trauma to

both patient and society and reinforce the need of taking action to reduce trauma in this

specific group of motorcyclists.

The present study highlighted important issues to be addressed in terms of both

primary and secondary prevention, including substance use, knowledge of the terrain,

speeding and the use of motorcycle clothing. Further research is needed to formulate ways to

effectively implement new injury prevention strategies specifically targeted at off-road

motorcyclists.



References

[1] World Health Organisation, International Classification of Diseases version 2010.

Definitions related to transport accidents.

(http://apps.who.int/classifications/apps/icd/icd10online2004/defs.htm)

[2] Federal Chamber of Automotive Industries (FCAI), National Sales Report 2012.

[3] Australian Bureau of Statistics. Motor vehicle census. 2013; 9309.0.

[4] Henley G, Harrison JE. Trends in serious injury due to land transport accidents, Australia

2000-01 to 2008-09. Injury and statistics series no. 66 2012; INJCAT 142. Canberra: AIHW.

[5] Johnston P, Brooks C, Savage H. Fatal and serious road crashes involving motorcyclists.

2008; Monograph 20.

[6] Cunningham G, Chenik D, Zellweger R. Factors influencing motorcycle crash victim

outcomes: a prospective study. ANZ J.Surg. 2012; 82 551-4.

[7] Henley G, Harrison G. Serious injury due to land transport, Australia 2008-09. 2012;

INJCAT 143. Canberra: AIHW.

[8] Bureau of Infrastructure, Transport and Regional Economics (BITRE). Road Deaths

Australia, 2012. Statistical Summary BITRE, Canberra ACT 2013.

[9] National Highway Traffic Safety Administration. Traffic Safety Facts 2005: Motorcycles.

National Highway Traffic Safety Administration 2007, Washington, DC.

[10] Department of Environment, Transport and the Regions. Tomorrow's Roads - Safer for

Everyone: The Government's Road Safety Strategy and Casualty Reduction Targets for

2010. London: Department of Environment, Transport and the Regions, 2000.

[11] European Co-operation in the Field of Scientific and Technical Research. European

Commission, Directorate Gerenal for Energy and Transport. Motorcycle Safety Helmets.

(ec.europa.eu/transport/roadsafety_library/.../cost327_final_report.pdf 2001; COST 327 final

report)

[12] Lin MR, Kraus JF. A review of risk factors and patterns of motorcycle injuries.

Accid.Anal.Prev. 2009; 41 710-22.

[13] Mikocka-Walus A, Gabbe B, Cameron P. Motorcycle-related major trauma: on-road

versus off-road incidence and profile of cases. Emerg.Med.Australas. 2010; 22 470-6.

[14] Forman JL, Lopez-Valdes FJ, Pollack K et al. Injuries among powered two-wheeler users

in eight European countries: a descriptive analysis of hospital discharge data.

Accid.Anal.Prev. 2012; 49 229-36.



[15] Ankarath S, Giannoudis PV, Barlow I, Bellamy MC, Matthews SJ, Smith RM. Injury

patterns associated with mortality following motorcycle crashes. Injury 2002; 33 473-7

[16] Cassell E, Clapperton A, O'Hare M, Congiu M. On- and off-road motorcycling injury in

Victoria. Hazard 2006; 64.

[17] Mathers C, Boerma T, Ma Fat D. The global burden of disease: 2004 update. Geneva,

Switzerland: World Health Organisation 2008, 160.

[18] Clarke JA, Langley JD, Disablement resulting from motorcycle crashes. Disabil.Rehabil.

1995; 17 377-85.

[19] Naumann RB, Dellinger AM, Zaloshnja E, Lawrence BA, Miller TR. Incidence and total

lifetime costs of motor vehicle-related fatal and nonfatal injury by road user type, United

States, 2005. Traffic Inj.Prev. 2010; 11 353-60.

[20] L. Blincoe, A. Seay, E. Zaloshnja, T. .Miller, E. Romano, S.Luchter, R.Spicer. National

Highway Traffic safety Administration. The Economic Impact of Motor Vehicle Crashes,

2000.

[21] Brown JB, Bankey PE, Gorczyca JT, Cheng JD, Stassen NA, Gestring ML. The aging

road warrior: national trend toward older riders impacts outcome after motorcycle injury.

Am.Surg. 2010; 76 279-86.

[22] Vlahogianni EI, Yannis G, Golias JC. Overview of critical risk factors in Power-Two-

Wheeler safety. Accid.Anal.Prev. 2012; 49 12-22.

[23] Harrison WA, Christie R. Exposure survey of motorcyclists in New South Wales.

Accid.Anal.Prev. 2005; 37 441-51.

[24] Tovell A, McKenna K, Bradey C, Pointer S. Hospital separations due to injury and

poisoning, Australia 2009–10. Injury research and statistics series no. 69. INJCAT 145.

Canberra: AIHW 2012.

[25] Soundappan SS, Holland A, Lam L et al. Off-road vehicle trauma in children: a New

South Wales perspective. Pediatr.Emerg.Care 2010; 26 909-13.

[26] Bevan CA, Babl FE, Bolt P, Sharwood LN. The increasing problem of motorcycle

injuries in children and adolescents. Med.J.Aust. 2008; 189 17-20.

[27] Ramakrishnaiah RH, Shah C, Parnell-Beasley D, Greenberg BS. Motorized dirt bike

injuries in children. J.Emerg.Med. 2013; 44 806-10.

[28] Clapperton AJ, Herde EL, Lower T. Quad bike related injury in Victoria, Australia.

Med.J.Aust. 2013; 199 418-22.

[29] Weiss H, Agimi Y, Steiner C, Youth. Motorcycle-related hospitalizations and traumatic

brain injuries in the United States in 2006. Pediatrics 2010; 126 1141-8.



[30] Shah CC, Ramakrishnaiah RH, Bhutta ST et al. Imaging findings in 512 children

following all-terrain vehicle injuries. Pediatr.Radiol. 2009; 39 677-84.

[31] Sexton B, Baughan C, Elliott M, Maycock G. The Accident Risk of Motorcyclists. Road

Safety Division, Department for Transport, London 2004.

[32] Kardamanidis K, Martiniuk A, Ivers RQ, Stevenson MR, Thistlethwaite K. Motorcycle

rider training for the prevention of road traffic crashes. Cochrane Database Syst.Rev. 2010;

(10):CD005240. doi CD005240.

[33] Meuleners LB, Lee AH, Haworth C. Road environment, crash type and hospitalisation of

bicyclists and motorcyclists presented to emergency departments in Western Australia.

Accid.Anal.Prev. 2007; 39 1222-5.

[34] Haworth NL, Greig K, Nielson AL. A comparison of risk taking in moped and

motorcycle crashes. 2009; Transportation Research Record 2140 182-7.

[35] Siskind V, Steinhardt D, Sheehan M et al. Risk factors for fatal crashes in rural Australia.

Accid.Anal.Prev. 2011; 43 1082-8.

[36] Fernandes FA, Alves de Sousa RJ. Motorcycle helmets--a state of the art review.

Accid.Anal.Prev. 2013; 56 1-21.

[37] Liu BC, Ivers R, Norton R et al. Helmets for preventing injury in motorcycle riders.

Cochrane Database Syst.Rev. 2008; (1):CD004333. doi CD004333.

[38] Philip AF, Fangman W, Liao J, Lilienthal M, Choi K. Helmets prevent motorcycle

injuries with significant economic benefits. Traffic Inj.Prev. 2013; 14 496-500.

[39] Steinhardt D, Mary S, Siskind V. A comparison of offroad and onroad crashes in rural

and remote Queensland. Proceedings 2006 Australian Road Safety Research, Policing,

Education Conference, Gold Coast. 2006.

[40] Motorcycle Council of NSW Inc. (MCC). (http://www.roadsafety.mccofnsw.org.au/).

[41] de Rome L, Ivers R, Fitzharris M, Du W., Haworth N, Heritier S, Richardson D.

Motorcycle protective clothing: protection from injury or just the weather? Accid.Anal.Prev.

2011; 43 1893-900.

[42] Grange JT, Corbett SW, Cotton A. Street bikes versus dirt bikes: a comparison of injuries

among motorcyclists presenting to a regional trauma center. J.Trauma 2004; 57 591-4.

[43] Blackman R, Cheffins T, Veitch C, O'Connor T. At work or play: a comparison of

private property vehicle crashes with those occurring on public roads in north Queensland.

Aust.J.Rural Health 2009; 17 189-94.

[44] Meuleners LB, Lee AH, Haworth C. Emergency presentations by vulnerable road users:

implications for injury prevention. Inj.Prev. 2006; 12 12-4.

http://www.roadsafety.mccofnsw.org.au/



[45] Lower T, Egginton N, Owen R. Agricultural motorcycle injuries in WA adolescents.

Aust.N.Z.J.Public Health 2003; 27 333-6.

[46] Thompson P, Hill D, Beidatsch K, Bramwell J. Road Safety Council of Western

Australia. Reported Road Crashes in Western Australia 2011.

[47] Trauma Services, Royal Perth Hosptial, 2013

(http://www.rph.wa.gov.au/traumaservices.html).

[48] Royal Perth Hospital. Trauma Registry Report - 2010 and 2011 Combined.

[49] American College of Surgeons. National Trauma Data Bank (NTDB): Annual Report

2005.

[50] Mullin B, Jackson R, Langley J, Norton R. Increasing age and experience: are both

protective against motorcycle injury? A case-control study. Inj.Prev. 2000; 6 32-5.

[51] Australian Government., Fair Work Act 2009.

(http://www.austlii.edu.au/au/legis/cth/consol_reg/fwr2009223/index.html#s3.01)

[52] de Rome L, Ivers R, Fitzharris M, Haworth N, Heritier S, Richardson D. Effectiveness of

motorcycle protective clothing: riders' health outcomes in the six months following a crash.

Injury 2012; 43 2035-45.

http://www.rph.wa.gov.au/traumaservices.html

http://www.austlii.edu.au/au/legis/cth/consol_reg/fwr2009223/index.html#s3.01



Appendices

APPENDIX I – Additional figures and tables

Figure 1 – details of 36 excluded patients.

25.0%

22.2%

5.6% 2.8%

44.4%

Refused participation

Glasgow Coma Scale <15

Discharged

Deceased during admission

Non-English speaking

Box 1 – criteria for the Emergency Department to involve trauma surgery in the line of care.

Physical signsa

Respiratory rate <10 or >29 respirations per minute

Systolic blood pressure <100 mmHg

Heart rate <50 or >120 beats per minute

Glasgow Coma Scale <14 points

Anatomical area

Airway compromise

Flail chest

Multiple body regions injured

Two or more extremity fractures

Amputation/crush injury proximal to the wrist or ankle

Degloved or mangled extremity

Suspected spinal injury

Burns >15% of body surface

Penetrating injury to the head, neck or torso

Pelvic fractures

Mechanism

Riding speed >30 km/h a occurring at any time following the accident

Documents

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