Citation
Motion capture as an assessment tool for the relationshbetweeneen knee stability and pediatric anterior cruciate ligament tears

Material Information

Title:
Motion capture as an assessment tool for the relationshbetweeneen knee stability and pediatric anterior cruciate ligament tears
Creator:
Burnim, Kayla ( author )
Place of Publication:
Denver, CO
Publisher:
University of Colorado Denver
Publication Date:
Language:
English
Physical Description:
1 electronic file (110 pages). : ;

Subjects

Subjects / Keywords:
Motion perception (Vision) ( lcsh )
Anterior cruciate ligament ( lcsh )
Genre:
bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

Notes

Review:
There has been significant advancement in the treatment of Pediatric Anterior Cruciate Ligament (ACL) tears, yielding a plethora of innovative surgical techniques. These new techniques for pediatric specific patients focus on reconstruction with minimal or no trauma to the growth plates. Their evaluation remains focused on the acceptance of the replacement graft and limb growth disturbances. While the purpose of ACL repair is to restore stability to the knee, the assessment and comparison of these new procedures has not yet been correlated to joint stability. Though knee stability is defined as the ability to maintain static position or control dynamic movement, it is clinically evaluated in qualitative passive single planar motion assessments. Currently, a universally accepted definition and measurement of dynamic knee stability does not exist. It was hypothesized that three-dimensional knee joint kinematics and kinetics have been altered after ACL injury and repair. This study proposes and validates a new six degrees-of-freedom (6DOF) marker set and model through comparison with a conventional set and previously published data. This study also evaluates the pilot procedure using the new marker set and from this, proposes a new knee stability protocol. The purpose of this prospective project is to isolate the variables associated with knee stability as it relates to ACL repair in skeletally immature patients. Motion capture technology was used to gather kinematic and kinetic data on sixteen pediatric subjects (12 asymptomatic, 4 symptomatic ACL-reconstructed). 6DOF knee joint motion was determined using a new marker set and model. Data between subject groups was compared using a customized graphical user interface (GUI). The new model was validated against concurrently captured data using correlation coefficients and published data by visual comparison of overlaid graphs. Differences in subject groups were most visible in kinetic data plots with significantly different extrema of knee power. New plot types such as center of pressure movement within the transverse plane have promise as relevant plots. The model, GUI, and knee stability protocol generated from this project have initially demonstrated to be valid and useful tools for future pediatric ACL tear motion capture research.
Thesis:
Thesis (M.S.)--University Colorado Denver. Bioengineering
Bibliography:
Includes bibliographic references.
System Details:
System requirements: Adobe reader.
General Note:
Department of Bioengineering
Statement of Responsibility:
by Kayla Burnim.

Record Information

Source Institution:
|University of Colorado Denver
Holding Location:
|Auraria Library
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
911141666 ( OCLC )
ocn911141666

Downloads

This item is only available as the following downloads:


Full Text

PAGE 1

MOTIONCAPTUREASANASSESSMENTTOOL FORTHERELATIONSHIPBETWEENKNEE STABILITYANDPEDIATRICANTERIOR CRUCIATELIGAMENTTEARS By KAYLABURNIM BME,UniversityofDelaware,2007 Athesissubmittedtothe FacultyoftheGraduateSchoolofthe UniversityofColorado inpartialfulllment oftherequirementsforthedegreeof MasterofScience Bioengineering 2015

PAGE 2

ThisthesisfortheMasterofSciencedegreeby KaylaBurnim hasbeenapprovedforthe BioengineeringProgram by RichardWeir,Chair JamesCarollo,Advisor JayAlbright April20,2015 ii

PAGE 3

Burnim,Kayla(MS,Bioengineering) MotionCaptureAsAnAssessmentToolForTheRelationshipBetweenKneeStabilityAnd PediatricAnteriorCruciateLigamentTears ThesisdirectedbyAssociateProfessorJamesJ.Carollo ABSTRACT TherehasbeensignicantadvancementinthetreatmentofPediatricAnteriorCruciateLigament (ACL)tears,yieldingaplethoraofinnovativesurgicaltechniques.Thesenewtechniquesforpediatric specicpatientsfocusonreconstructionwithminimalornotraumatothegrowthplates.Their evaluationremainsfocusedontheacceptanceofthereplacementgraftandlimbgrowthdisturbances. WhilethepurposeofACLrepairistorestorestabilitytotheknee,theassessmentandcomparisonof thesenewprocedureshasnotyetbeencorrelatedtojointstability.Thoughkneestabilityisdened astheabilitytomaintainstaticpositionorcontroldynamicmovement,itisclinicallyevaluatedin qualitativepassivesingleplanarmotionassessments.Currently,auniversallyaccepteddenition andmeasurementofdynamickneestabilitydoesnotexist. Itwashypothesizedthatthree-dimensionalkneejointkinematicsandkineticshavebeenaltered afterACLinjuryandrepair.Thisstudyproposesandvalidatesanewsixdegrees-of-freedom(6DOF) markersetandmodelthroughcomparisonwithaconventionalsetandpreviouslypublisheddata. Thisstudyalsoevaluatesthepilotprocedureusingthenewmarkersetandfromthis,proposesanew kneestabilityprotocol.Thepurposeofthisprospectiveprojectistoisolatethevariablesassociated withkneestabilityasitrelatestoACLrepairinskeletallyimmaturepatients. Motioncapturetechnologywasusedtogatherkinematicandkineticdataonsixteenpediatric subjects(12asymptomatic,4symptomaticACL-reconstructed).6DOFkneejointmotionwasdeterminedusinganewmarkersetandmodel.Databetweensubjectgroupswascomparedusinga customizedgraphicaluserinterface(GUI). Thenewmodelwasvalidatedagainstconcurrentlycaptureddatausingcorrelationcoe cients andpublisheddatabyvisualcomparisonofoverlaidgraphs.Di erencesinsubjectgroupsweremost visibleinkineticdataplotswithsignicantlydi erentextremaofkneepower.Newplottypessuch ascenterofpressuremovementwithinthetransverseplanehavepromiseasrelevantplots. Themodel,GUI,andkneestabilityprotocolgeneratedfromthisprojecthaveinitiallydemonstratedtobevalidandusefultoolsforfuturepediatricACLtearmotioncaptureresearch. Theformandcontentofthisabstractareapproved.Irecommenditspublication. Approved:JamesJ.Carollo iii

PAGE 4

DEDICATION ToLucas,mywonderfuldog.Thankyouforbeingmyears,neveraskingmequestions,and fallingasleepwithyourheadonmylapwheneverIwanted. iv

PAGE 5

TABLEOFCONTENTS Chapter 1Introduction 1 1.1Overview..........................................1 1.2ProblemStatement.....................................1 1.3StudyOutputs.......................................2 1.3.1SixDegreeofFreedomModel..........................2 1.3.1.1PrimaryAim1:.............................2 1.3.1.2Hypothesis1:...............................2 1.3.1.3Deliverable1:...............................2 1.3.2KneeStabilityViewer...............................2 1.3.2.1PrimaryAim2:.............................2 1.3.2.2Hypothesis2:..............................3 1.3.2.3Deliverable2:...............................3 1.3.3KneeStabilityProtocol..............................3 1.3.3.1PrimaryAim3:.............................3 1.3.3.2Hypothesis3:..............................3 1.3.3.3Deliverable3:...............................3 1.3.4QuantifyingQualitativeAssessments.......................3 1.3.4.1SecondaryAim1:............................3 1.3.4.2SecondaryHypothesis1:........................4 1.3.4.3SecondaryDeliverable1:........................4 2Background 5 2.1TheKneeJointandRoleoftheAnteriorCruciateLigament..............5 2.1.1AnatomicalOverviewoftheKnee........................5 2.1.2KneeMotion....................................7 2.1.3AnteriorCruciateLigament............................9 2.1.3.1ACLFunction..............................9 2.1.3.2MechanismsofInjury..........................10 2.2PediatricACLTears....................................10 2.2.1HistoricalTreatment................................11 2.2.2ConventionalAdultACLRepair.........................12 2.2.3PediatricSpecicSurgicalTrends.........................13 2.2.3.1BoneDevelopment............................13 2.2.3.2PrepubescentACLReconstruction...................14 2.2.3.3Adolescent(OpenPhyses)Resconstruction..............16 2.2.3.4Adolescent(ClosingPhyses)Reconstruction.............17 2.2.3.5ProtocolSurgery.............................17 2.2.4SurgicalEvaluation.................................18 2.2.4.1GrowthDisturbances..........................19 2.2.4.2Unknowns................................20 2.2.5Conclusion.....................................20 2.3KneeStability........................................20 2.3.1KneeStabilityDenitions.............................21 2.3.2RoleoftheACLinKneeStability........................21 2.4ClinicalAssessmentsofKneeFunctionality.......................22 2.4.1Surveys.......................................23 2.4.2QualitativeClinicalAssessments.........................23 2.4.2.1One-PlaneMedial............................26 2.4.2.2One-PlaneLateral...........................26 v

PAGE 6

2.4.2.3One-PlaneAnterior...........................26 2.4.2.4One-PlanePosterior...........................27 2.4.2.5AnteromedialRotary..........................28 2.4.2.6AnterolateralRotary..........................28 2.4.2.7PosteromedialRotary..........................28 2.4.2.8PosterolateralRotary..........................28 2.4.2.9MeniscusInjury.............................29 2.4.2.10IncorrectExaminationResults.....................29 2.4.3QuantitativeSinglePlanarAssessments.....................29 2.4.4KneeStabilityandReturntoSports.......................30 2.4.5Conclusion.....................................31 2.5ThreeDimensionalKneeAssessments..........................31 2.5.1MarkerBasedMotionCapture..........................32 2.5.1.1MarkerSet................................32 2.5.1.2ErrorsinMarkerBasedMotionCapture...............34 2.5.1.3BonePins.................................35 2.5.2OtherTypesofMovementAssessment......................35 2.5.2.1Radiography...............................35 2.5.2.2OtherTypesofSensors.........................36 2.5.3ResultsfromACLFocusedMotionCaptureStudies..............36 2.5.3.1GaitinRelationtoACL-RandACL-D................37 2.5.3.2DynamicTasks..............................38 2.6Conclusion.........................................39 2.6.1ClinicalRelevance.................................39 2.6.2ProtocolDevelopment...............................40 2.6.2.1MarkerSetandModel..........................40 2.6.2.2ProtocolTasks..............................40 2.6.3KnowledgeGained.................................41 3OverallMethodology42 3.1Overview..........................................42 3.2StudyInputs........................................42 3.2.1Subjects.......................................42 3.2.1.1AsymptomaticSubjectSpecics....................42 3.2.1.2SymptomaticSubjectSpecics.....................43 3.2.2Instrumentation..................................43 3.3DataCaptureProcedure..................................43 3.3.1Pre-Capture....................................43 3.3.2MotionCapture..................................44 3.3.2.1DynamicMotion.............................44 3.3.2.2PassiveMotion..............................45 3.4DataProcessing......................................45 3.4.1Pre-CaptureData.................................45 3.4.2ProcessingofMotionCaptureData.......................47 3.4.3Cross-TalkReprocessing..............................48 3.5MatlabProcessing.....................................49 3.5.1BatchProcessing..................................49 3.5.2Gait.........................................50 3.5.3Squat........................................50 3.5.4Hop.........................................51 3.5.5Pivot........................................51 vi

PAGE 7

4FenwayModel 52 4.1MarkerSetDevelopment..................................52 4.1.1CurrentMarkerSets................................52 4.1.2FenwayMarkerSet.................................53 4.2ModelCalculations.....................................54 4.2.1BodyBuilderIndependentTibialAxis......................54 4.2.2MatlabTranslationCalculations.........................55 4.3ModelValidationUsingGaitResults...........................57 4.3.1QuantitativeModelValidation..........................57 4.3.2QualitativeModelValidation...........................59 4.4Conclusion.........................................61 5KneeStabilityGUI63 5.1GraphicalUserInterfaceOverview............................63 5.2InterfaceUse........................................63 5.2.1Setup........................................64 5.2.2GraphicalUse....................................65 5.2.3GraphedVariables.................................66 5.2.3.1Kinematics................................66 5.2.3.2Translation................................66 5.2.3.3RelativeKinematics...........................67 5.2.3.4Forces...................................68 5.2.3.5Kinetics.................................69 5.2.3.6Three-D..................................70 5.2.3.7Velocity..................................71 5.3Conclusion.........................................72 6DynamicTasksResults74 6.1Overview..........................................74 6.2Results............................................74 6.2.1Gait.........................................75 6.2.2Squat........................................77 6.2.2.1SaggitalPlaneKinematics.......................77 6.2.2.2RelativeKinematics...........................78 6.2.2.3Kinetics..................................79 6.2.2.4Velocity..................................80 6.2.3Hop.........................................81 6.2.3.1Kinematics................................82 6.2.3.2RelativeKinematics...........................82 6.2.3.3Kinetics..................................83 6.2.3.4Velocity..................................84 6.3Conclusion.........................................85 6.3.1Observations....................................85 6.3.2NextSteps.....................................86 6.3.3KneeStabilityProtocolOutput..........................87 7ClinicalAssessments89 7.1MethodologyOverview...................................89 7.1.1DataProcessing..................................89 7.1.2QuantitativeCalculations.............................89 7.2Results............................................90 7.3Conclusion.........................................90 8OverallStudyConclusion92 vii

PAGE 8

References 94 viii

PAGE 9

LISTOFTABLES Table 2.4.1KneeRelatedSurveys..................................23 2.4.2ClinicalAssessments...................................25 2.6.1DynamicMotions.....................................41 3.2.1AsympomaticDemographics...............................42 3.2.2SymptomaticDemographics...............................43 3.4.1PediatricIKDCSurveyResults.............................46 3.4.2CrossTalkInvestigation.................................49 4.2.1JointCoordinateSystem................................56 4.2.2TranslationsandRotationsattheKnee........................57 4.3.1StasticalModelComparison...............................59 4.3.2Anterior/PosteriorKneeTranslationSourceComparison...............60 5.2.1KinematicGraphs....................................66 5.2.2TranslationPlots.....................................67 5.2.3RelativeKinematicPlotDescriptions..........................68 5.2.4ForcePlotDescriptions..................................69 5.2.5KineticPlotDescriptions................................70 5.2.6ThreeDimensionalPlotDescriptions..........................71 5.2.7VelocityPlotDescriptions................................72 ix

PAGE 10

LISTOFFIGURES Figure 2.1.1KneeAnatomyOverview.................................5 2.1.2AnteriorKneeAnatomy.................................6 2.1.3KneeMotion.......................................8 2.2.1TibioFemoralJoint....................................14 2.2.2ExtraarticularSurgicalTechnique............................15 2.2.3IntraArticularExample[2]oftheAndersonTechnique.................16 2.2.4SurgicalProcedureUsed.................................18 2.5.1ConventionalLowerBodyMarkerSetUsedatCGMA[6]..............33 3.4.1PediatricIKDCGraphicalResults...........................47 3.4.2DataprocessinginViconNexus.............................48 4.1.1MarkerSetComparison.................................53 4.1.2FenwayMarkerSet....................................54 4.2.1IndependentTibialAxisGeneration..........................55 4.2.2FemoralandTibialAxes................................56 4.3.1KneeFlexion/ExtensionDuringWalking........................58 4.3.2FrontalandTransversePlaneModelValidation....................58 4.3.3Anterior/PosteriorKneeTranslationDuringGait...................60 5.2.1KneeStabilityGUISetup................................64 5.2.2LoadedGUIExample..................................65 5.2.3TranslationPlots.....................................66 5.2.4RelativeKinematicPlots.................................68 5.2.5ForcePlots........................................69 5.2.6KineticPlots.......................................70 5.2.7ThreeDimensionalPlots.................................71 5.2.8VelocityPlots.......................................72 6.2.1GaitVariablesofNote..................................76 6.2.2SaggitalPlaneKinematicsforallSquatActivities...................78 6.2.3RelativeKinematicsforAllSquatActivities......................79 6.2.4KineticsforAllSquatActivities.............................80 6.2.5SaggitalPlaneKinematicVelocitiesDuringAllSquatTasks.............81 6.2.6KJCandNormalizedGRFVelocitiesforallSquatTasks...............81 6.2.7HopTasksKneeFlexionExtension...........................82 6.2.8KJCPositionChangesDuringHopTaskPhases....................83 6.2.9HopKneePowerDuringTakeO Phase........................84 6.2.10TargetKinematicVelocityPlotsforTake-O PhaseofAllHopTasks........84 6.2.11KJCandNormalizedGRFVelocitiesfortheTake-O PhaseofAllHopTasks...85 7.2.1AnteriorDrawerTestResults..............................90 x

PAGE 11

1Introduction 1.1Overview TheturnofthemillenniumhassparkedachangeinthetreatmentofPediatricAnteriorCruciate Ligament(ACL)tears.Asadultsurgicalrepairtechniquesinvolvetraumatothegrowthplatein skeletallyimmaturepatients,nonoperativetreatmentordelayingoperationuntilmaturationhad beenthecommonpractice.However,thevastquantityofsubsequentadditionalinjuriesasaresult ofinstabilityleadtoaneedforoperativerepairintheseskeletallyimmaturepatients.Ine orts tospareheavytraumatotheskeletalgrowthplate,aplethoraofsurgicaltechniqueshavebeen developed.Astheworryinthesenewsurgicaltechniquesisgrowthdisturbances,lackoflimblength discrepanciesorinstancesofabnormalkneeorientationinadditiontothegeneralgoallowinfection ratesarethecommonmeasuresofsuccessfuloutcomes.AsthepurposeofACLrepairistorestore kneestability,itisimportanttoassessthesenascentsurgicaltechniquesontherestorationofjoint stability. Kneestabilityisdenedastheabilityofthejointtomaintainstaticpositionorcontroldynamic motion.Currentclinicalassessmentsfocusonlaxitywhichisthepassiveresponseandmovementof thejoint.Theseexaminationsinvolveahighlytrainedclinicianmovingthekneeinatargetedplane ofmotionandassessingtheendfeelofthemotion.Currently,stabilityisnotdynamicallymeasured intheclinicandthereisnostandardmethodfordoingso. Currentresearchhasattemptedtodenestabilityduringvariousdynamicmotionbyquantifying themovementofthekneeinasingleplane.Acommonlyusedtoolisthreedimensionalmotion capture.Motioncaptureusesreectiveballsattachedtothesubjectandaglobalcoordinatesystem totrackmotion.Amodelisappliedtothesemarkersdeningtheirlinkagesinrelationtothehuman skeleton.Whilethecommonlyusedclinicalmodelassumesthreedegreesoffreedom(3DOF)atthe knee,thereareavarietyofresearchmodelsforasixdegreeoffreedom(6DOF)kneemodel.There isnoagreeduponmodelforcalculatingsixdegreesoffreedommotionatthekneenoristherea standardprotocolformeasuringdynamickneestability. 1.2ProblemStatement Thepurposeofthisprospectiveprojectistodeterminevariablesassociatedwithkneestability asitrelatestoanteriorcruciateligamentrepairinskeletallyimmaturepatients.Inordertocompare surgicaltechniquesforpediatricACLrepairakneestabilityprotocolmustbegenerated.Togenerate 1

PAGE 12

akneestabilityprotocolatoolforeasilyviewingandinterrogatingpilotdatamustbedeveloped.To generatethepilotdata,anappropriatesixdegreeoffreedommodelmustbecreatedandvalidated. 1.3StudyOutputs 1.3.1SixDegreeofFreedomModel 1.3.1.1PrimaryAim1: Createaminimalisticmarkersetforuseinmotioncapturethatcapturesthesixdegreesof freedomoftheknee.CurrentHelenHayes(HH)basedmarkersetsareminimalistictoensureease ofuse,simplicity,andshortsetuptimemakingthemspecicallybenecialinpediatricsubjects. Howeverduetothissimplicity,thesemarkersetsarelimitedtocalculatemovementinonlythree degreesoffreedomattheknee.Ifthekneeissimpliedtoresemblea3DOFtoahinge-likejoint ratherthantothemoreaccuratecamrocker,theroleofACLinpreventingexcessiveanterior translationismute.However,initialpublishedliteratureusingmarkersetsfor6DOFmovementat thekneehaveexcessiveandunrealisticquantitiesofmarkers.Aminimalisticsixdegreeoffreedom markersetandsubsequentmodelcalculationsoftranslationaldisplacementcanbecreatedand validatedagainstpublisheddata. 1.3.1.2Hypothesis1: SupplementingthecurrentlyusedHelenHayesclinicalmarkersetwithafewadditionalmarkers willcreateavalidsixdegreeoffreedomkneemodel. 1.3.1.3Deliverable1: Thesixdegreeoffreedommarkerset,necessaryVicon(OxfordMetricsInc.,Oxford,UK)les foruse,Matlab(TheMathWorksInc.,Natick,MA,USA)codesforcalculatingtranslation,and validationofthemodelcalculationsagainstpublisheddata. 1.3.2KneeStabilityViewer 1.3.2.1PrimaryAim2: Tocreateagraphicaluserinterface(GUI)forinterrogationofmotioncapturedata.Current toolsforviewingmotioncapturedatashowsimplesingleplaneofmotionwithstandardkinematic andkineticmeasurements.BycreatingacustomGUI,translationaldatamaybeaddedtothesingle 2

PAGE 13

planekinematicandkineticgraphicaloutputs.Additionally,investigationsintocoupledvariables canbegintoattempttolinkmultipledegreesoffreedommovementinthedenitionofkneestability.Finally,aneasiertonavigatetoolforgraphingalargequantityofvariablesallowsforsimple interrogationofthedata. 1.3.2.2Hypothesis2: Itispossibletodevelopanappropriatecustomtoolforviewingmultipletasksandresulting kinematicandkineticdata. 1.3.2.3Deliverable2: KneeStabilityGUI 1.3.3KneeStabilityProtocol 1.3.3.1PrimaryAim3: Tocreateaquantitativemeansofdiscriminatingbetweenasymptomaticandsymptomaticsubjectsusingdynamicmotiontests.Asymptomaticandsymptomaticsubjectperformanceduring specicathletictaskswillhighlightthevariousplanarmotionsofthekneejoint.Itisunknown whichtaskswillbestexposekneeinstabilityandtranslatequantiableperformancedi erencesbetweenasymptomaticandsymptomaticsubjects. 1.3.3.2Hypothesis3: Variableslinkedtokneeinstabilitycanbeidentiedthroughquantitativekinematicandkinetic di erencesbetweenasymptomaticandsymptomaticsubjectsduringspecicathletictasks. 1.3.3.3Deliverable3: Proposedkneestabilityprotocoltasksandfocalvariables 1.3.4QuantifyingQualitativeAssessments 1.3.4.1SecondaryAim1: Themotionanalysisinformationcapturedduringtheassessmentswillbetransformedtoquantitativedatawhichcanbecorrelatedwiththequalitativeresults.Currently,kneestabilityisassessed qualitativelybyatrainedclinicianinaseriesofpassivekneejointmanipulations.Correlatingthese 3

PAGE 14

qualitativeassessmentswithquantitative3-Dlowerextremitykinematicdatamayprovideamore reliableandrepeatablemethodofassessingkneestability.Asymptomaticandsymptomaticsubjects willbeassessedbyanexpertusingclinicalstandardqualitativeassessmentsofplanarmotion. 1.3.4.2SecondaryHypothesis1: Qualitativeresultsfromclinicalplanarmotionassessmentwilldirectlycorrelatewithspecic quantitativeplanardisplacementsderivedfrommotionanalysisdata. 1.3.4.3SecondaryDeliverable1: Assessmentofabilitytoquantitativelytrackqualitativeclinicalassessmentsusingmotioncapture technology 4

PAGE 15

2Background 2.1TheKneeJointandRoleoftheAnteriorCruciateLigament Thekneeisacomplexsixdegreeoffreedomjointthatconnectsthethightotheleg.Assuch, movementisacomplexsetofcoupledtranslationsandrotations.Duetoitscomplexity,itisone ofthemostfrequentlocationsofinjuryinthebody.Thekneeisbasicallyaligament-controlled joint,reinforcedbythequadriceps,hamstring,andgastrocnemiusmusclegroups[16].Thejoint complexisextremelyelaborateandincludesthreearticulatingsurfaces,whichformtwodistinct jointscontainedwithinasinglejointcapsule:thepatellofemoralandtibiofemoraljoint[17].This anatomicalcomplexityisnecessarytoallowfortheelaborateinterplaybetweenthejoint'smobility andstabilityroles.Thekneejointworksinconjunctionwiththehipandanklejointstosupportthe body'sweightduringstaticerectposture[51].TheanatomicalfocusofthisthesisistheACLwhich connectsthefemurtothetibia.Allsubsequentanatomicaldetailspresentedwillpertainspecically tothesestructures. Figure2.1.1:KneeAnatomyOverview Fromlefttorightthekneejointisshownrstwithallstructures;Inthecenterjustthe musculoskeletalsystemcanbeviewed;Ontherightonlythebonesandmajorligamentsare pictured.ThisgurewascreatedusingBiodigitalHuman(www.biodigital.com) 2.1.1AnatomicalOverviewoftheKnee TheACLisacomponentofthetibiofemoraljointthatlinksthethightothelegthroughthe femurandtibiabones.Thetibiofemoraljointiscomposedofthreebones:thefemur,tibia,and bula.Thefemuristhelongestboneinthebody,locatedinthethighandconnectingthehiptothe knee.Thelegiscomposedofthetibiaandbulawhichconnectthekneetotheankle.Thebony interfacebetweenthethighandthelegispredominantlybetweenthedistalcondylesofthefemur andthetibialplateau.Majorbonylandmarksandstructuresareshowninthebelowimage2.1.2. 5

PAGE 16

Figure2.1.2:AnteriorKneeAnatomy A:AnteriorViewshowingTibioFemoraljointwithrelevantbonylandmarks.B:Anteroinferior viewofthefemurwithlocationofACL.C:SuperiorviewofTibiawithlocationofACL.[55] Thegeometricallyincongruousnatureofthearticularsurfacesofthetibiaandfemurmeansthat thebonesarenotresponsibleforthestabilityofthejointastheyareinthehipjoint.Instead, stabilityisdependentonthesofttissuestructuressurroundingthejointwhicharethemuscles, ligaments,andmenisci.Themajormusclesandmusclegroupsactinguponthekneejointarethe quadricepsandhamstringsinthethighandthegastrocnemiusintheleg.Softtissuestructureswere shownpreviouslyin2.1.1. Thefourmainligamentsconnectingthefemurandthetibiaaregroupedintothecollateraland thecruciateligaments.Thetwocollateralligamentsareoutsidethesynovialjointcapsuleandattach laterallyandmediallytothefemurandtibia/bula.Thelateralcollateralligament(LCL)attaches tothelateralaspectofthefemurandthelateralaspectofthebulaandactstopreventvarus motion.Themedialcollateralligament(MCL)attachestothemedialaspectofthefemurandthe medialaspectofthetibiaandactstopreventvalgusmotion.Thetwocruciate(meaningcross) ligamentsareinsidethesynovialjointcapsuleandattachtheintercondylarnotchofthefemurto thetibialplateau.Theposteriorcruciateligament(PCL)attachestotheposterioraspectofthe intercondylareminenceofthetibialplateauandpreventsposteriortranslationofthetibiarelative tothefemur.Theanteriorcruciateligament(ACL)attachestotheanterioraspectandprevents anteriortranslationofthetibiarelativetothefemur. Thecruciateligamentscrosseachotherandaretheprimaryrotarystabilizersoftheknee.These strongligamentsarenamedinrelationtotheirattachmenttothetibiaandareintracapsularbut extrasynovial.Eachligamenthasananteromedialandaposterolateralportion.TheACLhasan additionalintermediateportion[54].Theseligamentsdi erfromthoseofotherjointsinthatthey 6

PAGE 17

restrictnormal,ratherthanabnormal,motion[17]. Themenisciarelocatedbetweenthetibiaandfemurtoaidinlubricationandshockabsorption. Themeniscipreventtheboneonbonecontactbetweenthetibiaandfemur.Withouttheirpresence, osteoarthritisoccursrapidly.Thediscshapeallowsmorecongruentjointsurfaces,whichhelps improveweightdistributionbyincreasingtheareaofcontactbetweenthecondylesandthetibial plateau.Finally,themenisciaidinmotionbyparticipatinginthe"locking"mechanismofthejoint bydirectingthemovementofthefemoralarticularcondyles[54]. 2.1.2KneeMotion Thecomplexityofthekneejointanditssixdegreeoffreedomclassicationallowsforavarietyof motionsinallanatomicalplanes.Thesemovementscanoccureitherisolatedorcoupled.Motionscan beclassiedbytheplaneinwhichtheyoccur.Flexion/Extensionandanterior/posteriortranslation occurinthesaggitalplane.Varus/Valgusandmedial/lateraltranslationoccurinthefrontalplane. Internal/Externalrotationandcompression/distractionoccursinthetransverseplane.Themotions illustratedbelowwillbediscussedaspartoftheresultsofmotioncapture. 7

PAGE 18

Figure2.1.3:KneeMotion Tocompletethelargequantitiesofmovements,thetibiofemoralmotionconsistsofbothrolling andslidingasisthenatureofthecam-rockersystemwhichisthemostaccuratemodelofkneejoint movement.Asthekneeexes,rollingmovementshiftsthefemurposteriorlyonthetibia,whereas slidingmovementtranslatesthefemuranteriorly[33].Duetothelargevarietiesandcombinationsof motionsavailableatthekneejoint,thekneejointaxischangesdependingontheloadingcondition andboneposition. Motioncanalsobeclassiedasclosedoropenkineticchain.Thefulllowerbodykineticchain includesthespinedistallythroughtheankle.Closedchainmotionatthekneeoccurswhentheleg isweightbearingorthefootisincontactwitharmsurface.Openchainmotionoccurswhenthe 8

PAGE 19

kneemoveswithoutcontactwithanysurface.Anexampleofthiswouldbeexingandextending thekneewhilesittinginachairwithouttouchingtheoor. Thekneemovement,aswellastheopen/closedchainnatureofthemotion,directlya ectsthe ACL.Thisligamenthastheleastamountofstressonitbetween30and60exion[54].During closed-chainkneeexionthedistancebetweenthetibialandfemoralinsertionsoftheACLincreases andtheamountofanteriortranslationincreases.Open-chainactivitiesproduceshearforcesatthe tibiofemoraljointinthedirectionoftibialmovement[17]. 2.1.3AnteriorCruciateLigament Theanteriorcruciateligament(ACL)islocatedwithinthekneejointandconnectsthefemurto thetibia.Namedduetoitsanteriorattachmentonthetibia,thisdiagonallytwistinganddescending ligamentresistsanteriortibialtranslationandlimitstibialrotationrelativetothefemur.The ligamenthasbothananteromedial(AM)andposterolateral(PL)bundleaswellasanintermediate portion.ArecentlypopularresearchtopicinadultACLrepairinvolvesthee ectofrestoringthis doublebundleconguration.Recentlaboratorystudieshaveclearlyshownthatthereisanuneven distributionofforcesbetweentheAMandPLbundlesoftheACLinresponsetoexternallyapplied loadstotheknee[95].Theanteromedialbundleistightinbothexionandextension,whereasthe posterolateralbundleistightonextensiononly[54]. Likeallligaments,theACLbehavesasaviscoelasticstructure,allowingittodissipateenergy andtoadjustitslengthandinternalloaddistributionasafunctionofloadhistory.Thismeans thatthenormalACLiscapableofmicroscopicadjustmentstointernalstressesovertime,thus inuencingthelaxity,stresses,andkinematicsofthejointinsubtlebutpotentiallyimportantways. Ananatomicalfactorthatcontributestotheselectiveberrecruitmentduringtensileloadingis thespeciclocationoftheinsertionsoftheACLonthefemurandthetibiaasdi erentbersare recruitedwitheachsubtlethreedimensionalpositionchange[17].Bothbundlecongurationand insertionsitesarecommonresearchtopicsinadultACLrepairsurgicaltechnique. 2.1.3.1ACLFunction Asiscommonthroughouthumananatomy,theoriginandinsertionoftheACLdictatethefunctionoftheligament.TheprimaryfunctionoftheACListorestrictexcessiveanteriortranslationof thetibiarelativetothefemur.Secondarily,theACLrestrainsbothinternalandexternalrotation andtoalesserextenttheligamentfunctionstocheckextensionandhyperextensionattheknee. Simply,theACLhelpscontrolthenormalrollingandglidingmovementofthekneejoint.Addition9

PAGE 20

ally,theACLcanactasashockabsorberbecauseitabsorbsnearly90percentoftheforcecausing anteriortranslation[17]. 2.1.3.2MechanismsofInjury AccordingtotheAmericanOrthopedicSocietyforSportsMedicine(AOSSM),roughly150,000 ACLinjuriesoccurintheUnitedStateseachyear.TheACLisanimportantstructureincontrollingkneejointstabilityandmovement,anditsruptureisoneofthemostcommonsportsrelated injuries[99].AsthemainfunctionoftheACListobothstabilizetheanteriortranslationofthetibia relativetothefemurandlimitexcessiverotationofthetibia,anexcessofeitherofthesemotions cancauseinjurytotheligament.Amid-substancetearoccurswhentheACLisstretchedbeyond theyieldstressandtheonsetoffailurebegins.Amid-substancetearcanbeeitherpartialorfulland isalsocalledamid-substancerupture.TheothertypeofACLinjuryiscalledanavulsionfracture andoccurswhenachunkoftheboneisdetachedwiththeligament.Thefocusofthisthesisison fullmid-substancetears. Amid-substanceteargenerallyoccursduringasportingeventwhereloadsarehighontheknee andanglesareextreme.Activitiessuchaslowforcedeceleration,landing,orcontactarecommon causesoftheinjury.Duetothehighforcesassociatedwithinjury,ACLrupturesareoftenassociated withotherinjuriesandsubsequentclinicalinstability[98].Themostcommonconcurrentinjuries aretearstotheMCLandmeniscus.Thesesimultaneouslyinjuredstructuresincreasethelevelof complicationoftreatment. TheresultofanACLinjurygenerallynecessitatessurgicalrepair.ACLinjuryleadstoknee instability,mainlyintheanterior-posteriortranslationandaxialinternal-externalrotation[48].A rupturetotheACLresultsinkneeinstabilityandepisodesofgivingway.AdecientACLalso increasesthechancesofsubsequentinjurytothemeniscusandotherstructuresoftheknee.The lackofperformanceinbothactivitiesofdailyliving(ADL)andathleticscoupledwithpainand swellingresultsinaneedforsurgicalrepair. 2.2PediatricACLTears Overthepast30years,muchhaschangedinthetreatmentofaskeletallyimmaturepatientwith anACLtear.Thehigherincidenceoftheseinjuriesisattributedtoanincreasedawareness,better imaging,andanincreasedparticipationinhighdemandsportsatanearlierage[86].Sportsinjuries accountfornearlyaquarterofallinjuriesinchildrenandadolescents[24].Additionally,athletesare 10

PAGE 21

specializinginaspecicpositionofaspecicsportatamuchyoungerage.Thiscausesrepetitive forcesandmotionsasthechildisdevelopingwhichhasbethoughttoincreaseinjuryrates.The historicalpracticeofnon-operativeconservativemanagementformid-substanceACLruptureshas showntohavepoorlongtermresults.Surgicalrepairremainsacontroversialapproachduetothe potentialforgrowthdisruption.E ectofsurgeryonthegrowthplategrowthdisturbanceisthe majorpotentialcomplicationinintra-articularsurgeryofthekneeinchildrenasthedistalfemur andtheproximaltibiaaccountfor65%ofthegrowthinthelowerlimbandsofttissueplacedacross agrowthplatehasbeenshowntopreventfusion[86].Physicianshaverecentlycomeupwitha varietyofadaptationstotheadultACLrepairsurgeryinordertosparetraumatothepediatric growthplate.Manyofthesesurgerytechniqueshaveyieldedpromisingshorttermresultswhilethe longtermoutcomeisstillunknown.Thoughgrowingevidencesuggeststhemanagementofthese injuriescanbetailoredspecicallytotheskeletalmaturityofthepatient,thereisstillcontroversy anddebateregardingthesafestandmoste ectivetechnique. 2.2.1HistoricalTreatment Mid-substancetearsoftheskeletallyimmaturepatientwereoncethoughttobeuncommon. Injurieswereoftenmisdiagnosedorwronglydiagnosedbecauseofthemisconceptionofchildrennot su eringfromligamentousinjuries[56,75].TheearlybeliefheldwasthatmostACLinjuriesinthe skeletallyimmaturepopulationwerepredominantlyavulsionfracturesofthetibialspine[73]rather thanrupturesoftheligamentitself.Inyoungpatientswithopenphyses,itisthoughtthatligaments arestrongerthantheadjacentphysealplates.Beforethegrowthplateisfused,theintercondylar eminenceo erslessresistancetotractionthantheligament[57].Inskeletallyimmaturepatients, theACLattachestothefemoralandtibialchondroepiphysesviaaperichondralcu ,which,with progressivematuration,transformstothebrocartilage-boneinterfaceobservedinadults[76]. AstheadultsurgeryforanACLtearinvolvesdrillingthroughboththegrowthplateinthe distalfemurandtheproximaltibia,itwasnotseenasanecessaryriskforyoungchildren.The acceptedmethodformanydecadeswasnon-operativeconservativemanagementwithdelayingoperationuntilskeletalmaturity.Physiciansinsteadwouldoptforimmobilization,rehabilitation, bracing,andcounselingonactivitymodication[38,57].Rehabilitationinvolvedquadricepsand hamstringstrengtheningtoideallyusemusclestrengthtocompensateforlackofjointstability. Aftertheskeletonhadadequatelymatured,theACLwouldbesurgicallyrepaired. Studiescomparingoperativeandnon-operativemanagementofACLinjurieshaveshownthat ACLreconstructionleadstolessinstability,lowerratesofre-injury,andincreasedreturntopre11

PAGE 22

injurylevelofactivitycomparedtonon-operativemanagement[86].Onethoughtwasthatthispopulationisoftennotcompliantwiththeactivityrestrictionsrequiredfornon-operativetreatment[56]. Therewereahighpercentageofpatientsneedingtobeoperatedonduringfollowup[36].Bracemanagementwasshowntohavenotpreventedeitherinstabilitynormeniscaltearsandpatientsreported frequentepisodesoftheknee"givingway"[27,38,57,56,1].Thechildwasalsoatriskforvery earlydegenerativearthritisand/orosteochondralfractures[56,38,1].Patientsalsoreportedalower activitylevel[36]. Thesuccessofthenon-operativeprocedureisreportedforpartialACLtears[38].However, itismorecommonforACLreconstructiontobereportedsuperiortoanonoperativeapproachin comparisonstudies[68,36,1,77,34,19].Thedelayofsurgerywasshowntoincreasetheincidenceof medialmeniscaltears4times[62]andincreasemedialmeniscuslesionsandtherateofmeniscectomies neededatthetimeofreconstruction[31]. Agrowingtrendoffurtherinjuriesandlackofcomplianceaswellasincreasedinstancesof ACLinjuryprecipitatedtheinvestigationandthedevelopofsurgicaltreatmentmethods.Asyoung athleteswantedtocontinueparticipationinsports,therewasalackofacceptancewiththeproposed delayedtreatment.Theeducationofthesechildrenandtheirfamiliesisacrucialcomponentofthe treatmentprocess.Despitetheurgencyassociatedwithsuchaninjuryinaprofessionalathlete, whoselivelihooddependsonareturntosportasimmediateaspossible,atornACLisnotasurgical emergency.Timecanbetakentodiscusswiththechildandfamilytheindividual'sfuturesports demands,avocationandvocationalconsiderations,treatmentoptions,outcomes,therisksinvolved withreturntocurrentlevelsofactivity,andsurgicalrisks[76].Skeletallyimmaturepatientsmust beemotionallymatureenoughtoactivelyparticipateintheextensiverehabilitationrequiredafter ACLreconstruction[39]. 2.2.2ConventionalAdultACLRepair Inadults,ACLreconstructivesurgeryistypicallyrecommendedtorestorethekneejointstability andfunctionafterACLinjury[25].AdultACLreconstructivetechniquesinvolveanatomic,intraarticularplacementoftheACLgraftthroughholeswhichhavebeendrilledacrossboththedistal femoralandproximaltibialphyses.CommongraftsusedarehamstringandpatellartendonautograftsaswellasAchillestendonallograftsfromcadaverdonors.Additionally,syntheticligaments areavailablebutarenotpopular.Asskeletallymaturepatientshavenishedgrowing,traumato thephysesisnotanissueandthisprocedureisappropriate.Thisisahighlycontroversialsurgical methodforpediatricpatientsespeciallythosewhowillstillexperiencesignicantgrowth.Thequest 12

PAGE 23

foranatomicalequivalencewithlackofgrowthplatedisturbancehavespurnedavarietyofiterations oftheadultACLsurgerytechniqueforpediatricpatients. 2.2.3PediatricSpecicSurgicalTrends PhysicianshaverecentlydevelopedavarietyofadaptationstotheadultACLrepairsurgeryin ordertospareorminimizetraumatothepediatricgrowthplate.Whilethesenewmethodsyield promisingshorttermresults,longtermoutcomesarestillunknown.Growingevidencesuggests themanagementoftheseinjuriescanbetailoredspecicallytotheskeletalmaturityofthepatient; thereisstillcontroversyanddebateregardingthesafestandmoste ectivetechnique. Allskeletallyimmaturepatientsarenotthesame.Somehaveatremendousamountofgrowth remaining,whereasothershaveessentiallynishedgrowing[42,39].Tannerstageisacommonlyused metricofphysicalmaturitylinkedtosexualdevelopment.InadditiontoTannerstage,radiographs arerecommendedforgooddiagnosiswhilealsoassessingphysealmaturity[76].Withregardsto pediatricACLreconstruction,childrenaredividedintothreegroups.Therstgroupisclassiedas prepubescentchildrenwhoareinTannerstage1or2,typicallyofmales 12yearsoldandfemales 11yearsold.ThesecondgroupisclassiedasadolescentswithgrowthremainingwhoareinTanner stage3or4whichismales 13-16yearsoldandfemales 12-14yearsold.Thenalgroupare theolderadolescentswithclosingphyseswhoareinTannerstage5whichareusuallymales 16 yearsofageandfemales 14yearsofage.Anolderadolescentwithaclosedphysesisconsidered skeletallymatureandgiventheconventionaladultACLreconstruction. 2.2.3.1BoneDevelopment Thetermskeletallyimmaturereferstotheincompletegrowthandfusionoftheskeleton.Skeletal growthinvolvescartilaginousgrowthaswellasossication.Cartilagegrowsinanorganized,linear fashionandisconvertedintobonethroughossication.Theprimaryossicationfrontsinlongbones suchasthefemurareknownasthephyses,orgrowthplates.Theprex"epi"meansaboveinlatin sotheepiphysis(abovethephysis)isthesmallregionbetweenthephysisandtheendofthebone. Theprex"meta"meansaftersothemetaphysis(afterthephysis)istheregionbetweenthephysis andtheshaftofthelongbone. Bonegrowthinlongboneslikethetibiaandfemuroriginatesinthephysesofthebones.About 65%ofthetotalgrowthofthelowerlimbcomesfromthephysesabouttheknee;thedistalfemoral physiscontributesabout37%andtheproximaltibialphysisabout28%[7].Disturbancesofthe physiscanresultingrowtharrestmostcommonlyprematuregrowthplateclosurebutalsoexcessive 13

PAGE 24

growth,causingadi erenceinlimblength. Figure2.2.1:TibioFemoralJoint Tibiaandfemurillustratedwithapproximatesiteofthephysesadded.Figurecreatedusing BioDigitalHuman(www.biodigital.com). 2.2.3.2PrepubescentACLReconstruction Asthepatienthassignicantgrowthremaining,surgicalproceduresforprepubescentchildren arephysealsparing.Theseproceduresweredesignedtoneitherdrillthroughthephysesnorattachhardwaretouchingthephyses.Thetwomainwaysofachievingthisareextraarticularand intraarticulartechniques. ExtraArticular(Alsocalledextraphysealorover-the-top) Physeal-sparing,extraarticularreconstructionattemptstofullysparethephysesoftheinsultof tunneldrillingbyattachingthereplacementgrafttopointsotherthanthearticularsurfaceofthe kneejoint.Itisanon-isometricandnon-anatomicreconstruction.SomeexamplesaretheMcIntosh, Losee,orEllisonreconstructions,whichusefascialatatotightenthelateralsideandpreventrotationalinstabilityasseeninthepivotshifttest[86].Thissurgicalprocedurewasoccasionallyusedin adultpatientsbutabandonedfortheintraarticularapproach.Duetothelackofdrillingnearthe physes,surgeonsagreedthatthetargetpatientpopulationforthisprocedurearethoseinTanner stage1[75]. Thegurebelowhighlightstwovariationsofthissurgicalcategory.Itiscommonforthesur14

PAGE 25

geontousethegracilis,semitendinosus,oraportionofthepatellartendonastheautograft.The surgeonkeepstheattachmentsiteonthetibiaintactandusesthetendonastheACLgrafteither extraarticularlyoverthetopasseenintheleftprocedureorpartiallyintraarticularlyasseeninthe rightportion. Figure2.2.2:ExtraarticularSurgicalTechnique Sometechniquesinvolvenodrillingasseenontheleft,whereasothersinvolveminimaldrillingas seenontheright[73]. Thisapproachhasbeenshowntohavemildsuccesswithreturntopre-injurysportsparticipation[57, 36,76].Anautograftofthepatellartendonorhamstringgraftsisrecommendedbysome[75].The maindisadvantagetothistypeofprocedureisthatthereisalackofisometryasthereplacement graftisplacedinanon-anatomicalpositionoverthetopandabovethephyses.Extraphysealreconstructionusingthesemethodscreatesanon-isometricreconstructedligament[73]. IntraArticular(Epiphyseal,Anderson,Transepiphyseal) Physeal-sparing,intraarticularreconstructioninvolvestunnelsthataredrilledintothearticularsurfaceofthebonesatanangletoexitbeforethephyses.Thegoalofthistechniqueistopositionthe graftinanisometriclocationwhileavoidingphysealviolationfromdrillingholes.Thistechnique requiresuoroscopicguidancetoensuresafetunnelpositioning[73].Itusesthetibialdockingtechniqueandallowsforcustomizedtunnelplacement[23].Thisreconstructioncanprovidesafe,reliable resultsinpatientswhohavesignicantgrowthremaining.However,itistechnicallydemandingand hasasmallmarginoferror.Therefore,itshouldbereservedforusebysurgeonsexperiencedinthe technique[73]. ThegurebelowshowsthemostcommonlyusedintraarticularsurgeryreferredtoastheAndersonTechnique. 15

PAGE 26

Figure2.2.3:IntraArticularExample[2]oftheAndersonTechnique Therehasbeensuccessreportedforstabilizationandlackofgrowthdisturbanceforpatientsin TannerstageIorII[2,23].Useofthebraidedhamstringgraftwithanendobuttontoaidxation isoneoptionpresented[2].Sincethistechniquewaspublished,smalliterationshavebeendiscussed. OnegroupwasabletocreateatechniquethatkeptthenativeACLattachmentswhilexingentirely intheepiphysis[50].Anothervariationofthisprocedurealoopwascreatedthroughtwoholesin thetibialepiphysis[52].Athirditerationproposedtheadditionofsoft-tissuebuttons[58].Itisclear thatthistechniqueisstillevolvingandrequiresahighlevelofskill. Combination Combinationsofthediscussedprocedureshavealsobeenperformed.Atransphyseal-intraarticular extraphysealprocedurewithahamstringorpatellartendongraftismentioned[75].Theholeis drilledinthetibiaandthegrowthplateofthefemurisspared.Thiscombinationprocedurewas recommendedforpatientsinTannerstage2. Physeal-sparing,combinedintra-articularandextra-articularreconstructionusingautogenous iliotibialbandgraftshasbeenreportedtobesuccessfulforprepubescentpatients[42,39,13,66]. Thisisacombinationoftheallepiphysealandtheoverthetopmethod.Acombinationofoverthe topandtransphysealonthetibialsidewithaniliotibialbandgraftwasshowntobesuccessful[31]. 2.2.3.3Adolescent(OpenPhyses)Resconstruction Proceduresforadolescentswithgrowthremainingarecommonlytransphysealreconstructions. Atransphysealreconstructionissimilartotheadultprocedureandinvolvesdrillingthroughthe openphysesbutxingthegraftfurtherawayandnotcontactingthephyseswithhardware.This methodhasbeenreportedtobesuccessfulwhenmimickingtheadultprocedure[68,5].MRIresults alsoconrmthatsignicantgrowthdisturbanceisunlikelyaftertransphysealACLreconstruction inadolescentpatients[97]. Thisprocedureisrecommendedforpatientsapproachingskeletalmaturity[75,43,81].Criteria 16

PAGE 27

forasuccessfuloutcomeconsistof:1)avoidanceofhardwareplacedacrossthephyses,2)secure femoralandtibialxationofthegraft,3)clinicalabsenceofproblematiclaxity,and,4)atfollowup,absenceofleg-lengthdiscrepancies,angulardeformities,andsymptomatickneeinstability[81]. Howeveritwasalsoshowntobea ectiveforpatientsonofTannerstage1and2[77]. Variationofthegraftchoicepointstoadi erenceinphysicianpreferenceratherthanoutcome. TheuseofanAchillestendonallograftwasproventobeaviabletreatmentoptionforpatients withaskeletalageof14years[5,81].ThesamemethodexhibitedsuccesswithcombinedACL-MCL injuriesandabraceaddedfortheMCLinjury[72].Ahamstringgraftwithanchoragewellawayfrom thegrowthplatewasalsoshowntobesuccessful[1,42,60,39,81,13,66,35,69].Patellartendon allograftswerealsousedsuccessfullywithspecialattentionplacedtotheboneplugandinterference screwplacementtoreducerisktothephyses[21].Anothergrouphadsuccesswithusinghamstring tendonswhentherewasanopenphysesbutpatellarwithaclosedorclosingphyses[26]. 2.2.3.4Adolescent(ClosingPhyses)Reconstruction TheconsensusforolderadolescentpatientsapproachingskeletalmaturityisthattheadultACL reconstructionprocedureisacceptable[42].Thissurgicalmethodwashighlightedpreviouslyin section2.2.2.However,theevolutionofanypediatricsurgerymustrequireminimizingtraumato thesegrowthplateswhilestillhavingsuccessinsurgery. 2.2.3.5ProtocolSurgery Thesurgicalmethodusedforsymptomaticsubjectsinthisresearchprotocolinvolvedavariation oftheAndersontechnique.Anintraarticulartunnelwasdrilledthroughthefemurwhileatransphysealtunnelwasdrilledthroughthetibia.Thequadricepstendongraftwasusedforallsubjects. Bonepinswereusedintheportionoftheholesclosesttothekneejoint.Buttonswereusedfor xationattachedoutsidethebone. 17

PAGE 28

Figure2.2.4:SurgicalProcedureUsed 2.2.4SurgicalEvaluation AsaclinicalstandardmethodforrepairofpediatricACLtearshasnotbeenestablished,itis importanttocontinuallyevaluatethevarietyofsurgicalmethodsavailable.Whilekneestability istheprimarypurposeforACLsurgery,therearemanyfactorsthatcontributetoevaluatinga successfulsurgicalprocedure.Generaldi erencesinthesurgerytypesoutlinedaboveincludegraft material,graftposition,andxationlocationistheprimarygroupoffactorstobeconsidered. Additionally,theageofthepatient,timesincesurgery,andadherencetorehabilitationregimen needtobeincludedforamorecomprehensive,andthereforeaccurateevaluationofthesurgical outcome. WhiletherestorationofkneestabilityistheprimaryreasonforsurgicalrepairingtheACL, thepediatricproceduralsuccesscriteriainsteadfocusoninfectionratesandphysicalabnormalities.Aspediatricspecicsurgicaltechniqueswerecreatedtocontroltraumatothephyses,growth disturbancesandmorespecicallylimblengthdiscrepancyareamainassessmentofthesuccess ofaprocedure.Additionally,kneealignmentconditionssuchasvarus/valgusaretracked.The e ectivenessofadultACLreconstructionforrestoringnormalkneekinematicsislargelyunknown, particularlyduringsportsmovementsgeneratinglarge,rapidlyappliedforces[80].Expandingthe focustoincludeadditionalmetricsthatareeasilymeasurablebutpertaintodynamicmovement isalogicalchange.Hence,theevaluationstandardsofsurgicalsuccessareevolving,andwillhave 18

PAGE 29

positiveimplicationsforthefutureofpediatricACLrepair. 2.2.4.1GrowthDisturbances GrowthdisturbanceswerethedrivingforceinadaptationstotheadultACLreconstruction procedureforskeletallyimmaturepatients.Itiscommonclinicalknowledgethattraumatothe physesresultsingrowthabnormalities.Clinicaldatasuggestthatplacingrelativelysmalltunnels (7%9%ofthephysealarea)acrossthephysisthatarecentrallylocatedandlledwithsofttissueare lesslikelytoresultingrowthdisturbance,whereas,theplacementoflarger,moreeccentrictunnels lledwithcancellousboneorplacedundersignicanttensionaremorelikelytoleadtogrowth arrest[7].Growthdisturbancescanbeclassiedasundergrowthandovergrowtharecommonly measuredandreportedaslimblengthdiscrepancies.Jointalignmentisalsoconsideredaformof growthdisturbanceandinthiscaseisreportedasangulardeformity. Leglengthdiscrepancieshavebeentrackedandreportedduringthedevelopmentofpediatric ACLsurgicalmethods.Ameta-analysisdoneon55articlesshowedthathamstringtransplants maylowertheriskofleg-lengthdi erencesoraxisdeviations,andphyseal-sparingtechniquesmay increasetherisk[20].Themeta-analysisfound19patientswithleglengthdi erencesand34casesof re-ruptureoutofthe935patientsstudied.Thesearegenerallyconsideredstatisticallylowrates.In anotherlargeanalysis,therewere15reportedcasesofgrowthdisturbance:8casesofdistalfemoral valgusdeformitywitharrestofthelateraldistalfemoralphysis;3casesoftibialrecurvatumwith arrestofthetibialtubercleapophysis;2casesofgenuvalgumwithoutarrest;and2casesofleg lengthdiscrepancy[40].Theauthorspointtoplacementofhardwareacrossthephysesastheroot causeforthesedisturbances.Anotherstudyoutlinedagrowtharrestresultinginlimbshortening of2cm[35].Overgrowthwasalsoviewedinafewcases[14,60].Inbothstudies,overgrowthwas minimal,1-1.5cm.AthirdcaseofovergrowthwasreportedinthesurveyconductedbyKocheret al.inwhichovergrowthwaslargerat3cm[40]. Kneevarus,valgus,andrecurvatumarealsogrowthdisturbancerelatedconditionsinwhich thekneealignmenthaschanged,resultinginknockkneesandotherangulardi erences.Valgus deformityhasbeenreportedasaresultofatransphysealintraarticularreconstruction[43].While therewasnotrauma,pain,orinstabilityaftertheprocedure,anincompletepreoperativeskeletal assessmentthatresultedinaninappropriateoperativetechniqueyieldedconsequences.Theresult wasthatthepatientneedingacorrectiveopening-wedgeosteotomy.Anothersurveybasedstudy reportedavalgusdeformitywasfoundin10patients[40].Thesecaseswerelikelyduetodistal femoralphysealarrest.Thesamesurveyalsoreported3casesofgenurecurvatumasaresultofthe 19

PAGE 30

closureofthetibialtubercleapophysis. 2.2.4.2Unknowns Assurgicalrepairofthemid-substanceACLruptureinskeletallyimmaturepatientsisarelatively newandrapidlyevolvingprocedure,therearestillunknowns.Itisunknownwhethersuchagraftwill, withpatientgrowth,hypertrophyinitsintra-articularsegmentandtakeonthesizeandmechanical propertiesofanadultACL[75].Therearealsoconcernsregardingatraumatickneelaxityandtunnel widening[60].Graftandsurgicaltechniquechoiceareimpactedbypatientswithopenphyses.This mayalsohaveanimpactonrehabilitationbutnoresearchstudiesappeartobepublishedinthis area[44]. VariationsinbonymorphologyhavealsobeenassociatedwithACLinjuryrisk.Therewas anincreasedmedialtibialslopeinACL-injuredteenagerswithopenphyses,whencomparedtoa controlgroupofteenagerwithopenphyseswithoutACLinjury[89].Theremaybemoreinformation forthcomingbystudyingbonemorphologyinthefutureasmedicalresearchcontinuestoprogress. 2.2.5Conclusion TheliteraturedistinctlyconcludesthatnonoperativetreatmentforACLrepairinskeletally immaturepatientsyieldspoorresults.Conventionaladultreconstructionisfrowneduponforyounger patientsduetothetraumatothephysis.Basedonthecurrentplethoraoftechniques,itisclear thatpediatricsurgicalrepairmethodologyisstillevolving.Successhasbeendemonstratedwitha varietyoftechniquesbutnosinglemethodhasbeenproventobethebest.Patientskeletalageand surgeonpreferencedictatetheoptionsforreconstruction,andsurgicalproceduralsuccesscurrently focusesongrowthdisturbancesratherthanrestorationofjointstability.Asystemforevaluating theseevolvingtechniquesbeyonde ectsongrowthwouldcertainlyprovebenecialforthegrowing numberofadolescentsrequiringACLreconstructivesurgery. 2.3KneeStability AsthelackofkneestabilityinACLdecient(ACL-D)kneesnecessitatesACLreconstruction, itisimportanttoinvestigatekneestabilityasitrelatestoACLsurgery.Thereisanimportant distinctionbetweenthetermslaxityandstability:laxityreferstothepassiveresponseofajoint, whereasstabilityfocusondynamicmovements.Thetermstaticstabilityisoftensubstitutedfor laxity.TounderstandtherelationshipbetweenkneestabilityofanACL-DkneeandofanACL 20

PAGE 31

repaired(ACL-R)knee,aclearunderstandingofbothcomponentsofstabilitymustbehad. 2.3.1KneeStabilityDenitions Stabilitycanbedenedastheabilityofthejointtomaintainposition(static)orcontrolmovement(dynamic).Kneestabilityisacombinationoflaxityandstabilitywhereasbothpassiveand dynamicmovementcontrolcontributetotheoverallstabilityofthejoint.Dynamicstabilityis anatomicallyrootedintheperformanceofbothmusclesandligamentsthatsupportandcontrolthe kneejoint.InadditiontotheACLasthefocalligamentofthisstudy,quadricepsandhamstring action[37],resectionsoftheproximalbula[9],fourmajorkneeligaments(ACL,PCL,MCL,LCL) [17],andothersuchstructureshaveallbeenshowntocontributetokneejointstability. Theassessmentoflaxityandstabilityareclinicallyseparate.Kneejointlaxityisofparticular interest,andhasbeenstudiedextensively.Thisisinpart,duetothehighincidenceofkneeinjuries, kneejointpain,anddegenerationthataccountforsubstantialmorbidity,functionalloss,andhealth careexpenditures[46].Orthopedicsurgeonsusekneejointlaxitytoassess(in)stability,butrecently, self-reportedinstabilitywasshowntobeunrelatedtokneejointlaxity[94].Theclinicalstandard diagnostictoolsfornotonlyACLinjurybutotherkneeinjuriesarelaxityfocused,qualitative assessmentssuchastheAnteriorDrawerandPivotShiftTests.Theseteststendtoexaminepassive motionandrelyuponthetactileexperienceofanexpertmedicalprofessionalforthepass/fail ranking.Quantitativekinematicdatadescribingstabilityfocusesonanteriortibialtranslation[53, 61],tibialrotation[48],orvarus/valgus[87].Thecurrentmetricsusedtoassessstabilityfocuseither onasingleplaneofmotionoruseaqualitativescale.Askneefunctionalmotioninvolvesglidingas wellasarotationandexion/extension,theentirerangeofexibilityandlinkagesbetweenthese motionsareunknown.Trueunderstandingofkneejointlaxitywillinvolvemotionanalysisinallsix degreesoffreedom. 2.3.2RoleoftheACLinKneeStability Anatomically,theACLfunctionsistolimitanteriortibialtranslation,axialrotation,andvarus movement.AfterACLinjury,kneejointstabilityandload-bearingpatternbetweencontactjoint surfacescanbealtered,resultinginabnormalloadingsonthecartilageduringfunctionalactivities [25].AnteriorkneelaxityhasbeencitedasriskfactorforACLinjurybutthemechanicalrelationship ofpassivekneelaxitytokneetranslationsduringdynamicactivitieshasnotbeendescribedin vivo[82]. ItisnotyetentirelyclearhowtoevaluatethesuccessofACLrepairrelativetokneestability. 21

PAGE 32

ResiduallaxitiesafterACLreconstructioninpatientswithpreoperativeanteromedialinstabilities mayincreasethestressonthegraft,compromisingtheremodelingprocessandincreasingtheincidenceoffailurerateofthesurgery[98].Avarietyofresearchhasattemptedtolinklaxitywith stability.Inthepast,staticstabilitymeasureshavenotcorrelatedwellwithanyknownmeasureof functionaloutcomeforACL-injuredsubjectsbeforeorafterreconstruction[80]. 2.4ClinicalAssessmentsofKneeFunctionality IthasbeenestablishedthattheACLisrepairedduetoalackofkneefunctionalstabilityboth passiveanddynamic.Awidevarietyoftoolsarecurrentlyusedtomeasurekneestabilityboth qualitativeandquantitative.Themaintypesofmeasurementsaresurveys,singleplaneclinical qualitativeassessments,machineassistedsingleplanequantitative,andmorerecentlythreedimensionalmotionanalysis.Eachtypeofkneestabilityassessmentsystemrequiresadi erentlevelof cliniciantrainingandfocusesonadi erentoutput.Duetothecomplexityofthekneejointinterms ofbothanatomyandfunctionality,theseassessmentsattempttosimplifythemotioninorderto focusonaspeciccomponentofstability.Kneestabilityassessmentsarebeusefulfordiagnosisof ACLinjury,comparisonbetweensurgicaltreatments,andestablishingreturn-to-sportstandards[49]. Thelargequantityofkneestabilityassessmenttoolstargetdi erentaspectsofstability.Surveys focusonperceivedfunctionalstabilityinADLsaswellaspainlevels.Qualitativeclinicalassessments andmachineassistedquantitativeclinicalassessmentslookatmovementinasingleplaneduring passivemotion.Thesefocusonlaxityratherthanstability.Finally,threedimensionalmotion analysisattemptstoquantifykneestabilityduringdynamicmotionbyfocusingonkinematicand kineticoutputs.Therelationshipbetweenpassiveclinicalinstabilityandlaxityisunclearandmay befurtherunderstoodiflaxitycouldbereliablyandaccuratelyquantied[46][3]. KneestabilityassessmentsareemployedduringthreephasesofACLinjury.Therstphasethey areusedisindiagnostics.Theassessmentsinthisphaseareusuallyclinicallaxityexaminationsand surveys.Thesecondphaseisintheevaluationofsurgicaltreatment.Theseassessmentsareboth intra-operative,evaluatingtheimmediatee ectofoperativetreatment,aswellasthecomparison ofdi erentreconstructiontechniques[49].Resultsinthissecondphasecanbebothqualitative andquantitative.Thethirdisinrehabilitationoftheinjuredjoint.Thisphaseislong-termand incorporatesdatausedtotrackprogress. 22

PAGE 33

2.4.1Surveys Agrowingnumberofpatientsurveysarebeingadministeredtoassesskneefunctionalstability. Theirfocusrangesfrompainlevelstouseduringsports.Thesesurveyshelpindiagnostics,inthe comparisonofpatients,intrackingprogressofhealing,andincomparisontoastandardofhealthy individuals.ThebelowtableisasnapshotoftheAOSSMClinicalOutcomeMeasuresforSportsRelatedKneeInjuriesreport.Itoutlinesthemostcommonlyusedsurveys,andtheirimportant characteristics. Table2.4.1:KneeRelatedSurveys Forstudy,thepediatricIKDCwasusedduetothestudypopulationaswellasthecommonuse inChildren'sHospitalColoradoOrthopedicClinic. 2.4.2QualitativeClinicalAssessments Qualitativeclinicalassessmentsarepartofthestandardofcareforallkneeinjuries.Theyare usedasinitialdiagnosticsaswellasassessmentsduringrehabilitation.Thesejointlaxitymeasures arepassivemotionexaminationswhichrequireaclinicalspecialistwithenoughtrainingtorecognize theappropriateendfeelofthejointmotion.Astheyarequalitative,theassessmentsaresubjective. 23

PAGE 34

Someinvestigatorshaveattemptedtolinkfunctionalsymptomstotheresultsoftheseexaminations. Onesuchexamplefoundpatientswithhighergradepivotshiftexaminationshadlesssatisfactionwith outcome,moreactivitylimitation,loweroverallkneefunction,morelimitedsportsparticipation,and lowerLysholmscores[41]. Therearealargenumberoftestsforeachdirectionofinstability.Commontestsandthetarget directionofmovementarelistedintable2.4.2.Theteststargetaspecicdirectionofmotioninorder toisolateasinglecomponentratherthanallsixdegreesoffreedomsimultaneously.Asindividual ligamentsaredi culttoisolateduetothemultifacetednatureoftheirfunction,multipleclinical examinationsareusedandcorroboratedwithimagingstudies.Forexample,theanteriorcruciate ligamentistheprimaryrestrainttoanteriortibialdisplacementandasecondaryrestrainttovaruvalgusmotioninfullextensionandrotation[54].Thespecicexaminationischosenbasedonthe cliniciansexperience,training,andthetargetstructure.Generally,thecontralateralkneeisusedas abaselineaseachpersonhasavaryingamountofnaturallaxityintheirjoints.Additionally,the levelofswellingandtheabilityofthesubjecttorelaxplayaroleintheresults. 24

PAGE 35

Table2.4.2:ClinicalAssessments Instability Test MainStructure One-PlaneMedial Abduction/ValgusStress MCL HughstonValgusStress MCL One-PlaneLateral Adduction/VarusStress LCL HughstonVarusStress LCL One-PlaneAnterior Lachman ACL AnteriorDrawer ACL ActiveDrawer ACL One-PlanePosterior PosteriorDrawer PCL ActiveDrawer PCL ReverseLachman PCL Godfrey PCL AnteromedialRotary Slocum's MCL Lemaire'santeromedialjolt MCL Dejour MCL AnterolateralRotary Slocum's ACL Losee ACL Jerk ACL PivotShift ACL Nakajima ACL Crossover(Arnold) ACL Flexion-RotationDrawer(Noyes) ACL Flexion-extensionValgus ACL Martens ACL PosteromedialRotary PosteromedialDrawer PCL PosteromedialPivotShift PCL PosterolateralRotary PosterolateralDrawer PCL ReversePivotShift(Jakob) PCL ExternalRotationalRecurvantum PCL Loomer's PCL Dial(TibialExternalRotation) PCL StandingApprehension PCL Meniscus McMurray Meniscus Apley's Meniscus BounceHome Meniscus O'Donohue's Meniscus ModiedHelfet Meniscus/Cruciate/Quad Steinman'sTendernessDisplacement Meniscus Payr's Meniscus Bohler's Meniscus Bragard's Meniscus Kromer's Meniscus AndersonMedial-LateralGrind Meniscus Other Mediopatellar Pilca PilcaStutter Pilca Hughston'sPilca Pilca Hulge Swelling Wipe Swelling Indentation Swelling PatellarGrind(Clarke's) PatellofemoralDysfunction PassivePatellarTilt PatellofemoralSyndrome LateralPull PatellofemoralArthralgia Zohler's ChondromalaciaPatellae Frund's ChondromalaciaPatellae 25

PAGE 36

Insubsequentsubsectionseachplaneofmotionwillbedescribedandanytestperformedaspart ofthisresearchprotocolwillbedescribed.Alltestshavemanyvariationsincludingkneeexion angleandhandposition.Thespecicexaminationperformedinthisresearchprotocolwaschosen basedonclinicalpopularityandphysicianpreference.Allexaminationshadthepatientinthesupine position. 2.4.2.1One-PlaneMedial One-plane-medialinstabilityisalsoknownasabductionorvalgusinstability.Itisinstability whenthetibiamovesawayfromthefemuronthemedialside.ThemostcommontestistheValgus (abduction)StressTestwhichtargetsthemedialcollateralligament. Theexaminerappliesavalgusstress(pushesthekneemedially)atthekneewhiletheankleis stabilizedinslightlateralrotationwiththehandorwiththelegheldbetweentheexaminer'sarm andtrunk[54].Thekneeshouldbeexedto30degreesoverthesideofthetable,withoneofthe examiner'shandsplacedonthelateralaspectofthekneewhiletheotherhadgraspsthefoot[16]. Painwiththismaneuveriscausedbyanincreaseintensionofthemedialcollateralstructuresorthe connectionofthesestructureswiththemedialmeniscus.Ifpainoranexcessiveamountofmotionis detectedcomparedwiththeotherextremity,ahyper-mobilityorinstability,shouldbesuspected[17]. 2.4.2.2One-PlaneLateral One-plane-lateralinstabilityisalsoknownasadductionorvarusinstability.Itisinstabilitywhen thetibiamovesawayfromthefemurlaterally.ThemostcommontestistheVarus(adduction)Stress Testwhichtargetsthelateralcollateralligament. Theexaminerappliesavarusstress(pushesthekneelaterally)atthekneewhiletheankleis stabilized[54].Theadductionforceisappliedatboth30degreesandfullextensions[16].Under normalconditions,theend-feelisrm,afterslightmovement[17]. 2.4.2.3One-PlaneAnterior One-plane-anteriorinstabilityisthefocusofthisthesisasthemainfunctionACListolimit anteriortibialtranslation.BoththeLachman'sexaminationandAnteriorDrawerTestwereperformed. TheLachmantestisalsoknownastheAnteriorDrawerinExtension,Ritchie,Trilliat,or Lachman-Trialliattest.Theexaminerholdsthepateint'skneebetweenfullextensionand30ofexion,applyingonehadtostabilizethefemurandtheothertostabilizetheproximaltibia[54].Firm 26

PAGE 37

pressureisappliedtotheposterioraspectofthetibiainane orttoproduceanteriorsubluxation[16]. Apostiivesignisindicatedbya"mushy"orsoftendfeelwhenthetibiaismovedforwardonthe femuralongwiththedisappearanceoftheinfrapatellartendonslope[54].Inthehandsoftheexperiencedclinician,theaccuracyofthistesthasbeenfoundtobe81.8percentsensitiveand96.8 percentspecic,increasingto100percentifthepatientisanesthetized[17]. TheLachman'sexaminationisoneofthefewteststhatattemptstogradetheinjurybyperceived quantitativemotion.Sourcesvaryastotheexactquantityofmotionoftheanteriormovementof thetibiarelativetothefemurtoeachspecicgradeofinjury.However,grade1(mild)isroughly 1-5mm,grade2(moderate)isroughly6to10mm,andgrade3(serious)morethan10mm,and somesourcesuseagrade4as16mm+ofmotion[54][17][49]. TheAnteriorDrawerTestisalsoknownastheDrawerSignandissometimesperceivedofas avariationoftheLachman's.Thelowerextremityshouldbeexedatthehipto45degreesand thekneeexedto80or90degreeswiththefootatonthetable[16].Inthisposition,theanterior cruciateligamentisalmostparallelwiththetibialplateau[54].Theclinicianxatesthepatient'sleg bysittingonthepatient'sfootinneutralrotation,placestheirhandsaroundtheproximaltibiausing theirngerstoensurehamstringmusclesarerelaxed,anddrawsthetibiaanteriorly[54][17][16]. TheAnteriorDrawerdi ersfromtheLachman'sexaminationinbothexpectedamountofmovementandaccuracy.Thenormalamountofmovementthatshouldbepresentisapproximately6mm [54].Theanteriordrawertesthasbeenfounttobe40.9percentsensitiveand96.8percentspecic [17].Ifwhendoingtheanteriordrawertest,thereisanaudiblesnaporpalpablejerk(Finochietto's jumpingsign)whenthetibiaispulledforwardandthetibiamovesforwardexcessively,ameniscus lesionisprobablyaccompanyingthetornanteriorcruciateligament.[54] 2.4.2.4One-PlanePosterior One-plane-posteriorinstabilityistheoppositeofone-planeanteriorinstability.Itisinstability whenthetibiamovesawayfromthefemurposteriorly.ThemostcommontestisthePosterior DrawerTest. ThePosteriorDrawerTestisalmostidenticaltotheanteriordrawertestexceptthedirectionof motionisopposite.Itisoneofthemoste ectivemeansofclinicallydiagnosingposteriorcruciate andposterolateral(popliteus)cornerinjuries[54].UnliketheACL,thePCLisrarelycompletely torn[17].Again,theexaminersitsonthedorsumofthefoot,positionshandssothatthemiddle ngerscanpalpatethehamstrings;thethumbsareplacedalongthetibiaatthejointline,and pushesstraightbackgently[16]. 27

PAGE 38

2.4.2.5AnteromedialRotary Anteromedialrotaryinstabilityreferstoexcessiveanteriortibialrotationrelativetothefemur. Noneoftheseexaminationswereperformedforthisproject.Ingeneral,theexaminerwatchesthe medialsideofthetibiatoseeifitrotatesanteriorlymorethantheuninjuredside[54].Thepathology involvestheACL,MCL,andposteriormedialcapsule,which,alongwithitsreinforcingbers,is termedtheposteriorobliqueligament[17]. 2.4.2.6AnterolateralRotary AnterolateralrotaryinstabilitywasanotherfocalpointofthisprojectasboththeLoseeand Jerktestswereperformed.Thetargetmovementisanteriorrotationofthetibiaonthelateral siderelativetothefemur.ThepathologyforthisconditionalmostcertainlyinvolvestheACLand, clinically,theinstabilityallowsthemedialtibialcondyletosubluxposteriorly,becausetheaxisof motionhasmovedtothelateraljointcompartment[17].BoththeLoseeandJerktestsarevariations ofthePivotShiftTest. TheLoseeteststartswiththeexaminerholdingthepatient'sankleandfootsothattheleg islaterallyrotatedwiththekneeexedto30andbracedagainsttheexaminer'sabdomen.The examinerplacestheotherhandoverthepatellaandappliesavalgusforcewhileextendingtheknee [54].Anendfeelresultinginaclunkforwardduetoanteriortibialsublexationmeansthetestis positive. TheJerktestisalsoknownastheJerkTestofHughston.Theexaminersupportsthelower extremityandexesthehiptoabout45degreesandthekneeto90degreeswhileatthesametime internallyrotatingthetibia[16].Thelegisthenextended,maintainingmedialrotationandavalgus stress[54].ThetermJerkreferstothesublexationofthelateralfemoralcondyleonthelateraltibial plateauwhichoccursatabout20to30degreesofexion[54][16]. 2.4.2.7PosteromedialRotary Posteromedialrotaryinstabilityreferstoexcessiveposteriortibialrotationonthemedialside relativetothefemur.Noneoftheseexaminationswereperformedforthisproject. 2.4.2.8PosterolateralRotary Posterolateralrotaryinstabilityreferstoexcessiveposteriortibialrotationonthelateralside relativetothefemur.Noneoftheseexaminationswereperformedforthisproject.Thistypeof 28

PAGE 39

instabilityisrelativelyrare,becauseitrequirescompleteposteriorcruciatelaxity[17]. 2.4.2.9MeniscusInjury MeniscalinjuriesarerelativelycommonconcurrentinjuriesinfullACLruptures.Forthisreason, aMcMurrayTestwasaddedtotheprotocolastheonlynon-ligamentousexamination.Becausethe menisciareavascularandhavenonervesupplyontheirinnertwothirds,aninjurytothemeniscus canresultinlittleornopainorswelling,makingdiagnosisevenmoredi cult[54]. Duringthistest,theclinicianmaximallyexesthehipandkneebygraspingthepatient'sfoot insuchawaythatthethumbislateral,theindexandmiddlengersaremedial,andtheringand littlengersholdthemedialedgeofthefootwiththethumbofonehandonthelateralaspectofthe patient'sknee[17].Theexaminerthenmediallyrotatesthetibiaandextendstheknee,repeatedly changingtheamountofexionandthenapplyingthemedialrotationtothetibiafollowedby extension[54].Thismethodfocusesontheposterioraspectofthemeniscus. 2.4.2.10IncorrectExaminationResults Bothfalse-positiveandfalse-negativetestscanoccurduetoacombinationofclinicianand subjectfactors.Clinicalpositioningandmovementarecrucialtotargetingthecorrectstructure. Additionally,concurrentinjuriescanmuddleresults.Ifthesubjectisguardingortenseratherthan relaxedthismayalsoe ectresults.SpecicallyfortheAnteriorDrawertests,atornPCLcanleadto afalse-positivebecausegravitycausesthetibiatosagposteriorlyoratornmedialmeniscuswedged againstthemedialfemoralcondyle,orhamstringspasmmayresultinafalse-negativetest[54]. Additionally,thepatient'sactivelyraisinghisorherheadproduceshamstringtightening,which canaltertheresultsofthetest[16].Toincreaseaccuracyorreliability,machineshavebecomemore commonplacetoaugmenttheseexaminations. 2.4.3QuantitativeSinglePlanarAssessments Agrowingnumberofcliniciansareusingsimplemachinestoperformcommonplaceclinical assessments.Theuniplanararthrometersattempttoquantifydisplacementoftheknee.These devicesusedisplacementtransducersand/ordigitizedbonylandmarkpositionstomeasuretibial translationwithrespecttothepatellaunderanappliedload[46].Theyareusedprimarilytoassist indiagnosingligamentinjuriesbydetectingabnormalmotion,toprovideaquantiedmeasurement ofmotion,andtomeasuretheamountofmotionaftersurgery[54].Asinthequalitativeclinical 29

PAGE 40

assessments,thecontrallaterallegisoftenusedasacontrol.Theanteriortibialdisplacementis measuredinmillimeterswiththelaxityresultsisoftenpresentedinside-to-sidedi erence[49]. ThemostcommonlyuseddeviceistheKT-1000(andnewKT-2000)whichtestsanteroposterior displacement.OtherdevicesaretheGenucom,Rolimeter,andStrykerkneelaxitytester.The KT-1000isaninstrumentthathasbeendevelopedforanobjectivemeasurementforkneeanteriorposteriorlaxityonsaggitalplane[49].KT-1000isthebestavailablemethodtoestimatekneelaxity intheclinic,butlegpositionduringmeasurementandexaminerexperiencemayalsoa ectthe results[28].Asintheclinicalqualitativemeasurements,theresultsdependonpositioning,muscle relaxation,andoperatorskill.Varioustechniquesotherthandisplacementtransducershavebeen usedtomeasuretibialmotion,includingplanarstressradiography,RSA,andMRI[46]. Recentstudieshavebeguntocorrelatethesesingleplanarassessmentswithkneestability.Postoperatively,therewasgreateranteroposteriorlaxityandgreatervarus-valguslaxityinthegroup withMCLinjurycomparedtothegroupwithanACLlesiononly[98].Onestudyfoundwhenusing theKT-1000thattherewasnostasticaldi erenceinkneelaxitybetweenboysandgirlsofsimilar agesbutthedi erencewassignicantlygreaterinyoungerchildren[18]. Othershavebeguntocorrelatethesesingleplanarassessmentswithmotioncapturedata.FHA DirectionIndexandtotalFHAtranslationshowedweakbutsignicantcorrelationswithKT-1000 estimatesandtheBeightonHypermobilityScore[28].Amajorndingofthisstudywasthatpeak anteriortibialtranslationwaspositivelycorrelatedwithKT-1000inbothhealthymalesandfemale adultkneeswhenperformingasti drop-landingmotion[82].Thesestudiesshowthatthereisalink betweenkneelaxityandfunctionalstabilitywhichcouldpossiblyincreasefutureriskofinjury. 2.4.4KneeStabilityandReturntoSports AmajorendgoalofsurgicalACLrepairistoreturntopre-injuryathleticactivities.Standardized andobjectivecriteriatoassessathletes'safereturn-to-sportsarelimited[49].Criterionforclearance fromcliniciansforthepatienttoreturntoplayarerootedinmusclerecoverybecausestrengthisa majorcomponentofrehabilition.Quadricepsmusclerecoveryisoneofthesecriteria.While85% quadricepsstrengthisatargetgoal,itisalsoimperativetohavefullkneerangeofmotion,good dynamicbalance,andfunctionalabilitycomparablewiththeuninvolvedextremityforsafereturn tosports[93]. ThetypeofrehabilitationmethodisamajordecisionafterACLreconstruction,andiscritical toacquiringadequatemusclerecovery[93].Evenso,functionalkneestabilityshouldbeoneofthe criteriathatdetermineasafereturn-to-sports[49]. 30

PAGE 41

2.4.5Conclusion Thewidespreaduseandrelativeaccuracyofclinicalassessmentsofkneelaxityhighlightstheir appealande ectivenessasdiagnostictools.WiththeinventionofmachinesliketheKT-1000, relaiblequantitativeresultsarecurrentlyavailabletosupplimentqualitativeassessments.While manyaspectsofkneestabilityexaminationarereproducible,multiplanarquanticationofcoupled kneemotionsduringstabilitytestingremainsimprecise[67].Engineeringmodelsofbothlaxityand stabilitydi erfromthedailyusedclinicalassessments.Asthekneeisacomplexsix-degree-offreedomjointitcanbeinferedthatbothkneelaxityandstabilitycannotbesimpliedtooccurin asingleplaneofmotion.WhileithasbeenestablishedthatarupturedACLincreaseskneelaxity, therelationshipbetweenpassiveclinicalinstabilityanddynamicinstabilityremainsunclear[3].The relationshipbetweenthetworemainsasubjectforcontinuedresearch. 2.5ThreeDimensionalKneeAssessments Thekneeisacomplex6DOFjoint.Itcanbeinferredthatmechanismsofbothstaticand dynamicstabilizationoccurinalldirectionsanddonotactindependently.AsACLinjurylikely occursasaresultofmulti-directionalloading,focusingonsingleplanemotion(mostcommonly saggital)doesnotreectrealworldsituations[11,61][32].Forthatreason,dynamicassessmentof 3Dskeletalkinematicsisnecessarytoassessthee ectivenessofACLreconstructionsurgeryfor restoringnormalkneefunction[80].Toolssuchasmotioncaptureandbiplaneuoroscopyhave recentlybeenusedinresearchassociatedwithgeneralkneestability.Thesenascentstudieshave focusedonsinglekinematicmetricssuchastibialrotation[48,70],varus/valgus[87],anddeninga nitehelicalaxisintheknee[28].Thefullthreedimensionalmultivariablekinematicandkinetic pictureofkneestabilityisstillunknown. Dynamicassessmentofthree-dimensionalskeletalkinematicsisessentialforunderstandingnormaljointfunctionaswellasthee ectsofinjuryordisease.Whilejointmotionisdrivenbyacombinationofdynamicphysicalforces,activemuscularforces,constraintsimposedbypassivestructures, articularsurfacegeometry,ligaments,etc.,thespeciccombinationsoftheseforcesoccurringduring mostactivitiesareunknown[78].Toaccuratelydenekneestabilitythee ectsofallthesevariables onkneemovementmustbeaddressed. 31

PAGE 42

2.5.1MarkerBasedMotionCapture Themostcommonlyusedmethodforgeneratingthreedimensionalquantitativehumanmovement dataismarkerbasedmotioncapture.Thistechnologyusesretro-reectivesurfacemarkersattached totheskintotrackmovement.Amodelisappliedwhichusestherelationshipsbetweenthemarkers torecreatetheskeletonanditssegmentalmotion.Positionandrelationshipbetweenmarkersisthen usedtocalculatekinematicanglesanddisplacements.Themethodisnon-invasiveandmotioncan beregisteredcontinuouslyduringfunctionaltasksbutsofttissueartefacts(STA)appearwhenskin andmusclesmoverelativetotheunderlyingbone[28].Thespecicmodelappliedtothemarkerset dictatestheoutputvariables.Additionaldatacanbetakensimultaneouslyusingforceplatformsor electromyographicdevices(EMG)amongothertools.Kineticsgatheredfromforceplatformswillbe usedinthisstudybutnotdatagatheredfromEMG.Thisvideobasedmotioncapturetechnology isidenticaltothatwhichisusedinliveactionanimationforHollywoodproductionstoanimate characterssuchastheHulkandGolum. 2.5.1.1MarkerSet Markerbasedmotioncaptureusesthespecicplacementofsurfacemarkerstoinferthelocation andtrajectoriesofskeletalsegments.Thesebodysegmentsaredenedbytherelationshipsbetween individualmarkers.Thearrangementofthemarkersdictatesboththeaccuracyandavailability ofthemeasurements.Themotioncapturecamerastrackthemovementofeachindividualmarker withinaglobalcoordinatesystem. Themarkersetitselfisastandardarrangementofmarkerswhich,whencombined,cano erthe positiondataneededfortheresultingkinematicoutput.Markersetsareacombinationoftracking andreferencemarkersaswellassinglemarkers,wands,andclusters.Theyusethebasicpremise thattwopointsmakesalineandthreepointsmakesaplane.Itisgeneralpracticeformarkersets tofocusonanatomicallandmarkstoensureconsistancyacrosssubjectsandclinicians. Astherearealargevarietyofkinematicvariablesthatdenehumanmovement,therearealso alargequantityofmarkersets.Avarietyofsetshavebeenproposedforusebutthemajorityin clinicalusearebasedonsomevariationoftheHelenHayes(HH)set[15].Thesemodelthelower limbsassevenrigidsegments(onepelvis,twoeachofthigh,shankandfoot)whicharedenedby 13markers[6].ThismarkersetisclinicallyusedattheCenterforGaitandMovementAnalysis (CGMA)atChildrens'HospitalColorado. 32

PAGE 43

Figure2.5.1:ConventionalLowerBodyMarkerSetUsedatCGMA[6] TherearevariationsinmarkersetsduetotheneedtoreduceSTA.Clustersaregroupsofmarkers arearigidlyconnectedonasurfaceinsteadofdirectlyattachedtotheskin.Theseclustersareplaced awayfrombonylandmarksandtherelationshipofeachindividualmarkerintheclusterinrelation toabonylandmarkisusedtominimizethesofttissueartifact[15][3][28].Atothertimes,alarger markersetwillbeemployedtominimizethee ectsofsofttissueartifact[25].Itispossibleto avoidskinmotionartifactsbydirectlymeasuringbonemovement,eitherbyphysicallyattaching measurementdevicestotheboneorviamedicalimagingtechniques[78].Thesemethodswillbe discussedinsubsequentsections. Thereareacoupleofacceptedassumptionsformarkerbasedmotioncapture.Therstmajor assumptionisthatthemovementbetweentwomarkersforasinglesegmentislinear.Thislinearity assumption,alongwiththeassumptionthatthedynamicdeformationthatwillberecordedduring anactualactivityisequivalenttothestaticdeformation,limittheapplicabilityofthistechnique[3]. Studieshavecomparedthekinematicresultsfromtheuseofdi erentmarkersets.Whilethe goalofeachmarkersetissimplytorecreatetheskeleton,theoutputresultscanvarydependingon thesubjectmotionormarkersetitself.Somestudyshaveshownresultstohavevisablyidentiable di erences[96][15]whileothershavebeenusedtopositivelycorrelatesets[22]. Onceamarkersetisestablished,amodelisappliedtoaspecicmarkersetforkinematicand kineticcalculations.Themodelwillallowforlinkagesofmarkersintosegmentsandrelationships 33

PAGE 44

ofsegmentsintojoints.Forexample,atCGMA,ViconPlug-In-Gait (PiG)isappliedtoaHelen Hayesbasedmarkerset.Justasavarietyofproductscanbeusedtocapturethemotionofthe retro-reectivemarkers,avarietyofsoftwarecanbeusedtocalculatekinematicsandkinetics.The threemostcommonsoftwareplatformsusedforcreatingmodelsareViconMotionCaptureSuite, Visual3D(C-MotionInc.,Rockville,MD),andMatlab. Markersetandmodelcalculationscreatedspecicallyforthisprotocolwillbediscussedinlater sections. 2.5.1.2ErrorsinMarkerBasedMotionCapture Thereareanumberofknownsourcesoferrorassociatedwithmarkerbasedmotioncapture. Theseerrorscanhavevaryinge ectsonthekinematicresults.Astheprocessisveryhandsonand reliesuponpropertraining,humanerrorisacommonoccurrence.Themajorerrorsareskeletal landmarkidentication,crosstalk,andsofttissueartifact.Ingeneral,usingsurfacemarkersto calculateskeletalmotioncanprovideagoodestimatedmovementbutwillnotbeperfectlyidentical. Landmarkidenticationisoftentherstsourceoferrorencounteredduringthedatacapture process.Eachmarkerinthemarkersetisgivenanabreviationwhichisgenerallylinkedtoaskeletal bonylandmark.Theclinicianpalpatesthelandmarkbeforeattachingthemarkertotheskin.Bony landmarksarerarelyperfectlycircularofastandarddiametersotheyarenotidenticallyshapedwith themarkerbase.Theanatomicallandmarksarefrequentlycurvedordi culttopalpatecreating avariablitythatcontributestoerrorsinjointangles[15].Identicationofanatomicallandmarks canvary.OnestudyfoundveryhighpositivecorrelationsfortheY-andZ-coordinates,while theX-coordinatesshowedslightlylowerpositivecorrelationsthantheY-andZ-coordinates[22]. Additionally,landmarkscanbeobscuredbysupercialtissueanddi culttoaccuratelypalpate. Softtissueartifactisafrequentlydiscussedsourceoferror.Byattemptingtorecreatethe internalskeletonbyplacingmarkersontheskin,therewillbeanaturalmovementdi erencebetween thesupercialsofttissueandthebones.SomestrategiestominimizeSTAarewiththeuseof clustersasdiscussedabove,least-squareorroute-meansquarestechniquestohandlenoisymarker trajectories[28][22],orusingmarkersetsthatfocusonsupercialbonylandmarks.Crosstalkwill bediscussedinagreaterdetaillaterinsection3.4.3. Thecommonmethodofinterpretingmotioncaptureresultsistolookatsinglevariableora singledegreeoffreedom.Inpractice,itisraretobeabletoisolateamotionthatoccursentirely inoneplane.Forexample,itisnotfeasibletocompareanteriortibialtranslationwhilekeeping kneeextensionconstant[96].Askneemotioniscoupled,itisgoodpracticetolookatalldegreesof 34

PAGE 45

freedomsimultaneously. 2.5.1.3BonePins Theuseofxedbonepinsisastrategyforimprovingaccuracyofmotioncapturedatabydirectly trackingskeletalmotion.Rigidpinsaretemporarilyxedintothebonesofthesubjectsatoneend whiletheotherendprotrudesfromtheskin.Markersareattachedtothesupercialendsofthe pins.Whiledirecttrackingofskeletalmotionisachievedwiththeuseofbonepins,thenegative issuesassociatedwiththismethodologyoutweighthepositiveones. Issueswiththeuseofbonepinsinvolvetheirdi culttouseandinvasivenature.Intra-cortical bone-pinscouldpotentiallyalterthenormalmotion[8].Additionally,duetotheinvasivenaturebone pinsarenotpresentedasageneralreplacementforconventionalvideo-basedmotionanalysisdueto therisksassociatedwiththemarkerimplantation[78].Theuseofbonepinsisalsotimeconsuming andcanbepainful.Additionally,becausetheapplicationinvolvesmorehighlytrainedpersonneland amoresterileenvironment,ithasbeenfoundnottobeafeasible,economic,orreasonableprotocol. 2.5.2OtherTypesofMovementAssessment 2.5.2.1Radiography Radiographicmovementanalysisinvolvestheuseoffairlynewandcompleximagingtechnology. Biplaneuoroscopymachinesallowformultipleplanesofimagestobetakensimultaneouslyas thesubjectismoving.Resultsofradiographicstudiesareconsideredaccurateastheanatomical coordinatesystemisapplieddirectlytotheimagesoftheskeleton.Magneticresonance(MR)imaging canachievesubmillimeteraccuracyandenablesdirectvisualizationofsofttissue[79],whereasskin basedmotioncapturecannot. Somestudieshavecomparedsurfacemarkerdatawithbiplaneuroscopicdata.Onestudy foundnosignicantrelationshipswereobservedbetweenpeakkneevalgusanglesasmeasuredby themotionanalysissystemandpeaktranslationvaluesasmeasuredbythebiplaneuoroscopy system[83].However,thesamestudyfoundthatingeneral,themotionanalysissystemproduced larger(~57 ¡ )jointangularvaluesinallthreeplanesatthekneeduringthelanding[83].Biplane radiographictechniquesincombinationwithtraditionalmotioncapturemethodsshowpromisein investigatinghowtheunderlyingneuromuscularcontrolmechanicsareemployedandarealtered and/orrelatedtokneejointfunctionasthefunctionaldemandofthekneeincreasesthroughboth internalandexternalforcesandmoments[84]. 35

PAGE 46

Issueswiththeuseofradiographictechnologyformotioncapturearelinkedtosafetyandlimitsof thetechnology.Thebiplaneuoroscopymachineislimitedbyitseldofviewandspeedofimaging (framespersecond).Additionally,theenvironmentsaretoorestrictiveformostdynamic,weight bearingactivities[80].Themajordeterrentisthequantityofradiation.Theuseofradiographyis notpresentedasageneralreplacementforconventionalvideo-basedmotionanalysisduetotherisks associatedandtheexposuretoionizingradiationrequired[78]. 2.5.2.2OtherTypesofSensors Varioussensorsorcustomdeviceshavebeenusedtocapturekinematicdata.Devicessuch aspotentiometers,goniometers,orgyroscopescanbeusedtotrackmovementordisplacement. Whereasmotioncapturetracksthemovementofmarkersvisuallyinaglobalcoordinatesystem, thesesensorsoutputdynamicmeasurementslocallyrelativetoothersensorsorthroughoutthe sensorsystem.Goniometersarepronetoerrorbecauseofsofttissuedistortionandthedi cultyin keepingthegoniometerintheproperposition.[88]. Previouspublishedliteraturedescribeskinematicand/orkineticdatageneratedfromsensorsor othercustomizedsetups.Potentiometersplacedonthepatellaandtibialtuberositywereusedto detectmeasurementsofthetibiarelativetothefemurwhenaforcewasappliedinastaticstance [61].Custombuiltsensorsystemcomprisedpartlyofelectromagneticsensorsandloadcellwas usedtooutputanteriortibialtranslitiontolinkitwithhamstringsti ness[11].Anelectromagnetic motioncapturesystemwasusedinplaceofacamerabasedsystem[10].Goniometersystemshave alsobeenusedtostudykneekinematics[99,88]. 2.5.3ResultsfromACLFocusedMotionCaptureStudies Avarietyofhumanmovementresearchhasbeenconductedinattemptstodenekneestability and/orunderstandthee ectofanACLtear.Theproceduresforgeneratingkinematicsandkinetics canvaryfrom3-DOFHelenHayesor3-DOFPCTbasedmarkersets[30,65,96,83,85,91,92,48], novel6DOFmarkersets[4,8,25,28,45,74,90],usingBiPlaneFluoroscopywithorwithoutsurface markers[12,33,63,80,82,84],orevencustomizinggoniometer-likedevices[10,11,61,88,99].Out ofthese,roughlyhalfwerefocusingspecicallyonACLinjurywhileonlyonenon-ACLstudyhad apediatricpopulation.Theseresultsarebrieydescribedbelow. 36

PAGE 47

2.5.3.1GaitinRelationtoACL-RandACL-D Themostcommonactivityofdailylivingiswalking.GaitadaptationsinindividualswithACL injurywhohavereconstructivesurgeryarelessclear.Veryfewcomprehensivegaitanalyseshave beenconductedonthispopulation,thelargevariationinsurgicalandrehabilitationprocedures, patientcharacteristics,andinpatientcompliancewithrehabilitationlimitthegeneralizationof thesepotentialresults[17].Asthemovementofthekneeiscontrolledbypassiveconstraintsin combinationwiththeexternalloadsapplied,itislikelythatbyeliminatingaligamentwhichacts asamajorpassiveconstraintthemotionofthekneewillchange.Thegoalinthesemotioncapture studieswastoinvestigatthecompensatorymechanismsinACL-Dand/orACL-Rkneesduring walking. Theresultsofgaitfocusedmotioncapturestudiesappeartovaryslightly.Moststudiesfocus onjointmovementinthesaggitalplaneastheprimaryjoboftheACListorestrictanteriortibial translation.OnestudyfoundthatanadaptivestrategyforACL-Dkneesistolimitkneeextension andthatthispostponedexionpeaktemporalspatialpatternkinematicadaptionhadnotfully returnedtonormalinACL-Rknees[25].Anotherstudycounteredthatobservatoinbyndingthat theACL-Dkneestendedtoexmore[12].Afurtherstudyfactoredinlegdominanceandfound non-dominantACL-Rkneesexhibitedlessextensionduringthemid-stancethantheircontralateral kneesandhypothesizedthatthereducedextensionwasaprotectiveadaptiontoprotecttherepaired knee[90].OtherstudiesfoundthetibiatobepositionedmoreanteriorlyduringlocomotioninACL-D knees[99]whileasecondfoundACL-Dkneeskepttomovemoreanteriorlyduringtherestofthe stancephasecomparedtothenormalkneeswithsignicantdi erencesinthelatespancephase[12]. Specically,anteriortranslationrangehasbeenshowntohavethelargestrangeofmovement[3]in ACLintact(ACL-I)kneesbutreducepriortoheelstrikeinACL-Dknees[4].Atthepresenttime, thereisnouniversalconsensusonthesaggitalplanekinematice ectofACL-DorACL-Rknees. AnotherroleoftheACListolimittibialrotationwhichisafocalkinematicvariableformotion capturestudies.TheACL-DkneesexhibitedlesstibialexternalrotationcomparedtotheACL-I kneesduringmostpartofthegaitcycle,andthedi erencereachedstatisticalsignicanceduringa largeportionofswingphase[25].ACLdecientknee,thetibiahadreducedexternalrotationasthe kneeextendedpriortoheelstrike[4].Asmallrotationalo setforbothACL-DandACL-Rknees wasobserved[25]aswellasfordominantACL-Rknees[90]. Fewstudieshaveinvestigatedfrontalplanekinematics.Injuredknees,bothACL-DandACL-R, werealsoshowntohaveaslightvaruso set[25].Medial-lateraldisplacementshowedtheleast 37

PAGE 48

amountofmovementduringACL-Iwalking[3].ThislackofmotioninthefrontalplaneinACL-I kneescouldresultinminimalfocusforACL-DandACL-Rmotionstudies.Publisheddataonother kinematicvariablesorkineticdataissparse. Thesestudiesdiscussedhavefocusedonuncoupled,singleplanekinematicadaptationstodecientorrepairedACLknees.Gaitadaptationscanbeinkinematics,kinetics,aswellasEMG data.AstheACLisamajorrestraintintwodegreesoffreedomoftheknee(anteriortranslation andtibialrotation),itwouldbelogicaltolookatall6DOFforadaptations.Asmostwalkinggait dataiscapturedwitha3DOFmodel,thegeneralkinematicmotionprolewouldbeincomplete.To fullydenegaitadaptationstoACL-DorACL-Rknees,a6DOFmodelisnecessary.Additionally, couplingmotionsmayhighlightkinematicandkineticadaptationsmoree ectively. 2.5.3.2DynamicTasks AstheACLisminimallystressedduringwalking,resultsfromgaitstudiesonACL-DorACL-R kneesareinaccurateindirectapplicationtohighlyathletictasks.Kneetissuesarehighlyviscoelastic andrespondnonlinearlytothemagnitudeandrateofloadingsothebehaviorofthekneeunder low-demandconditionscannotbesimply"scaledup"topredictbehaviorduringmoredemanding functionalactivities[79].StudieshavebeguntoinvestigatethedynamicimpactofACL-Dand/or ACL-Rkneesduringmoreballisticmovements.Taskssuchassquats,hops,running,andcutting arethemostpopularmovementsoftheseinvestigations. Onceagain,manystudiesfocusonthee ectofanteriortibialtranslation.Onestudyfound ACL-Rkneesdisplayedlesskneedisplacementduringcutting[10].Althoughstatisticalsignifcance wasnotachieved,ACL-Rpatientslandedwiththekneeinaslightlymoreextendedpositioncomparedtothecontrolgroup[91].Anotherstudyfoundthatrestorationofnormalanterior/posterior motionpatternsdoesnotnecessarilyimplynormalkneefunction[80].Itisclearthatsaggitalplane kinematicsarenotthesolefactorinACLrelatedadaptations. Manyotherstudiescontinuetofocusonrotationasrotationalstabilityisdiscussedasapositive indicatorofsurgicaloutcome.Internalandexternaltibialrotationsinconjunctionwithtibialtorques havebeenshowntoincreaseACLstraininvitro,withinternaltibialtorquesexertingagreater inuence.Onestudyfoundnodi erencesinthosewhoexhibitloworhighpeakinternaland externaltibialrotations[83].OtherstudieshavefoundtibialrotationintheACL-Rgroupwaslower comparedwiththecontrolgroupduringpivoting[85][92],droplanding[91],andsinglelimbhop[91]. AnotherstudyfoundanincreaseintibialrotationforACL-Dkneesduringpivotingbutarestoration ofthismovementafterACLreconstruciton[48].Thepivottaskplaceshighrotationloadatthe 38

PAGE 49

knee,andisstudiedtoinvestigatetheACL-Rfunction.It(ACL-R)isexpectedtoincreasetibial rotationandtherecouldbeachangeinloaddistributionduetolocationofnewACL. Duringthesemorestrenuousmaneuvers,thereisincreasingfocusonkineticadaptationsas wellaskinematics.Researchstudieshavefoundanincreaseinexternalvarus/valgus[74][49]and internal/externalrotation[49]momentsappliedtothekneeduringcutting.Anotherstudyfound anincreaseintimetoreachpeakgroundreactionforce(GRF)duetoslowervelocities[10].One studyfocusedonagedi erencesinathletesandfoundthatpre-pubertalathletesexhibitedlarger kneeadductormomentsandGRF'swhencomparedtothepubertalandpost-pubertalgroups[74]. Additionalfocusonkineticscouldhighlightlowerbodyadaptations,e ectofskeletalmaturity,and redistributionofloadsasaresultoftheinjury. Inthesemoreballistictasks,therehasbeenanincreasingattempttolinkmultiplevariablesin ordertoprovideamorecompletepictureofkneeadaptaiontoACLinjury.Onefoundthatneither highkneevalgusanglesnorhighkneeabductionmomentsarepredictiveofpeakanteriortibial translation(ATT),lateraltibialtranslation(LTT),andmedialtibialtranslation(MTT)translations duringdroplanding[83].Anotherdiscoveredthatlargertibialinternalrotationwasassociatedwith moreslidingmotioninthemedialcompartmentduringrunning[33].Athirdinvestigationshowed di erenceswhichsuggestthatsubject'sstrength,timing,andpowermaybereduced,thusresulting inadecreasedabilitytogeneratelowerextremityforce[10].Lastly,astudyfoundnorelationship betweenpeakkneeshear(anteriororposterior)forceorpeakkneeextensormomentwithpeakATT orLTTduringthedroplandingswhichisbelievedtooccurduetoanincompletesummationofshear force[84].Thesestudiesshowaneedtofurtherinvestigatetherelationshipsbetweenkinematicand kineticvariables. 2.6Conclusion 2.6.1ClinicalRelevance TheneedforsurgicalACLrepairforskeletallyimmaturepatientshasbeenwelldocumented. TheuniquenessofthecombinationoftheadultACLreconstructionprocedureandpediatricmusculoskeletalanatomyaroundthekneejointhasresultedinthedevelopmentofmanynewrepair techniques.Theabilitytocomparetheseproceduresbasedontheire ectivenessforreturningstabilitytothekneejointwillallowfortheadoptionofacommonsetofstandardpractice.While thestandardofcarecurrentlyistotestkneestabilitybasedonqualitativesingleplanarexaminations,thesetestsrequireextensivetraining,simplifyarathercomplexjoint,andfocusonpassive 39

PAGE 50

kneelaxityratherthandynamickneestability.Byaddingourincreasingknowledgeofquantitative biomechanics,adeeperunderstandingofthee ectsofthisligamentreconstructionwillimprovethe processfromsurgerytorehabilitation. 2.6.2ProtocolDevelopment 2.6.2.1MarkerSetandModel ThereisadearthofmotioncaptureresearchinkneebiomechanicsforPediatricACLtears.Combiningdynamicmotion,ACLtears,andsix-degree-of-freedommodelingisrareinadultpopulations andvirtuallynon-existantinsketallyimmaturesubjects.Togainasuitablebaseofunderstanding foraddressingACLinjuriesinadolescents,itisnecessarytoexamineallsixdegreesoffreedomat thekneejoint.Logicalnextstepsarethedevelopment,testing,andvalidationofasixdegreeof freedommarkersetandamodelcalculationmethodtoaddresstheseshortcomings.Themarkerset andmodeldevelopedforthisstudywillbedescribedinasubsequentchapter4. 2.6.2.2ProtocolTasks Byutilizingmotioncapturestudiespreviouslydescribed,commonlypracticedrehabexercises andplyometrics,acomprehensivelistofdynamicmovementswascompiledforcompletionunder motioncaptureforthisstudy(2.6.1).Thesedynamictaskswereinitiallynarroweddownbasedon thelimiteddatacapturespace.Thenaltaskswerethenchosenbasedonmotionsthatstressthe kneeinthedirectionswheretheACLismostcommonlystressed,butalsoonpopularityofusein bothpreviousresearchandsituationslikegymclasswherethesubjectwouldhavebeenpreviously exposedtothemovement.Additionally,arangeoflevelsofchallengetothefunctionalstabilityof thekneewassaught.Passiveclinicalassessmentsweredescribedextensivelyinpreviouschapters (2.4.2).Thenumberofcombinedpassiveanddynamicmovementswerelimitedtothegoalofaone hourdatacapturetolimitfatigueandattentionspan. 40

PAGE 51

Table2.6.1:DynamicMotions Activity Category SingleHopforDistance Jump TimedHop TripleHopforDistance CrossoverHop OneLegHop MaximumControlledLeap SingleLegHopforTime AgilityHop StairsHopTest SidetoSideHop FrogHop VerticalJump Figure-of-eight Run DecelerationTest Carioca ShuttleRun Heal/CalfRaise Strength Squat SingleLegSquat Gait Walk GaitInitiation DuckWalk 2.6.3KnowledgeGained Thereareanumberofinitialconclusionsthathavebeendrawnfrompreviouslycompleted researchandmotioncapturestudies.Theyarenotlistedinanypriorityorderasallsignicantly contributetotheoverallconclusionsandfurthermethodologyforthisproject. 1.TheACLissurgicallyrepairedduetoaneedforstabilityofthekneejoint. 2.Atpresent,auniversallyacceptabledenitionofdynamicstabilitydoesnotexist. 3.PediatricACLsurgerydi ersfromskeletallymatureadultACLsurgery 4.Comparisonsofthee ectivenessofACLsurgeryonadolescentsversusadultsonrestoring functionalstabilityhavenotbeendone. Thisprojectwilldetermineifthemotioncaptureenvironmentisane ectivetoolforthecomprehensivestudyofkneestability.Additionally,itwillchartthebasicdi erencesbetweenastable andunstablekneejoint.Ifthisstudyidentiesvariable(s)responsibleforkneestabilityindynamic andpassivemotion,itwillleadtofuturestudiesinvestigatingthedi erencesinpediatricACLreconstructionmethodologyaswellastheirrehabilitationtimelines.Resultsofthisstudyhavethe potentialtoimprovetheunderstandingofkneestabilitybasedonallsixdegreesoffreedomandthe e ectofACLrepaironthejoint.Thisstudyhelpstobegintheprocessofcreatingamoreuniversally acceptedprotocolforassessingkneestabilityandrepairofpediatricACLinjuries. 41

PAGE 52

3OverallMethodology 3.1Overview Thisisanexploratorydescriptivestudythatisthefoundationforfuturestudiesonkneestability andpediatricACLtears.Thestudywasdesignedtoquantifykneestabilityusingmotioncapture technology.Themetricsandtaskswerechosenfromasubsetofthosecommonlymeasuredand itwasnotintentedtobeallincompassing.Beforecapturingdata,appropriatedocumentationwas createdandapprovedbytheappropriateInstitutionReviewBoard(IRB).Thisstudywascompleted perIRB14-0115.Thischapterwilloutlineanoverviewofthemethodologyusedinthisstudyand furtherdetailswillbepresentedinsubsequentchapters. 3.2StudyInputs 3.2.1Subjects Atotalof16subjectswererecruitedforthisstudy;12asymptoticand4symptomatic.All subjectswerebetweentheagesof8and18.Thisstudywasapprovedbyourinstitution'sIRBand allsubjectsandparentsreviewedandsignedaninformedconsentbeforeparticipating. 3.2.1.1AsymptomaticSubjectSpecics Additionalexclusioncriteriaforasymptoticsubjectsincludedorthopedicsurgeryatthehip,knee, oranklewithinthelast2years,previousdiagnosisofACLinjury,leglengthdiscrepancygreater than2cm,andcongenitalpathologythata ectsgaitorlowerlimbstability/coordination.Intotal, therewere12asymptoticsubjectstestedanddemographicsarelistedinthetablebelow3.2.1. Table3.2.1:AsympomaticDemographics SubjectID Age Gender Height(in) Weight(kg) KA1001 18 M 72 88.8 KA1002 13 M 75 101.8 KA1003 9 F 53.25 30.4 KA1004 13 F 65.5 52.2 KA1005 11 M 58.1 41 KA1006 8 M 48 23.2 KA1007 18 F 62 56.6 KA1008 10 F 56 35.6 KA1009 11 M 59.5 35.6 KA1010 11 M 62.5 46.2 KA1011 8 F 49 23.6 KA1012 14 M 64.5 45.8 42

PAGE 53

3.2.1.2SymptomaticSubjectSpecics SymptomaticsubjectswererecruitedthroughtheChildren'sHospitalColoradoOrthopedicClinic andwereDrAlbright'spatients.Patientswhowerelessthantwoyearspostsurgeryandthosewho werepre-surgeryweretargetedbutnonewereavailableforthisstudy.Additionalexclusioncriteria forsymptomaticsubjectsincludedpatientswithadditionalorthopedicinjuriesa ectinggait,leg lengthdiscrepancygreaterthan2cm,andcongenitalpathologythata ectsgaitorlowerlimb stability/coordination.Intotal,foursymptomaticsubjectsweretestedanddemographicsarelisted inthetablebelow3.2.2. Table3.2.2:SymptomaticDemographics SubjectID Age Gender Height(in) Weight(kg) TimeSinceSurgery(weeks) Leg KS1001 9 F 53.8 45.2 26 L KS1002 16 M 75.5 96.4 31 R KS1003 14 F 65.8 51.4 9 L KS1004 13 F 64.5 56.8 9 R 3.2.2Instrumentation Motioncaptureinvolvesathree-dimensionaldigitalopticalsystemthatusedcamerastorecord markertrajectory.Additionally,theenvironmentisequippedwithtenforceplatformsandtwohigh denitionvideocamerastorecordadditionaldata.The13ViconMXcamerasrecordedmarkertrajectoryforkinematicsat120Hz.AnalogdatafromBertecforceplatforms(BertecCorp.,Columbus, Ohio)forkineticswascollectedatafrequencyof1080Hz. 3.3DataCaptureProcedure ParticipationinvolvedaonehourmotioncapturesessionattheCenterforGaitandMovement Analysis(CGMA)atTheChildren'sHospitalColorado.Thestudyinvolvedtwophases;pre-test andmotioncapture. 3.3.1Pre-Capture Thepre-capturephaseconsistedofprovidinginformationtothesubjectandparent(s)incompliancewiththeinstitutionalIRBandpreppingformotioncapture.Uponarrival,subjectswere givenaninformationpacketincludingconsentformstobesigned.Informedconsentwasobtained priortothestartofthestudy;assentwasalsoobtainedwhenappropriate.Copiesofallsigned formswerebegiventothesubjectandparent(s).Allpersonsobtaininginformedconsentwerebe membersoftheresearchteamandhaveappropriateIRBandHIPAAtraining.Thesubjectswere 43

PAGE 54

askedtolloutPediatricIKDCsurvey.Uponcompletion,subjectswereinstructedtochangeinto appropriateathleticclothingasneeded.Anthropometricmeasurementsrequiredformotionanalysis weremeasuredandrecordedwithatapemeasure,calipers,andscale. 3.3.2MotionCapture ThesecondphaseinvolvedmotioncaptureinthemainlabofCGMA.Initially,14mmretroreectivemarkersrequiredforkinematicanalysiswereplacedonbonylandmarks.Themarkerset usedwillbedescribedinthenextchapter.Atthebeginningofeachmotioncapturesession,a statictrialwastakenperlaboratorystandardprotocol.Themotioncapturesessionconsistedoftwo components;dynamicandpassivemotion. 3.3.2.1DynamicMotion Afterthestatictrial,eachsubjectperformedvariousmovementtaskswhilekinematicandkinetic datawascapturedandvideowasrecorded.Subjectsreceivedinstructionpriortoeachtaskandwere askedtopracticethetaskatleastonetimepriortotherecordedtrialforthepurposeofensuring thatthetaskwasperformedadequately.Inbetweentasks,subjectswerebegiventheopportunity torestand/ordrinkwaterasnecessary.DynamictaskswerebeobservedbyDrAlbrightandany abnormalitiessuchasguardingwerenoted.Symptomaticsubjectswereexemptfromcertaintasks dependingontheirinjurytimelineandpainlevelperDrAlbright. Taskinstructionswereintendedtogeneratesubjectselectedmovementratherthanatargeted metricsuchasmaximumangle.Alltaskswerecompletedatasubjectselectedtempo.Three perceivedgoodtrialsofeachdynamictaskwascaptured.Fiveperceivedgoodtrialswerecaptured forgait.Listedbelowaretaskspecicinstructionsthatweregiventothesubjects. GaitAtaselfselectedtempowalkacrosstheroom. SquatTasks(DoubleandSingleLimb)Standwithfootorfeet(shoulderwidthapart)pointing forward,squatdownwithoutlosingbalancetoapproximately60 ¡ to90 ¡ ofkneeexion,andthen standbackup.Torsopositionistoremainverticalwithoutforwardtrunkexion,feetmustremain atorasclosetoataspossibleandsubjectswerenotbeallowedtosupportthemselvesonany stationaryxtureorwiththenon-squattinglimbinsinglelimbsquatsduringthisactivity.For doublelimbsquats,subjectswereinstructedtoplaceeachfootinthecenterofaforceplateto ensuregoodkineticdata.Forsinglelimbsquats,subjectswereinstructedtoplacethesquatting 44

PAGE 55

limbinthecenterofasingleforceplate. HopTasks(ForwardandLateralsinglelimb)Standingononeleg,jumplateralorforwardandthen landbackonthesamelegthatwasusedtopropelthejumpsequence.Subjectwasinstructedto begintaskwiththehoppinglimbinthecenterofasingleforceplate.Theuseofupperextremeities wasselfselected.Subjectmustlandandnotusethecontralaterallimbforabalancesupport/ capture.Subjectwasinstructedtofocusona"gymasticslanding"ratherthanmaximumdistance. Subjectwasnotinstructedtotargetaforceplateduringlanding. PivotSlowlyjogforwardforroughly5mtothecenterofthenalforceplate,thenpivot90 ¡ using thetargetlimb,andcontinue1m.Duringthepivot,thesubjectmustnotjump,walk,orpause whenchangingdirection. 3.3.2.2PassiveMotion Afterthedynamictrialswerecompleted,anexaminationtablewasplacedinthecenterofthe roomandusedforthepassivemotioncomponentofdatacapture.Duringthepassivemotionphase, clinicalassessmentsdescribedpreviously(2.4.2)werebeperformedoneachkneebyDr.JayAlbright. Alltestsarecurrentstandardofcareforpatientsseeninclinicforkneeinjuries.Subjectwasasked toliecomfortablyonatableinthecenterofthemainlabandanymarkersonthebackandankle wereremoved.Dr.Albrightinstructedthepatienttochangepositionorrelaxasneededduringthe assessments.Kinematicdatawasbecollectedduringthisphase.Additionally,anyabnormalitiesin endfeelduringtheclinicalassessmentswerenotedbyDr.Albright. 3.4DataProcessing Onceprocessed,themotioncaptureandkineticdataforeachmotioncapturetaskisstoredin ac3dle.ThecustomMatlabprograms,describedintheDataAnalysissection,willextractand usethenecessaryinformationfromeachc3dletocalculatethestudy'skinematic,kinetic,and nonlinearvariables. 3.4.1Pre-CaptureData Initialdataforeachsubjectwascollectedbeforemotioncapturewasentered.Thisdataset includedanthrompometricsandthePediatricIKDCsurvey.Thescoringofthesurveywascompletedperpointsystemoutlinedinthesurveyinstructions.Tables(3.2.1and3.2.2)withsubject 45

PAGE 56

demographicsweregeneratedfromthismethod. ResultsfromthePediatricIKDCarelistedbelow. Table3.4.1:PediatricIKDCSurveyResults Subject Age Gender TimeSinceSurgery Score KA1001 18 M N/A 95.65 KA1002 13 M N/A 80.43 KA1003 9 F N/A 81.52 KA1004 13 F N/A 100 KA1005 11 M N/A 100 KA1006 8 M N/A 100 KA1007 18 F N/A 100 KA1008 10 F N/A 100 KA1009 11 M N/A 98.91 KA1010 11 M N/A 98.91 KA1011 8 F N/A 100 KA1012 14 M N/A 100 KS1001 9 F 26 48.91 KS1002 16 M 31 95.65 KS1003 14 F 9 52.17 KS1004 13 F 9 55.43 ItisnotedthatthemotherofsubjectKA1003thoughtthatthesubjectwasexaggeratingthe painlevels.Additionally,subjectKS1002wasthefarthestfromsurgeryandpreparingtoreturnto fullactivityshortly.GraphicalresultscreatedinJMPStatisticalSoftware(SASInstituteInc.,Cary, NorthCarolina)areinthegurebelow.Quartileboxplotshighlightadi erenceinscoresbetween thetwosubjectgroups.Additionally,at-testwithunequalvarianceyieldedstasticaldi erence (p=0.0267)evenwiththissmallsamplesize. 46

PAGE 57

Figure3.4.1:PediatricIKDCGraphicalResults Quartileboxplotsshowthescoreresultsineachsubjecttype.Thegreylinesarethegroupmeans. 3.4.2ProcessingofMotionCaptureData MotioncapturetrialswereprocessedusingViconNexusTMaccordingtostandardCGMAprotocol.Thisprocessingprotocolinvolvesreconstructingandcroppedtoappropriatelength,labeling markers,llinggapsinmarkertrajectories,applyingaWoltringlter,insertingtaskeventssuchas footstrike,andapplyingthestandardViconPiGmodel.ThenewmarkersfortheFenwaysetwere thenlabeled,gapswerelled,andtheFenwaymodelwasapplied.Thisbasicprocessingisshownin thebelowgure. 47

PAGE 58

Figure3.4.2:DataprocessinginViconNexus 3.4.3Cross-TalkReprocessing Cross-talkatthekneejointisacommonlyoccurringerrorduetomalalignmentofthekneejoint axisduringthestatictrial.Thiserrorcanbearesultofamisalignmentofthethighwand,knee alignmentdevice(KAD),orboth.Theresultsofthemalalignmentcausekneeexion/extension signaltoproduceartifactinthekneevarusvalguscurves.Whilethisalsoe ectsotherjoints,for thepurposeofthisprojectonlythekneewillbediscussed.Tooptimizethedataset,twodi erent alignmentcongurationsofeachsubject'sstatictrialwerecreatedandthea ectonawalkingtrial wascomparedtotheoriginal. TherstalternativestaticcongurationfocusedontheerrorduetotheKAD.Theuseofa KADadjuststhighrotationfor+/-10deg,allowingslightlyimperfectplacementofthethighwand. Withoutitsuse,theassumptionisthethighwandplacementperfectlydenesthefrontalplane.To negatetheuseofanderrorduetotheKAD,thestandardstatictrialisreplacedbyadynamictrial whichhasbeencroppedfornomotion.Thistrialhasthesubjectinthesameanatomicalposition asthestandardstatictrialbutdoesnothavetheKADormedialanklemarkers.Thighrotation valueswerechangedtozerointhesubjectparametersandthenewstatictrialwasreprocessed. Thesecondalternativestaticcongurationfocusedontheerrorduetothighwandplacement. RichardBakerdevelopedaBodyBuildermodelcalledDYNAKADwhichfocusedonretrospectively correctingcrosstalk.Thetheorywasthatanyvariationinthemeasuredvarus/valgusangleis likelytobeaconsequenceofmisplacementofthethighmarker[6].DYNAKADcreatesvirtual thighmarkersbyrotatingthepositionofthetruethighmarkerthroughaknownangleaboutan 48

PAGE 59

axisbetweenthekneemarkerandthehipjointcenter.Itndsthevirtualmarkerwhichgivesthe minimumvarianceofkneevarus/valgusandusesthismarkerinsteadofthethighwand.Thismodel iscommonlyusedtocorrectforcrosstalkretrospectively[59,64,71]. Thewalkingtrialinitsoriginalformandreprocessedusingthetwoalternativestaticcongurationsdescribedabovewerecomparedsidebyside.Kneevarus/valgusangleswerevisuallyinspected forpossibleimprovement.Ifthechangingofthestatictrialminimizedcrosstalkwithoutnegatively e ectingotherplanesofmotion,thanitwasusedtoreplacethestandardstatictrial.Thetable belowshowswhichstaticcongurationswerechosenpersubject. Table3.4.2:CrossTalkInvestigation Subject StaticTrial KA1001 RightSideDynaKAD KA1002 DynaKAD KA1003 AltCal KA1004 Standard KA1005 AltCal KA1006 Standard KA1007 Standard KA1008 AltCal KA1009 Standard KA1010 Standard KA1011 Standard KA1012 AltCal KS1001 Standard KS1002 Standard KS1003 AltCal KS1004 AltCal Standardreferstotheoriginalprocedure.AltCalistherstalternativestatictrialdescribed above.DynaKADisthesecondalternativestatictrialdescribedabove. 3.5MatlabProcessing Matlabwasusedforsecondaryprocessingandinspectionofthemotioncapturedata.Custom codewaswrittenspecicallyforthisproject.Thegeneralprocessbeganwithbatchprocessing the.c3dlesoutputtedfromNexusandsavingthegroupdataasan.matleforfutureviewing inthecustomGraphicalUserInterface(GUI).Thetranslationaldisplacementcalculationswillbe describedin4.2.2.TheGUIforviewingresultswillbedescribedinchapter5. 3.5.1BatchProcessing AfterprocessingtheindividualtrialsinNexus,the.c3dleswereimportedintoMatlabindividuallyoringroups.Thebatchprocesscodeopenedandreadthese.c3dlesthenextractedthe 49

PAGE 60

targetinformation.Thedatawasplacedintoastructurebasedonidentierssuchasvariable,leg, task,andsubject.Theoutputofthebatchprocesscodeisanorganizedstructureofdatathatis savedasaneworexisting.matle.Thesinglestructureofdatainthe.matlecanbereadby thematchingGUIforgraphing.Thoughafullbodymarkersetwasusedfordatacapture,onlythe lowerbodydatawasrelevanttothisstudysoalldataabovethepelviswasnotprocessedinMatlab. 3.5.2Gait UsingtheeventscreatedinNexus,thegaitdatawasparsedintogaitcycles.Thisprocess iscommontotheclinicaldataasthegaitcycleisastandardunitofmeasurement.Fivetrials ofwalkingdatawerecapturedpersubject.Toensurethateachsubjecthasequalweightina groupaverage,vegaitcyclesperlegwerechosenfromallthedata.Usingbothtemporalspatial andkinematicdata,thevemostrepresentativegaitcyclesperlegbasedonvarianceratiowere identied. Fortheasymptomaticsubjects,itwasassumedthattheleftandrightleggaitcycleswere identical.Avisualinspectionforequalvarianceratiosbetweenlegsprovedthistobeacorrect assumption.Fivegaitcyclesperlegwerecombinedtoyield10gaitcyclespersubject.Thedata wasthenaveragedtwice,rsttocreateanintrasubjectaverage.matleandsecondtocreatean intersubject.matle. Thegaitdatafromthesymptomaticsubjectswasprocessedtocreateintrasubjectaverages.The ACL-IandACL-Rlegwasidentiedandstoredaspartoftheintrasubjectaverage.matlecreated. Theasymptoticpopulationdatasetwasusedtocomparewithsymptomaticdataandpublished data. 3.5.3Squat Bothdoublelimbandsinglelimbsquattrialswerecroppedtobeginwhenthetargetknee(s) exed5degreesfromtherstframeofdata.Thetrialsweresimilarlycroppedtoendwhentheknee waswithin5degreesofkneeexionfromthenalframe.Thiscreatedrelativelyconsistentpatterns ofmotionacrosssubjectsandtrials.Forsinglelimbsquats,onlythesquattinglegdatawasrelevant forthisstudysotheoppositelegdatawasnotsaved.Datawassavedbothastimenormalizedfrom 0to100%ofthetaskcycleaswellasrawframe.Assubjectswerenotgivenaspecictimeto completethetasksnoranglerequirements,interandintrasubjectaverageswerenotcalculated. 50

PAGE 61

3.5.4Hop Theprocessingofforwardandlateralhoptasksfollowedthesameprocessingprocedures,includingcroppingandtimenormalization,asthesquattasks.Thehoptasksweresavedinfourphases: thewholetrial,take-o phase,airbornephase,andlandingphase.Thephasedelineationwasmade usingthegaiteventswhereasthetakeo phaseendedatthe"footo "frameandthelandingphase beganatthe"footon"framewiththeairbornephaseoccurringinbetween.Assubjectswerenot givenaspecictimetocompletethetasksnoranglerequirements,interandintrasubjectaverages werenotcalculated. 3.5.5Pivot DuringinitialprocessingofpivottaskdatainNexus,itwasobservedthatboththeintraand intersubjectvariabilityinprocedurewasunexpectedlylarge.Thetargetmotionwasforthefoot tohittheforceplateandrotate90degrees.Howevertheresultingmovementsdidnotmeetthis intention.Somefootstrikesoccurredmidrotationwhileothersappearedmorelikeashu # e.As thetargetmotionwasnotcompletedconsistently,thedatawillnotbeused.Instructionswerenot specicenoughtoresultinthedesiredmovementpatternconsistentlyand,therefore,modications totheinstructionswillberequiredbeforemovingforwardwiththistask. 51

PAGE 62

4FenwayModel 4.1MarkerSetDevelopment Theobjectiveofthenewmarkersetwastocreateaminimalisticsixdegreeoffreedommarker setthatyieldedequivalentkinematicstopublisheddataandcouldbeimplementedinfutureclinical use.TheabilitytocalculatetranslationsatthekneejointwasessentialduetotheroleoftheACLin limitinganteriortibialtranslation.Asthesetranslationaldisplacementswereexpectedtobesmall, theuseofbonylandmarksandclustersinthemarkersettoreduceSTAwereparamount.Afocus onsimplicityandminimalmarkerusagewouldallowforfutureimplementationinaclinicalsetting. Additionally,asthefocalpopulationwaschildren,alargemarkersetwouldnotonlytakealong timetoapplybutitwouldplacetheindividualmarkerstooclosetogetheronsmallerbodies. 4.1.1CurrentMarkerSets TheclinicalmarkersetcurrentlyinuseatCGMAisaHelenHayesbased3DOFmarkerset. Thismarkersetusesthekneejointcenterasacommonpointforthethighandleg.Thismakes calculatingdisplacementsbetweenthetwosegmentsimpossible.Specically,thePiGmodelcreates anaxisatkneejointcenterusingthehipjointcenter,femoralwand,andlateralkneemarkerand anotheraxisattheanklejointcenterusingthekneejointcenter,tibialwand,andlateralankle marker.Asthereisacommonlysharedpointatthekneeforbothsegments,onlythreedegreesof freedomarepossible. Markersetsusedinpublishedliteratureforsix-degree-of-freedommotionatthekneevarygreatly. Thequantityofmarkersin6DOFmodelsstudyingthekneerangedfrom35toaround83fromthe pelvistothefoot.Markersetsusedwerebothindividualmarkers,clusterbased,oracombination ofboth.AstheCGMAmarkersetuses15markersduringdynamictrials,the6DOFmarkersets inpreviouslypublishedliteratureweretoolargeforpracticaluse.Anoverabundanceofmarkers cannotonlybecumbersomeinsetup,butcanleadtoissueswithtrackingandlabelingduringdata captureandprocessing.Itwouldappearcommonpracticetopublishavalidationorcomparison studyofthe6DOFmodelagainstaclinicalstandard3DOFmodel[3,15,22,78,8]. 52

PAGE 63

Figure4.1.1:MarkerSetComparison Fenwaymarkersetcomparedtoapublished6DOFmarkerset[25]usedinACLresearch. 4.1.2FenwayMarkerSet Withthefocusoncreatingane ectivesixdegreeoffreedommarkersetwithasfewmarkersas possible,thenewmarkersetforuseinthisstudybecameasupplementediterationoftheCGMA HHbasedmarkerset.ThisnewmarkersethasbeennamedFenway.Twomarkersandacluster wereaddedtotheCGMAHHmarkersetonthelowerbodytocreateanindependenttibialaxis. AsthekneejointaxisinPiGmodelistechnicallycalculatedfromfemoralmotion,therelationship withthiskneejointcenter(KJC)axisandthenewindependenttibialaxisallowsfor6DOFatthe knee. Thetwoadditionalmarkersareplacedatthetibialtubercleanddistallyalongthetibialcrest. TheOxfordFootModelisacommonlyused,multi-segmentedfootmodelthathasalegcomponent whichusesthetibialtubercle(TT).TheuseoftheTTmarkerintheFenwaymodelwasinspired bytheOxfordFootModel.Additionally,boththeTTandthetibialcrest(TC)areeasilypalpable withlittlesupercialsofttissuetocreatenoise.OtherlandmarkssuchasGerty'sTubercleand thelateralcondylewereinitiallyconsideredbutnotchosenforthenalmarkerset.Markersetis illustratedbelow. 53

PAGE 64

Figure4.1.2:FenwayMarkerSet 4.2ModelCalculations Whileliteratureshowsthatsixdegreeoffreedommotionsatthekneecanbecalculatedusinga varietyofsoftwaresuchasVisual3D,forthisprojectBodyBuilderandMatlabwereusedforeaseof troubleshootingandadeeperunderstandingofthecalculations.ABodybuildermodelwascreated andappliedduringtheprocessingphaseinViconNexus.Thissimplemodelcreatesandexportsan independenttibialaxis. 4.2.1BodyBuilderIndependentTibialAxis AcustomBodyBuildercodewascreatedtoexportanaxisgeneratedfromtheadditionalmarkers andclusterutilizedinthecreationoftheFenwaymarkerset.Thisaxiswascalculatedwithoutthe useofthelateralkneemarkerallowingforallsixdegreesoffreedomatthekneejoint.InthePiG model,theankleaxisistranslatedbackuptoproximaltibiaandsubtractsshankrotationfromknee rotation.Thisindependenttibialaxisoriginatesatthetibialtubercleinsteadoftheanklewhich eliminatesthecontributionoftheentireshanktokneerotationangle. Thecreationoftheindependenttibialaxisisillustratedbelow.First,aplaneiscreatedusing theclusters.Nextthetibialtuberclemarkerisprojectedintothisplane.Finally,theaxisiscreated beginningwiththez-axisasthelinefromthetibialcrestmarkertothetibialtubercle.They-axis 54

PAGE 65

iscreatedfromthetibialtubercletotheprojectionintheclusterplane.Finallythex-axisisthe crossproductofthosetwovectors.Thisprocessisillustratedbelow. Figure4.2.1:IndependentTibialAxisGeneration 4.2.2MatlabTranslationCalculations AcustomizedMatlabscriptwasdevelopedtocalculate6DOFanglesanddisplacementsatthe knee.ThisscriptusestheoutputkneejointaxisfromthePiGmodelandtheindependenttibial axisgeneratedfromtheFenwaymodel.Itfollowsthecalculationsforajointcoordinatesystem describedbyGroodandSuntay[29].Afterexperimentingwithtranslationmatrices,directionof cosines,Eulerangles,andothertrigonometricandgeometrictools,themethodwaschosenbased onitssimplicityandpopularity.Itisacommonlyusedmethodincurrentliterature[8,30,65,78, 80,33,82,84,83,22,63,74]mainlyin6DOFmodelsatthekneeandadvancedfootmodeling.A simpliedversionofthemethodissubsequentlyoutlinedwithnomenclatureandvariablesmatching theparentarticle. The6DOFkneejointwascreatedusinganon-orthogonalsystemcreatedfromthetwocoordinate systemsofthefemurandthetibia.Inthismodel,thefemuristheparentandthetibiaisthechild sotheoutputsarethemotionofthetibiainrelationtothefemur.Thisisthemostcommon relationshipinpublishedliteratureandalignswithclinicalexaminations. Thecalculationsbeginwithpositiondataofthefemoralandtibialaxis.Theseeightpointsare illustratedinthebelowgureandincludetheendpointsoftheaxisaswellastheaxisorigin. 55

PAGE 66

Figure4.2.2:FemoralandTibialAxes Points(red)havebeenexportedfromNexus.Thegure[29]wasalteredtocorrespondwiththe CGMAlaboratoryglobalcoordinatesystem.Note:Yispositivetothemedialsideontherightleg butlateralsideontheleftleg. Aseriesofunitvectorsareusedtocalculatebothangularmotionanddisplacements.Unitvectors e1ande3arecalculatedbysimplyusingthecoordinatesdescribingthevectorsintable4.2.1. Table4.2.1:JointCoordinateSystem AlphaDirection AnatomicalDescription CorrespondingUnitVector I LateralFemoral e1 J AnteriorFemoral e1r K SuperiorFemoral N/A i LateralTibial N/A j AnteriorTibial e3r k SuperiorTibial e3 Finalvectore2becomesthecommonperpendicularofthetwovectorsandisalsocalledthe oatingaxis. e 2 = e 3 e 1 | e 3 e 1 | Oncethissystemofunitvectorswascreated,translationswerecalculatedusingsimpledot productsofeachunitvectorandthedistancevectorbetweenthetwobodies(H).Additionally, rotationswerecalculatedusingtrigonometricrelationshipstoalternatedotproducts.The6DOF movementcalculationsandvariablesarelistedinthetablebelow. 56

PAGE 67

Table4.2.2:TranslationsandRotationsattheKnee Movement Variable Calculation APTranslation q2 H e 2 MLTranslation q1 H e 1 Compression/Distraction q3 H e 3 Flexion/Extension sin = # e 2 K Abduction/Adduction cos = I k ; # 2 rightknee 2 # leftknee Rotation # sin # = # e 2 i rightknee sin # = # e i leftknee Translationaldisplacementscanbeexplainedinmoresimpliedlanguage.Anterior-Posterior (AP)translationortibialdraweristhemovementofthetibiainrelationtothefemuralongthee2 oroatingaxis.Medial-lateral(ML)translationortibialthrust/shiftisthemotionalongthee1or lateralfemoralaxis.Jointdistraction-compressionisthemovementalongthee3orsuperiortibial axis. Asthedisplacementistheendgoalofthetranslationcalculations,thet=0valuewasusedasthe zerovalueforalltasks.Thegoalofthetranslationoutputswastomeasurethedisplacementina certaindirection.Todoso,therelativezerostartingpointmadeitpossibletoeasilycomparedi erent subjectsorpopulationaveragesthroughoutasingletask.Normalizationtoananthropometric measurementasisdoneinkineticsdoesnotresultinlogicallycomparabledata. 4.3ModelValidationUsingGaitResults ValidationofthisnewsixdegreeoffreedommodelknownasFenwayusedgaitdataandconsistedoftwocomponents.Therstportioncomparedthekneejointanglescalculatedfromthetwo di erentmodels,PiGandFenway.ThesecondportionvisuallycomparedtheFenwaycalculated translationdisplacementscurveswithpreviouslypublisheddata.Throughcomparisontoconcurrentlycalculatedanglesandpreviouslypublisheddata,thevalidityoftheminimalisticFenwaymodel canbeproven. 4.3.1QuantitativeModelValidation TherstvalidationusesthesamedatatocomparePiGwithFenwaycalculatedkneeexion/extensioncurves.EachmodelusesthePiGcalculatedhipjointcentertokneejointcenter astheproximalvector.Themaindi erenceinthesecalculationsisthedistalsegment.Thedistal vectorinPiGisthekneejointcentertoanklejointcenter.ThedistalvectorinFenwayistheaxis fromthetibialtubercledistallyalongthetibialcrest. 57

PAGE 68

Figure4.3.1:KneeFlexion/ExtensionDuringWalking AcomparisonofPiGandFenwayModels Statistically,thesetwodatasetsarecorrelated.Inpreviousmarkersetvalidationstudies[22,15] thetwomarkersetswerecomparedusingPearson'scorrelationcoe cient.Inthecaseoftheabove validation,usingJMP,thecorrelationcoe cientwas0.99(P<0.001).Thekneeexionishighly correlatedbetweenthetwomarkersets. Additionalstatisticalcomparisonsandmovementplaneswerealsolookedat.Theseareshown inthegureandtablebelow.Itcanbeseenthatthemodelsarevalidinallthreeplanesofmotion atthekneejoint. Figure4.3.2:FrontalandTransversePlaneModelValidation 58

PAGE 69

Table4.3.1:StasticalModelComparison KneeFlexion/Extension KneeVarus/Valgus KneeRotation PiG Fenway PiG Fenway PiG Fenway PearsonCorrelation 0.99(P<0.001) 0.99(P<0.001) 0.50(P<0.001) RootMeanSquareError 4.31 2.57 4.45 AverageStandardDeviation 6.11 6.45 5.00 7.60 5.13 14.89 Coe cientofVariation 19.20 16.70 25.22 17.13 42.04 16.45 4.3.2QualitativeModelValidation Thesecondvalidationcomparesanterior/posteriorkneetranslationcalculatedwiththeFenway modeltothatdoneinpublishedliterature.Allofthepublishedliteratureusesdi erentmarker setsanddi erentmethodsforcalculatingthedisplacement.Thebelowgureoverlayspublished gaitdataontoaplotcreatedfromtheasymptoticsubjectsusingtheFenwaymarkersetandmodel calculations.TheFenwaydataisshowninthebackgroundinpurplewithaonestandarddeviation shadedareainalighterpurple.Onemajordi erenceofnoteisthesubjectsforthepublished dataarealladults.Atablehasbeenincludedbelowthegurewithdetailsoftheoverlaiddata correspondingtothenumerickey.Alloverlaidgraphsmaintaintheiroriginalaxeswiththeexception ofkeynumber3whichhasbeeny-axisshiftedpositiveforeasiervisualcomparison. 59

PAGE 70

Figure4.3.3:Anterior/PosteriorKneeTranslationDuringGait AvisualcomparisonofFenwayresultsandPublishedData Table4.3.2:Anterior/PosteriorKneeTranslationSourceComparison Key# Author Subject N Technique Notes Category 1 Andriacchi[3] ACL-I 10 Surface 2 LaFortune[47] ACL-I 5 BonePin 3 Benoit[8] ACL-I 1 Surface Stancephaseonly BonePin Fourtrialsforasinglesubject 4 Chen[12] ACL-I 10 BiPlaneFluoro StancePhaseOnly ACL-D ContrallateralLimb 5 Gao[25] ACL-I 15 Surface ACL-R 14 ACL-D 14 6 Wang[90] ACL-I 19 Surface DominantLimb ACL-R Non-DominantContrallateralLimb ACL-I 22 Non-DominantLimb ACL-R DominantContrallateralLimb Amajorobservationalndingisthatthereisavariationintheplotsofthepublisheddata. Whereasthekneeexion/extensionanglecurveshaveconsistentlydistinctshapeswithtargetextrema,theanterior/posteriordisplacementcurvesdonot.Thisisaproductofthelargevarietyof 60

PAGE 71

methodsusedtomeasure6DOFmotion.Datausedforthisoverlayincludedsurfacemarker,bone pin,andbiplaneuoroscopymethods.Somestudieschosetoonlyfocusonstancephase,those wereincludedaswell.Anadditionalvariationinmethodisthey-axiso set.Somestudieschoseto zeroattimezero,othersusedastatictrial,whileanothergroupdidnotmentionanything.Asthe measurementplottedisadisplacementratherthantheconventionalangle,startingvaluescouldbe asourceofdi erenceinmethodology.ImprovementtotheFenwaymodelcouldoptimizethisy-axis o setratherthanbeginwithazerolevel. Whilemethodforgeneratinganterior/posteriorkneetranslationcurvescouldhavecausedthe variationinresults,thereareothersourcesofinconsistenciesorerror.Thenumberofsubjectsused togenerateplotsalsovariedaswellastheirhistoryofACLinjury.Alargersamplesizewillcreate amorerepresentativepopulation.STAcouldalsobeasourceoferror.Finally,resolutionisadirect productoftechnologyandCGMAmotioncapturesystemallowsforsub-millimeterresolution.If theresolutionofthesystemusedisnotsu cient,asourceoferrorcouldbeduetothemeasurement capabilities.Itisclearfromthevarietyofmethodsandresultsthatacommonprocedureisnecessary forcrosslaboratorycomparisons. Regardlessofthegeneralvariation,thereseemstobeaspecicpatternthatthemajorityof thepublisheddataaswellastheresultsfromthisstudyfollow.Thegaitcyclebeginswithan increaseinanteriortranslationwhichcreatesalocalmaxima.Theanteriortranslationdecreases graduallyfollowedbyalocalminima.Theanteriortranslationthenincreasesatrstslowthenata muchhigherratetoamaximumcyclevalueduringswingphasesimilarlytokneeexion/extension. Finally,theanteriortranslationdecreasessharplytoalocalminimarightbeforehealstrikeand increasesslightlyafterendingthegaitcycleonapositiveslope.Astheresultsfromtheuseofthe Fenwaymodelandmarkersetcorrespondwiththepatternandrangesofthepublisheddata,the secondportionofthevalidationissuccessful. 4.4Conclusion Therstprimaryaimofthisstudywastocreateaminimalistic6DOFmarkerset,develop necessarymodelcalculations,andvalidatetheseagainstpublisheddata.TheFenwaymarkerset onlyaddstwomarkersandoneclusterperlegtotheHHbasedCGMAmarkersetusedforclinical datacapture.TheViconrelatedsoftwarelesneededforusewerecreatedandappliedtosuccessfully outputanindependenttibialaxis.Themodelcalculationsoutlinedwerebasedonacommonly acceptedmethodforcalculatingthemotionoftwoindependentbodies.TheMatlabroutineswere 61

PAGE 72

writtenformodelcalculationsthatoutputtedall6DOFmotionattheknee. Themodeldevelopedtoapplytothisnewmarkersethasbeenprovenvalidagainstboththe concurrentlyappliedPiGmodelaswellaspublisheddata.Eachmodelwasappliedtothesamedata andcomparisonofthekneeexion/extensionangleduringthegaitcycle(GC)provedequivalent. Publishedplotsofanterior/posteriortranslationduringwalkingwereoverlaiduponasymptoticresultsfromthisstudy.VisualanalysisprovedtheFenwaymodeloutputsasimilargraphicalpattern, withslopesandextremasintherangesofpreviouslypublisheddata.Overall,thisstudyobjective hasbeenachieved. 62

PAGE 73

5KneeStabilityGUI 5.1GraphicalUserInterfaceOverview AcustomGUIwascreatedinMatlabasamajordeliverableofthisprojecttostreamlineviewing oftheresults.TheKneeStabilityGUIallowstheusertoimportasymptomaticand/orasymptotic populationthathasalreadybeenbatchprocessedandsavedasa.matleasdescribedpreviously in3.5.1.Thesubsequentsectionsdescribethedi erenttypesofcustomizationfortheinputdata aswellasthecategoriesofplotsavailableforviewing.Thesefeaturesareimportantasitallowsfor clinicalpersonneltoviewthepopulation'smotioncapturedatafrommultipleperspectives-thus providingavastlyimprovedsystemofdatainterrogation. Asthekneeisanincrediblydynamicjoint,anotherfocusofthisprojectwastoinvestigatethe relationshipbetweensingleplanarvariables.Inadditiontothestandardsingleplanarsetsofplots andthenewlygeneratedtranslationcurves,aseriesofplotshasbeengeneratedwithtwoorthree variablesplottedagainsteachotherratherthanasinglevariableplottedagainsttime.Thesenew plottypeswereaninitialattempttounderstandamoredynamicpictureofkneemovementand stability.Theirusefulnessandapplicabilityinthisinitialinvestigatorystudywilldictatetheirfuture useinakneestabilityprotocol. 5.2InterfaceUse TheKneeStabilityGUIisasimpletousegraphicaltoolcreatedfromsoftwarecodecustomized andwrittenspecicallyforthisprotocol.Theuseofthistoolisbrokenintotwocategories-setup andgraphicaluse.Setupreferstoloadingofthedataandcustomizingtheinputdataforplotting. Graphicalusereferstothecategoryofplotsdisplayedandinteractingwiththeactualgrapheddata. 63

PAGE 74

5.2.1Setup Figure5.2.1:KneeStabilityGUISetup TherststepforusingtheGUIistoimportdatabyaddingthe.matle(s)createdintheBatch Processing(3.5.1)section.Datasetscanbeinsertedintotheasymptomaticand/orthesymptomatic databoxes.Thisisaccomplishedbyclickingontheaddbuttonandbrowsingtothecorrectle. Thereisaremovebuttonforeachdataboxwhichallowstheusertoremovetheincorrectlyselected .matle.Theuserthencustomizesthetypeofdataaverage,timenormalizationscheme,taskphase, andtasktype. Thetypeofdataaverageischosenusingtheaveragedropdownmenu.Theintersubjectaverage istheaverageofallsubjectsacrossalltrialsandwillplotonlyonedataset.Theintrasubject averageistheaverageofalltrialsacrossasinglesubjectandwillplotthequantityofdatasets asthesubjectsinthe.matle.TheNoneoptionallowstheusertoplotalltrialsandallsubjects loaded. Theoptiontotimenormalizeornotisavailableinthecorresponding"TimeNormalized"drop downmenu.Thetwooptionsareyesorno.Yesreferstoplottingtimenormalizeddatawhichwill begraphedfrom0to100percentofthetask.Noimpliesrawdatawhichwillbeplottedagainstthe framenumber. Thenaluserinputsarethetaskandthephase.Thetaskdropdownmenulistsalltasksin whichdatawascapturedforthisprotocol.Ifthe.matledoesnothavethattaskloaded,itwillnot graph.Thephasemenuisonlyapplicabletothehoptaskwhichhasbeenbrokenintofourphases asdescribedpreviouslysection3.5.4.Oncealloptionsbelowarecorrectlyentered,importeachdata 64

PAGE 75

setbyclickingtheimportbutton(s). Themanydropdownmenusallowforquickandsimpledatainterrogation.Theabilitytoswitch betweentask,normalization,andphasewithoutreprocessingdataorreloadinglesishelpfulfor smoothowwhenexaminingthedata.Theplethoraofgraphsallowstheusertoviewspecicpieces ofinformationaswellasforbroadcomparisonsbetweensubjects. 5.2.2GraphicalUse Oncealldatahasbeenimported,thecentralgraphicalcategorytabswillbecomeactive.Each tabcreatesavisualofatmost12graphsarrangedina3x4matrix.Graphcategoriescanbechanged byclickingonadi erenttab.Atanypoint,normalization,task,andphasemaybechangedintheir respectivedropdownmenus.Todisplaythesenewgraphsacategorytabatthetopneedtobe clickedagain.Acolorkeyhasbeenaddedforreferencebelowthelargeaxistothelowerrightofthe GUI.Thecontentsofthegraphsdisplayedbyeachtabwillbedescribedinthenextsection. Interactionanddatainterrogationispossibletoalimitedextent.Ifanyofthe+buttonslocated totheupperrightofeachaxisareclicked,thedataonthataxisisthenprojectedontothelarge axistothefarright.Thelargeaxisislinkedtothezoomandrotatebuttonstoallowforamore in-depthlookatthedata.Additionally,theselectcursorcanbeusedtofurtherexaminethedata. Byclickingonaspeciclineandthenunselectingthecursor,thecoordinatesofthespecicpoint selectedaredisplayedandthetrialandsubjectaredisplayedinthelistboxbelow.Finally,under singlevariablegraphsisagreyrectangleindicatingtheframeorpercenttaskrangeofmaximum kneeexion.AnexampleoftheGUIloadedwithdataisshowninthegurebelow. Figure5.2.2:LoadedGUIExample ShowingKinematicDoubleLimbSquatTaskData 65

PAGE 76

5.2.3GraphedVariables ExamplesofgraphicaldataavailableinthisGUIaredetailedinthesectionsbelow.Alldata displayedisdoublelimbsquat,timenormalizeddatathatiszoomedtottightlyintheaxis.Tables havebeenincludedtodescribethegraphsbasedonlocationwiththeplottedvariable(s)listed.The rstmovementofthevariableslistedisthepositivedirectionontheyaxis. 5.2.3.1Kinematics ThekinematicgraphsareidenticaltothegraphicalsetupusedforclinicaldataatCGMA.Each rowrepresentsaspeciclowerbodyjointfrompelvis,hip,knee,andnallytotheankle.Each columnrepresentsaplaneofmotionfromsaggitaltofrontaltotransverse.Allthesevariablesare calculatedusingthestandardPiGmodel.GraphscanbeseeningureXabovewithdescriptions inthetablebelow. Table5.2.1:KinematicGraphs PelvicTilt PelvicObliquity PelvicRotation HipFlexion/Extension HipAb/Adduction HipRotation KneeFlexion/Extension KneeVarus/Valgus KneeRotation AnkleDorsi/PlantarFlexion FootProgression AnkleRotation 5.2.3.2Translation ThetranslationgraphsarethevariablescalculatedbytheFenwaymodel.Therstrowistranslationaldisplacementsandthesecondrowiskinematicangles,allatthekneejoint.Aspreviously stated,eachtranslationaldisplacementusest(0)=0asastandardy-axisshift. Figure5.2.3:TranslationPlots 66

PAGE 77

Table5.2.2:TranslationPlots Anterior/PosteriorTranslation Medial/LateralTranslation Distraction/Compression Flexion/Extension Varus/Valgus Rotation Allplottedvariablesareattheknee 5.2.3.3RelativeKinematics Thealternativekinematicgraphswerecreatedforthepurposeoflinkingtwovariables.Instead oftimeorframeonthexaxis,thegraphplotsarevariablexvsvariabley.Thefocusoftheseplots werekneejointcenter(KJC),centerofmass(CoM),andcenterofpressure(CoP).TheKJCisthe rawglobalcoordinatemotioninthexandydirectionofthePiGkneejointcenter.Thisisplottedas ifoneislookingdownonthekneemovementfromabirdseyeview.TheCoMisofthewholebody, whereastheCoPistheGRFofasingleforceplate.Forthesetwovariablestobetracked,good kineticsareneeded.Togetgoodkineticdatathefootmusthitonlyoneforceplateatatime.Once again,theverticalmovementisignored.Thesevariablesareplottedasglobalcoordinatepositionas wellasvariousdi erencerelationshipsdetailedinthebelowtable.Finally,acoupledplotofanterior kneetranslationandkneeexionextensionwascreatedtoseethelinkedrelationshipofsaggital planekinematics. 67

PAGE 78

Figure5.2.4:RelativeKinematicPlots Table5.2.3:RelativeKinematicPlotDescriptions GRFPosition NormalizedGRFPosition KJCandCoMassPosition GRF-KJC NormalizedGRF-KJC CoMass-KJC GRF-KJC(t(0)=0) NormalizedGRF-KJC(t(0)=0) CoMass-KJC(t(0)=0) KneeAnterior/PosteriorTranslation None None vsKneeFlexion/Extension Positionplotsareinglobalcoordinates 5.2.3.4Forces TheforceplotswerecreatedusingthePiGmodelandkineticdatafromtheforceplates.The forcesareplottedinNewtonsnormalizedtopercentageofbodyweight(%BW)creatingunitsof N/Kgtoallowforcomparisonacrosssubjects.Goodkineticsarenecessaryfortheiraccuracyand applicability.Taskphasessuchasairborneandlandinginthehopphasesdidnothavegoodkinetics byinstructionandthereforearenotrelevant. 68

PAGE 79

Figure5.2.5:ForcePlots Table5.2.4:ForcePlotDescriptions HipFlexion/ExtensionForce KneeFlexion/ExtensionForce AnkleDorsi/PlantarFlexionForce HipAb/AdductionForce KneeVarus/ValgusForce AnkleAb/AdductionForce HipRotationForce KneeRotationForce AnkeRotationForce 5.2.3.5Kinetics Thekineticgraphs,likekinematics,areidenticaltothegraphicalsetupusedforclinicaldata atCGMA.Eachcolumnrepresentsajointfromhip,knee,andtotheankle.Eachrowrepresents planeofmovementforjointmomentsfromsaggitaltofrontaltotransversewithanadditionalrow displayingjointpower.Asinforces,goodkineticsarenecessaryfortheplotapplicability.All dataisnormalizedto%BWmakingthejointmomentunitsN*mm/Kg.Powerbydenitionisthe rateofdoingworkwhichmechanicallytheiscombinationofforcesandmovement.Likeforcesand moments,powerisalsonormalizedto%BWcreatingunitsofW/Kg. 69

PAGE 80

Figure5.2.6:KineticPlots Table5.2.5:KineticPlotDescriptions HipFlexion/ExtensionMoment KneeFlexion/ExtensionMoment AnkleDorsi/PlantarFlexionMoment HipAb/AdductionMoment KneeVarus/ValgusMoment AnkleAb/AdductionMoment HipRotationMoment KneeRotationMoment AnkeRotationMoment HipPower KneePower AnklePower 5.2.3.6Three-D Likethealternativekinematicplots,thethreedimensionalplotswerecreatedinordertolink multiplevariablesinthiscasethree.Eachaxisintheplotsisadi erentvariable.Bothlineand meshplotswerecreatedtoexploremultiplewaysofdatadisplay. 70

PAGE 81

Figure5.2.7:ThreeDimensionalPlots Table5.2.6:ThreeDimensionalPlotDescriptions x y z CoMass(x) CoMass(y) KneeFlexion/Extension CoMass(x) CoMass(y) KneeAnterior/PosteriorTranslation KneeFlexion/Extension KneePower KneeAnterior/PosteriorTranslation AnkleDorsi/PlantarFlexion HipFlexion/Extension KneeFlexion/Extension Thex,y,zvariablesforeachrowaredetailed 5.2.3.7Velocity Thenalgraphcategorytabdisplaysvelocityplots.Thesevelocityplotsarecalculatedusing previouslydisplayedkneejointvariables.Itwashypothesizedduringthecourseofthisstudythat kneestabilityislinkedtotherateofmotion.Additionally,aspowerhasavelocitycomponentas itistorquemultipliedbyangularvelocityandkneepowerisanimportantvariable,itwasalso 71

PAGE 82

hypothesizedthatvelocitywouldbeaninterestingcategoryofvariablesforfurtherexplorationand study. Figure5.2.8:VelocityPlots Table5.2.7:VelocityPlotDescriptions KneeFlexion/Extension KneeVarus/Valgus KneeRotation KneeAnterior/PosteriorTranslation KneeMedial/LateralTranslation KneeDistraction/Compression GRF NormalizedGRF KJC Thevelocityoftheabovevariablesareplotted. 5.3Conclusion Thesecondprimaryaimofthisstudywastocreateatoolforinterrogationofthekneestabilitymotioncapturedata.ThedevelopedGUIallowsforcongurationofthedatabasedontask, phase,timenormalization,anddatasetaveragetype.Itdisplays66di erentplotsforeachcustom congurationoftheinputdata.Anadditionalfocusofthisstudywastoexplorethedatabeyond asingleplaneofmotion.Inadditiontothestandardkinematicandkineticplots,newcategories ofplotswerecreatedanddisplayedlinkingtwoorthreevariables.Thecalculationoftranslational displacementsandvelocities,aswellasthelinkedvariablesexpandsthetypesofdatadisplayed beyondwhatiscurrentlyclinicallyavailableatCGMA.Thesesupplementalcatagoriesallowfora 72

PAGE 83

deeperlevelofdetailavailablefordatainterrogationthereforeincreasestheutilityofthecustomized softwarepackagecreatedforthesecondaimofthisprotocol. Theplethoraofplotsandinputdatacongurationsavailableaswellastheeaseofnavigational usemeansthatthiscustomkneestabilityGUIsuccessfullycompletesthesecondstudyaim. 73

PAGE 84

6DynamicTasksResults 6.1Overview Duringthedynamicmotionphaseoftheprotocol,subjectswereaskedtoperformvarioustasks whilekinematicandkineticdatawascapturedandvideowasrecorded.Anoverviewofthesetasks andinstructionsgiventothesubjectswerediscussedpreviously(3.3.2.1).Asthisisaninvestigative studyandamajorgoalwastocreateakneestabilityprotocol,theuseoftheGUItooldescribed inthepreviouschapterwasnecessary.TheGUIwasusedtocalculatespecicvariablesanddisplay dynamicresultstodiscoverwhichtasksandvariablesorcombinationsofvariableswereusefulfor successfullyinvestigatingtherelationshipofkneestabilityandpediatricACLtears.Thischapter willdescriberesultsfromthedynamicmovementtasksandconcludewitharecommendedknee stabilityprotocolforfuturestudiesbasedontheseresults. 6.2Results Duringcross-functionalprotocolresultsdiscussions,severalvariableswereassumedtocontribute tokneestability.Saggitalplanekinematicsatthekneebothexion/extensionandanterior/posterior translation,wereafociofexpecteddi erencesastheACListheprimaryrestraintofanteriortibial translation.Additionally,kneerotationwasexpectedtodi erastheACLcanalsobetorndue toexcessiverotarymotion.Powergenerationatthekneewasalsohypothesizedtobelessinthe symptomaticpatients.Finally,velocityatthekneewasexpectedtodi erinpattern. Amajorobjectiveofthisstudywastocreateakneestabilityprotocolbasedontheresultsfrom thispreliminaryinvestigation.Whenexaminingtheseresults,thefocuswastolookforsignalsof di erenceineitherdiscretepointsorplotpatternbetweenthesymptomaticACL-Rlegandboththe controllegandasymptoticpopulation.Highlightsoftheanalysisareexpectedtobevisualpattern andshapedi erencesaswellasminimalstatisticaldi erencesbetweenasymptoticandsymptomatic groups. AstheGUIandtheextensivequantityofplotsweredetailedinthepreviouschapter,itisnot necessarytoreiteratethisinformation.Thereare66plotsavailableforeachcongurationofthe GUI,totalingover2500plotsgeneratedforthedatasetusedinthisproject.Notalloftheplots andcongurationsarerelevant.Therefore,onlyafewselectedvariableswillbehighlightedinthe resultssectionwithafocusonthekneeratherthanotherlowerbodyjoints. 74

PAGE 85

6.2.1Gait Gaitisthemostcommonlycompletedactivityofdailyliving.Itissubsequentlythemost researcheddynamicactivityformotioncaptureandthemovementactivityforclinicalgaitanalysis. Becauseofthis,thegaitdatawasusedasmodelvalidationinapreviouschapter(4.3).Whilewalking doesnotstresstheACL,di erencesinresultsfrommotioncapturestudiesbetweenACL-Iknees, ACL-R,andACL-Dkneeshavebeenreportedinpreviouslypublishedliteratureanddiscussedin section2.5.3.1.Themainpurposeofthegaitdatawasformodelvalidationandthismovementtask canbecompletedeasilywithoutriskwithACL-Dknees.Hence,therewillbelimitedfocusonthis data. Saggitalplanekinematicshavebeenthemainfocalpointofpreviouslypublishedliteraturewith di erencesmainlyinthetimingandslightchangestoextremaratherthanextremepatterndi erences.Whilethegeneralexion/extensionandanterior/posteriortranslationplotsforthisdataset showsimilarshapestotheasymptoticdata,onesubject(bothlegs)andanothersubject(ACL-R) di er.Thesethreecurveslieoutsidetheonestandarddeviationofasymptoticpopulationwhereas therestofthesymptomaticdatalieswithin. 75

PAGE 86

Figure6.2.1:GaitVariablesofNote Asymptomaticpopulationaverageisshowninblackwithonestandarddeviationingrey. Symptomaticintrasubjectaveragesareplottedwithcyan(ACL-R)andblue(ACL-I). Anadditionaldi erencewasnotedinthedistraction/compressioncurve.Thetemporalpointof maximumcompressionlookstovarygreaterinthesymptomaticthanasymptoticpopulation.This couldbedueeithertotheinjuryortothesmallnumberofsubjects.Thesamethreecurvesthat wereoutsidethegreystandarddeviationregioninthesaggitalkinematicplotswhichalsoexhibit morecompressionthantherestofthepopulation.Asallthreeshowdi erencesfromthepopulation 76

PAGE 87

acrossthreeseparatekinematicvariables,theseshouldbelookedatingreaterdetailwhenalarger datasetisacquired. 6.2.2Squat Double(DLS)andsingle(SLS)limbsquattaskswereselectedforthisstudybecausethemotion stressesthekneejointandACLspecicallyintheanteriordirection.Allgraphsdisplayedbeloware timenormalizedtothetasklengthunlessnoted. 6.2.2.1SaggitalPlaneKinematics Asthesquattingmotionwaschosentospecicallystressthekneeinthesaggitalplane,the ACL-Rkinematicswerehypothesizedtobea ected.Whileallsubjectsseemtohavesimilarknee exion/extensionkinematics,asinglesymptomaticsubjecthadadi erentsquattingpatternin duringdoublelimbsquat.Thissubjecthadamuchslowerrstpartofthetasktomaximumknee exionthanthereturntostandingsectionexhibitedbyasmallerslopeandlargerpercentageof timedevoted. Thereisaclearpatternnotedforbothsaggitalplanekinematicvariablesduringallsquattasks. AlltranslationshapesandmagnitudesforACL-IandACL-Rlegsexhibitthesamerelativegraphical patternswithasimilarangularrange.Foranteriortranslation,theACL-Rmagnitudesareonthe lowerendforallsquattasksbutstillwithintheACL-Irange.Thisismorepronouncedduringthe singlelimbsquattasks.Thisobservationcouldbeasamplesizetrendasonlytwosubjectsmade uptheACL-Rpopulationforsinglelimbsquattasks. 77

PAGE 88

Figure6.2.2:SaggitalPlaneKinematicsforallSquatActivities 6.2.2.2RelativeKinematics RelativekinematicplotsshowcommonpatternswhenlinkingCoMandKJCaswellaslinking bothsaggitalplanekinematicvariables.Thegoalofcouplingthesevariableswastoattemptto inspectthemovementofmultipledegreesoffreedomtogetherratherthanindividually.Thesaggital planekinematicplotsshowadistinctarchpatternduringallsquattasks.Bothlegsofthesymptomaticsubjectsappeartowardsthelowerendofthefullpopulation.Whileitwasnotedinthe abovesectionthatACL-RdatawasonthelowerendofAPtranslationcurves,thisclusteringis morepronouncedandoccursforbothlegsofthesymptomaticsubjectsinthebelowplots. ApatternalsoemergeswhenCoMandKJCmovementsarecoupledduringdoublelimbsquat butnotduringsinglelimbsquats.ThisirregularloopshapeduringDLSappearstooccuratamore obtuseangleinmostofthetrialsofthesymptomaticsubjects.TheirregularmovementduringSLS highlightsadi erenceinCoMmovementwhenthereisonlyonecontactlimb. 78

PAGE 89

Figure6.2.3:RelativeKinematicsforAllSquatActivities 6.2.2.3Kinetics Forceandmomentdataexhibitsimilartrendsandgraphicalpatterns.Thisproveslogicaldue asmomentsarethecombinationofaforcevectorandadistancevector.Bothforcesandmoment curvesinthegurebelowexhibitaconvexshapeforallsubjects.Thereisavisualdi erencein magnitudebetweenACL-RandACL-Ikneeswhichcreatesamoreshallowcurve. Kneepowerplotsalsodisplayadistinctpatternbutthiscaseissimilartoacubicspline.Forall tasks,theACL-RdataisnoticeablylessthanallACL-Idata.Visually,theACL-Rlegseemsalmost linearatzeropowergeneration.Whilegraphsarenotdisplayedhere,powergenerationintheankle andhipwereobservedtobewithintherangeofACL-Idata. 79

PAGE 90

Figure6.2.4:KineticsforAllSquatActivities StatisticswerecompletedtocomparetheDLSpowerextrema.AonewayANOVAwasusedasin previouslypublishedcomparisons[25,74,83]withapost-hocTukey'sHonestlySignicantDi erence (HSD)procedureduetotheunequalsamplesizes.Theminimumandmaximumpowervalueswere foundtobesignicantlydi erent(p<0.05)whencomparingtheACL-Rlegtothecontrallateral ACL-Isideaswellastobothleftandrightasymptoticlegs. 6.2.2.4Velocity Whilethevelocityplotscouldpossiblyshowapattern,thefocusismagnitudeduetoitsrelationshipwithPower.Thevelocityplotsforallofthesquattasksshowedatrendofsmallervelocities forthesymptomaticsubjectsforallvariablesplotted.Thesewerevisiblewhenthedatawasplotted withouttimenormalization.Thegurebelowincludessaggitalplanekinematicvelocityforallsquat tasks.Thiswasincludedtoshowthegeneraltrendinlowersymptomaticvelocity.Thistrendis morepronouncedwhenthelimbsareisolatedinSLS. 80

PAGE 91

Figure6.2.5:SaggitalPlaneKinematicVelocitiesDuringAllSquatTasks ThebelowplotarethenormalizedGRFandtheKJCvelocitiesduringallsquattasks.The GRFplotsshowthesymptomaticsubjectstohavevisiblylowervelocity.Thistranslatestoamore stationaryorslowermovingcenterofpressure.TheKJCvelocitiesseemtoalsobelowerbutnotas pronouncedastheGRF. Figure6.2.6:KJCandNormalizedGRFVelocitiesforallSquatTasks 6.2.3Hop Thepurposeofthehoptasksingeneralwastostressthekneeandtheabilitytostabilizethe jointduringamoredemandingmotionthanthesquattasks.Theforwardhopwasaimedtostress 81

PAGE 92

theanterior/posteriorkneestabilitywhilethelateralhopwaschosentostressthelateralandrotary kneestability.Thesubjectswereinstructedthatlandingthehopwasmoreimportantthanjump lengthwhichresultedinawiderangeofdistancecoveredduringthehoptasks. 6.2.3.1Kinematics Thecurvesintake-o andlandingphaseswerevisuallythesameforbothlateralandforwardhop taskswhencomparingkneekinematics.Anexampleofthisisillustratedinthekneeexion/extension curvesinthegurebelow.Forsimplicity,leftandrightleghopcurveshavebeenplottedonthe sameaxis.Thereisasimilarpatternforthegeneralpopulationhoweveritislessdistinctcompared withthesquattasks.TheACL-Rlegsappearonthelowerendoftheoverallpopulationduringthe take-o phasebutnotduringthelandingphase.Thenoisydataseenonsomeofthecurvesbelow couldbearesultofSTA. Figure6.2.7:HopTasksKneeFlexionExtension 6.2.3.2RelativeKinematics Observingthemotionofthekneejointcenterwasexpectedtonotonlydi erentiatethehoptypes butalsotopotentiallyvisualizekneestability.Asseeninthegurebelow,theKJCmovementsof thewholepopulationdi ernotonlyinphaseoftaskbutalsoinhoptype.Forwardhopinboth phasesexhibitsalargerrangeofanteriormotion(xdirection)thanthelateralmotion(ydirection). Itcanbesurmisedthatthekneemovementduringforwardhopisalmostdoubleintheanterior directionbutonlyslightlylargerinthelateraldirectionofmotionduringthetake-o phasevsthe 82

PAGE 93

landingphase.Thelateralhoptaskexhibitslessofapatternthantheforwardhoptaskatrst glance. Theorientationofthesubjectissuchthatmedial/lateral(xdirection)andanterior/posterior(y direction)areoppositeforwardhoptask.However,eachhoptaskhasthesametargetdirectionof trajectorywiththexpositivedirectionfortheleftlegandxnegativefortheright.Bothtaskphases appearasthoughthemajorityKJCmotionwasinthedirectionoftravelwithafewexceptionsof theKJCmovingoppositeofthedirectionoftravel.Themagnitudesofthenon-targetdirection (anterior/posteriorforlateralhopsandmedial/lateralforforwardhops)appeartoshowagreater rangeforthelateralhoptask.Conversely,thedirectionoftravelappearsinthelateralhopstobe almost50%smallerthantheforwardhopsduringtake-o butsimilarduringlanding. Therearelessvisualdi erencesinsymptomaticandasymptoticdataintheseplots.Themovementrangesappeartobeslightlylessinallplots.Thisismostvisibleinthelateralhoplanding task.However,theACL-Rdatadoesnotvisuallydi erfromtheoverallpopulation. Figure6.2.8:KJCPositionChangesDuringHopTaskPhases 6.2.3.3Kinetics Asinthesquattasks,kneepowerisvisuallylessintheACL-Rlegs.Onlythetake-o phasehas goodkineticdatasothatiswhatisshownintheplotbelow.Thereappearstobeaclearshape oftheindividualpowercurvesbutunlikethesquattasks,thesecurvesdonotaligncleanlyeven whentimenormalized.TheACL-Rmaximumandminimumpowergenerationexhibitsthesame 83

PAGE 94

reductionasseeninprevioustasks. Figure6.2.9:HopKneePowerDuringTakeO Phase 6.2.3.4Velocity Asstatedbefore,thefocusofthevelocityplotsweretoinvestigatethedropinpowergeneration. Duetothis,onlytake-o phasewillbediscussed.Inattemptingtodiscovertherootcauseofthe dropinACL-Rkneepower,specickinematicandrelativekinematicplotshavebeenisolated.The rstsetofvelocityplotsarethetargetkinematicvariables.Thesearesaggitalplanevelocitiesfor forwardhopsandkneerotationandvarus/valgusforlateralhops.Theseshowasmallreductionin ACL-Rvelocityinthetargetdirectionbutnotassubstantialasthesquattasks. Figure6.2.10:TargetKinematicVelocityPlotsforTake-O PhaseofAllHopTasks ThesecondvelocityvariablesplottedareKJCandnormalizedGRF.Likethesquattasks,the normalizedGRFplotsshowamorecompactvelocityproleforthesymptomaticsubjects.TheKJC 84

PAGE 95

velocityprolesshowasimilarrangetothesymptomaticsubjects,whichdi ersslightlyfromthe squattask. Figure6.2.11:KJCandNormalizedGRFVelocitiesfortheTake-O PhaseofAllHopTasks 6.3Conclusion Therewasanoverwhelmingquantityofvariablesandplotsavailablefordatainterrogationfrom thisprotocol.Narrowingdowntheover2,500possibleplotstoamanageablequantitycreateda focusononlykneejointspeciconeandtwovariablegraphs.Thisresultingsetofgureswere choseninattempttotesthypothesesandcreatearecommendedkneestabilitystudyprotocol.Due totheinvestigatorynatureoftheprotocolandthesmallsamplesize,plotswereinspectedvisually forsignalswithinthedatapointingtodi erentiatingrelevantplotsandtasksinordertoselectthose ofimportance. 6.3.1Observations Visualinspectionofthedatayieldedbothcorroboratinganddi eringobservationsthoseexpected duetooriginalhypothesesinbothsquatandhoptasks.Kinematicplotswerethemostsurprisingly di erentfromhypothesizedresults.Afewrelativekinematicplotslookedpromisingforfuturestudy. Kineticdatabesthighlightedthedi erencesinACL-Rdata. Di erencesin6DOFACL-Rkinematicmovements,especiallyinthetargetsaggitalplane,were 85

PAGE 96

notaspronouncedaspredicted.Thiscouldbeduetothesuccessfulcompletionofalltasksin accordancewiththephysician'srequirementsandstandardsastherewerenoobservationsofguarding orirregularmotion.Itcouldalsobearesultofthetaskinstructionshavingbeenself-selectedand withincomfortrangesratherthanrequiringmoreextrememotion.Theinstructionscouldbealtered infuturestudiestoextremityofmotionasindepthofsquatordistancehops. Themajorityofkneerelatedkinematicanglesandtranslationaldisplacementsshowedaclear patternduringsquattasksorphasesofthehoptasks.Thesepatternsconsistedofslopesandextrema insequentialorderandwereeasilyvisualizedwhenthedatawastimenormalized. Theattemptstolinkkinematicandkineticdataintherelativekinematicsplotswasaninitial success.Themovementofthekneejointcenterinthetransverseplanealoneorinrelationtothe centerofmassshowspromiseasarelevantplot.Additionally,plottingkneeexion/extensionagainst kneeanterior/posteriortranslationresultedinpatterneddatainalltasksandphases.TheACL-R curveswerenotrecognizablydi erentintheseplotsthoughsomeshowedslighttrendstowardone endoftheoverallpopulationdata. Plotsofkineticdatashowedthelargestdi erenceinACL-Rlegs.Allkneerelatedplotsexhibited patterneddata.Forces,moments,andpowersforACL-Rcurveswerevisuallysmallerandless pronouncedatthekneebutwithintheasymptoticrangefortheankleandhipjoints.Theextrema inpowergenerationatthekneewassignicantlydi erentwhenstatisticswererunforthedouble limbsquat.Thiswasexpectedtobethesameforalltasks. Threedimensionalplotswerenotasbenecialasexpected.Whiletheplotswerevisuallyappealing,furtherstudy,discussion,andmodicationneedstooccurbeforetheyaretobeprovenuseful. Patternsweredi culttodiscernwiththevariablesandplottypeschosen. Velocityplotswerechoseninanattempttoinvestigatetherootcauseofthelackofpower generation.Bothtasksshowavisiblereductioninkinematicvelocityespeciallyinthetargetplanar variables.ThisreductionismorepronouncedduringSLStasks.Thecenterofpressureappearsto moveataslowervelocityinACL-Randthecontrallaterallegthanintheasymptoticgroup.This couldbearesultofthesmallsamplesizeoritcouldbelinkedtothereductioninpower.Combining observations,thereductioninpoweratthekneeislikelyduetolowerkinematicvelocityandamore stationarykneejoint. 6.3.2NextSteps Additionaldatamanipulationandcross-functionaldiscussionscouldimproveuponthetwoand threevariableplots.Therelativekinematicplotswereaninitialattempttolinkkinematicandkinetic 86

PAGE 97

variables.Aseconditerationcouldpossiblyyieldmoreusefulplotsandeliminatetheredundantor non-usefulplots.Thethreedimensionalplotsneedadditionaltesting,iterating,andstudytoprove useful.Selectingothervariablesorplottypescouldperhapshelp.Additionally,exploringclinically relevantcontourplotscouldalsoprovebenecial. Ithasbeennotedthatthemajorityoftheplottedvariablesshoweddistinctpatternsduringthe dynamictasks.Assemblingallkeyvariablesforataskandextractingthegraphicalidentierssuch asslopecanbeusedtocreateanindex.ThiscustomKneeStabilityindexmodeledaftertheGait DeviationIndexcommonlyusedforcomparingwalkingdata,wouldallowforamorequantitative comparisonacrossalltasksforthesubjectgroups. Asmentionedmultipletimesbefore,taskchoiceandinstructionsshouldbeafocalpointbefore thenextiterationofdatacapture.Thepivottaskinstructionsinparticularneedtobereworked tosuccessfullyresultinrepeatablemovementpatternsbothintraandintersubject.Instructingfor extremaduringsquatandhoptaskscouldbetterdi erentiatethesubjectcategories.However,that wouldcreateamoretargetedmotionthatislessnatural. Finally,theGUIcanbeexpandedtoincludetwootherdi erentiators.Explorationintoleg dominanceandthee ectonmovementshouldbenoted.Datamayalsodi erbetweentannerstage groupsasminimaldi erencesareseeninthetwoyearagegroupsofgaitdatainthenormaldatabase atCGMA. 6.3.3KneeStabilityProtocolOutput Thethirdobjectiveofthisprojectwastocreateaquantitatemeansofdiscriminatingbetween asymptomaticandsymptomaticsubjectsusingdynamicmotiontasks.Theoutputofthisobjective wastoproposeakneestabilityprotocolforuseinfuturestudies. 1.Squattasks:Continuecapturingallthreesquattaskswithslightalterationstogainextrema inkinematicsaswellasincreasedi cultyofthetask. (a)Instructionchanges:Squatasdeepaspossiblewithoutlosingbalance. (b)TargetVariables:Saggitalkneekinematics,therelationshipbetweenthevariables,and theirvelocities;movementandvelocityoftheKJCandresultingrelationshipbetween thehipandanklejointcenters;kneepowerandvelocitiesofthecenterofpressure. 2.HopTasks:Splittaskintotake-o andlandingtogainkineticsinbothphases.Take-o being capturedbytheHoptask. 87

PAGE 98

(a)Instructionchanges:Hopforwardandlateralfordistance.Onlyfocusontakeo ,unstable landingisacceptable. (b)TargetVariables:Saggitalkneekinematicsandvelocitiesforforwardhops;Varus/valgus androtationaswellasvelocitiesforlateralhops;movementandvelocityoftheKJC; Kneepowerandvelocitiesofthecenterofpressure. 3.DropLandingTask:Newtaskdesignedtogainkineticsinlandingphaseofhop. (a)Instruction:Oneleggedhopo boxeitherlateralorforwardandlandonsameleg.Only focusonlanding,heighofhopo theboxisuserselected. (b)TargetVariables:Saggitalkneekinematicsandvelocitiesforforwardhops;Varus/valgus androtationaswellasvelocitiesforlateralhops;movementandvelocityoftheKJC; Kneepowerandvelocitiesofthecenterofpressure. 4.PivotTask:Instructionchangestolessnaturalmotion.Ensurestargetingoftheforceplate forkineticsaswellasconsistentmovement. (a)Instructionchanges:Stepforwardontothecenteroftheforceplateononeleg,rotate internally90degreesandwalktwosteps. (b)TargetVariables:Varus/valgusandrotationaswellasvelocities;movementandvelocity oftheKJC;Kneepowerandvelocitiesofthecenterofpressure. Thesenewdirectionswouldallowforadditionalimportanceonextremaaswellaskineticdataforall tasks.Asthesignalsfromtheexploratorydatacollectedforthisprotocolaremostvisibleinkinetic data,thischangewouldbehelpful.Novelplottypessuchaskneejointcenterprovedinformative andshouldcontinuetobestudied.Velocityplotsalsoprovidedinsightwhenthevariableswere non-timenormalized.Overall,thisinitialinvestigatorystudyprovedsignicantlyusefulincreating amorethoughtoutprotocolandinexperimentingwithnewplottypes. 88

PAGE 99

7ClinicalAssessments 7.1MethodologyOverview QualitativeexaminationsareamajorcomponentduringthecareofACLinjuries.Thesehandson examinationsinvolveassessingtheendfeelofatargetmovement.Consequently,theexactrangesof motionthatdictateapassorfailareunknown.Motioncapturetechnologyisanovelwaytoquantify thesequalitativeexaminationsbutitisunknownifthetechnologyisappropriateore ective.The clinicalexaminationmethodologyhasbeenpreviouslydescribed. Foreachclinicalexamination,thereisaspecicrangeanddirectionofmotionofthekneejoint. Duetotheplethoraofdataalreadyprocessed,thecomplexityofsomeoftheclinicalexaminations, andthegoalofaproofofconcept,thedecisiontofocusonlyontheAnteriorDrawerTestwasmade. Thiswasdatawasusedinordertotesttheapplicabilityofmotioncapturetechnologytoquantifying qualitativeexaminations. 7.1.1DataProcessing Processingofthesetrialswassimilartothedynamicmotiontrials.Amajordi erencewasthe sacralmarkerwasobscuredduetothesubjectlyinginaproneposition.Vectorrelationshipswere usedfromthestatictrialtoestimatethelocationofandinsertthemissingsacralmarkerusing BodyBuilder.Becauseofthisinexactsacralpositioning,thehipandkneejointcentersarealso likelyabitdi erentfromtherelativelocationsinthesubject'sothertrials.Asthisdataistobe usedforproofofconcept,thisinexactpositioningissu cientbutshouldbeaddressedgoingforward. 7.1.2QuantitativeCalculations AniterationofoneoftheMatlabcodesusedfordynamicmotiontrialswascreatedforcalculating 6DOFkneemotionduringthesepassiveexaminations.Thetrialwasprocessedandthetargeted variablewasplottedagainstframenumber.Duringdatacapture,onecontinuoustrialforeach examinationoneachlegwastaken.Averbalcuetoindicateoccurrenceofagoodexaminationwas givenandtherelativeframenumberwasrecorded.Theseframenumberswerethenusedtopullout localmaximaandminimaofthatspecicexamination.Therangesbetweenthelocalextremawere thencalculatedwithinthesameMatlabprogram. 89

PAGE 100

7.2Results Thebelowplotshowsanterior/posteriorkneetranslationthroughoutthetrial.Pointsofgood examoccurrencearestarredandafewrangevalueshavebeenalsoaddedtothegure.Astrial nishedafterthenalexamination,thelargermagnitudecouldbeduetoareturntorestingposition oftheleg. Figure7.2.1:AnteriorDrawerTestResults 7.3Conclusion Thepurposeofthissecondaryaimwastoassessifquantitativeresultscouldbeaddedtothe qualitativeclinicalexaminations.Itwasexpectedthatdatafromalltrialswouldbeabletobeused whichturnedoutnottobethecase.However,theresultspresenteddoprovethatmotionisableto betracked. Therewereseveralawsintheprotocolwhichcanbeimproveduponforfuturetesting.Ensuring fullvisibilityofmarkersisparamountforaccuracy.Theanteriordrawertest,forexample,was performedoneachlegforallsubjects.Outofthe32trialsonlyonehadallnecessarylegmarkers inthebeginningandattheendofthetrial.Asthesacrumispartofthepelviswhichcreatesthe hipjointcenter,andthehipjointcenterisusedtocreatethefemoralkneejointcenter,anaccurate methodforaddingtheobscuredsacralmarkerneedstobedeveloped. 90

PAGE 101

Basedonthelimiteddatapresented,itispossibletoquantifytheanteriordrawertestusing motioncapture.Futurestudyintoclinicalassessmentsundermotioncapturecanexpandthisdata setusingthelessonslearnedfromthisexperiment. 91

PAGE 102

8OverallStudyConclusion Thegeneralconclusionofthisprojectisthatthenewmodel,developedGUI,andproposedknee stabilityprotocolhaveinitiallydemonstratedtobevalidandusefultoolsforsuccessfullyevaluating kneestabilityanditsrelationshiptoPediatricACLtears. Theoriginalclinicalgoalofthisstudywastocomparethekinematicandkinetice ectsof di erentpediatricACLtearsurgicalrepairmethods.Conventionaladultreconstructionisfrowned uponforyoungerpatientsduetothetraumatothephysis.Becauseofthisfact,thereiscurrently aplethoraoftechniquesdesignedtorepairtheACLwhileminimizingphysealtraumainskeletally immaturepatients.Thesetechniquesareprimarilyevaluatedonthequantityandseverityofgrowth disturbances.AstheACLisrepairedduetoinstabilityintheknee,itisbeapparentthatan assessmentofthesenascentpediatricspecicACLsurgicalmethodsshouldbeevaluatedrelativeto therestorationofkneestability.Currentliteraturesupportedtheseinitialanalysesofestablishing moree ectiveprotocolsforevaluatingbothadultandpediatricACLrepairs. Thisoriginalstudyfocusthenshiftedtothecurrentstandardsandassessmentsofkneestability. Thecommonclinicalassessmentofkneestabilityinvolvesqualitativeexaminationshighlighting passivesingleplanarjointmotion.Thereappearstobenodynamicprocedureforthequantication ofkneestability.Noristhereadynamickinematicandkineticdenitionofkneejointstability.The creationofakneestabilityprotocolbecametherstprimaryaimandoutputofthisstudy. Asthestudyplanshiftedtodevelopmentofakneestabilityprotocol,itbecamenecessaryto captureandevaluatethecorrectkinematicandkineticvariables.TheACLisaprimaryrestraint inanteriorkneetranslationandthismovementisnotcapturedinthedefault3DOFmarkersetand modelusedclinicallyatCGMA.Thetwonalprimarystudyobjectiveswere:Todevelop,test,and validateanew6DOFmarkersetandmodel;and,Tocreateatooltoe ectivelyinterrogateand displaytheresultsfromthisstudy. ThenewFenwaymodelandmarkersetdevelopedforthisprojectappearstobeavalidmethod forcapturing6DOFattheknee.Theminimalisticmarkersetisidealfortheyoungerpopulation duetosubjectphysicalsizeconsiderations.Additionally,themodelcalculatesjointangleswhichare positivelycorrelatedtothosecalculatedwiththeclinicallyusedPiGmodel.Thetranslationcalculationswerevalidatedbyoverlayingpublisheddataforapositivevisualcorrelation.Whenevaluated fromtheseperspectives,theFenwaymodelhasthepotentialtogreatlyenhancetheknowledgeof pediatricspecicmovements. ThecustomKneeStabilityGUIcreatedforthisprojectprovedtobeausefultoolfordata 92

PAGE 103

interrogation.TheGUIcontainedthestandardkinematicandkineticvariablesanalyzedforclinical gaitanalysisaswellasadditionalplotsforagreaterdepthofknowledge.Theseadditionalplots pairedmultiplevariablesforamorecompletepictureofjointmotion.Throughtheuseofthistool, signalsinvisualdi erencesbetweenACL-IandACL-Rmotioncapturedatawereobserved. AkneestabilityprotocolwasproposedforuseinfuturepediatricACLresearch.Inestablishing thetasks,graphs,andvariablesforthisprotocol,asignicantnumberofplotcongurationsacross multipletaskswereinspected.Taskinstructionswerealteredtobetterfocusthesubjectmotionsto targetspecicvariablesforcomparison.Thequantityofvariablesandplotswerenarroweddownto thosewhichshowedinitialsignalsinthispilotstudy.Thenalselectionofvariablesstillprovided asu cientande ectivedatasetforcomparisonofACL-IandACL-Rgroups. Whilethisstudybeganinordertocomparesurgicalmethods,itwasquicklybecameclearthat morefoundationalknowledgeandunderstandingofkneestabilitywasimportant.Thisproject focusedoncreatingamethodologytomeasurekneemovement,atooltovisualizeresults,anda correspondingstudyprotocol.Itisalsorecommendedthattofurthercontinuetounderstandthe e ectivenessoftheseinnovativepediatricACLsurgicalprocedures,futurestudiesshouldbedesigned tocomparesurgicalmethodsandtotracktheprogressofhealingbasedonthebackgroundknowledge gainedinthisproject. 93

PAGE 104

REFERENCES [1]PMAichroth,DVPatel,andPZorrilla.Thenaturalhistoryandtreatmentofruptureofthe anteriorcruciateligamentinchildrenandadolescents. TheJournalofBoneandJointSurgery 84:3841,2002. [2]AllenFAnderson.Transepiphysealreplacementoftheanteriorcruciateligamentinskeletally immaturepatients.Apreliminaryreport. TheJournalofBoneandJointSurgery ,93(3):648; authorreply648649,2003. [3]TPAndriacchi,EJAlexander,MKToney,CDyrby,andJSum.Apointclustermethod forinvivomotionanalysis:appliedtoastudyofkneekinematics. JournalofBiomechanical Engineering ,120(6):7439,December1998. [4]ThomasPAndriacchiandChrisODyrby.Interactionsbetweenkinematicsandloadingduring walkingforthenormalandACLdecientknee. JournalofBiomechanics ,38(2):2938,February 2005. [5]EricRAronowitz,TheodoreJGanley,JoelRGoode,JohnRGregg,andJamesSMeyer.AnteriorCruciateLigamentReconstructionInAdolescentsWithOpenPhyses. AmericanJournal OfSportsMedicine ,28(2):168175,2000. [6]RichardBaker,LFinney,andJOrr.Anewapproachtodeterminethehiprotationprolefrom clinicalgaitanalysisdata. HumanMovementScience ,18:655667,1999. [7]LeslieSBeasleyandStevenCChudik.Anteriorcruciateligamentinjuryinchildren:updateof currenttreatmentoptions. CurrentOpinioninPediatrics ,15(1):4552,2003. [8]DanielLBenoit,DanKRamsey,MarioLamontagne,LanyiXu,PerWretenberg,andPer Renstršm.E ectofskinmovementartifactonkneekinematicsduringgaitandcuttingmotions measuredinvivo. Gait&Posture ,24(2):15264,October2006. [9]JacobBickels,YehudaKollender,TamirPritsch,IsaacMeller,andMartinMMalawer.Knee stabilityafterresectionoftheproximalbula. ClinicalOrthopaedicsandRelatedResearch 454:198201,January2007. [10]Jaynie;BjornaraaandRichardFabio.KneeKinematicsFollowingACLReconstructionin Females;TheE ectofVisiononPerformanceDuringaCuttingTask. TheInternationalJournal ofSportsPhysicalTherapy ,6(4):271284,2011. [11]JTroyBlackburn,MarcFNorcross,andDarinaPadua.Inuencesofhamstringsti nessand strengthonanteriorkneejointstability. ClinicalBiomechanics ,26:27883,March2011. [12]ChihHuiChen,JingShengLi,AliHosseini,HemanthR.Gadikota,ThomasJ.Gill,andGuoan Li.Anteroposteriorstabilityofthekneeduringthestancephaseofgaitafteranteriorcruciate ligamentdeciency. Gait&Posture ,35:467471,2012. [13]AnneMarieChicorell,AdamYNasreddine,andMininderSKocher.Physeal-sparinganterior cruciateligamentreconstructionwithiliotibialband. ClinicalSportsMedicine ,30(4):76777, October2011. [14]FranckChotel,JulienHenry,RomainSeil,JulienChouteau,BernardMoyen,andJŽr™me BŽrard.GrowthdisturbanceswithoutgrowtharrestafterACLreconstructioninchildren. Knee Surgery,SportsTraumatology,Arthroscopy ,18(11):14961500,November2010. [15]ThomasDCollins,SalimNGhoussayni,DavidJEwins,andJennyaKent.Asixdegrees-offreedommarkersetforgaitanalysis:repeatabilityandcomparisonwithamodiedHelenHayes set. Gait&Posture ,30(2):17380,August2009. 94

PAGE 105

[16]RobertDonatelliandMichaelJWooden. OrthopaedicPhysicalTherapy .ChurchillLivingstone, NewYork,3rded.edition,2001. [17]MarkDutton. OrthopaedicExamination,Evaluation,andIntervention .McGraw-Hill,New York,2004. [18]JMFlynnandWMackenzie.ObjectiveEvaluationofKneeLaxityinChildren. JournalOf PediatricOrthopedics ,20(2):259263,2000. [19]JeremySFrankandPeterLGambacorta.Anteriorcruciateligamentinjuriesintheskeletallyimmatureathlete:diagnosisandmanagement. TheJournaloftheAmericanAcademyof OrthopaedicSurgeons ,21(2):7887,March2013. [20]Karl-HeinzFrosch,DirkStengel,TobiasBrodhun,ImmanuelStietencron,DirkHolsten,ChristianJung,DominikReister,ChristineVoigt,PhilippNiemeyer,MarkusMaier,PeterHertel, MichaelJagodzinski,andHelmutLill.Outcomesandrisksofoperativetreatmentofrupture oftheanteriorcruciateligamentinchildrenandadolescents. Arthroscopy ,26(11):153950, November2010. [21]RobinFuchs,WilliamWheatley,JohnW.Uribe,KeithS.Hechtman,JohnE.Zvijac,and MatthiasR.Schurho .Intra-articularanteriorcruciateligamentreconstructionusingpatellar tendonallograftintheskeletallyimmaturepatient. Arthroscopy ,18(8):824828,October2002. [22]TakashiFukaya,HirotakaMutsuzaki,HirofumiIda,andYasuyoshiWadano.Twodi erent protocolsforkneejointmotionanalysesinthestancephaseofgait:correlationoftherigid markersetandthepointclustertechnique. RehabilitationResearchandPractice ,2012:586348, January2012. [23]TheodoreJGanley.ACLreconstructioninadolescentandpreadolescentpatients. Orthopedics 32(11):833,November2009. [24]TheodoreJGanley,StephanGPill,JohnMFlynn,andJohnRGregg.Pediatricandadolescent sportsmedicine. CurrentOpinioninOrthopaedics ,12:456461,2001. [25]BoGaoandNaiquanNigelZheng.Alterationsinthree-dimensionaljointkinematicsofanterior cruciateligament-decientand-reconstructedkneesduringwalking. ClinicalBiomechanics 25(3):2229,March2010. [26]HMGaulrappandJHaus.Intraarticularstabilizationafteranteriorcruciateligamenttear inchildrenandadolescents:results6yearsaftersurgery. KneeSurgery,SportsTraumatology, Arthroscopy ,14(5):417424,May2006. [27]BenKGraf,RichardHLange,CKeithFujisaki,GregoryLLandry,andRKSaluja.Anterior CruciateLigamentTearsinSkeletallyImmaturePatients:MeniscalPathologyatPresentation andAfterAttemptedConservativeTreatment. Arthroscopy:TheJournalofArthroscopicand RelatedSurgery ,8(2):229233,1992. [28]HGripandCHŠger.Anewapproachtomeasurefunctionalstabilityofthekneebasedon changesinkneeaxisorientation. JournalofBiomechanics ,46(5):85562,March2013. [29]ESGroodandWJSuntay.Ajointcoordinatesystemfortheclinicaldescriptionofthreedimensionalmotions:applicationtotheknee. JournalofBiomechanicalEngineering ,105(May 1983):136144,1983. [30]ShuyangHan,ShirongGe,HongtaoLiu,andRongLiu.AlterationsinThree-dimensional KneeKinematicsandKineticsduringNeutral,SqueezeandOutwardSquat. JournalofHuman Kinetics ,39(December):5966,December2013. 95

PAGE 106

[31]JulienHenry,FranckChotel,JulienChouteau,MichelHenriFessy,JŽr™meBŽrard,andBernard Moyen.Ruptureoftheanteriorcruciateligamentinchildren:earlyreconstructionwithopen physesordelayedreconstructiontoskeletalmaturity? KneeSurgery,SportsTraumatology, Arthroscopy ,17(7):74855,July2009. [32]STHerfat,DanielBoguszewski,RebeccaNesbitt,andJasonShearn.E ectofPerturbinga SimulatedMotiononKneeandAnteriorCruciateLigamentKinetics. JournalofBiomechanical Engineering ,134(10):114,2012. [33]YuichiHoshinoandScottTashman.Internaltibialrotationduringinvivo,dynamicactivity inducesgreaterslidingoftibio-femoraljointcontactonthemedialcompartment. KneeSurgery, SportsTraumatology,Arthroscopy ,20(7):126875,July2012. [34]JoshuaLHudgensandDianeLDahm.Treatmentofanteriorcruciateligamentinjuryin skeletallyimmaturepatients. InternationalJournalofPediatrics ,2012:16,January2012. [35]CatherineHui,JustinRoe,DuncanFerguson,AlisonWaller,LucySalmon,andLeoPinczewski. OutcomeofanatomictransphysealanteriorcruciateligamentreconstructioninTannerstage1 and2patientswithopenphyses. TheAmericanJournalofSportsMedicine ,40(5):10938,May 2012. [36]PMJanarvandANystršm.Anteriorcruciateligamentinjuriesinskeletallyimmaturepatients. JournalOfPediatricOrthopedics ,16(5):673677,1996. [37]TobiasMJung,AnneLubowicki,AnnaWienand,MichaelWagner,andAndreasWeiler.Knee stabilityafterposteriorcruciateligamentreconstructioninfemaleversusmalepatients:a prospectivematched-groupanalysis. Arthroscopy:TheJournalofArthroscopicandRelated Surgery ,27(3):399403,March2011. [38]PekkaKannusandMarkkuJarvinen.KneeLigamentInjuriesinAdolescents.EightYearFollowUpofConservativeManagement. JournalofBoneandJointSurgery ,70:772776,1988. [39]MininderSKocher.Anteriorcruciateligamentreconstructionintheskeletallyimmaturepatient. OperativeTechniquesinSportsMedicine ,14:124134,July2006. [40]MininderSKocher,HillarySSaxon,WDavidHovis,andRichardJHawkins.Managementand complicationsofanteriorcruciateligamentinjuriesinskeletallyimmaturepatients:surveyof theHerodicusSocietyandTheACLStudyGroup. JournalOfPediatricOrthopedics ,22(4):452 457,2002. [41]MininderSKocher,JRichardSteadman,KarenKBriggs,WilliamISterett,andRichardJ Hawkins.RelationshipsBetweenObjectiveAssessmentofLigamentStabilityandSubjectiveAssessmentofSymptomsandFunctionAfterAnteriorCruciateLigamentReconstruction. AmericanJournalOfSportsMedicine ,32(3):629634,April2004. [42]MSKocher.ReconstructionoftheAnteriorCruciateLigamentintheSkeletallyImmature Patient. OperativeTechniquesinOrthopaedics ,15:298307,October2005. [43]JonDKomanandJamesOSanders.Valgusdeformityafterreconstructionoftheanterior cruciateligamentinaskeletallyimmaturepatient.Acasereport. TheJournalofBoneand JointSurgery ,81(5):711715,1999. [44]LisaMKruse,BenjaminLGray,andRickWWright.Anteriorcruciateligamentreconstruction rehabilitationinthepediatricpopulation. ClinicalSportsMedicine ,30(4):81724,October2011. [45]AnthonySKulas,TiborHortob‡gyi,andPaulDevita.Theinteractionoftrunk-loadand trunk-positionadaptationsonkneeanteriorshearandhamstringsmuscleforcesduringlanding. JournalofAthleticTraining ,45(1):515,2010. 96

PAGE 107

[46]JCKŸpper,BLoitz-Ramage,DTCorr,DaHart,andJLRonsky.Measuringkneejoint laxity:areviewofapplicablemodelsandtheneedfornewapproachestominimizevariability. ClinicalBiomechanics ,22:113,January2007. [47]M.a.Lafortune,P.R.Cavanagh,H.J.Sommer,anda.Kalenak.Three-dimensionalkinematics ofthehumankneeduringwalking. JournalofBiomechanics ,25(4):347357,1992. [48]Mak-HamLam,DanielTik-PuiFong,PatrickShu-HangYung,EricPo-YanHo,Kwai-Yau Fung,andKai-MingChan.Kneerotationalstabilityduringpivotingmovementisrestored afteranatomicdouble-bundleanteriorcruciateligamentreconstruction. TheAmericanJournal ofSportsMedicine ,39(5):10328,May2011. [49]Mak-HamLam,DanielTpFong,PatrickShYung,EricPyHo,Wood-YeeChan,andKai-Ming Chan.Kneestabilityassessmentonanteriorcruciateligamentinjury:Clinicalandbiomechanicalapproaches. SportsMedicine,Arthroscopy,Rehabilitation,Therapy&Technology ,1(20):9, January2009. [50]JToddRLawrence,AndreaLBowers,JonathanBelding,StephanieRCody,andTheodoreJ Ganley.All-epiphysealAnteriorCruciateLigamentReconstructioninSkeletallyImmaturePatients. ClinicalOrthopaedicsandRelatedResearch ,468(7):19711977,July2010. [51]PamelaLevangieandCynthiaNorkin. JointStructureandFunction .F.A.DavisCompany,5th edition,2011. [52]MariosG.Lykissas,SenthilT.Nathan,andEricJ.Wall.All-EpiphysealAnteriorCruciate LigamentReconstructioninSkeletallyImmaturePatients:ASurgicalTechniqueUsingaSplit TibialTunnel. ArthroscopyTechniques ,1(1):e133e139,September2012. [53]TatsuoMae,KonseiShino,NorinaoMatsumoto,KenjiYoneda,HidekiYoshikawa,andKen Nakata.Immediatepostoperativeanteriorkneestability:double-versustriple-bundleanteriorcruciateligamentreconstructions. Arthroscopy:TheJournalofArthroscopicandRelated Surgery ,29(2):213219,February2013. [54]DavidJ.Magee. OrthopedicPhysicalAssessment .ElsevierSaunders,Philadelphia,Pa,4th enhancedition,2006. [55]ElaineN.Marieb. HumanAnatomy&Physiology .PearsonEducation,Inc.,SanFrancisco,CA, 6thedition,2003. [56]JRMcCarroll,KDShelbourne,DaPorter,aCRettig,andSMurray.Patellartendon graftreconstructionformidsubstanceanteriorcruciateligamentruptureinjuniorhighschool athletes.Analgorithmformanagement. TheAmericanJournalofSportsMedicine ,22(4):478 484,1994. [57]JohnRMcCarroll,ArthurCRettig,andKDonaldShelbourne.Anteriorcruciateligament injuriesintheyoungathletewithopenphyses. TheAmericanJournalofSportsMedicine 16(1):4447,1988. [58]MoiraMMcCarthy,JessicaGraziano,DanielWGreen,andFrankACordasco.All-epiphyseal, All-InsideAnteriorCruciateLigamentReconstructionTechniqueforSkeletallyImmaturePatients. ArthroscopyTechniques ,1(2):231239,December2012. [59]BronaC.McDowell,ClaireKerr,ConnorKelly,JoseSalazar,andAidanCosgrove.Thevalidity ofanexistinggaitclassicationsystemwhenappliedtoarepresentativepopulationofchildren withhemiplegia. Gait&Posture ,28(3):442447,2008. [60]AmyLMcIntosh,DianeLDahm,andMichaelJStuart.AnteriorCruciateLigamentReconstructionintheSkeletallyImmaturePatient. Arthroscopy ,22(3):132530,December2006. 97

PAGE 108

[61]MMelnyk,BKoer,MFaist,MHodapp,andAGollhofer.E ectofawhole-bodyvibration sessiononkneestability. InternationalJournalofSportsMedicine ,29:83944,October2008. [62]PeterJMillett,AndrewaWillis,andRussellFWarren.Associatedinjuriesinpediatricand adolescentanteriorcruciateligamenttears:doesadelayintreatmentincreasetheriskof meniscaltear? Arthroscopy ,18(9):955959,November2002. [63]DLMirandaandPDFadale.Kneebiomechanicsduringajump-cutmaneuver:E ectsofgender &ACLsurgery. MedicalScienceinSportsandExercise ,45(5):942951,2013. [64]MMolloy,J.Salazar-Torres,CKerr,B.C.McDowell,andAPCosgrove.Thee ectsof industrystandardaveragingandlteringtechniquesinkinematicgaitanalysis. Gait&Posture 28(4):559562,2008. [65]YasuharuNagano,HirofumiIda,MasamiAkai,andToruFukubayashi.E ectsofjumpand balancetrainingonkneekinematicsandelectromyographyoffemalebasketballathletesduringasinglelimbdroplanding:pre-postinterventionstudy. SportsMedicine,Arthroscopy, Rehabilitation,Therapy&Technology ,page3:14,January2011. [66]BenedictUNwachukwu,EricDMcfeely,AdamNasreddine,JohnHUdall,CraigFinlayson, DavidWShearer,LyleJMicheli,andMininderSKocher.ArthrobrosisAfterAnteriorCruciateLigamentReconstructioninChildrenandAdolescents. JournalOfPediatricOrthopedics 31(8):811817,2011. [67]AndrewDPearle,DanielJSolomon,TonyWanich,AlexandreMoreau-Gaudry,CarinneC Granchi,ThomasLWickiewicz,andRussellFWarren.Reliabilityofnavigatedkneestability examination:acadavericevaluation. TheAmericanJournalofSportsMedicine ,35(8):131520, August2007. [68]AEPressman,RMLetts,andJGJarvis.AnteriorCruciateLigamentTearsinChildren: AnAnalysisofOperativeVersusNonoperativeTreatment. JournalOfPediatricOrthopedics 17(4):505511,1997. [69]LaurenHRedler,RebeccaTBrafman,NatashaTrentacosta,andChristopherSAhmad.AnteriorCruciateLigamentReconstructioninSkeletallyImmaturePatientswithTransphyseal Tunnels. Arthroscopy ,28(11):17101717,November2012. [70]SRistanis,GGiakas,CDPapageorgiou,TMoraiti,NStergiou,andaDGeorgoulis.Thee ects ofanteriorcruciateligamentreconstructionontibialrotationduringpivotingafterdescending stairs. KneeSurgery,SportsTraumatology,Arthroscopy ,11:3605,December2003. [71]J.J.Salazar-Torres,B.C.McDowell,CKerr,andA.P.Cosgrove.Pelvickinematicsandtheir relationshiptogaittypeinhemiplegiccerebralpalsy. Gait&Posture ,33(4):620624,2011. [72]WudbhavNSankar,LawrenceWells,BrianJSennett,BrentBWiesel,andTheodoreJGanley. Combinedanteriorcruciateligamentandmedialcollateralligamentinjuriesinadolescents. JournalOfPediatricOrthopedics ,26(6):733736,2006. [73]AKSchachterandASRokito.ACLinjuriesintheskeletallyimmaturepatient. Orthopedics 30(5),2007. [74]SusanSigward,ChristinPollard,KathrynHavens,andChristopherPowers.TheInuenceof SexandMaturationonKneeMechanicsduringSide-StepCutting. MedicalScienceinSports andExercise ,44(8):14971503,2012. [75]ClStanitski.AnteriorCruciateLigamentInjuryintheSkeletallyImmaturePatient:Diagnosis andTreatment. TheJournalOfTheAmericanAcademyOfOrthopaedicSurgeons ,3(3):146 158,1995. 98

PAGE 109

[76]ClStanitski.Anteriorcruciateligamentinjuryintheskeletallyimmatureathlete. Operative TechniquesinSportsMedicine ,6(4):228233,1998. [77]NikolausaStreich,AlexanderBariÂŽ,TobiasGotterbarm,MaximilianKeil,andHolgerSchmitt. Transphysealreconstructionoftheanteriorcruciateligamentinprepubescentathletes. Knee Surgery,SportsTraumatology,Arthroscopy ,18:14811486,November2010. [78]ScottTashmanandWilliamAnderst.In-VivoMeasurementofDynamicJointMotionUsing HighSpeedBiplaneRadiographyandCT:ApplicationtoCanineACLDeciency. Journalof BiomechanicalEngineering ,125(2):238,2003. [79]ScottTashmanandDaisukeAraki.E ectsofanteriorcruciateligamentreconstructiononin vivo,dynamickneefunction. ClinicalSportsMedicine ,32(1):4759,January2013. [80]ScottTashman,DavidCollon,KyleAnderson,PatriciaKolowich,andWilliamAnderst.AbnormalRotationalKneeMotionDuringRunningAfterAnteriorCruciateLigamentReconstruction. AmericanJournalofSportsMedicine ,32(4):975983,April2004. [81]MatthewThompson,BSJohnFlynn,LawrenceWells,andJTheodore.SingleIncisionArthroscopicACLReconstructioninSkeletallyImmaturePatientsWithDirectVisualizationofthe FemoralandTibialPhyses. Orthopedics ,29(6):37,2006. [82]MichaelRTorry,CMyers,WWPennington,KBShelburne,JPKrong,JEGiphart,JR Steadman,andSavioL-YWoo.Relationshipofanteriorkneelaxitytokneetranslationsduring droplandings:abi-planeuoroscopystudy. KneeSurgery,SportsTraumatology,Arthroscopy 19(4):65362,April2011. [83]MichaelRTorry,KevinBShelburne,CaseyMyers,J.ErikGiphard,WWesleyPennington, JacobPKrong,DanielPeterson,JRichardSteadman,andSavioL-YWoo.HighKneeValgus inFemaleSubjectsDoesNotYieldHigherKneeTranslationsDuringDropLandings:ABiplane FluoroscopicStudy. JournalofOrthopedicResearch ,31(2):257267,2013. [84]MRTorry,CaseyMyers,KBShelburne,DanielPeterson,J.ErikGiphard,andWWesley Pennington.RelationshipofKneeShearForceandExtensorMomentonKneeTranslations inFemalesPerformingDropLandings:ABiplaneFluoroscopyStudy. ClinicalBiomechanics 26(10):10191024,2011. [85]AlexanderTsarouhas,MichaelIosidis,DimitriosKotzamitelos,GiannisSpyropoulos,ThemistoklisTsatalas,andGiannisGiakas.Three-dimensionalkinematicandkineticanalysisofknee rotationalstabilityaftersingle-anddouble-bundleanteriorcruciateligamentreconstruction. Arthroscopy:TheJournalofArthroscopicandRelatedSurgery ,26(7):88593,July2010. [86]MMUtukuri,HSSomayaji,VKhanduja,GSEDowd,andDMHunt.Updateonpaediatric ACLinjuries. TheKnee ,13(5):345352,October2006. [87]MvanderEsch,MSteultjens,JHarlaar,NWolterbeek,DLKnol,andJDekker.Knee varus-valgusmotionduringgaitameasureofjointstabilityinpatientswithosteoarthritis? OsteoarthritisandCartilage ,16(4):5225,April2008. [88]aVergisandJGillquist.Sagittalplanetranslationofthekneeduringstairwalking.Comparison ofhealthyandanteriorcruciateligamentdecientsubjects. TheAmericanJournalofSports Medicine ,26(6):8416,1998. [89]ShailVyas,CarolaFVanEck,NinaVyas,FreddieHFu,andNormanYOtsuka.Increased medialtibialslopeinteenagepediatricpopulationwithopenphysesandanteriorcruciate ligamentinjuries. KneeSurgery,SportsTraumatology,Arthroscopy ,19(3):372377,March2011. [90]HongshengWang,JamesE.Fleischli,andNaiquanNigelZheng.E ectoflowerlimbdominance onkneejointkinematicsafteranteriorcruciateligamentreconstruction. ClinicalBiomechanics 27:170175,2012. 99

PAGE 110

[91]KateEWebsterandJulianaFeller.Tibialrotationinanteriorcruciateligamentreconstructed kneesduringsinglelimbhopanddroplandings. ClinicalBiomechanics ,27(5):4759,July2012. [92]KateEWebster,SimonEPalazzolo,JodieaMcClelland,andJulianaFeller.Tibialrotationduringpivotinginanteriorcruciateligamentreconstructedkneesusingasinglebundle technique. ClinicalBiomechanics ,27(5):4804,June2012. [93]LawrenceWells,JulieAnneDyke,Je reyAlbaugh,andTheodoreJGanley.Adolescentanterior cruciateligamentreconstruction:aretrospectiveanalysisofquadricepsstrengthrecoveryand returntofullactivityaftersurgery. JournalOfPediatricOrthopedics ,29(5):486489,2009. [94]HamidRFallahYakhdani,HamidAbbasiBafghi,OnnoGMeijer,SjoerdMBruijn,Nicolette vandenDikkenberg,AntoonBStibbe,BarendJvanRoyen,andJaapHvanDie‘n.Stability andvariabilityofkneekinematicsduringgaitinkneeosteoarthritisbeforeandafterreplacement surgery. ClinicalBiomechanics ,25(3):2306,March2010. [95]Y.Yamamoto.KneeStabilityandGraftFunctionAfterAnteriorCruciateLigamentReconstruction:AComparisonofaLateralandanAnatomicalFemoralTunnelPlacement. American JournalofSportsMedicine ,32(8):18251832,November2004. [96]CHYeow,WLGan,PVSLee,andJCHGoh.E ectofananterior-slopedbracejointonanteriortibialtranslationandaxialtibialrotation:amotionanalysisstudy. ClinicalBiomechanics 25(10):102530,December2010. [97]WonJoonYoo,MininderSKocher,andLyleJMicheli.GrowthPlateDisturbanceAfter TransphysealReconstructionoftheAnteriorCruciateLigamentinSkeletallyImmatureAdolescentPatients:AnMRImagingStudy. JournalOfPediatricOrthopedics ,31(6):691696, 2011. [98]StefanoZa agnini,SimoneBignozzi,SandraMartelli,NicolaLopomo,andMaurilioMarcacci. DoesACLreconstructionrestorekneestabilityincombinedlesions?:Aninvivostudy. Clinical OrthopaedicsandRelatedResearch ,454:9599,January2007. [99]Li-QunZhang,RichardGShiavi,ThomasJLimbird,andJayMMinorik.Sixdegrees-offreedomkinematicsofACLdecientkneesduringlocomotion-compensatorymechanism. Gait &Posture ,17(1):3442,February2003. 100