Clinical Characteristics of WAD, Grades I-II: Investigations into the Stabilty System of the Cervical Spine

Abstract

The studies upon which this thesis is based were intended to identify measurable physical impairment in the stability system of the cervical spine in patients with chronic whiplash-associated disorders (WAD), grades I-II. Case-control and test-retest designs were used to identify and define the clinical characteristics investigated. Questionnaires were used to investigate self-reported characteristics and two radiographic studies explored the passive integrity of the cervical spine. The same subjects, all women, participated in the three above mentioned studies. Two studies into the muscular system investigated the deep pre- and paravertebral cervical muscles respectively. In three successive studies relocation and movement accuracy of the cervical spine were investigated. Different number of subjects participated in these five last mentioned studies.

The results from the questionnaires indicated that women with chronic WAD have symptoms which are more disabling than women with chronic insidious onset neck pain (IONP). The first radiographic study revealed that, in the WAD group, the upper cervical lordosis was relatively increased and the lower cervical spine lordosis was relatively decreased. The C4 vertebra was also more kyphotic in the WAD group than in the asymptomatic group. The second radiographic study revealed increased segmental motion in the mid cervical segments of one third of the WAD group. These results point to mechanical instability in the lower cervical spine in a subgroup of patients with chronic WAD.

A new test, the cranio-cervical flexion test, identified altered patterns of muscle co-ordination within the cervical flexor synergy in neck pain patients that could indicate inhibition of the deep ventral muscles. Ultrasound imaging revealed that the cervical multifidus muscle in WAD patients is smaller than in asymptomatic subjects. The diminished size of this muscle further reduces the weight bearing capacity of the cervical spine and contributes to deficient control of intersegmental motions. These findings indicate that the deep pre- and paravertebral muscles provide inadequate support in neck pain patients. Cervical spine proprioception was measured using a 3D measurement device (Fastrak) connected to specially designed software programmes. The measurements revealed relocation inaccuracy in neck pain patients, a deficit that tended to be greater in whiplash patients. A new clinical test, developed to measure movement inaccuracy of the cervical spine was able to discriminate between an asymptomatic group and a chronic WAD group.

When the results from all these investigations are viewed as a whole, a definite pattern of musculoskeletal impairment emerges. Among patients with chronic WAD, there exists a subgroup which has an identifiable pattern of clinical characteristics indicating impaired stability of the cervical spine. This impairment pattern may be linked to the unphysilogic movements of the cervical spine which have been documented as occurring during the early phase of a rear-end collision. The between–group variance for the WAD groups, IONP groups and/or the asymptomatic groups overlapped to a different degree for each clinical characteristic investigated, suggesting that the variance in clinical characteristics in patients with chronic WAD is greater than earlier anticipated. It is therefore recommended, that patients with WAD be comprehensively evaluated to ensure that all clinical characteristics are investigated. In the future, the evaluation should include a detailed physical examination, the implementation of specially designed tests to detect subtle physical impairment and altered pain responses, and questionnaires to screen for diverse psychosocial factors.

Key words: whiplash, cervical, instability, segmental, physical impairment, measurements

Full text

EYÞÓRB.KRISTJÁNSSON,PT
___________________________________________________
ClinicalCharacteristicsofWhiplashAssociatedDisorders
(WAD),gradesIII
Investigationsintothestabilitysystemofthecervicalspine
_____________________________________________________________________
FacultyofMedicine,UniversityofIceland,Reykjavík,Iceland
incooperationwith
DepartmentofPhysiotherapy,UniversityofQueensland,Brisbane,Australia
DoctoralDissertation
FacultyofMedicine
Reykjavík,May2004

2
"Ihaveassumedthatnodemonstrationisrequiredofhownecessarytheknowledgeof
humanpartsisforuswhohaveenlistedunderthebannerofmedicine,sincethe
conscienceofeachandallwillbearfulltestimonytothefactthatinthecureofillness
theknowledgeofthosepartslaysrightfulclaimtofirst,secondandthirdplace;and
thisknowledgeistobesoughtprimarilyfromtheaffectedportion........"
AndreasVesalius,Epitome(1543)*

ClinicalCharacteristicsofWhiplashAssociatedDisorders,
gradesIII
Investigationsintothestabilitysystemofthecervicalspine

©EyþórB.KristjánssonPT,2004
DesignerÓlöfBjörnsdóttir
PrintedinIcelandbyGutenberg
Allrightsreserved
ISBN:9979951338
*FromtheintroductoryLetterinwhichVesaliusdedicatedhisEpitometoKingPhilipIIofSpain(In:
TheEpitomeofAndreasVesalius,transl.byL.R.Lind(1949).M.I.T.Press;Cambridge,Mass.).

3
Tomywife
,
Ingebjørg
andchildren:

IdaRún
EirikValgeir
IngridEir
OlavBragi
Hildur
EyrúnÖsp
BryndísBjörk
ThisthesisisalsodedicatedtothememoryofmymotherAuðurÓlafsdóttir,(1922
1978).

4
ClinicalCharacteristicsofWhiplashAssociatedDisorders(WAD),gradesIII
Investigationsintothestabilitysystemofthecervicalspine
___________________________________________________________________________
EythorKristjansson,PT
ABSTRACT
The studies upon which this thesis is based were intended to identify measurable physical
impairment in the stability system of the cervical spine in patients with chronic whiplash
associated disorders (WAD), grades III. Casecontrol and testretest designs were used to
identify and define the clinical characteristics investigated. Questionnaires were used to
investigate selfreported characteristics and two radiographic studies explored the passive
integrityofthecervicalspine.Thesamesubjects,allwomen,participatedinthethreeabove
mentioned studies. Two studies into the muscular system investigated the deep pre and
paravertebral cervical muscles respectively. In three successive studies relocation and
movement accuracy of the cervical spine were investigated. Different number of subjects
participatedinthesefivelastmentionedstudies.

TheresultsfromthequestionnairesindicatedthatwomenwithchronicWADhavesymptoms
whicharemoredisablingthanwomenwithchronicinsidiousonsetneckpain(IONP).The
first radiographic study revealed that, in the WAD group, the upper cervical lordosis was
relativelyincreased andthe lowercervical spine lordosis was relativelydecreased. TheC4
vertebra was also more kyphotic in the WAD group than in the asymptomatic group. The
secondradiographicstudyrevealedincreasedsegmentalmotioninthemidcervicalsegments
of one third of the WAD group. These results point to mechanical instability in the lower
cervicalspineinasubgroupofpatientswithchronicWAD.
Anewtest,thecraniocervicalflexiontest,identifiedalteredpatternsofmusclecoordination
withinthecervicalflexorsynergyinneckpainpatientsthatcouldindicateinhibitionofthe
deep ventral muscles. Ultrasound imaging revealed that the cervical multifidus muscle in
WADpatientsissmallerthaninasymptomaticsubjects.Thediminishedsizeofthismuscle
furtherreducestheweightbearingcapacityofthecervicalspineandcontributestodeficient
control of intersegmental motions. These findings indicate that the deep pre and
paravertebral muscles provide inadequate support in neck pain patients. Cervical spine
proprioception was measured using a 3D measurement device (Fastrak) connected to
speciallydesignedsoftwareprogrammes.Themeasurementsrevealedrelocationinaccuracy
inneckpainpatients,adeficitthattendedtobegreaterinwhiplashpatients.Anewclinical
test, developed to measure movement inaccuracy of the cervical spine was able to
discriminatebetweenanasymptomaticgroupandachronicWADgroup.
Whenthe results fromall these investigationsare viewed as a whole, a definite patternof
musculoskeletal impairment emerges. Among patients with chronic WAD, there exists a
subgroup which has an identifiable pattern of clinical characteristics indicating impaired
stability of the cervical spine. This impairment pattern may be linked to the unphysilogic
movementsofthecervicalspinewhichhavebeendocumentedasoccurringduringtheearly
phaseofarearendcollision.Thebetween–groupvariancefortheWADgroups,IONPgroups
and/or the asymptomatic groups overlapped to a different degree for each clinical
characteristicinvestigated,suggestingthatthevarianceinclinicalcharacteristicsinpatients
with chronic WAD is greater than earlier anticipated. It is therefore recommended, that
patientswithWADbecomprehensivelyevaluatedtoensurethatallclinicalcharacteristicsare
investigated.Inthefuture,theevaluationshouldincludeadetailedphysicalexamination,the
implementationofspeciallydesignedtests to detectsubtlephysicalimpairmentandaltered
painresponses,and
questionnaires
toscreenfordiversepsychosocialfactors.

5
Keywords:whiplash,cervical,instability,segmental,physicalimpairment,measurements
Líkamlegsérkennisjúklingameðviðvarandieinkenniíhálshryggeftir
bílaákeyrslur
Rannsóknirástarfrænumtruflunumístöðugleikakerfihálshryggjar
___________________________________________________________________________
ÁGRIP
Rannsóknirnar sem þessi doktorsritgerð er byggð á er ætlað að finna aðferðir til að mæla
starfrænar truflanir í stöðugleikakerfi hálshryggjar hjá sjúklingum með viðvarandi einkenni
eftir bílaákeyrslur. Sjúklingaviðmiðunarsnið og endurteknar mælingar voru notaðar til að
finnaogskilgreinahreyfitruflaniríhálsi.Konurmeðviðvarandieinkennieftirbílaákeyrslur
annars vegar og álagseinkenni hins vegar svöruðu spurningakönnunum um einkenni sín.
Sömukonur,aukhópseinkennalausrakvenna,tókueinnigþáttítveimurröntgenrannsóknum
sem athuguðu annars vegar svæðisbundinn og hins vegar staðbundinn stöðugleika
hálshryggjarliðanna.Djúpuvöðvarnirsemstyðjaviðhálshryggjarsúlunaaðframanogaftan
voru rannsakaðir í tveimur aðskildum rannsóknum. Stöðu og hreyfiskyn hálshryggjar var
metiðí áföngummeð þremur rannsóknum.Mismunandi fjöldieinstaklinga tókþátt í fimm
síðastnefndurannsóknunum.
Niðurstöðurspurningakönnunarinnar gefatil kynnaað einkenni kvennanna með viðvarandi
einkenni eftir bílaárekstra hafi víðtækari áhrif á líðan þeirra og skerði athafnir daglegs lífs
meirasamanboriðviðkonurnarmeðviðvarandiálagseinkenni.Fyrriröntgenrannsókninsýndi
aðsveigjaníefrihálshryggvarhlutfallslegaaukinensveigjaníneðrihálshrygghlutfallslega
minnkuð hjá slysahópnum. Fjórði hálshryggjaliður var einnig óeðlilega frambeygður hjá
slysahópnumboriðsamanviðeinkennalausanhóp.Seinniröntgenrannsókninsýndióeðlilega
aukna hreyfingu á þriðja og fjórða hálshryggjarlið hjá um þriðjungi þátttakenda í
slysahópnum. Þetta bendir til aflfræðilegs óstöðugleika í hálshryggjarliðum hjá ákveðnum
hópisjúklingameðviðvarandieinkennieftirbílaákeyrslur.
Rannsóknirádjúpuvöðvumhálshryggjarinsgáfutilkynnaaðþessirvöðvargetaekkisinnt
stöðugleikahlutverki sínu sem skyldi. Með nýju klínísku prófi var hægt að sýna fram á að
samhæfing beygjuvöðva hálshryggjar er trufluð sem bendir til vanvirkni í djúpu
hálsvöðvunumaðframan.Sónarvarnotaðurtilaðrannsakadjúpuhálsvöðvanaaðaftan,sem
mældustrýrarihjáslysahópnumsamanboriðviðþanneinkennalausa.Þettagefurtilkynnaað
burðarþol hálshryggjar geti verið minnkað og að stjórn á hreyfingum á milli einstakra
hryggjarliða sé ábótavant. Stöðu og hreyfiskyn hálshryggjar, sem var metið með
þrívíddarhreyfigreini (Fastrak) sem var tengdur sérhönnuðum hugbúnaði fyrir þessar
rannsóknir, var truflað hjá sjúklingum með einkenni frá hálsi. Stöðu  og hreyfiskynið var
mesttruflaðhjáslysahópnum.
Niðurstöðurþessararannsóknasýnaaðhreyfitruflunístöðugleikakerfihálshryggjarmyndar
sérstakt mynstur hjá ákveðnum hópi slysasjúklinga. Þetta mynstur er í samræmi við nýjar
rannsóknir á lífaflfræði hálshryggjar sem sýna að ólífeðlisfræðilegarhreyfingar eiga sér þá
stað í hálshrygg í árekstursaugnablikinu. Breytileikinn á milli slysa/álags og/eða
einkennalausu hópanna skaraðist mismikið háð því hvaða hreyfitruflun var metin. Þetta
bendir til að breytileikinn í slysahópnum sé meiri en áður hefur verið gert ráð fyrir. Í
framtíðinniþegarþessirsjúklingarerumetnirþáermikilvægtaðkomastaðöllumsérkennum
þeirra til að geta flokkað þá í undirhópa þannig að hægt sé að gefa einstaklingsbundna
meðferðogfylgjastmeðframgangimeðferðar.Þettaerhægtaðgerameðþvíaðframkvæma
almennaogsértækalíkamsskoðunogmetahreyfitruflanirístöðugleikakerfihálshryggjarog
breytta sársaukaskynjun með sérhönnuðum tækjaprófum. jafnframt að leggja
spurningakannanirfyrirsjúklinganatilaðskimasálfélagslegaþætti.

6
Lykilorð:hálsslinkur,hálshryggur,stöðugleiki,hreyfitruflun,mælingar
ListofOriginalPapers
Thethesisisbasedonthefollowingpapers,whichwillbereferredtobytheirRoman
numeralsinthechapterheadingsandbytheirArabicnumeralsinthetextalongwith
otherreferences
I.SymptomcharacteristicsinwomenwithchronicWAD,gradesIII,andchronic
insidiousonsetneckpain.Acomparativestudywithan18monthfollowup.
JournalofWhiplash&RelatedDisorders:InPress
II.Isthesagittalconfigurationchangedinwomenwithchronicwhiplashsyndrome?
Acomparativecomputerassistedradiographicassessment.
JournalofManipulativeandPhysiologicalTherapeutics2002;25:550555
III.Increasedsagittalplanesegmentalmotionofthelowercervicalspineinwomen
withwhiplashassociateddisorders,gradesIII:Acasecontrolstudyusinganew
measurementprotocol.
Spine2003;28:22152221
IV.Impairmentinthecervicalflexors:acomparisonofwhiplashandinsidiousonset
neckpain.
ManualTherapy:2004;9:8994
V.Reliabilityofultrasonographyforthecervicalmultifidusmuscleinasymptomatic
andsymptomaticsubjects.
ManualTherapy:2004;9:8388
VI.Cervicocephalickinaesthesia:reliabilityofanewtestapproach.
PhysiotherapyResearchInternational2001;6:224235
VII.Astudyoffivecervicocephalicrelocationtestsinthreedifferentsubjectgroups.
ClinicalRehabilitation2003;17:768774
VIII.Anewclinicaltestforcervicocephalickinestheticsensibility:"TheFly"
ArchivesofPhysicalMedicineandRehabilitation2004;85:490495



7
TABLEOFCONTENTS
LISTOFFIGURES viii
LISTOFTABLES ix
1 INTRODUCTION 1
1.1 Clinicalbackgroundandstatementoftheproblem 1
1.2 TheQuebecTaskForceclassificationofWAD 2
1.3 WAD,gradesIII:Aborderlinedisorder 4
1.4 Epidemiology 6
1.5 Lowvelocitywhiplashbiomechanics 8
1.6 Theorganicversusthebiopsychosocialexplanationmodel 10
1.7 Anintegratedmodelofmusculoskeletalfunction 11
1.7.1 Thepassivesubsystem 14
1.7.2 Theactivesubsystem 16
1.7.3 Theneuralsubsystem 19
2 AIMS 22
3 MATERIALANDMETHODS 23
3.1 Investigationbyquestionnaires–Selfreportedcharacteristics(PaperI) 25
3.2 Radiographicinvestigations(PapersII,III) 25
3.2.1 Cervicallordosisanalysis(II) 26
3.2.2 Segmentalmotionanalysis(III) 27
3.3 Investigationsintothedeepcervicalmuscles(PapersIV,V) 28
3.3.1 Craniocervicalflexiontest(IV) 28
3.3.2 Ultrasonographyanalysis(V) 29
3.4 Cervicocephalickinaesthetictests(PapersVI,VII,VIII) 29
3.4.1 Relocationtests(VI,VII) 30
3.4.2 Movementtest(VIII) 31
4 RESULTS 33
4.1 Thequestionnaires–Selfreportedcharacteristics(PaperI) 33
4.2 Theradiographicinvestigations–Thepassivesubsystem(PapersII,III) 35
4.2.1 Cervicallordosisanalyses(II) 35
4.2.2 Segmentalmotionanalyses(III) 36
4.3 Thedeepcervicalmuscles–Theactivesubsystem(PapersIV,V) 39
4.3.1 Craniocervicalflexiontest(IV) 39
4.3.2 Ultrasonographyanalysis(V) 41
4.4 Thecervicocephalickinesthetictests–Theneuralsubsystem(PapersVI,VII,VIII) 42
4.4.1 Relocationtests(VI,VII) 42
4.4.2 Movementtest(VIII) 43
5 DISCUSSION 45
5.1 Self–reportedcharacteristics(PaperI) 46
5.2 Thepassivesubsystem(PapersII,III) 48
5.3 Theactivesubsystem(PapersIV,V) 52
5.4 Theneuralsubsystem(PapersVI,VII,VIII) 54
6 CONCLUSIONS 57
6.1 Selfreportedcharacteristics(PaperI) 58
6.2 Thepassivesubsystem(PapersII,III) 58
6.3 Theactivesubsystem(PapersIV,V) 59
6.4 Theneuralsubsystem(PapersVI,VII,VIII) 59
ACKNOWLEDGEMENTS 60
REFERENCES 62

8
LISTOFFIGURES
Figure1–RegisteredincidenceofWADindifferentcountries 6
Figure2–UnphysiologicalSshapedmotionsofthecervicalspineduringacollision 9
Figure3–Thethreesubsystemsthatcontributetospinalstabilisation 12
Figure4–Schematicorganisationplanofthemechanismsandpathwaysbywhichthemechanicaland
sensorypropertiesoftheligamentsmaycontributetojointstability,musclecoordinationand
proprioception 17
Figure5–Fiducialisandlinesusedtoformthemeasuredlordosisangles 26
Figure6–Definitionofsagittalplaneangleanddisplacementforalowercervicalmotionsegment 27
Figure7–Thecraniocervicalflexiontestdemonstratingthevisualfeedbackwiththepressuresensor
andmeasurementswithsurfaceEMG 28
Figure8–UltrasonogramofthemultifidusmusclecrosssectionalareaattheC4levelinan
asymptomaticsubject 29
Figure9–Experimentalsetupfortherelocationtestprocedures 30
Figure10–MovementpatternsABCtracedby"theFly"whichtheparticipantswererequiredto
followbymovingtheirhead 31
Figure11–Ratiooflowertouppercervicalspinelordosis 36
Figure12a–Anexampleofdocumentationofrotationalhypermobilityinanindividualcase 38
Figure12b–TheactualandpredictedtranslationalmotionforthesameindividualasinFig.12a 38
Figure13a–Theactualrotationalmotioninanindividualcase 39
Figure13b–Anexampleofdocumentationoftranslationalhypermobilityforthesameindividualasin
Fig.13a 39
Figure14–Themeansfortheshortfallinpressurefromthetargetpressuresforeachstageofthe
craniocervicalflexiontestforthreedifferentsubjectgroups 40
Figure15ThemeansforthenormalisedRMSvaluesforsternocleidomastoidineachstageofthe
craniocervicalflexiontestforthreedifferentsubjectgroups. 41
Figure16Plotofintertesteragreementfortheasymptomaticgroup. 42
Figure17Plotofintertesteragreementforthesymptomaticgroup 42
Figure18aAnexampleofrotationalhypermobilityintheC4/C5segment. 50
Figure18bThetranslationalmotioninthesameindividualasinFig.18a 51

9
LISTOFTABLES
Table1QTFclassificationofWAD 3
Table2InclusionandexclusioncriteriainthestudiesinIceland. 24
Table3CharacteristicsofthesubjectgroupsinthestudiesinAustralia 25
Table4Prevalenceofspecificcomplaintsoverthelast12months 34
Table5Characteristicsofsymptomaticsubjectsatfollowup 35
Table6Comparisonofmeanrotationalmotionsinthesagittalplane 36
Table7Comparisonofmeantranslationalmotionsinthesagittalplane 37
Table8Fisher'sexacttestoftherelationshipbetweenhypermobilityandnormalsegmental
mobility 37
Table9WithindaysaveragerelocationerrorfollowingaxialrotationandtheICC’sfor
betweendayagreement 43
Table10Errormagnitudesand95%confidenceintervalsforeachmovementpatternforthe
asymptomaticgroupandtheWAD
group......................................................................................44

10
ABBREVIATIONS
APD anteriorposteriordimension
CCFT craniocervicalflexiontest
CCN centralcervicalnucleus
CCR cervicocollicreflex
CNS centralnervoussystem
CSA crosssectionalarea
EMG electromyography
EZ elasticzone
FHP forwardheadposture
GTO Golgitendonorgan
IAR instantaneousaxisofrotation
ICC intraclasscorrelationcoefficient
IONP insidiousonsetneckpain
LD lateraldimension
LUH LandspitaliUniversityHospital
MVC motorvehiclecollision
NHP naturalheadposture
NZ neutralzone
PCS posturalcontrolsystem
ORs oddsratios
QTF QuébecTaskForce
RMS rootmeansquare
ROM rangeofmotion
SCM sternocleidomastoid
UQ UniversityofQueensland
VCR vestibulocollicreflex
VNC vestibularnuclearcomplex
VOR vestibularocularreflex
WAD whiplashassociateddisorders

11
1INTRODUCTION
1.1 Clinicalbackgroundandstatementoftheproblem
Twentytwoyearsago,ItoldawomanIwastreatingforchronicsymptomsaftera
lowspeedmotorvehiclecollision(MVC)thatIwouldbebetterabletohelpherafter
mypostgraduateclinicaleducationinmanualtherapy.Althoughtrueformostpatients
withmusculoskeletalcomplaints,thisdidnotapplytochronicwhiplashpatientswho
only gained shortterm relief, which by definition is an ineffective treatment. The
difficulties encountered in the efficient physical therapy treatment of patients with
chronic whiplash associated disorders (WAD) are manifold. Many patients with
WAD are extremely sensitive to external physical stimuli and their symptoms are
consequently easily provoked by conventional physical therapy methods. In the
1980s,Norwegianmanualtherapistswhowereengagedinmedicalexercisetherapy
suggestedthatphysicaltreatmentforthisparticularpatientgroupshouldnotinitially
involvethecervicalspinebutratherthearmsandtrunk,therebytargetingthecervical
spine indirectly. Most physical therapists today, however, are using treatment
modalitiesaimedatreducingtheunrelentingmuscleguardingandtendernessinthe
cervicalregionaswellasrestoringnormalcervicalrangeofmotion(ROM).
Clinical experience indicates that many patients with chronic WAD have abnormal
andpainfulmotionsinthecervicalsegmentsandinadequatemuscularsupportofthe
cervical spine. These patients commonly adopt a forward head posture (FHP) with
protraction and elevation of the shoulder girdle. They also seem to have a poor
awarenessoftheirheadneckposture,andsomeindeedcomplainabouta"wobbling"
head. However it is not possible through clinical examination to verify these
complaintsobjectivelynortodetectothersubtlemusculoskeletalimpairmentsinthe
cervicalspine.Thetreatmentmaybejudgedunsuccessful,sincenomeasurementscan
beperformedtoidentifytheprecisenatureofthephysicalimpairmentnortomonitor
thetreatmentprogression.

12
Thelackofreliableandvaliddiagnostictestsforthecervicalspinemayexplainwhy
nophysicaltreatmenthasbeenoptimisedforvariousmusculoskeletaldisordersinthis
area. The plethora of symptoms and the lack of objective findings on xrays, CT
scans, MRI and other sophisticated medical instrumentation, together with the fact
that most patients with chronic WAD are therapy resistant to current treatment
strategies, has led to divergent medicolegal views. The contrasting views about
patients with WAD are no less conflicting now than fifty years ago (1), as the
symptoms in most patients with chronic WAD continue to puzzle health care
practitioners.PatientswithWADfrequentlyattendoutpatientphysicaltherapyclinics
for relief of their symptoms and offer therefore a great challenge for physical
therapistsandothersinvolvedinthediagnosisandconservativetreatmentofpatients
with musculoskeletal disorders. Better identification and classification of different
levelsofmusculoskeletalimpairmentinWADwouldopenuppossibilitiesformore
efficient physical treatment of individual patients. The eight studies that form the
basisofthisthesiswerethereforeintendedtoidentifyphysicalclinicalcharacteristics
relatedtothestabilitysystemofthecervicalspineinpatientswithchronicWAD.
1.2 TheQuébecTaskForceclassificationofWAD
In the late 1980s, the government of Quebec and the province’s car insurance
companies, the Société d'assurance automobile du Québec (SAAQ) became
concernedabout theincreasing paymentratesforwhiplashclaimants andrequested
thatthemanyfacetsofthewhiplashproblembescrutinised.Itwasessentialforthe
QuébecTaskForce(QTF)toestablishinadvance,asoliddefinitionandclassification
oftheproblemthatwouldbehelpfulintheevaluationofallarticlesidentifiedonthe
topic.However,only0,6%ofthearticlesmettheTaskForce'sinclusioncriteriaand
these,alongwiththeirowncohortstudy(2)formedthebasisfortheQTFreport.
TheQTFintroducedanddefinedtheterm"WhiplashAssociatedDisorders"(WAD):
"Whiplash is an accelerationdeceleration mechanism of energy transferto
theneck.Itmayresultfromrearendorsideimpactmotorvehiclecollisions,
butcanalsooccurduringdivingorothermishaps.Theimpactmayresultin

13
bonyorsofttissueinjuries(whiplashinjuries),whichinturnmayleadtoa
varietyofclinicalmanifestations(Whiplash–AssociatedDisorders)"(2,p.22).
The QTF provided also a descriptive clinicalanatomical classification scheme for
WAD,Table1(2).TheQTFreportwaspublishedin1995andeightyearslateronly
two prospective studies have been conducted to evaluate the clinical utility of this
classification scheme. The first study concluded that the classification did not
correspond to the severity of the injury (3). The major limitation of this former
research,however,wasthatthegradingofinitialsymptomstookplaceatemergency
hospitals, which may not be very reliable because subjective complaints often
outweigh objective findings at the initial stage. The second study found that the
classificationsystemwasrepresentativeoftheinitialinjuryseverityandpredictivefor
theprognosiswhenappliedwithinthesameweekastheaccident(4).
Grade ClinicalPresentation
0 Nocomplaintabouttheneck
Nophysicalsign(s)
I Neckcomplaintofpain,stiffness,or
tendernessonly
Nophysicalsign(s)
II NeckcomplaintsAND
Musculoskeletalsign(s)*
III NeckcomplaintsAND
Neurologicalsign(s)**
IV NeckcomplaintsAND
Fractureordislocation
Table1QTFclassificationofWAD
*Includedecreasedrangeofmotionandpointtenderness
**Includedecreasedorabsenttendonreflexes,weaknessandsensorydeficits
Deafness, dizziness, tinnitus, headache, memeory loss, dysphagia and temporomandibular joint pain
areamongthesymptomsanddisordersthatcanbemanifestinallgrades.
Although the QTF classification scheme may be reliable for the classification of
patientsintobroadgroupsandtherebysatisfiestheneedsofemergencydepartments
and insurance companies, it will be argued that the QTF classification has very
limited utility in the therapeutic management of patients with WAD, grades III.
Firstly,theQTF(2)andmorerecentlytwoseparateexpertmedicalpanelsthatalso
usedtheROM and point tenderness toclassifypatientswith WAD into grades III
wereunabletoprovideevidencebasedrecommendationsforthetreatmentofpatients

14
with chronic WAD (5,6). Neither could they recommend any reliable and valid
diagnostictestsforpatientswithWAD,gradesIII.Secondly,morethan80%ofthe
WADpatientswhobecomechronic(>6months)correspondtogradesIII(5).Health
careprovidershavethereforenotbeenverysuccessfulattreatingpatientswithWAD,
gradesIII,armedwiththegeneralROMandpointtendernessparametersastheonly
physical measures and attendant treatment directives. Given the current status of
knowledge, it is therefore impossible to classify most patients with WAD into
meaningfulsubgroupsinordertoguidetherapeuticinterventions.
Thepurposeofadiagnosisistoprovideboundariesaroundsubgroupsofillnessina
population since each subgroup presumably has a different underlying mechanism,
naturalhistory,courseandresponsetotreatment(7,8).Inthisthesisitwillbeargued
that patients with WAD who need conservative care should be classified into
subgroups according to their level of physical impairment in order to enhance the
developmentofmoresuccessfulphysicaltreatmentstrategies.Aprerequisiteforsuch
an approach is that special clinical characteristics be identified for patients with
WAD. These characteristics may later serve to generate hypotheses about the
underlyingnatureoftheproblem(8).Thesimilarityofreportedsymptomsandtheir
vocalised behaviour in all grades of WAD (2,5,9,10,11) strongly suggests some
common underlying mechanisms and brings into questions the validity of the QTF
classification scheme. The importance of detecting distinct subgroups of chronic
patientstotailortreatmentinterventionsandtocontrolforsubgroupdifferenceswhen
evaluating treatment outcome has been highlighted by several researchers (1215).
DiscrepantresultsacrosspreviousstudiesintoWADmayinfactbeaccountedforby
variable representation of different subgroups in the various study samples. This
problem has therefore to be resolved before meaningful controlled trials can be
conducted.
1.3 WAD,gradesIII:Aborderlinedisorder
The descriptive validity of WAD is threatened by the lack of a clearcut boundary
betweentheclinicalpictureofpatientswithWAD,gradesIII,andotherneckpain
patients. It has been pointed out that complaints of similar symptoms are also

15
commoninthegeneralpopulation(16,17)andithasevenbeenproposedthatWAD
patients may simply be attributing some of their complaints to the MVC (18).
However,WADhasgoodfacevalidityamongmostclinicianswhousuallyrecognise
chronicpatientswithWADbytheirclinicalpresentationalone.Thegamut,instability
and unilaterality of symptoms and the low aggravation threshold for symptom
provocation,mostofteninyoungfemalepatients,arecardinalcharacteristicsthatalert
aclinician(19).AlthoughsomesubjectivecharacteristicsofpatientswithWADmay
havehigherdescriptivevaliditythanothers,theclinicalpictureasawholeisstilltoo
vagueforobjectivepresentation.
Questionnaires have been the most popular instrument for identifying subgroups in
"nonspecific"lowbackpainpatients(15)andmaybeofgreatvalueinidentifying
thedisabilitystatusandpsychosocialprofileofanindividualWADpatient.However,
whilethegoal of the physical treatment is pain relief and improved functional and
disabilitystatusirrespectiveoftheunderlyingphysicalcauses,currenttreatmenttends
tobebasedonatrialanderrorapproach.Measuresofphysicalimpairmenthavebeen
amissinglinkintheevaluationofpatientswithmusculoskeletaldisordersingeneral
andinpatientswithmusculoskeletaldisordersofthevertebralcolumninparticular.
Thelackofreliableandvalidmeasuresforidentifyingphysicalimpairmentreflects
the fact that patients' functional limitations and disability status have not been
anchoredtoanyidentifiableunderlyingphysicalcauses(20).Inanattempttoprevent
thechroniccourseofWADitisparticularlyurgenttoidentifymeasurablephysical
clinicalcharacteristicsinthispatientgrouptobetterdirecttreatment.
The pitfalls of linking low speed whiplash biomechanics to injury and chronic
symptomsaremany.Theaetiologyorthenatureoftheunderlyingpathophysiological
processesforWAD,especiallyingradesIII,concernsitsconstructvalidityandisthe
one that is most difficult to support by empirical evidence (21). One of the most
important criteria concerning the construct validity of WAD, grades III, is its
biological plausibility (21). This means that the association between the MVC and
subsequentsymptomsmustbesensibleaccordingtoavailablebiologicalknowledge
(21). It is therefore a special challenge to establish such a relationship in WAD,
grades III, i.e. in the absence of visible pathoanatomic signs. This requires a
differentialdiagnosticprocesswherediagnostichypothesesbuiltonpriorknowledge

16
and experience are generated, followed by research asking specific questions to
reducethenumberofproposedhypothesestoprogressivelyruleoutspecificdisorders
(22).AnexampleofsuchadiagnosticprocessconcerningpatientswithWADishow
symptomsattributedtothepostconcussionsyndromeareinaprocessofundergoinga
shift of empahsis from suspected cerebral pathology towards explanations built on
newknowledgeofneurophysiologicalpainmechanisms(2327).
1.4 Epidemiology
The incidence and prevalence of WAD are among the most controversial
epidemiological issues in medicine today(28,29). Figure 1 shows that the reported
incidenceofWADshowsagreatvariancebetweencountries.Viewsaboutthecauses
andprevalenceofchronicWADsymptomshavebeenvigorouslydebatedandopinion
is polarized (see section 1.6). It was the cohort study by the QTF on WAD which
reportedanannualincidencerateof70per100,000inhabitantsthatsetthescenefor
thecurrentcontroversyregardingtheepidemiologyofWAD(2).ThisQTFstudyhas
since been rightfully criticised for gross methodological flaws (30,31). The large
differencesinthereportedprevalenceandincidenceofwhiplashindifferentcountries
havebeenrelatedtoculturalvariablessuchasdisabilityexpectation,amplification,
Figure1RegisteredincidenceofWADindifferentcountries(seealsoreference
nr.2)

Incidencepr.100.000inhabitants
42
70
301
422
450
700
850
883
0
100
200
300
400
500
600
700
800
900
1000
Norway19941997
Quebec1987
Denmark2001
Sweden2003
GreatBritain1995
Sasketewan1987
BritishColumbia1992
Iceland2002

17
and attribution of preexisting symptoms to the trauma in chronic pain reporting
(18,32). However the most rational explanation for different incidence rates across
countriesis nonstandardised diagnostic criteria, different terminalogy and different
sourcesofdata.
The Nordic countries have very similar health care and insurance systems, and in
thesecountries peopleinvolved inMVCsusually enterthesystemthroughhospital
emergency departments. Consequently the incidence of WAD in these countries is
most often based on figures from the emergency departments and/or the insurance
companies.Despitethesesimilarities,thereappearstobeaconsiderabledifferencein
thereportedincidenceofWAD.Figure1showsthattheunofficialincidenceratein
Reykjavik,Icelandis883per100.000inhabitants(33),whichisdoubletherateofa
catchment area in northern Sweden (34) and almost three times higher than the
estimatedincidenceinDenmark(35).Anexceptionallylowincidencerateisreported
in Norway where estimates are only 42 per 100,000 inhabitants (5), a twentyfold
difference compared to Reykjavík, Iceland! The most likely explanation for the
divergingincidenceratesacrosstheNordiccountries,whichshareacommoncultural
background and lifestyle standard, is the different registration strategies and/or
differentinjuryregistrationsources.Thehighincidenceratereportedfromtheonly
emergencydepartmentin Reykjavik (33) maybebecause many people involvedin
MVCsvisit the emergencydepartment for thepurposeof rulingoutan injury after
being exposed to risk and are therefore misclassified as WAD. The source for the
incidence rate in Norway is the Norwegian Financial Services Association, which
maintainsaTrafficAccidentStatisticsdatabasewhichisthoughttocontainover90%
of all motor vehicle injuries that result in insurance claims (5). The fact that some
peopledonotdevelopsymptomsuntillaterordonotseekfinancialcompensationis
onepotentialsourceofunderreporting.ThetrueincidenceofWADinthesecountries
has therefore not yet been established as no populationbased studies have been
conductedwhichprovideanestimateoftheactualrisk.
Brisonetal.providedasoundapproachfordeterminingthenaturalcourseofWAD,
gradesIII,afterrearendMVCs(36).Theyconductedaprospective2yearfollowup
studyof385WADpatients,gradesIIIwhofulfilledcertaininclusioncriteria.They
found30%ofthepatientswithnopriorsymptomstobestillsymptomaticatthe3

18
monthfollowup,aprevalenceratewhichremainedfairlysteadyovertherestofthe
followupperiod.AnotherprospectiveCanadianstudyof2627subjects,conductedby
Suissa et al., concluded that 12% of WAD patients were still symptomatic at 6
monthspostaccident(37).Bothstudieswereconductedinprovinceswithanofault
insurance system which makes it difficult to receive compensation for pain and
disability. The former study was based on an emergency department patient
population but the latter on retrospective medical chart reviews from the insurance
companies of compensated injuries. This latter study excluded all subjects with
complaintsfromotherbodyregionsotherthantheneckandusedcessationoftime
losscompensationasanindicatorforrecovery.ThestudybyBrisonetal.isdoubtless
muchmorevalidindeterminingthenaturalcourseofWADandcontradictsthelatter
study and other oftencited studies conducted by those who speak in favour of the
(bio)psychosocialmodelofWAD(18,32,38).
1.5 Lowvelocitywhiplashbiomechanics
Crowe first used the term "whiplash" at a research meeting in 1928 to explain the
effects of sudden external accelerationdeceleration forces on the neck (39).
Concomitant with the rise in popularity of the automobile after the Second World
War, the term appeared first in the medical literature in 1945 (40). Hyperflexion,
associated with "extensor recoil" of the neck, was then proposed to be the injury
mechanism (40). In 1955, Severy et al. recorded whiplash loading to a human
volunteeronfilmandrecognisedthathyperextension,followedbyhyperflexion,was
thecorrectsequenceofeventsinrearendcollisions(41).Atthattime,hyperextension
oftheheadandneckwasthoughttoberesponsibleforthepossibleinjurymechanism
(4244). In 1969, head restraints were made mandatory in cars in USA to prevent
excessive movement of the head and neck (45). Despite the introduction of head
restraints,thefrequencyofinjuriesinlowspeedwhiplashloadingcontinuedtorise
(46).It wasnotuntil1993that McConnelldiscoveredthat nowhole cervicalspine
hyperextensiontookplaceinlowspeedMVCs(47).
Thesequenceofeventsinwhiplashmechanismisoverintheblinkofaneyeorless
than half a second (4749). Modern technology, including highspeed photography,

19
highspeedcineradiographyandaccelerometers,hasbeenusedtorecordtheoverall,
local,segmentalandcomponentkinematicresponses(49).Theoverallpicturegiven
byMcConnelletal.wasscrutinisedin1994byMatsushitaetal.whoforthefirsttime
used highspeed cineradiography to measure cervical intersegmental motions in
volunteers (50). Since then, several separate research teams have added important
pieces of information to the picture. The results across various animal, dummy,
humanneckcadaver(5156)andvolunteerstudies(48,57,58)havebeenremarkably
consistent.Thisknowledgeservesasabasisforourpresentunderstandingofwhyand
howinjuriesmayoccurinlowspeedMVCsandgivesusinsightintowhatsofttissues
maybetargeted(59).Thesummarybelowisnotallinclusivebutprioritiseswhata
clinicianmustknowwhenexaminingandtreatingpatientswithWAD.
Theneckexperiencescompression,tension,shear,flexionandextensionatdifferent
cervical levels during the different phases of low speed MVCs (56,60). The initial
phaseiscrucialforunderstandingpossibleinjurymechanismsinrearendlowspeed
MVCs(49).Theoccupant'shipsandlowback
arefirstthrustforwardsandthenupwardsuntil
thismovementreachesthetrunk(torso),which
isacceleratedforwardbytheseatback(47).The
trunk also moves upward due to straightening
ofthe thoracic kyphosisandinclination of the
seatback (47,56). This upward movement
(ramping) of the trunk causes axial
compression of the cervical spine because the
head is relatively stationary (47,49,56). At the
sametimetheforwardaccelerationimpulseon
the trunk is first transmitted to the lower
cervicalspineintheformofshearforceswhich
cause straightening of the cervical lordosis
followedbyanS shapeddynamic formof the
cervicallordosis(54,61,62).TheSshapedmotionoccursabout100millisecondsafter
the impact (depending on the acceleration impulse) and is produced by segmental
extensionat the lowercervicalspine (inducedfrombelow) and localflexionat the
uppercervicalspine(inducedfromabove)asaresultoftheinertiaofthehead(54,62
Figure2TransientunphysiologicalS
shapedmotionofthecervicalspine

duringa

collision.

20
64).Eventuallytheheadcatchesupwiththetranslatinglowercervicalspineandthe
wholecervicalspineundergoesnormalCshapedextensionandfinallyreboundsinto
flexion(53,54).Thisfinalphasemaycauseinjuriesincollisionsathigherspeed(65).
Compression of the cervical spine segments loosens the lower cervical spine
ligaments and renders them less capable to withstanding shear forces (66). The
coupledcompression/slidingofthefacetjointsresultsinabnormalposteriorrotation
aroundan instantaneousaxis ofrotation(IAR)locatedin themoving vertebra.The
rostral location of the IAR causes gapping anteriorly and further compression
posteriorly in the lower cervical spine segments (62). In some cases this injury
mechanismmayexceedthenormalphysiologicallimits(54,60,67).Theinitialsmall
uppercervicalflexiongeneratedbythecompressiveforcesandtheinertiaofthehead
is immediately reinforced by local tension in the upper cervical spine due to the
relativelyfasterupwardmotionoftheheadcomparedwiththatofthemuchheavier
trunk(59,60).Itisthereforehypothesizedthatthelowercervicalspinesegmentsmay
beinjuredasaresultofabnormalcoupledcompression,shearandrotationalforces,
while abnormal tensionflexion seems to be the main force induced in the upper
cervicalspine(56,59,60).Thisisconsistentwithclinicalresearchwhichhasidentified
thezygapophysialjointsasthesinglemostcommonsourceofneckpaininWAD(68)
Newresearchhasidentifiedsofttissueinjuriesinunembalmedcadaverssubjectedto
rearimpactsatlowspeed(69,70).Althoughrecentresearchintolowspeedwhiplash
biomechanics has enormously enriched our understanding of possible injury
mechanismsinWAD,theclinicalsideoftheproblemisstillunsolved.
1.6 Theorganicversusthe(bio)psychosocialexplanationmodel
ThediagnosisofWAD,gradesIII,isanarchetypeofthediagnosisofasofttissue
injury where the diagnosis is mainly based on the exclusion of visible trauma on
standard imaging modalities (71). As mentioned, opinioin is polarised and
controversyragesaboutchroniccomplaintsinpatientswithWAD,gradesIII,dueto
thelackofidentifiableobjectiveclinicalcharacteristics.Opinionsarequitestrongon
bothsidesasthevalidityoftheWADdiagnosisisnotonlyamedicaldilemma,but
alsoalegalandsocialone(7274).Theproponentsfortheorganicviewpointpropose

21
thatinvisibilityisnotevidenceoftheabsenceofinjury,butisratheranindicationthat
aninappropriatetoolhasbeenusedtolookfortheinjury(71).Thespokesmenforthe
opposite view state that chronic symptoms in WAD do not result from a chronic
injury.Theylookatthe MVC as a risk factor triggering diverse psychological and
social responses that contribute to the maintenance of an initial neck pain (75,76).
Neithercamphasbeensuccessfulinprovidingevidencebasedguidelinesforprimary
health care providers in general and physical therapists in particular, on how to
diagnoseandtreatpatientswithchronicWAD.(6).
1.7 Anintegratedmodelofmusculoskeletalfunction
Research is about asking and answering questions. The questions asked reflect
differentemphasesandunderstandingsandthusdirectthekindofanswersrevealed
throughtheresearch.Thecorequestionaskedinthepathophysiologicalexplanation
model is: "What hurts?" Highly sophisticated imaging techniques and surgical
procedureshavebeendevelopedto address this question. A great majority or circa
85%oflowbackpainpatientsarelabelledashaving"nonspecific"pain,asthepain
isnotspecifictoanyidentifiablepathologicalstructureonimagingmodalities(77).
Drivenbytheinadequacyofcontemporarymedicineinresolvingthecostlylowback
painproblem,researchershavestartedtoaskdifferentquestions,suchas:"Whyisthe
lower back and pelvis no longer able to sustain and transfer the loads required for
normalfunction?"(78)Toanswerthisquestion,theresearchmustexplorehowthese
regions function in order to appreciate why the patient is in dysfunction (78). The
resultofscientificenquiriestoaddressthesequestions,andinterdisciplinarysharing
of ideas has led to the development of a new integrated model of musculoskeletal
lumbarpelvicfunction(79).
Panjabi promoted this research activity into spinal problems, when in 1992, he
introducedanewworkinghypothesisforclinicalinstability(80,81).Inhishypothesis
(Fig.3) the spinal stabilizing system is conceptualised as consisting of three
subsystems:

22
The passive musculoskeletal subsystem includes vertebrae, facet articulations,
intervertebraldiscs,spinalligaments,andjointcapsules,aswellasthepassive
mechanical properties of the muscles. The active musculoskeletal subsystem
consistsofthemusclesandtendonssurroundingthespinalcolumn.Theneural
andfeedback subsystem consistsofthe various forceandmotion transducers,
locatedinligaments,tendonsandmuscles,andtheneuralcontrolcenters.These
passive,activeandneuralcontrolsubsystems,althoughconceptuallyseparate,
arefunctionallyinterdependent(80,p.384).
NewclinicalresearchforlowbackpainpatientshasbeenbasedonPanjabi'smodel,
andemphasisesdisturbancesandinteractionsbetweentheneural(control)subsystem
andactive(muscle)subsystem.(82,83).Asimilarmodel,anintegratedmodelofjoint
function,wasdevelopedbyVleemingandLeeforthepelvicgirdlebutusingdifferent
terms: form closure (passive subsystem); force closure (active subsystem); motor
control(neuralsubsystem)(78).VleemingandLeealsoaddedafourthcomponentto
themodeli.e.emotionsandawarenesstounderlinetheimportanceofthesefactorsin
promotingmotorlearningandchangeinmotorbehaviour(78,79).

Figure3–Thethreesubsystemthatcontributetospinalstabilisation(AdaptedfromPanjabi
(80))
Theseconceptual models are notnewhowever. Payr introducedhis"kineticchain"
theory at a research meeting in 1927 where he proposed that ligaments, bones,
muscles, and receptors act synergistically to provide safe, stable motion of a joint
(84).However,itisonlyinthelast1520yearsthatthismodelhasgainedincreasing
scientificandclinicalverification(8587).Theresultingresearchactivityaroundthe
preservation of joint stability from this comprehensive approach was first
concentratedonthejointsintheextremities,especiallythekneejoint(85).Theterms
functional instability and dynamic instability have been used to denote inadequate

23
functioningof theknee jointduringeverydaytasksand sportactivities (85,87,88).
Different clinical presentations of altered function have been observed that do not
correlate with the status of the passive integrity of the knee joint (88,89). This
research highlights the importance of neuromuscular control of the mechanically
instablekneeforadequatefunctioning(85).
The conceptual approach in this thesis is based on the aforementioned models and
previous research activity into the extremity joints as well as low back and pelvic
impairment (78,79,82,83,85). However, it must be recognised that significant
differences exist in the anatomy and function, as well as the mechanism of load
transferandinjury,ofthewellstudiedlumbarspineandtherelativelylessresearched
cervical spine (90). Extrapolation from the lumbar spine is therefore neither
straightforwardnorappropriate.Ascervicalspinesofttissueinjuries(sprains)arestill
thought by some as analogous to ankle sprains (91), it is interesting to recall what
Severywrotein1955:
 "The neck is able to withstand a very considerable acceleration and sustain
onlyminorsofttissueinjuries.Theseinjuriesproducesymptoms,whichlastfor
anunusuallylongperiodoftime.Thisisnotcharacteristicoftheaccident,but
characteristicofthereactionofthenecktoanytypeofpainfulcondition"(41,p.
756).
Thisisanimportantstatementasitrecognisesthatthecervicalspineisanextremely
vulnerablestructure.Indeedthecervicalspine,especiallytheuppercervicalspine,isa
verydelicatesensoryorganduetoitsdirectneurophysiologicalconnectionstovital
organsandfunctionsinthehead(9295).Thepresentshortcominginunderstanding
the underlying biological nature of WAD may be because the wrong research
questions have been asked. To understand the peculiar consequences of soft tissue
injuriesto the cervicalspine,questions like: "Whyisthecervical spine notableto
tolerate the normal loads of activities of daily living?" or "Is there some type of
functionthatisuniqueforthecervicalspine?"havetobeasked.Thelatterquestion
hasbeenaddressedtosomeextentinrecentPhDtheses(96,97),butthereisapaucity
ofresearchfocusingonintegratedandmeasurablephysicalimpairmentinthecervical
spine. A clinical model of synergistic function and dysfunction of the segmental,

24
muscular and control elements will be described in subsequent sections in order to
give a clinically relevant understanding of how dysfunctions in independent
subsystemsactsynergisticallytogeneratephysicalimpairmentinsofttissuecervical
spineinjuries.
1.7.1 Thepassivesubsystem
Orthostaticequilibriumoftheheadneckregionismechanicallybestachievedbyan
adequatecervicallordosis.Thisassertioncanbesupportedbythefactthatthecervical
lordosis is an inbuilt mechanical construction (98,99) and is a prerequisite for
adequaterangeofmotion(100).Despitethis,theclinicalimportanceofalterationsin
thecervicallordosisforoverallstabilityofthecervicalspineisdisputed(101104).
ThisisbecauseFHPanddifferentconfigurationsofthecervicallordosishavebeen
observed in patients with WAD (105,106), patients with insidious onset neck pain
(107109) and in asymptomatic subjects (110,111). As previously described (see
section 1.5), regional and segmental alterations of the cervical lordosis might be
suspectedinWADandthesemaydifferfrominsidiousonsetneckpainpatientsand
asymptomaticpeople.Mostclinicalresearchonthecervicallordosishasfocusedon
thelowercervicalspinelordosisandinafewstudiesthecervicallordosisasawhole
(112). No research has ascertained whether the upper cervical lordosis may be
increasedwhilethelowercervicalspinelordosisisdecreasedinWADpatientsorvice
versa.Suchalterationsmaybeofgreatclinicalimportancefortheoverallmechanical
stabilityoftheheadneckregionafterMVCs.
The question that many clinicians automatically ask themselves when examining
patients with WAD is: "Is it a sprain?" Hitherto they have relied on clinical
presentations of such problems and their own clinical skills because conventional
imagingmodalitieshavebeenunabletoverifytheirclinicalsuspicion.Despitemany
attempts to quantify intersegmental movements in the spine and to describe the
movementsqualitatively,nomethodhasyetbeenvalidatedtoreliablydetectminor
segmental instabilities in the spine (113). Minor segmental instabilities therefore
remainanintenselycontroversialsubjectwhilethereisnoconsensusaboutitsprecise
definition(114116).Theearlydegenerativeprocessofthespinehasbeenrecognised

25
asapotentialphysiologicalbasisforminorsegmentalinstabilities(117,118).Inmost
patientswithWAD,nosuchpathophysiologicalbasishasbeenrecognised.
Thecervicalspineisthemostmobilepartofthevertebralcolumn.Itsmobilitycomes
attheexpenseofitsmechanicalstabilitybecausethemagnitudeofbone,whichisthe
frameworkofmovement,hasbeenreduced(119).Inthefaceofwhiplashloading,the
softtissuesofthecervicalspinearethereforecriticalinmaintainingitsintegrity(90).
Research has clearly demonstrated that the noncontractile soft tissues govern the
biomechanicalresponsesofthecervicalspineunderexternalloading(120).Whenthe
cervical column is exposed to increased external forcesand deformation in MVCs,
moreandmoreligamentfibres,capsularfibres andannular fibresarebroughtinto
increasethestiffness,accordingtothedirectionsoftheloads(121).Thestiffnessof
the soft tissues is further increased by muscle action, tensing of fascia layers and
builtinmechanicalprinciplessuchasstraighteningofthecervicallordosis(121).The
invivosofttissueelasticstiffnesscoefficientisthereforenotconstantbutofahighly
variable and controllable size (122). From an engineering point of view, a column
composedofmanyfunctionalunitslikethevertebralcolumnisextremelyvulnerable
toskewloads(123).Thenonphysiologicexternalloadsappliedtothecervicalspine
inlowspeedwhiplash biomechanics (see section 1.5) may therefore have potential
hazardouseffects.
Panjabiintroducedthetermsneutralzone(NZ)andelasticzone(EZ)toexpressthe
biphasic nonlinear loaddisplacement behaviour of the soft tissues 'in vitro' (81).
Panjabiandcoworkersfoundthatunderprogressiveexperimentalinjuryconditions
theNZparameterincreasedfirst,moresothantheEZparameterandthesingleROM
parameters(124).TheyconcludedthattheNZwasthemostsensitiveparameterfor
detectingincreaseddisplacementinamotionsegment(124)andproposedthatitwas
the most appropriate parameter for describing what happens in injured motion
segmentswherenoorfewanatomicallesionscanbeobserved(81).Amajorobstacle
is that it is still not possible to measure the NZ 'in vivo', but this parameter is
neverthelessusefulasaconceptualbasisforbiomechanicalexplanationsofminoror
subfailure soft tissue injuries (81). An increase in the NZ indicates greater
displacement for a given load before resistance from the passive structures is
encountered to control the segmental motion. Conversely, less force is required to

26
producethesamedisplacement.Thisconceptisthereforeinaccordancewithaccepted
models of segmental instability (125) but highlights a loss of stiffness in the mid
rangeofamotionsegment.Hypothetically,whenprogressiveinternaldisorganisation
occurs in the collagen, its viscose and tensile material properties will be further
compromisedleadingtomorepermanentchangesintissuecompliancewhichcanbe
detectedasincreaseddisplacementattheendrangeofmotion(126).
1.7.2 Theactivesubsystem
Sincethebeginningofthelastcentury,differenttheoriesandmodels,includingthe
reflex,hierarchicalandsystemtheories,havecontributedtoourcurrentunderstanding
ofmotorcontrol(127).Differentneuromuscularrecruitmentpatternsarenecessaryto
beabletorespondefficientlytoeverchanginginternalandexternalforcesaswellas
topredictedandunpredictedperturbations(128130).Allmuscles(23oneachside)
thatconnecttheheadtotheaxialskeleton/shouldergirdlearethoughttocontributeto
the stabilization and mobility of the cervical spine albeit in different ways (131).
Many centuries ago, Leonardo Da Vinci (14521519) referring to the influence of
muscular architecture, stated: "The more central muscles stabilize, the more lateral
bendtheneck"(132).However,thisstatementdidnotgainscientificverificationuntil
the last decades. Bergmark highlighted a division of the muscular system in the
(lumbar)spineintotheglobal(superficial)andthelocal(deep)musclesaccordingto
theirbiomechanicaladvantages(133).ThedeepshortmusclesareclosertotheIARs
ofthevertebralsegmentsandthereforeundergominimallengthchangesthroughout
theROMcompared with the more superficial torqueproducingmuscles(133137).
Thissimplebiomechanicalclassificationofthemuscularsysteminthespinecanalso
besupportedfromneuralandhistologicalperspectives(138,139)andisnowgaining
increasingclinicalsignificance(82).
Cumulativeevidencesuggeststhatanunderlyinglevelofneuralcontrolisneededfor
efficientjointstabilityandisprovidedbysustained(intrinsic)andmodulated(reflex
mediated)musclestiffness(140143).Musclestiffnessisthespringlikebehaviourof
muscle and is defined as the ratio of force change to length change in the muscle

27
(142). Reflex mediated muscle stiffness is controlled by the excitability of the γ
motoneurones,theafferentsoftheγmusclespindlesystem,whicharecrucialinthis
respect (143). After integrating reflex input from various sources such as the skin,
musclesandjointreceptors(seeSection1.7.3)aswellasdescendinginformation,the
γmusclespindlesystemservesasthefinalcommonpathwayfortheregulationofthe
muscle stiffness required for various neuromuscular performances (143). In this
contextitisimportanttonotethatthedensityofmusclespindlesismuchhigherinthe
deep(layersofvertebral)muscles(144,145).Thedeepermusclesarethereforebetter
suited to
producing fine
graded reflex
mediated
muscle
stiffness than
the more
superficial
muscles.Ithas
recently been
suggested that
scaling muscle spindle counts to a motor unit number may better represent the
sensitivity of the γ muscle spindle system (146). Moreover, the distribution of the
spindles seems to be strategically arranged for a particular function. New evidence
show that the longus colli muscle has significantly greater spindle density than the
multifidus in the same cervical region, but the multifidus comprises a greater
proportionof Type I fibers(147).Themuscle spindles of thismusclepair are also
arranged differently (146,147). This might reflect the different functional
requirementsofthesemuscles,i.e.thelonguscollimayactmoreasabalancerofthe
cervicallordosis(148)whilethemultifidusactsasasegmentaladjuster(149).This
evidence suggests that the CNS recruits the deep muscles in a generic manner to
increasespinalstiffnessandrecruitsthesuperficialmusclesfordirectionalmovement
control(150).
Researchers agree that changed neuromuscular recruitment patterns may seriously
compromise the mechanical stability of the spine (82,83,85). A Swedish research
Figure4Schematicorganisationplanofthemechanismsandpathwaysby
whichthemechanicalandsensorypropertiesoftheligamentsmaycontribute
tojointstability,musclecoordinationandproprioception.(Withkind
permissionfromJElectromyogrKinesiol.ref.nr.143)

28
teamhasoutlinedtheneurophysiologicalmechanismsbehindnormalneuromuscular
recruitment patterns (143). However, what happens to the muscular system in
responsetopathologicaland/orpainfulspinalconditionsismuchdebatedbecausethe
exact mechanisms underlying such neurophysiological conditions are largely
unknown (151). Experimental research teams that have stimulated diverse passive
structuresinanimalsandthelumbarpelvisregioninmanbyshortlastingmechanical,
chemicalorelectricalstimulihaveobservedincreasedmuscularEMGactivityinboth
the deep and superficial muscles (86,152). The authors of these studies draw the
conclusionthatpainfulirritationofthepassivestructuresinvivoresultsinincreased
andprolongedmuscleactivationthatmaycauseaviciouscircleofpain.Theypropose
that the clinical picture often seen in spinal patients is one of tense and painful
paraspinalmusclesandreducedflexibility(86,152,153).Recentclinicalresearchinto
the lumbar spine and pelvis has, on the other hand, identified a more complex
phenomenonofselectiveatrophy,inhibitionand/ordelayedmuscleactivationofthe
deepmusclesandincreasedEMGactivityinthesuperficialmuscles(154157).The
resultsofthisresearchareinaccordancewithexperimentalandclinicalevidenceof
reflexinhibitioninthekneejoint(158161).Theincreasedactivityinthesuperficial
musclesinthisclinicalresearchisthoughttocounteractthereductioninjointstiffness
andstaticreflexgainfromthedysfunctionaldeeplocalmuscles(150,162).

Histologicalresearchonthecervicalmusclesindicatesthetransformationofmuscle
fibresfrom"slowoxidative"(typeI)to"fastglycolytic"(typeIIc),interdependentof
underlyingpathology,gender,ageandwhetherthemuscleinquestionis originally
moretonicormorephasic(163,164).Thisimpliesthatthestabilisingfunctionofthe
deep paravertebral and prevertebral muscles may be compromised. This is in
accordance with one pilot study and clinical observations that have indirectly
identifiedreducedstaticendurancecapacityinthedeepuppercervicalflexormuscles
andincreasedEMGactivityinthesternocleidomastoidmusclesinWAD(165).Two
otherpilotstudieshaveidentifiedatrophyofthedeepsuboccipitalmusclesinchronic
neck pain patients (166,167). Overactive superficial cervical muscles together with
delayed activity and/or atrophy in the deep local cervical muscles is strongly
suspectedofbeingapartoftheclinicalcharacteristicsofsomepatientswithchronic
WAD.

29
1.7.3 Theneuralsubsystem
The postural control system (PCS), the mechanism by which the body maintains
balance and equilibrium, has been divided into several subsystems, that is the
vestibular, the visual and the somatosensory subsystems (168170). The vestibular
systemcanonlygiveinformationabouttheorientationoftheheadinspacebutnot
abouttheorientationoftheheadinrespecttotherestofthebody(169).Anetworkof
mechanoreceptorsinthemusculoskeletaltissuehasthereforeevolvedtoprovidethis
information (171). The upper cervical spine is peculiar in this respect in that it
containsanabundanceofmechanoreceptors,likeareceptorfield,whichhavedirect
neurophysiologicalconnectionstothevestibularandvisualsystems(92,94,172,173).
This is the only somatosensory information that has direct access to the sense of
balance and sense of sight (94). As a consequence, the upper cervical spine is an
extremelyvulnerablestructureandasourceofaplethoraofsymptoms,likedizziness
(95) and visual problems (96), which do not arise from any other musculoskeletal
regionofthebody.Preciseneuromuscularcontrolofthemobileuppercervicalspine
isthereforecriticalforefficientutilisationofthesevitalorgans.Reducedawarenessof
headneckpostureandfaultycontrolovercervicalspinemovementsareofconcernin
thisthesis.
The focus in musculoskeletal disorders is now more on subtle changes in motor
controlasaresultofalteredproprioceptivefunction.Proprioceptionhasbeendefined
as the cumulative neural input to the CNS from mechanoreceptors in the soft
structures, including joint capsules, meniscoids, ligaments, discs, muscles, tendons,
fascialayersandskin(174).Thesereceptorshavevariousmechanicalandchemical
characteristicsmakingthemcapableofmonitoringvarioustypesofstimuliranging
fromlowtohighmechanicaltissuedeformation,andappliedloadaswellaspainful
damagingstimuli(85,143,175177).Movementstowardsthelimitofjointrangeresult
in progressively smaller length changes in the muscle and in progressively larger
tensionintheligamentsandjointcapsules(175).Itisthereforereasonabletobelieve
thatthemusclespindlesandgolgitendonorgans(GTOs)aremoresensitiveinmid
rangeof motion,whereas thejointreceptorsaremore sensitivetowardsextremeof
range(175).Modifyingthisviewisthefactthatthedeepparavertebralmusclesmay

30
activate through their attachment the joint capsules and ligaments throughout the
whole ROM (178). The role of the joint receptors in providing efficient protective
musclereflexesattheextremeofmotionhasalsobeenquestioned,asthefeedbackis
tooslowinrapidmovements(143).Ithasbeenproposedthattheinputfromthejoint
receptorsservesasafeedforwardorpreprogrammingmechanismthatcontributesto
musclecoordinationandjointstabilityoncenewtasksandcomplexmovementshave
been learned (143). This is in accordance with the ensemble coding theory, which
holdsthatthesensoryinformationcreatedbyallthemechanoreceptorsthatareactive
duringaspecificmotorcontrolperformanceistransmittedtotheCNSinpopulation
codes (143). This implies that ascribing a specific mechanoreceptor function to a
particular motor control function is not relevant (143). Research indicates that the
muscle spindle afferents play the first violin in this ensemble but that other
mechanoreceptors act to fine tune the afferent muscle spindle information by their
reflexeffectsontheγmotoneurones(143).
Patients with chronic WAD are difficult cases in which the joint stability may be
compromised by permanent changes in tissue compliance or direct damage to the
mechanoreceptorsandtheiraxonsbecausetheyhavelowertensilestrengththanthe
surroundingcollagenfibres(176,179).Chemicalchanges,broughtaboutbyischaemic
orinflammatoryevents,mayaffectthesensitivityofthereceptors(180,181)aswell
asreflexjointinhibitionofthemusclespindles(181183).Creepdeformationofthe
ligamentsandthedisks,inducedbypassiveloadingonanimalspine,hasbeenshown
to desensitise the mechanoreceptors within the tissue and to result in a significant
decrease or complete elimination of reflexive muscular stabilising forces in the
multifidus muscle in the lumbar spine (184,185). Altered joint biomechanics,
irrespectiveofthereasons,alsocausesdifferentmechanoreceptorstofiretoolateor
too early, too little or too much (143,186). Patients who are affected by these
conditionsareunlikelytorespondtoconventionalphysicaltherapyormanualtherapy
approaches alone. The consequent faulty recruitment muscle patterns result in the
underestimation or overestimation of the situation, making the soft tissue liable to
repeatedmicrotraumaor"selfinjury"(121,187).Thismaycauseuncertaintyforthe
injuredpersonandincreasedmuscularguarding(121,122).Thisisthoughttobean
importantfactorinthemaintenance,recurrenceorprogressionoflocalandreferred
symptoms (161,188191). Identifying and resolving disordered cervical

31
proprioceptive function is therefore thought to be an important key in preventing
chronicityinthisparticularpatientgroup.
Kinesthesiacanbedefinedasasensationwhichdetectsanddiscriminatesbetweenthe
relative weight of body parts, joint positions and movements, including direction,
amplitude and speed (192). This term therefore includes all the qualities that are
supposedtobearesultofproprioception(193)andcanbetestedactivelyinaclinical
setting.Itisthereforethemostappropriateterminclinicalmeasurementsforaltered
cervicalproprioceptivefunction.Theproprioceptivemechanismscontrollingthehead
onthebodyhavebeentestedclinicallybysimpletargetmatchingtasks.Theaimhas
eitherbeentorelocatethenaturalheadposture(NHP)afteranactivemovement(194
197) or to actively relocate a set point in range (198). Studies have found reduced
relocation accuracy in whiplash patients compared with asymptomatic people
(195,196,198)butresults vary with regardtothepresence of kinesthetic deficits in
people with insidious onset neck pain (194,197). The reliability of prior test
procedureshas not been reported, and these procedures may rely moreonpatients'
memory than their cervical proprioceptive function. Moreover, no effort has been
made to test movement control of the cervical spine during active movements.
Cervicalproprioceptionthereforeneedsfurtherclinicalscrutiny.

2 AIMS

32
Withregardtotheinformationpresentedintheintroductoryreview,thestudiesupon
whichthisthesisisbasedweredesignedtoachievethefollowingaims:
2.1Todeterminewhethersymptomcharacteristicsinwomendiagnosedwithchronic
WAD,gradesIII,differfromthoseinwomendiagnosedwithchronicinsidious
onsetneckpainandwhetherthepersistenceofsymptomsdiffersbetweenthetwo
groups(PaperI)
2.2TorevealwhetherwomenwithchronicWADsymptoms,gradeIII,demonstrate
evidenceof:
2.2.1Regionaland/orsegmentalradiographicsignsofalteredcervicallordosis
(PaperII)
2.2.2Abnormalsegmentalmotionsinthelowercervicalspine(PaperIII)
2.3Toascertainthestatusofthedeepcervicalmusclesinpatientswithchronic
WAD,gradesIIIby:
2.3.1Comparingthefunctionalperformancestatusofthedeepcervicalflexorin
theuppercervicalspineinthreegroups:patientswithchronicWAD,grades
III,insidiousonsetneckpainpatientsandasymptomaticsubjects
(PaperIV)
2.3.2Assessingthereliabilityofanultrasonographyprotocolwhenmeasuringthe
sizeofthecervicalmultifidusmuscleinpatientswithchronicWAD,grades
IIIandasymptomaticsubjects(PaperV)
2.4Todevelopnewreliableclinicalteststoascertaindeficitsincervicocephalic
kinestheticsensibilityinpatientswithchronicWAD,gradesIII,which
discriminatethemfrominsidiousonsetneckpainpatientsand/orasymptomatic
subjectsrespectively(PapersVI,VII,VIII)
3 MATERIALANDMETHODS

33
TheclinicalcharacteristicsofpatientswithchronicWADinthisthesisweredefined
byusingtestretestandcasecontroldesigns.Thereliabilityofthosetestprocedures
thathadnotbeenassessedbeforewasascertained(PapersII,V,VI,VIII).Thecase
controldesignwasusedinallstudies(exceptstudyVI)toexplorehowfrequentlythe
clinical characteristics investigated were present in patients with chronic WAD
compared with patients with chronic insidious onset neck pain (IONP) and/or 
asymptomaticsubjects.Eightstudies,withrelativelysmallsamples,wereconducted
tobetterclarifytheclinicalpictureofchronicsymptomsinpatientsdiagnosedwith
WAD,gradesIII.
A questionnaire based study (Paper I) and two radiological studies (Papers II, III)
wereconducted at Landspitalinn, University Hospital in Reykjavik, Iceland. Eighty
women (Paper I) and one hundred and twenty women (Papers II, III) participated
respectively on a voluntarily basis. There were equal groups of WAD and IONP
(Papers I) and an additional asymptomatic group (Paper II, III). The symptomatic
participantswererecruitedfromdoctorsandphysicaltherapistsoverafixed7month
periodin1998–1999inasmalltown,Reykjavik,Iceland.Theasymptomaticgroup
was a sample of convenience from hospital staff and students. The inclusion and
exclusioncriteriaforthesestudiesarepresentedinTable2.
Inclusion Exclusion
General 1. Age:16–48 1. Systematicdiseasesofanykind
2. Employedorstudent 2. Personalitychanges

34
3. Drivingacaronaregular
basis
3. Pregnancy
WAD*
Priortothecrash: 1. >1crash/accidentbeforethe
examination
1. Healthy(nosymptomsfrom
theupperpartofthebody)
2. Pronetogetmusculoskeletal
symptomspriortotheMVC
Afterthecrash: 3. Roadaccidentofanotherkind
thaninacar
2. WADgradesIII,asoutlined
intheQTF‡onWAD
4. Carcrashinruralsetting
3. Symptomsfor>6monthsand
<48months
IONP†
1. Muscuolskeletalsymptoms
fromtheupperpartofthe
bodyincludingtheneck
1.MVCoranothertypeofinjury
2. Attendstheprimaryhealth
careforhelp,becauseof
symptomsof>6month
durationand<48months
2.Signsofradiculopathyinthe
arm(s)
3. Thesymptomsareonthescale
slightsevere
Table2InclusionandexclusioncriteriainthestudiesinIceland.
*WAD(WhiplashAssociatedDisorders)
†IONP(InsidiousOnsetNeckPain)
‡QTF(QuebecTaskForce)Seereferencenr.2
Onestudyon the deep neck flexors (Paper IV) and two studies on cervicocephalic
kinesthetic sensibility (Papers VI, VII) were conducted at the Department of
Physiotherapy, The University of Queensland, in Brisbane, Australia. Twenty
asymptomatic subjects were recruited for a testretest trial (Paper VI). All three
subject groups, represented by approximately 25 subjects in each group and both
genders,wereenrolledforthetwootherstudiesconductedinAustralia(PapersIV,
VII).ThecharacteristicsofthesubjectsinstudyVIIwhoalsoparticipatedinstudyIV
arepresentedinTable3
Group1
Asymptomatic
(n=21)
Group2
NonTrauma
(n=20)
Group3
Trauma
(n=22)
Male/Female 10/11 11/9 11/11
Age(years)
26.9
r
6.4
30.0±9.1 33.4±10.6
PainDuration(months)  28.6±15.5 21.9±12.5
Paininpastweek(VAS)  3.15±2.11 4.50±2.7
Currentpain(VAS)*  1.82±2.0 3.37±2.8
NeckPainandDisabilityIndex*  20.53±11.18 39.98±18.0
*(p<0.05)IndependentTtest
Table3CharacteristicsofthesubjectgroupsinthestudiesinAustralia

35
Thesymptomaticsubjectsinthesestudiesweresoughtfromtheuniversity'sWhiplash
ResearchClinicandreferringclinicians.Volunteersfromuniversitystaffandstudents
represented the asymptomatic subjects in the Australian studies. The inclusion and
exclusioncriteriainthesestudiesweresimilartothestudiesinIceland.
An ultrasonography study (paper V) and a study into cervicocephalic kinesthetic
sensibility–(PaperVIII)wereconductedatanoutpatientmusculoskeletalresearch
clinic in Reykjavík. Ten women with chronic WAD and ten asymptomatic women
wererecruitedforstudyV,while20womenwererecruitedforstudyVIIIforeachof
thetwogroupsrespectively.Thedemographicdata,inclusionandexclusioncriteria
werethesameasinprevoiusstudies.
3.1 Investigation by questionnaires – Selfreported characteristics
(PaperI)
Symptom characteristics in chronic WAD, grades III, and chronic IONP were
comparedtorevealwhetherthesymptomsinthesetwogroupsdifferedinthechronic
setting. The standardised Nordic questionnaires for the analysis of musculoskeletal
symptomswasusedinamodifiedform.Thequestionnairewaspresentedtopatients
onarrivalattheDepartmentofRadiography.Thewomenansweredthequestionnaires
priortoradiographicexaminations(PapersII,III).Eighteenmonthsafterthesubjects
hadansweredthequestionnaires,atelephoneinterviewwasadministeredtodetermine
the overall subjective status of former complaints. The frequency distribution of
duration and nature of neck pain and related disorders were the main outcome
measures.
3.2 Radiographicinvestigations(PapersII,III)
ConventionalXrayimagesweretakeninasittingpositionwiththesubjectslooking
straight ahead (II) and in maximally flexed and extended positions (III). A special
chairwasconstructedtofixthethoraxsothatthedefinedendrangeoftotalcervical
flexionextensionmovementcouldbereachedinspace(III).Anexaminerwhowas

36
blindtothe subjectgroupsassistedtheflexionextensionmovementsandusedcold
spray in an attempt to inhibit muscle guarding in the superficial flexorextensor
musclespriortothelatterinvestigation(III).
3.2.1 Cervicallordosisanalysis(II)
Theradiogramsweredigitalisedandasoftwareprogram,NUDD,wasusedtomark
the fiducials on the radiograms (Fig. 5). The
fiducialswererecordedintheformofxandy
coordinates for each point. The sagittal
configuration of the upper cervical lordosis
wasmeasuredusingtheangleformedbylines
projectedparalleltothebaseoftheskulland
paralleltotheinferioraspectofC2.Thelower
part of the curve was measured by the angle
formedbetweentheaforementionedreference
lineforC2

andacorrespondinglineprojected
parallel to the caudal aspect of C6. The
segmental angle of each individual vertebra
wasmeasuredbylinesprojectedparalleltothe
endplateofthecranialvertebrainrelationto
theendplateofthevertebrabelow.Anegative
value indicated lordosis, a positive value
kyphosis. Two examiners marked 40
radiogramsindependentlyofeachothertoassessthereliabilityofthemeasurements.


3.2.2 Segmentalmotionanalysis(III)
Figure5Fiducialsandlinesusedtoform
themeasuredangles.

37
A new protocol (109) determined the rotational and translational motions of the
segmentsC3/C4,C4/C5andC5/C6withhighprecisionandcomparedresultsbetween
the WAD and the IONP groups as well as against a database comprising
asymptomaticwomen(n=101).Figure6showsamappingofthecontoursthatcanbe
identifiedinthelateralradiographicimageofcervicalsegmentsfromC3toC7.The
anglebetweentwovertebraeisderivedfromtheanglebetweentheirmidplanes.The
angleisconsideredpositiveifthewedgeopensanteriorly.Therotationalmotionofa
segment is defined as the difference of the angle in extension minus the angle in
flexionandisquotedindegrees.
Perpendicular lines are constructed
from the center points of adjacent
vertebrae onto the bisectrix between
the midplanes. Posteroanterior
displacementisdefinedasthedistance
between those points where the
perpendicular lines intersect the
bisectrix. Thus, displacement is
measuredalongadirectioncoinciding
(in good approximation) with the
midplaneofthedisc.Displacementis
consideredpositive iftheprojection ofthecranial centerpointis locatedanteriorly
fromtheprojectionofthecaudalcenterpoint.
Translationalmotionisthedifferencebetweenthedisplacementinextensionminus
displacement in flexion. As quotients of lengths, displacement and translational
motionaredimensionlessquantitiesasthedisplacementmeasuredinmillimetresis
dividedbythemeandepthofthecaudalvertebra.Thisnewprotocolthereforeenables
the sagittal plane angle and posteroanterior displacement to be measured virtually
uninfluenced by distortion with respect to axial rotation, lateral tilt, and offcenter
positioningofthevertebrae.
3.3 Investigationsintothedeepcervicalmuscles(PapersIV,V)
Figure6Definitionofsagittalplaneangle
anddisplacementforalowercervicalmotion
segment.Corners14arelocatedonthevertebral
contourbyacomputeraidedalgorithm.

38
The deep ventral muscles in the upper cervical spine (IV) and the deep segmental
musclesin thelowercervical spine(V)were investigatedbya functionalapproach
andamorphologicaltoolrespectively.
3.3.1 Craniocervicalflexiontest(IV)
A new test was developed to indirectly measure the functional holding (static) and
endurancecapacityofthedeepcervicalflexorsintheuppercervicalspine(161).The
subjectswerepositionedinsupinelyingandanairfilledpressuresensor(Stabiliser,
Chattanooga Pacific), was placed between the testing surface and the back of the
neck,suboccipitally,andinflated
to a baseline pressure of
20mmHg (Fig.7). A contraction
ofthedeepuppercervicalflexors
causes a subtle flattening of the
cervicallordosis(148)whichwas
registered as an increase in
pressure in the sensor. The test
was performed in five
progressive stages of cranio
cervical flexion movement.
Performance was guided by
feedback from the pressure sensor with each of the five stages corresponding to a
2mmHg increase of pressure, from 22mmHg to a maximum of 30mmHg. Surface
EMGwasusedoverthesternocleidomastoid(SCM)musclestomeasuremyoelectric
activity of the superficial flexors during the test. Electrodes were located over the
lower one third of the muscle bellies of the SCM muscles (199). Measurement of
activity in the superficial muscles was conducted to determine any changes in the
patternsofmuscleusebetweenthedifferentsubjectgroups.
3.3.2 Ultrasonographyanalysis(V)
Figure7Thecraniocervicalflexiontestdemonstrating
thevisualfeedbackwiththepressuresensorand
measurementwithsurfaceEMG.

39
A 7.5 MHz linear array transducer (Logiq 200, General Electrics, Milwaukee, WI)
wasusedtoscanthemultifidusmuscleattheC4level(Fig.8).
The subjects were positioned prone on an examination table with both arms lying
alongthesidesofthebody.Axialimageswereobtainedbyplacingthemiddleofthe
array perpendicular to the long axis
oftheposteriorneckattheC4level.
Each side was imaged separately.
The cervical multifidus muscle was
identified by the following
landmarks: inferiorly by the
echogenic vertebral laminae;
mediallybytheechogenicspinousprocessesandsuperiorlylaterallybythebrightness
of the fascia layer dividing the
semispinaliscervicismuscleandthecervicalmultifidusmuscle.Thecrosssectional
area(CSA)wasmeasuredusingonscreencallipersbyfollowingtheaforementioned
contoursofthemultifidusmuscle.Theanteriorposteriordimension(APD)andlateral
dimension(LD)weremeasuredatrightanglestoeachotherasthegreatestdistance
frombordertoborder.Twoindependentexaminersperformedallmeasurementstwice
oneachsubjecttoassessthereliabilityofthemeasurements.
3.4 Cervicocephalickinaesthetictests(PapersVI,VII,VIII)
A3SpaceFastraksystemwasusedinallthesestudies(PolhemusNavigationScience
Division,KaiserAerospace,Vermont).TheFastrakisanoninvasiveelectromagnetic
measuring instrument, which tracks the positions of sensors in threedimensions
relativetoasource.Onesensorwasalwaysplacedontheforeheadandanotherover
thespinousprocessofC7(VI&VII)oronthebackofthehead(VIII).Aninnerring
fromahelmetwasusedtoensurethesameplacementoftheheadsensorsduringall
movements.Theelectromagneticsource(transmitter)wasplacedinaboxattachedto
the back of a wooden chair. A previous study has demonstrated that the 3 Space
Isotraksystem,whichissimilarequipment,isaccuratetowithin 0.2degrees(200).
Figure8Ultrasonogramofthemultifidusmuscle
crosssectionalareaatC4levelinanasymptomatic
subject.

40
TheFastrakwas connected to anIBMcompatiblePC and continually recorded the
positionsofthesensorsrelativetothesourceduringtheentiretestsequences.
3.4.1 Relocationtests(VI,VII)
Three new tests and two previously designed tests were used in these studies. The
reliabilityofthefivetestprocedures,allofwhichusedaxialrotationmovements,was
assessed (VI). Head relocation
accuracy using the very same
fivetestswascompared across
groups (VII). A software
program was written to format
and process the data for
analysis.Thesoftwareprogram
madeitpossibleto convertthe
datadirectlyintoanglefilesand
graphs and to visualise the
entire test process in real time
on the screen. The primary
movement of axial rotation and the simultaneous coupled rotations of
flexion/extension and lateral flexion were recorded, representing the accuracy with
whichthesubjectscouldrelocatethetargetpositionsineachtask.
3.4.2 Movementtest(VIII)
A new test, called “the Fly”, was designed to detect any deficit in cervicocephalic
kinestheticsensibilitywhilesubjectsweremovingtheheadandneck.Anewsoftware
programtoformatandprocessthedataforanalysiswaswrittenforthisstudy.The
differencebetween the locationofthe foreheadsensorrelative to thesensoron the
Figure9Experimentalsetupfortherelocationtest
procedures.

41
backofthehead,bothverticallyandhorizontally,wascalculatedandthisdatawas
usedtoindicatethemovementoftheheadonthescreen.Thisdatawasthenprocessed
andprojectedintoasquare(boundingbox)onthescreen.Twocursorswerevisiblein
thesquareonthescreen:Ablueone(derivedfromthenewsoftwareprogram)tracing
unpredictable movement patterns and a black one indicating the movement of the
head(derivedfromtheFastraksystem).Thenewsoftwareprogrammadeitpossible
torecordtheabsolutedistance(radius)betweenthetwocursorsduringtheentiretest
sequenceandtostorethisinformationalongwithinformationabouthoweachofthe
threemovementpatternwasgenerated(Fig10ac).Atestretesttrialwasconducted
onhalfofthestudysample.

42
Figure10a–c.MovementpatternsABCtracedbytheFly
whichtheparticipantswererequiredtofollowbymovingtheirhead.
Statisticalanalyses
The reliability of the test procedures was assessed by intraclass correlation
coefficients (ICCs) (201) and/or by plotting the differences between repeated
measurements against their means (202). In Paper I the demographic data was
comparedby usingthettestorthe MannWhitneyUtest. TheChisquare testwas
usedtocomparethedistributionoftheanswersbetweengroups.Oddsratios(ORs)
with 95% confidence intervals were used as summary measure to compare the
complaintsbetweenthegroups.Descriptivestatisticswasusedontheoutcomeofthe
telephoneinterview.TheFisher'sexacttest,ttestandmixedmodelsofANOVAwere
usedforanybetween–groupcomparisonintheotherstudies(PaperIIVIII).Number,
subjects, means and SD were used for description of data in these studies. The
significancelevelforalltestswassetat0.05.
Ethicalconsiderations
ThelocalEthicalCommitteeatLandspítalinn,UniversityHospital,andtheIcelandic
Radiation Protection Institute approved the studies in Iceland. The Medical Ethics
Committee at The University of Queensland approved the studies in Australia. All
eligiblesubjectsgavetheirinformedconsent.TheResearchCommitteeattheFaculty
of Medicine, The University of Iceland, accepted the protocols for the studies in
Iceland. In these protocols it was presumed that the patients with WAD would be
recruited from the Emergency Department at Landspítalinn, University Hospital.
However, the Chief of the Emergency Department refused to allow access to the
department'sjournals,and sosubjectswererecruited,as previouslydescribed,from
those attending doctors and physical therapists in Reykjavik. No other ethical
considerationswerecompromisedintheclinicalstudiesinthisthesis.

43
4 RESULTS
Theclinicalcharacteristicsinvestigatedinthisthesisweredividedintoselfreported
characteristics(I)andcharacteristicsrelatedtothepassive(II,III),active(IV,V)and
neural subsystems (VI,VII,VIII) of the stability system of the cervical spine. An
overview of the results for the selfreported characteristics and each of the three
independentsubsystemsispresentedbelow.
4.1 Thequestionnaires–Selfreportedcharacteristics(PaperI)

The results of the questionnaires and followup telephone interview indicated that
women with chronic WAD, grades III, have more severe symptoms and are more
affected than women with chronic IONP. Positive answers were reported at a
significantlyhigherratebytheWAD–groupfordiffusenumbnessinthearms,lossof
memoryandpoorconcentration.(Table4).TheORsofotherspecificcomplaintsin
Table 4 was not significantly different between groups. A good response rate was
achievedfromthetelephonequestionnaire.Table5showstheresultsforthesubjects
who were still symptomatic after 18 months, indicating that more women in the
WAD–grouphadpersistentproblems.

44

Table4.ResponsesoftheWADgroup(n=41)andtheIONPgroup(n=39)tospecificquestions
      
A.TheHead     
 WAD IONP OR(95%CI) p 
 Yes/No Yes/No    
Ears
b
 14/23(n=37)
a
 11/27(n=38)
a
 1.5(0,54.4) 0.57 
Eyes
c
 22/17(n=39)
a
 18/18(n=36)
a
 1.3(0.53.5) 0.75 
Face
d
 8/27(n=35)
a
 6/32(n=38)
a
 1.6(0.45.9) 0.64 
Headache
e
 27/11(n=38)
a
 20/15(n=35)
a
 1.8(0.65.4) 0.32 
      
B.TheArms     
 WAD IONP OR(95%CI) p 
 Yes/No Yes/No    
Coldness 14/21(n=35)
a
 6/22(n=28)
a
 2.4(0.78.8) 0.19 
Numbness 25/9(n=34)
a
 10/17(n=27)
a
 4.7(1.416.4) 0.01
f

Weakness 22/13(n=35)
a
 16/11(n=27)
a
 1.2(0.43.7) 0.98 
Clumsiness 10/24(n=34)
a
 9/18(n=27)
a
 0.8(0.32.8) 0.96 
      
      
C.Thepostconcussionsyndrome   
 WAD

IONP

OR(95%CI) p 
 Yes/No Yes/No   
Depression 15/26 7/32 2.6(0.88.5) 0.10 
Dizziness 16/25 14/25 1.1(0.43.1) 0.95 
Fatigue 26/15 22/17 1.3(0.53.6) 0.68 
Lability 21/20 12/27 2.4(0.96.5) 0.10 
Anxiety 13/28 9/30 1.5(0.54.7) 0.54 
Insomnia 21/20 13/26 2.1(0.85.7) 0.16 
Restlessness 13/28 9/30 1.5(0.54.7) 0.54 
Memoryloss 18/23 3/36 9.4(2.445.4) 0.001
f

Poorconcentration 23/18 10/29 3.7(1.410.7) 0.01
f

a
Thenumberofrespondersdifferedonthesequestions
b
Pain,tinnitus,hearingloss.

c
Pain,blurredvision,diplopia,fixationtrackingproblem.
d
Pain,dysesthesia,numbness
e
Migrainetype
f
Statisticallysignificant



45


46


 WADGroup
(n=37)
IONPGroup
(n=36)
Symptomatic
Better
Same
Worse
36(97.3%)
8(22.2%)
13(36.1%)
15(41.7%)
17(47.2%)
7(41.2%)
5(29.4%)
5(29.4%)
Whatmakesyoursymptomsbecomeworse?
Physicaldemands
Mentaldemands
Bothphysical/mentaldemands
Nothingspecial

9(25.0%)
0(0.0%)
17(47.3%)
10(27.7%)

3(17.6%)
0(0.0%)
11(64.8%)
3(17.6%)
Doesworkinginasittingpositionaffectyoursymptoms?

Yes
No


30(83.3%)
6(16.7%)


11(64.7%)
6(35.3%)
Doyouusemedications?
Yes
No

17(47.2%)
19(52.8%)

6(35.3%)
11(64.7%)
Doyougetanyformofphysicaltreatment?
Yes
No

22(61.1%)
14(38.9%)

9(53.0%)
8(47.0%)
Dothesymptomsaffectyouinanyway?
No
Moderately
Severely

Istheinsurancecompensationclaimfinalised?
Yes
No


4(11.1%)
14(38.9%)
18(50.0%)


22(61.1%)
14(38.9%)

4(23.5%)
11(64.7%)
2(11.8%)







Table5Characteristicsofsymptomaticsubjectsatthefollowuptelephoneinterview.
4.2 The radiographic investigations– The passive subsystem(Papers
II,III)
4.2.1 Cervicallordosisanalyses(II)
SignsofcompromisetopassiveregionalstabilitywererevealedintheWADgroup.
Theratio ofthe lowertouppercervicalspine lordosiswaslowestforthe whiplash
group but between–group differences were not statistically significant (Figure 11).
The C4/C5 level in the WAD group was significantly more kyphotic than the
asymptomaticgroupwithameandifferenceof3°(95%CI:0.8–5.2).Thealignment

47
of other segments was not significantly different between groups.

48
15%
27%
32%
85%
73%
68%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Whiplash
Insidiousonset
Asymptomatic
Meanproportion
Uppercervical
spine
Lowercervical
spine
Figure11Ratiooflowertouppercervicalspinelordosis.
4.2.2 Segmentalmotionanalyses(III)
The passive segmental stability in the lower cervical spine was compromised at a
higherrateinwomenwithchronicWADthaninwomenwithchronicIONP.Thiswas
demonstratedwhenthegroupswerecomparedonsegmentalrotationalmotion(Table
6)andonmeasuredversuspredictedtranslationalmotionsforsegmentsC3C6(Table
7).
Segment Group n
Angular
values
Group
Differences
Values
Group
Differences
p
Dvoráketal.1993¶
C3C4
WAD* 34 19.3°(3.70)
3.50°(5.05) <0.001§
18.5°(4.57)
IONP† 35 15.8°(3.96) 16.5°(2.51)
WAD 34 19.3°(3.70)
4.10°(4.13) <0.001§
ND‡ 92 15.2°(4.27)
C4C5
WAD 34 21.1°(4.07)
2.60°(4.90) 0.01§
21.6°(5.15)
IONP 35 18.5°(3.64) 19.3°(4.03)
WAD 34 21.1°(4.07)
4.10°(5.14) <0.001§
ND‡ 95 17.0°(5.46)
C5C6
WAD 34 21.3°(4.69)
0.93°(5.98) 0.39
21.3°(5.49)
IONP 34 20.3°(4.13) 16.8°(6.00)
WAD 34 21.3°(4.69)
3.40°(6.15) <0.001§
ND‡ 92 17.9°(6.60)
Table6ComparisonofMeanRotationalMotionsintheSagittalPlane(1SD'sinparenthesis)
*WAD(WhiplashAssociatedDisorders)
†IONP(InsidiousOnsetNeckPain)
‡ND(NormalDatabase)
§p<0.05(Independentttest).
¶Atraumagroupandadegenerativegrouprespectively(seereferencenr.12)
SignificantlymorewomenintheWADgrouphadsegmentalrotational/translational
hypermobility(Table8)accordingtothedefinitionused(Figure1013).Withrespect

49
to translational hypermobility alone (measured values minus predicted values), no
significantdifferencewasfoundbetweengroups.
Segment Group n
Translation,
actual‡
Translation,
predicted‡
Difference:
Actual
minus
predicted‡
Difference:
Actual
minus
predicted§
Actual
versus
predicted
values
p
C3C4
WAD*
34
20.79(5.69) 18.51(3.53) 2.27(6.29) 0.43(0.96) 0.04¶
IONP† 35 17.07(4.69) 15.42(3.88) 1.65(4.24) 0.40(0.96) 0.03¶
C4C5
WAD 34 19.73(5.70) 18.36(3,40) 1.37(6.18) 0.28(1.02) 0.21
IONP 35 16.89(4.65) 16.35(3.25) 0.54(5.11) 0.16(0.89) 0.54
C5C6
WAD 34 12.41(5.94) 10.49(2.30) 1.94(4.95) 0.36(1.12) 0.03¶
IONP 34 11.26(4.46) 9.86(2.04) 1.40(4.38) 0.37(1.09) 0.07
Table7ComparisonofMeanTranslationalMotionsintheSagittalplane(1SD'sinparenthesis)
*WAD(WhiplashAssociatedDisorders)
†IONP(InsidiousOnsetNeckPain)
‡Inunitsofmeanvertebraldepth.§InunitsofSDofthenorm.¶p<0.05(Pairedttest).
Rotational Translational Normal Total
WAD* 6 6 22 34
IONP† 0 3 32 35
Total 6 9 54 69
Twosidedp=0.01
Table8Fisher'sExactTestoftheRelationshipbetweenHypermobilityandNormalSegmental
Mobility
*WAD(WhiplashAssociatedDisorders)
†IONP(InsidiousOnsetNeckPain)


50
Figure12aAnexampleofdocumentationofrotationalhypermobilityinanindividualcase.The
actualrotationintheC4/C5segmentdifferedbymorethan±1.96SDfromthenormaldatabase.
Inthisfigureaswellasinfigures12b13b:solidline:normalmean;errorbars:measurement
errors(1SD).
Figure12bTheactualandpredictedtranslationalmotionforthesameindividualasinFig.12a
forcomparison.
Figure13aTheactualrotationalmotioninanindividualcase.

51
Figure13bAnexampleofdocumentationoftranslationalhypermobilityforthesameindividual
asinFig13a.TheactualtranslationintheC3/C4segmentdifferedbymorethan±1.96SDfrom
itspredicted(normal)value.
4.3 Thedeepcervicalmuscles–Theactivesubsystem(PapersIV,V)
4.3.1 Craniocervicalflexiontest(IV)
The craniocervical flexion test (CCFT) was able to discriminate between
symptomatic and asymptomatic subjects, but no statistical difference was found
betweenthetwosymptomaticgroups.Theanalysisrevealedastrongpositivelinear
relationshipbetweentheEMGmeasuresoftheSCMmusclesandthestageoftheC
CFT,buttherelationshiplevelledoffforthewhiplashgroupatthehighestpressure
target.BoththeneckpainandwhiplashgroupshadsignificantlyhigherEMGvalues
thanthecontrolgroupateachstageoftheCCFT(Figure14).

52
0
0 , 1
0 , 2
0 , 3
0 , 4
0 , 5
0 , 6
0 , 7
0 , 8
0 , 9
22mmHg 24mmHg 26mmHg 28mmHg 30mmHg
Teststages
NormalisedRMS
C o ntro ls
N e c k P a in
Whipla s h
Figure14ThemeansforthenormalisedRMSvaluesforsternocleidomastoidineachstageof
thecraniocervicalflexiontestforcontrol,insidiousonsetneckpainandwhiplashgroups.
Thedifferencesbetweenthetargetpressureandthemeanpressureachievedforeach
stageofthetestforeachgrouparepresentedinFigure15.Withineachteststage,the
mean shortfalls in pressure for the neck pain and whiplash groups were not
significantlydifferent,butthoseforbothgroupsweresignificantlygreaterthanforthe
controlgroup.

53
0
0,5
1
1,5
2
2,5
3
3,5
22mmHg 24mmHg 26mmHG 28mmHg 30mmHg
Teststages
PressureshortfallsmmHg
Controls
NeckPain
Whiplash

Figure15Themeansfortheshortfallinpressurefromthetargetpressuresforeachstageofthe
craniocervicalflexiontestforcontrol,insidiousonsetneckpainandwhiplashgroups.
4.3.2 Ultrasonographyanalysis(V)
TheultrasonographymusclemeasurementsattheC4levelwerefoundtobereliable
for the asymptomatic group and for the symptomatic group if the same tester
performed the measurements. The wider limit of agreement for the intertester
measurementsinthesymptomaticgroup(Fig.16andFig.17)wasduetoobliteration
ofthebrightnessofthefascialayerbetweenthesemispinaliscervicismuscleandthe
cervicalmultifidusmuscle.Asignificantdifference,inthecrosssectionalarea(CSA)
of the cervical multifidus muscle, 0.23 cm
2
 (95% confidence interval, 0.13 – 0.33)
wasfoundbetweentheasymptomaticandthesymptomaticgroup.

54
0,5
0,4
0,3
0,2
0,1
0
0,1
0,2
0,3
0,4
0,5
0 0,5 1 1,5 2
Averageoftester1andtester2
Meandifference(tester1tester2)
meandifference+2SD
meandifference2SD
meandifference
Figure16Plotofintertesteragreementfortheasymptomaticgroup.Meandifferenceis0.02cm
2

and2SD(+0.18).
0,5
0,4
0,3
0,2
0,1
0
0,1
0,2
0,3
0,4
0,5
0 0,5 1 1,5 2
Averageoftester1andtester2
Meandifference(tester1tester
2)
meandifference2SD
meandifference+2SD
meandifference
Figure17Plotofintertesteragreementforthesymptomaticgroup.Meandifferenceis0.07cm
2

and2SD(+0.30).
4.4 The cervicocephalic kinesthetic tests – The neural subsystem
(PapersVI,VII,VIII)
4.4.1 Relocationtests(VI,VII)
Theresultsofthereliabilitystudy(VI)areshowninTable9.Theteststargetingthe
naturalheadposture(NHP)weretheeasiestonesandweremorereliablethanthetest

55
targetingasetpointinrange.Thisstudyusedbothintraclasscorrelationcoefficients
(ICCs)andplotsofthebetweendaydifferencesagainsttheirmeans(201,202).The
study confirmed that the plots are superior to ICCs in rehabilitation research. The
secondstudy(VII)comparedheadrelocationaccuracyamongpatientswithchronic
WAD and IONP and asymptomatic subjects when targeting the NHP and complex
predeterminedpositions.Asignificantdifferencewasfoundbetweengroupsinoneof
the tests targeting the NHP (Test 1) (p = .001). Post hoc pairwise comparisons
revealed a significant difference between the asymptomatic group and each
symptomatic group. The difference between the symptomatic groups was non
conclusiveduetolowpower,butadefinitetendencytowardsgreaterrelocationerrors
was observed in WAD subjects. None of the other four tests revealed clinically
importantdifferences.
Test Target
Position
Directionof
movement
Relocation
error
Day1
Mean
(SD)
Relocationerror
Day2
Mean
(SD)

ICC
Test1 NHP Fromleft 2.16°
(1.36)
2.96°
(1.20)
0.44
NHP Fromright 2.45°
(1.48)
2.26°
(1.18)
0.35
Test2 NHP Fromleft 3.20°
(1.90)
2.87°
(1.57)
0.82
NHP Fromright 3.54°
(2.75)
3.55°
(2.61)
0.62
Test3 NHP Fromleft 5.01°
(3.38)
5.32°
(3.56)
0.72
NHP Fromright 6.78°
(5.02)
6.68°
(4.28)
0.74
Test4 NHP
After

f
2.04°
(1.46)
2.81°
(1.62)
0.67
Test2 30° Toleft 7.19°
(3.87)
5.81°
(4.20)
0.74
30° Toright 5.03°
(3.37)
5.39°
(3.71)
0.69
Test3 30° Toleft 7.05°
(5.73)
6.68°
(5.63)
0.61
30° Toright 4.80°
(3.20)
5.31°
(5.03)
0.52
Test5
f
During
movement
4.77°
(3.19)
4.86°
(3.05)
0.90
Table 9  Withindays average relocation error following axial rotation and the ICC’s for
betweendayagreement(n=19).
4.4.2 Movementtest(VIII)
Thisstudyinvestigatedthereliabilityanddiscriminativeabilityofanewtest,called
"the Fly", designed to detect the accuracy of neck movements. This study again

56
confirmed that plotting the difference against the mean was more appropriate than
calculating ICCs. Repeated measure ANOVA revealed a significant difference
between groups. The Tukey posthoc test showed significant betweengroup
differencesforeachmovementpatternasshowninTable10.Foreachsuccessivetrial
a slight improvement for the asymptomatic group and a slight worsening for the
WADgroupwasdetected.
95%Confidence
Interval
Movement
Pattern
Group
Error
magnitude
[mm]
Lower
Bound
Upper
Bound
p
A
Asymptomatic 3.97 3.58 4.36
.02
WAD 5.17 4.23 6.11
B
Asymptomatic 3.51 3.10 3.93
.01
WAD 4.65 3.94 5.36
C
Asymptomatic 3.97 3.50 4.43
.03
WAD 4.97 4.09 5.86
Table10Errormagnitudesand95%confidenceintervalsforeachmovementpatternforthe
asymptomaticgroup(n=20)andtheWADgroup(n=20).

57
5 DISCUSSION
The present investigations have identified a definite pattern of musculoskeletal
impairmentinasubgroupofpatientsdiagnosedwithchronicWAD,gradesIII.These
patients have specific clinical characteristics related to the stability system of the
cervical spine. This impairment pattern clarifies the clinical picture of chronic
complaints in WAD. Moreover, this pattern may be linked to the unphysilogic
movements documented as occurring during the early phase of a rearend collision
(seesection1.5).Theresultsfromthequestionnairessuggestthatwomenwithchronic
WAD are on average more affected than women with chronic IONP (203). These
self–reported results were strengthened by the results from the two radiographic
investigations,inwhichthesamewomenparticipated.Theseinvestigationsrevealed
thatthepassiveintegrityofthecervicalspinemaybecompromisedinsomewomen
withWAD(204,205).Theresultsoftheotherstudiesinthisbodyofresearchmakeit
possibletoproposeaninterlinkedpatternofimpairment.Itmaybereasonedthatthere
couldbeassociationsbetweentherelativelyincreasedlordosisintheuppercervical
spineinsomepatientswithchronicWADandthereducedcontractilecapacityofthe
deep ventral flexors revealed by the CCFT (204,205). The relatively decreased
cervical lordosis and increased segmental motion in the lower cervical spine
(204,205),alongwiththedecreasedsizeofthecervicalmultifidusmuscle(207),may
alsobeinterlinked.Thedeficienciesinrelocationaccuracyandmovementcontrolof
the cervical spine (208210) close the vicious circle of impaired musculoskeletal
function in the stability system of the cervical spine, that exists in a subgroup of
patientswithchronicWAD.

Inthevariousstudiesthatcomprisedthisreserach,thechronicWADsubjectsmore
oftenexhibitedhighermeasurementsofpain,disabilityandimpairmentthanthosein
theIONPgroupsand/ortheasymptomaticgroups.Nevertheless,thebetween–group
varianceoverlappedtoadifferentdegreeforeachclinicalcharacteristicinvestigated.
The results therefore suggest that the variance in clinical characteristics in patients
diagnosed with chronic WAD, grades III, is greater than earlier anticipated. The
following discussion relates to the clinical characteristics of the three independent

58
subsystemsofthecervicalstabilitysysteminpatientswithchronicWAD,butstarts
withtheselfreportedcharacteristics.

5.1 Self–reportedcharacteristics(PaperI)

Theresultsofthequestionnaireandfollowuptelephoneinterviewstudyindicatethat
womenwithchronicWAD,gradesIIIaremoreaffectedthanwomenwithchronic
IONP.Strongconclusionsfromthecomparativelysmallnumbersofsubjectsshould
be avoided, but the results of the questionnaires revealed that the most marked
differencesbetweenthetwochronicneckpaingroupswererelatedtocomplaintssuch
as memory loss, poor concentration and diffuse numbness in the arms (Table 4).
Uppercervicalspinedysfunction,notinvestigatedinthesegroups,likelyexplainsthe
twoformercomplaints. Pain from dysfunctional upper cervicalspinestructureshas
directaccesstothelimbicsystem,thalamusandfrontalcortexthroughthetrigeminal
nuclei complex in the upper spinal cord and brainstem (25,27,95). The observed
between–group difference regarding numbness in the arms (Table 4) may be a
reflectionofthefactthatmorewomenwithWAD,gradesIII,exhibitedcompromises
tothepassiveintegrityofthemidcervicalspinethanwomenwithIONP(204,205).It
iswellestablishedthatneuraltissueissensitivetotractionforces(211214),andsuch
forces may be induced on the brachial plexus at the moment of an MVC (215).
Kyphotic and hypermobile mid–cervical segments (204,205) may maintain a low
traction force on the cervical spinal nerves as they are fixed in the gutter of the
transverseprocesses. Increasedactivityin thescaleneand pectoralis minormuscles
may induce a compressive force on already irritated nerve fibres (216). This may
explain why numbness in the arms often develops weeks or even months after the
accident in the absence of clinical signs of nerve compression. This hypothesis
warrantsfurtherinvestigation.
Itisstronglyrecommendedthatthefirstlevelofdistinctionintheseeminglychaotic
WAD symptomatology be the classification of the symptoms according to whether
they stem from the upper or the lower cervical spine. For decades this has been a
common clinical practice in the treatment of other neck patients but is seldom
mentionedinresearchonpatientswithWAD.Thismayindicatethatcomplaintsfrom

59
patients with chronic WAD have been underestimated or misrepresented. As has
already been mentioned (see section 1.6), a substantial number of contemporary
medical experts attribure the symptoms of chronic WAD to purely psychosocial
factors (18,32,38,75,91). However, no study has demonstrated that patients with
chronic WAD have a psychological profile distinct from other patients with
musculoskeletal and neurological disorders (217,218). There is evidence in fact to
suggestthatpsychologicalresponsesdevelopafterphysicalsymptoms(219221)and
tend to improve parallel to the patients' somatic improvements (222224). The
doubters contend that no initial injury nourishes the chronic complaints of chronic
WADpatients(18,32,38,75,76,91),buttheirmedicalthinkingmaybeseverelybiased
bysocialinfluences(73).Researchhasascertainedthatthereisindeedaninteraction
betweenphysicalandpsychosocialfactors,andthisview,arguedherebyTurk(225),
isnowwidelyaccepted.
"The experience of pain is a complex amalgam maintained by an
interdependentset of biomedical,psychosocial,and behaviouralfacts,whose
relationships are not static but evolve and change over time. The various
interactingfactorsthataffectanindividualwithchronicpainsuggestthatthe
phenomenon is quite complex and requires a biopsychosocial perspective"
(p.24)
Thecriticalpointintimeforthechronicmanifestationofsymptomsisabout3months
post motor vehicle collision, after which time most patients with WAD do not
improve(36,219,220).Thismeansthatacriticalevaluationofsymptomaticsubjects
withWADmusttakeplacebeforethispointintime,definitelynolater.Itisimportant
tobeabletodistinguishtheprimarysymptoms,bothintheacuteandchronicphases,
fromthosethatdevelopsecondarilyduetocompensatorymechanisms.Whennosuch
distinction can be made, the treatment regimen tends to be preoccupied with the
consequencesratherthantheunderlyingcausesoftheproblem.Identifyingthebasic
impairmentthushelpstodefinetheprimarysymptoms.

60
5.2 Thepassivesubsystem(PapersII,III)
AftervonLackum'sconjecturein1924thatinstabilityinthelumbosacralregionisa
causative factor in clinical symptoms (226), many attempts have been made to
establish accurate criteria for defining compromises to the passive integrity of the
spinal segments. This reflects the longstanding and deeply rooted assumption in
medicinethatthemostvaliddiagnosesarethosewhoseaetiologyisknown;andasa
corollary, that the most effective way of establishing the validity of a clinical
syndromeistoelucidateitsaetiology(8).Avitalcriterionisthereforethebiological
plausibility of a syndrome  meaning that the association between cause and effect
mustbesensibleaccordingtocurrentbiologicalknowledge.Thishasbeenthemain
problem concerning WAD, grades III (see section 1.3). However, what is
biologically plausible depends upon the biological knowledge of the day. Recent
advances in low speed whiplash biomechanics have clearly demonstrated that the
passive structures of the cervical spinal segments may be threatened in rear–end
MVCs(seesection1.5).Theresultsofthetworadiographicstudiespresentedinthis
thesisgiveusacluethat thisis thecase fora subgroupof patientsdiagnosed with
chronicWAD,gradesIII.Whentheresultsofthefirstthreeinvestigationsconducted
on the very same study samples are viewed as a whole (203205), a relationship
between biological cause and biological effect and the subsequent clinical
presentation of symptoms is therefore plausible for a subgroup of patients with
chronicWAD,gradesIII.

Researchintothebiomechanicsoflowspeedwhiplashinjurieshasdemonstratedthat
the mid cervical spine is the main transition area in the nonphysiologic S–shaped
cervical movement produced during rearend collisions (62). This concurs with the
kyphoticalignmentoftheC4vertebraandincreasedsegmentalmobilityoftheC3/C4
andC4/C5vertebraefoundinthewomenwithchronicWADinthiscurrentresearch
(204, 205). The kyphotic alignment of the mid cervical spine greatly reduces the
weightbearingfunctionofthecervicalspineasawhole(227)andimposesmoreload
ontheintervertebraldisc(228).Tocompensate,thesuperficialmusclesincreasetheir
activity (128) so that the weight of the head can be adequately supported. The
observed increased lordosis in the upper cervical spine may be the way the body

61
compensatesforthedecreasedmechanicalstabilityofthelowercervicalspine.The
increased lordotic alignment in the upper cervical spine is mainly caused by the
positionoftheatlas.Theatlasisthevertebrathatcontributesbyfarthemosttothe
totalcervicallordosiseveninasymptomaticsubjects(204,229).Thismayparallelthe
clinicalobservationthatpatients,whohavebeenexposedtomorethanonerearend
collisionandhavebeentrainedafterthefirstcollisiontorestorethenormalcervical
lordosisandtocarrytheirheadproperly,commonlyreportthatthecarriageoftheir
headchangesimmediatelyafterthesecondcollisiontowardschinpoke.
Aclinicalexperimentalstudy,conducted61yearsago,on100asymptomaticyoung
subjects,demonstratedanincreasedlordosisintheuppercervicalspineanddecreased
lordosisinthelowercervicalspineinallparticipatingsubjectswhenloadwasapplied
totheregion(230).Thesubjectshadtobear12kilosontheirheadinonepartofthe
studyand18kilos(12kilosforwomen)intheirarmsoneithersideinanotherpartof
thestudy.Itcanbereasonedthatthesegreaterloadconditionsincreasedtheactivity
inthetorque–producingsuperficialmusclesandthatthedeepparaandprevertebral
musclescouldnotmaintainthenormalalignmentofthecervicallordosisundersuch
highloadconditions.Thealteredconfigurationofthecervicalspinedemonstratedby
thewomenwithchronicWAD(204)maythereforebetriggeredbypainfulconditions
and/or mechanical segmental instability as a consequence of the unphysilogic
movements occurring during the early phase of rearend collisions. The altered
configurationmaybemaintainedbythemuscleimbalancebetweenthedeepertonic
musclesandthemoresuperficialtorque–producingmuscles(seesections1.7.2and
5.3).
Theincreasedsegmentalmotionobservedinthemidcervicalspineinwomenwith
chronic WAD, grades III (Table 6 and Table 7), contradict the widely held
assumptionthatonlyreducedcervicalspinemobilitycharacterisesWAD,gradeII,as
isdefinedintheQTF classificationofWAD(Table1).Inthis research,theC3/C4
andC4/C5segmentsinpatientswithchronicWAD,gradesIII,exhibitedincreased
sagittal plane segmental motion when compared to both a normal database and to
women with chronic IONP (205). Clinical experience indicates that increased
segmentalmobilitymaybemaskedbyunrelentingmusclestiffnessinsomepatients
withchronicWAD.Themethodologyusedinthecurrentresearchtookadvantageof

62
thisclinicalknowledge(205).ItseemsthatsomepatientswithchronicWAD,grade
II,mayhavereducedROMduetomuscularstiffnessandacombinationofincreased
decreasedsegmentalmotionsindifferentcervicalspinesegments.GradeIintheQTF
classificationofWADassumesthat when the total cervical ROM is within normal
limitsnothingiswrongwiththemobilitystatusofthatpatient.However,thisisnot
necessarily so. Clinicians have known for a long time that although the ROM
parameter may be normal, some cervical segments may exhibit a combination of
decreasedincreasedsegmentalmotion.TheROMparametermeasuresthereforeonly
generalmobilityandisnotsensitivetoanunderlyingincreaseinsegmentalmobility
in one or more spinal segments. This has been clearly demonstrated through
cineradiography(F.Kaltenbornpersonalcommunication2001).Suchadistinctionin
themobilitystatusofthecervicalsegmentsisessentialinclinicalpractise.Atthevery
minimum, therapists treating the spine have to know when to mobilise, when to
stabiliseorwhentoleavethesegmentalone.Thequestionthatmustsubsequentlybe
answerediswhetherthesegmentthatneedsmobilisation/stabilisationhasaslightora
significant degree of decreased/increased motion. The answer to this question is
thoughttobeanimportantfactorinpredictingtheprognosis.Decisionsaboutthetype
oftreatmentdependonthedegreeofimpairedmotioni.e.whethersegmentalmotion
isslightlyorsignificantlyaffected.Itisthereforeapparentthatdividingpatientswith
WADintogradesIIIaccordingtothetotalROMparameterhasverylimitedvaluein
guidingtherapeuticintervention,bothintheacutechronicphases.
The new precision
measurement protocol
developed by Frobin et al.
(113) has several advantages
over prior protocols which
measure the position of the
vertebrae from static
flexion/extension radiograms
(231233). However, the
main weakness of the new
method is that the baseline
measurementsfromwhichthepredictedtranslationalmotioniscalculatedisderived
Figure18aAnexampleofrotationalhypermobilityinthe
C4/C5andC6/C7segments.

63
from the measured segmental rotational motion. The following example best
demonstrates this fault: A woman with WAD exhibited considerable increased
segmental rotational motion in the C4/C5 segment or 30.1° (Fig. 18a) The actual
translational motion in this segment was 4.11 mm, which was one of the greatest
translationalmotionsmeasuredinthiscohort.However,asthepredictedtranslation
perdegreeofrotationamountedtoalmostthesameamount,duetothegreatextentof
rotationalmotioninthissegment,nodifferencebetweenactualandpredicted
translational motion was
detected (Fig. 18b).
Consequently the
translational motion in this
segment was judged to be
normalbythisprotocol.However,segmentC5/C6inthesamewomandemonstrated
abnormaltranslationalmotionasthecorrespondingrotationalmotionwaswellwithin
thenormallimits(Fig18a18b).Thenewprotocolisthereforenotverysensitivefor
detecting increased translational motion in segments with abnormal increased
rotational motion. This example shows how difficult it is to establish a valid
measurementmethodforintersegmentalspinalmotions.Ithasbeensuggestedthat,to
makethetranslationalparametermoresensitive,itshouldbemeasuredseparatelyin
flexionandextension(234).
Theterm"clinicalinstability"usedtobeusedprimarilytodescribethe'instabilityof
symptoms'inonepopulardefinitioninthe1980s(235).Biomechanicalconsiderations
ofintersegmentalmotionscameonlylatertohelpexplainthesesymptoms(114).In
thequestionnairestudy,themajorityofwomenwithWADcomplainedaboutintense
tirednessinthebackoftheneck,heavinessofthehead,orofincreaseddeep/heavy
neckpainwithapressureheadachewhensittingwiththeheadneckinasemiflexed
position (203). Mechanical instability of the mid cervical segments (204,205) may
helptoexplainthesecomplaintsandmayindicatedamagetotheintervertebraldiscs
(236)atthemidcervicallevelsinsomeneckpainpatients.Furthermore,researchhas
demonstrated that motion in a mechanically dysfunctional cervical spine has a
tendencytostartinthehypermobilesegments(237)whichmayexplainthechronic
courseofsymptomsinsomepatientswithWAD.However,asignificantportionof
thewomendidnotshowsignsofmechanicalinstabilityaccordingtothenewprotocol
Figure18bThetranslationalmotioninthesameindividualas
inFig.18a.

64
used,despitereportingtheaforementionedcomplaints(203,205).Thesewomenmay
be affected by painful zygapophysial joint pain (68) which in turn may inhibit the
deep paraspinal muscles (238). This may be an important contributing factor in
deficient neuromuscular control of the cervical spine or functional/dynamic
instability,whichisnowanacceptedconditioninotherjoints,forexampletheknee
jointandthelumbarspine(82,83,8589).Deficientmechanicaland/orneuromuscular
controlofthecervicalspinemaythereforebethesinglemostimportantfactorinthe
maintenanceorprogressionofsymptomsinpatientswithchronicWAD.
5.3 Theactivesubsystem(PapersIV,V)
Theresultsofthisresearchindicatethatthedeepmuscularsystem–thelonguscapitis
–longuscollimusclesandthemultifidusmuscleattheC4level–wasdysfunctional
in patients with WAD (206, 207). The craniocervical flexion test (CCFT) is an
indirecttestoftheanatomicalactionofthedeepventralmusclesintheuppercervical
spine,butnodirecttestofthesemusclesisapplicableinaclinicalsetting(206).The
results showed that this test could not to distinguish between patients with chronic
WADandchronicIONPandsuggestthatthemusclereactionwasagenericreaction
toneckpain.
Littleattentionhasbeenpaidtothecervicalmultifidusmuscleintherehabilitationof
patients with neck disorders. The results of the reliability study for the
ultrasonographymeasurements(207)indicatethatthesizeofthecervicalmultifidus
muscleattheC4levelmaybediminishedinsomepatientswithchronicWAD,which
meansthatthemultfidusmusclewillnotbeabletofulfilitssegmentalstabilisingrole
in the mid cervical spine. It is strongly suspected that the clinically observed
unrelentinghyperactivityinthesuperficialneckextensormusclesisacompensatory
actiontobalancetheheadonamechanicallyand/oradynamicallyunstablecervical
spine. The present study suggests that it is now urgent to conduct research to
scrutinizethedeficientfunctionofthissmallbutimportantcervicalmuscleandmore
importantly, to examine how imbalance between the deep and superficial dorsal
cervicalmusclesmaycontributetothemaintenanceofsymptoms.Inthemidcervical
region,thesmallcervicalmultifidusandrotatormusclesarethemainmuscleswith

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directattachmentstothebonyvertebraeasthesemispinaliscervicisattachesonlyto
the tip of the spinous processes in this area and has its major attachments to the
second and seventh cervical vertebrae (239). It can therefore be reasoned that the
cervicalmultifidusmusclehasavitalroleinsegmentalalignmentandintersegmental
controlofthemidcervicalregion.

Untilrecently,humanvolunteerstudiesconcludedthatinunawaresubjects,theneck
musclesreactedtoolatewithtooweakacontractiontoinfluencelowspeedwhiplash
biomechanics (62). However, new research indicates that the superficial cervical
muscles, especially the ventral ones, are active early in rearend collisions and can
sustainalengtheningmusclecontractionandpotentialmuscleinjury(240,241).This
mechanismofinjurymayexplaintheinitialsymptomsofmusclestiffness;tenderness
andpaininmanywhiplashpatientsthatissimilar,ifnotidentical,tomuscleoveruse
syndromesassociatedwithexerciseandsports(242).Thevalidityofthisassumption
isstrengthenedbythefactthatthesesymptomssubsideinmostcases.However,such
muscle injuries may become chronic due to positive feedback loops from
overstretchedmusclespindlesthatsendacontinuousdischargeofafferentimpulsesto
the CNS (243). It is well established in electronic engineering that such positive
feedbacksystems tend togrowin amplitude