Erika Nelson-Wong, Michal Glinka, Mamiko Noguchi, Helene ...
Transcript of Erika Nelson-Wong, Michal Glinka, Mamiko Noguchi, Helene ...
CanadianSocietyforBiomechanicsAnnualMeeting–July20,2016
ErikaNelson-Wong,MichalGlinka,MamikoNoguchi,HeleneLangevin,RhondaMaple,JimFox,andJackCallaghan
AMultifactorialProblem
MechanisticPathoanatomicSpinalLesions
Imaging≠diagnosis
Kent&Keating,2005
Behavioral/PsychosocialKinesiophobiaà Hypokinesia
Roleofmechanics?
Leeuwetal.,2007
AlteredMovementStrategiesMaladaptiveMovement
Causaloradaptive?
Hodges&Smeets,2016Nelson-Wongetal.,2010,2013
PathophysiologicalModelConnectiveTissue(perimuscularfascia)
InflammatoryProcessesInadditiontoabovefactors
Langevin&Sherman,2007
¡ FunctionoftheTLF§ Sustains/distributesloads§ Stabilizesspinalstructures§ Attachmentpointformuscles§ Sensesbodypositionandpain
¡ DecreasedTLFshearplane
mobilityinpeoplewithns-LBP▪ Langevinetal.,2011
¡ ReplicatedinporcinemodelwithsurgicalinjurytoTLF
▪ Bishopetal.,2016 Willardetal.,JAnat(2012)221,507-536
¡ Investigatetheinfluenceofasimulatedmuscle‘sprain’injuryonthestressrelaxationresponseoftheTLFusingaporcinemodel§ Expectedsamplesfrominjuredpigstohavedecreasedstressrelaxationresponse(lowerstressdecay)thanthosefromhealthypigs.
StrainEnergyandHysteresisGlinkaetal.,Poster#T49,Thursday
StiffnessNelson-Wongetal.,ASB,poster
• 10domesticswineàInjured(n=5)andControl(n=5)• Unilateral surgical injury (4 cm2 at the L3/4 level) à usual
activity• Euthanizedat8weeks, tissueblocksexcisedcontralateral to
injury• Frozenat-80°C,shippedtoWaterlooformechanicaltesting
Nelson-Wongetal.,submittedJBiomech,2016
Bishopetal.,2016
¡ Displacementcontrolled§ %initialrakewidth
¡ Measureforce§ transverse,longitudinal
¡ Rakedisplacement§ ‘stretchratio’=amountof
displacementrelativetoinitial
Uniaxiallongitudinalconfigura0on
Biaxialconfigura0on
¡ ThreeLoadingConditions§ UniaxialLongitudinal§ UniaxialTransverse§ Biaxial–analyzedindependentlyasBiaxial
Longitudinal,BiaxialTransverse
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Force(m
N)
Displacemen
t(um
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Time(sec)DisplacementForce
240s
25%
35%
45%
240s
240s
5cycles
Pre-tensionto10mNPrecondition:5cyclesat10%
Nelson-Wongetal.,submittedJBiomech,2016
¡ Stresscalculatedfrommeasuredforceandinitialsampledimensions:
¡ Normalizedtopeak,time-varyingplotscreatedforeachcondition
¡ StressRelaxationResponseexpressedasstressdecay:
Stress = TensileForceInitialCrossS ec tionalArea
SRR =100%−EquilibriumStress
PeakStress
Injured
HealthyControl
Group
Uniaxial
Biaxial
Loading
Transverse
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Orientation
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35%
45%
StretchCondition
Interestedinmaineffectofinjurygroupand/orsignificantinteractionswithinjurygroup
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StressRelaxa+
onRespo
nse(%
Decrease)
StretchCondi+on
Control Injured
*p=.02NS
NS
¡ Simulatedmuscle‘sprain’withsurgicalinjury§ Inflammationwithoutstructuraldamage§ Lowbackmechanicsunchanged(theoretically)§ Testedtissuecontralateraltoinjurysite
¡ Stressrelaxation§ Time-dependent,viscoelasticresponseinbiologicaltissues
§ Allowsdeformedtissuestoreturntorelaxedstressstate§ Potentiallyminimizestotalstressinthetissue
¡ Decreasedrelaxationwithinjuryat45%stretch§ 45%stretchratiomaybenearend-rangelimitsofphysiologicalflexion
§ Coulddisruptloadsharingbetweenpassiveconnectivetissues,impactmuscleactivation(flexionrelaxation?)
§ PotentialmechanismforLBPrecurrence/chronicityfollowingmuscleinjury(inflammation)?
MechanisticPathoanatomic
Mechanicaleffectson
fascia
Behavioral/PsychosocialHypokinesia
Decreasedmobilityimpactsfascia
Bishopetal.,2016
AlteredMovementStrategies
Connectivetissueimpactsmuscle
function
PathophysiologicalModelConnectiveTissue(perimuscularfascia)
InflammatoryProcessesRelatedtoabovefactors
Langevin&Sherman,2007
Biochemicalstudiesrequiredtoisolatepotentialmechanisms
Thankyou!
Dr.LangevinissupportedthroughNCCHIResearchGrantR01AT004400