Lower extremity injuries in side-impact vehicle crashes

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  • This article was downloaded by: [University of Guelph]On: 25 October 2012, At: 02:34Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: MortimerHouse, 37-41 Mortimer Street, London W1T 3JH, UK

    International Journal of CrashworthinessPublication details, including instructions for authors and subscription information:http://www.tandfonline.com/loi/tcrs20

    Lower extremity injuries in side-impact vehiclecrashesN Arndt & R H Grzebietaa Department of Civil Engineering, PO Box 60, Monash University, Vic., 3800, Australiab Department of Civil Engineering, PO Box 60, Monash University, Vic., 3800, Australia

    Version of record first published: 08 Jul 2010.

    To cite this article: N Arndt & R H Grzebieta (2003): Lower extremity injuries in side-impact vehicle crashes,International Journal of Crashworthiness, 8:5, 495-512

    To link to this article: http://dx.doi.org/10.1533/ijcr.2003.0255

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  • Woodhead Publishing Ltd 0255 495 IJCrash 2003 Vol. 8 No. 5 pp. 495512

    Corresponding Author:R H Grzebieta, Associate Professor (Structures), Civil EngineeringMonash University, PO Box 60, Monash University 3800Tel 61 3 9905 4970 Fax +61 3 9905 4955Email raphael.grzebieta@eng.monash. edu.au

    INTRODUCTION

    Vehicle crashes are a major cause of LE injuries to motorvehicle occupants. Occupant protection regulations arelimited with regard to the lower extremity. There are noregulations regarding the knee, lower leg or ankle/foot inside-impact. Neither the EuroSID nor the US-SID (side-impact dummies) have the capability of measuring therisk of injury to the lower extremity below the pelvis.Crash-induced LE injuries are common, costly anddebilitating. In the case of frontal impacts, reduction inthe risk of head injuries was achieved by the introductionof the seat belt, the pretensioning retractor, the airbagand by the reduction of the intrusion of the steering wheelinto the passenger compartment by means of structuralimprovements [36]. This reduction in head injury riskhas now brought to prominence the importance of LE

    injuries. LE injuries are second only to head injuries infrequency [27] and severity [15].

    UK data reveals that lower limb injuries account for37% of all injuries sustained by front seat occupants infrontal, side and rear impacts [25]. According to Gibson[10] there were more LE injuries in 1990 as a result ofroad injury diagnosed in Australian hospitals than injuriesto any other body region. Several researchers [2, 19, 35]concluded that injuries of the ankle and foot were themost common types of injuries to the regions below theknee. Crandall and Martin [2] have stated that Morethan half the more severe LE injuries occurring in frontal-crashes were of regions below the knee. The foot andankle constitute the most frequently injured regions with30% to 40% of severe LE injuries.

    Automobile crashes cause higher energy injuries thanslips and falls and therefore have poorer prognoses. LEinjuries resulting from motor vehicle crashes are the mostfrequent cause of permanent disability and impairment[4, 9, 18, 27]. These injuries are debilitating due to theloss of weight bearing function. Fractures of the knee andankle joints are far more difficult to treat than femoralshaft fractures [13].

    Lower extremity injuries in side-impactvehicle crashes

    N Arndt and R H GrzebietaDepartment of Civil Engineering, PO Box 60, Monash University, Vic., 3800, Australia

    Abstract: Lower extremity (LE) fractures and dislocations resulting from car crashes are costly anddebilitating. In particular, occupant safety regulations for side-impact crashes are deficient in protectingthe knee, lower leg and ankle/foot. Hence further side-impact research is required to understandinjury mechanisms of these parts of the LE. In addition, side-impact dummies so far cannot measureforces and injury criteria in these lower parts of the LE. The aim of this paper is to identify andcharacterise LE fractures and dislocation injuries in side-imacts and propose some injury mechanisms.There appears to be some consensus on mechanisms describing how fractures and/or dislocations ofthe LE occur in frontal crashes. However, as far as the authors are aware, the mechanisms for side-impact have yet to be described and published. This paper presents some preliminary results of casestudies of LE injuries incurred in vehicles subjected to side-impact crashes in Australia between 1989and 2002. A summary of the findings to date is presented. Three basic injury mechanisms have beenidentified. They are: (1) Intrusion causing entrapment resulting from leg area volume reduction witha bending side-force, acting alone or together; (2) High-energy, side-impact, striking force resultingfrom being in direct contact with the struck portion of the vehicle; and (3) Inertial movement of thebody causing loading of the LE resulting from its interaction with the vehicle interior and whereintrusion is not the cause of the injury. This paper also proposes some injury mitigation strategies.

    Keywords: Vehicle Crashworthiness, Side Impacts, Lower Limb Injuries, Lower Leg Fractures and Dislocations

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  • N Arndt and R H Grzebieta

    IJCrash 2003 Vol. 8 No. 5 496 0255 Woodhead Publishing Ltd

    Miller et al. (1995, cited in Manning et al. [19]) reportedthat in the US in 1993, lower limb injuries amounted to$21.5 billion in passenger-vehicle occupant injury costs.Forty percent of the total annual motor vehicle traumatreatment costs in Maryland in 1994 were for LE injuries[18].

    Gibson et al. [11] assessed that of the ten injury priorityareas relating to body regions, LE injuries came third inpriority in terms of harm after the head and thorax inAustralia. Morgan et al. [21] reported that injuries to thethigh have been reduced to around 10% but knee injuriesstill account for 20% to 30% of LE injuries in frontal-crashes.

    The commonness and cost of injuries of these lower,weight-bearing segments indicate that attempts shouldbe made to reduce the harm associated with these injuries.In order for countermeasures to be developed for side-impact, it is important to understand the types andmechanisms of injury resulting from these types of crashes.

    Side-impacts constitute between 17% and 38% ofcrashes in Australia, Europe and the USA [8, 16, 26, 17].Vehicle occupants are particularly vulnerable in side crashes[30]. They are the second most frequent injury causingcrash configuration after frontal-impacts [5]. Near-sideimpacts are 2.3 times more common than far-side impacts[12]. Stolinski et al. [30] reported more injuries to near-side occupants compared with far-side (60% near-sidecompared to 40% far-side).

    In regards to LE injuries in side-impact crashes, littlework has been reported regarding statistical data andresearch work has yet to be described and published. Hence,this paper is attempting to provide some understandingof the injury mechanisms of lower extremity (LE) injuriesin both far and near-side impact crashes and, as a result,proposes some injury mitigating countermeasures. It isthe hope of the authors that the work described in thispaper may aid future developments in regulating LE injurycriteria in side-impact vehicle crashes.

    RESEARCH OBJECTIVES

    The following objectives were pursued when carrying outthe research presented in this paper.

    To identify any associations between occupant, crashand vehicle characteristics and fracture and dislocationmechanisms of the LE in side-impacts;

    To identify the types and mechanisms of fractures anddislocations of the Knee, Lower Leg and Ankle/Footoccurring in side-impacts.

    SIDE-IMPACT SAMPLE STUDIED ANDMETHODOLOGY

    Data used in this study have been taken from MonashUniversity Accident Research Centres (MUARC) twoCrashed Vehicle File (CVF) databases. The first CVF

    database contains information about crashes collectedbetween 1989 and 1992 and the second CVF, from April2000 (CVF2000). A third database used in this study isthe ANCIS (Australian National Crash In-depth Study).The CVFs include information about real-world Australiancrashes where an occupant was killed or injured severelyenough to be hospitalised. The ANCIS database containsdata taken from injured occupants of crashes where thevehicle had to be towed from the crash site.

    The databases contain details about the crash (includingdelta-V, angle of impact, location of impact, impactingobject/vehicle), vehicle (including mass, speed, make,model, year) and occupant (including the injuriessustained, the injury severity, location of injury) as wellas other variables. The information about the occupantsalso included seating position (driver or passenger), height,weight and age. The number of occupants in the vehicleswas also included.

    For the CVFs, a nurse surveyed the hospitals for patientsand interviewed them. The nurse also contacted the coronerfor patients who were admitted to hospital or who died asa result of a vehicle crash. For the ANCIS data tow-truckcompanies notified MUARC for vehicles which weredamaged and towed from the crash site.

    The occupants of the vehicles who were injured in thevehicles were contacted. After signing a consent form(stating that their vehicle and medical information can beused for research purposes but would remain confidential)their medical records were examined and their vehicleinspected. If the vehicle was involved in a two car crash,the other (bullet) vehicle was inspected whenever possible.

    The injuries

    A nurse at MUARC was responsible for interviewing anysurviving injured occupants and also examined all themedical records, including X-rays and reports. For fatalcrashes, the coroners reports were examined for thoseinjured, who died. The nurse described, recorded andcoded every injury using the Abbreviated Injury Scale(AIS, a threat to life scale from 0-6, 0 being least severe).Detailed descriptions of each injury were recorded andadded into the databases.

    Out of the 24 crashes and 25 injured occupants, 19fracture or dislocation injuries were classified as havingseverity of AIS 3 and 18 injuries had a severity rating ofAIS 2. Figure 6 shows the AIS of the injuries of the knee,lower leg and ankle/foot regions for each case in the studyreported here. The details in the case report includedtype and location information about each fracture and/ordislocation. Fracture descriptions and diagrammatic vehicledamage descriptions were more detailed for the CVFs. Inthe ANCIS database, there were fewer crashes in which aLE fracture and/or dislocation was reported comparedto the CVF to date when this paper was written.

    The possible fracture mechanisms were deduced froma detailed reconstruction of each crash using the range ofinformation available for each case and examination of

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  • Lower extremity injuries in side-impact vehicle crashes

    Woodhead Publishing Ltd 0255 497 IJCrash 2003 Vol. 8 No. 5

    and side-impacts combined). The CVF2000 had 309injured occupants in side-impacts out of 1040 cases in theentire CVF2000, including frontal, rear and side-impacts.The entire ANCIS database was not available, however, 7side-impacts with 7 injured occupants were available foranalysis.

    The number of crashes was graphed against the impactangles for each crash. The mass ratios were calculated for22 of the 24 crashes. Two crashes had unknown vehiclesrecorded so their mass ratios could not be calculated. Thenumber of crashes by the mass ratio of each crash wasplotted. The cumulative percent of LE injuries was plottedagainst maximum intrusion for the crashes. The delta-Vcumulative distribution was plotted for the crashes whereit could be calculated. The impact objects involved in theside-impact crashes analysed were also graphed. Thesewere also divided into specific injuries by impact object,showing the injury distribution for the knee, lower legand ankle/foot regions.

    The occupants

    For this study, only cases in which there was a LE fractureand/or dislocation of the knee, lower leg or ankle/footincurred in a side-impact were identified and analysed.Only front seat occupants were investigated in this studyas the only rear seat passenger with a LE fracture ordislocation was lying down (not in a typical position) andthus not included in this study. If one person had morethan one fracture and/or dislocation of the LE, they werecounted as one case (occupant). (Four people had lowerleg and ankle/foot fractures/dislocations and one had kneeand lower leg fractures/dislocations. These cases were allresulting from two-vehicle crashes).

    Twenty-four crashes, 25 injured occupants sustaining37 lower extremity fractures and/or dislocations of oneor more of the knee, lower leg and ankle/foot regionswere analysed. There were 20 near-side cases (injuredoccupants) and 4 far-side cases. For near-side impactsthere were 33 injuries incurred by 20 occupants. Therewere 4 far-side occupants injured with one LE injuryeach, all in the CVF. There was only one crash in which

    the detailed records of the injuries including x-ray reportswhich the nurse in the study had examined. Anunderstanding of biomechanics, anatomy, physics andengineering was utilised. The number of injuries for eachLE body region analysed was graphed. The number ofinjuries by the identified injury mechanisms was alsographed to see the proportions of each type of injurymechanism for the knee, lower leg and ankle/foot, andfor the LE in general. The injury severity distributionwas also plotted.

    The crashed vehicles

    The information about the crashed vehicles includedphotographs, diagrams of the intrusions inside and outsidethe vehicles and the Collision Deformation Codes usedto give information about the location, extent and angleof impact. The vehicle was also inspected by an engineerfor interaction of the occupant with the vehicle, the contactsources of injury (where there was visible deformation ofthe vehicle caused by contact of the occupant with it).Details were noted and recorded.

    The masses of vehicles in this study were also recordedand classified i...

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