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QuadricepsTendonAllograftsareBiomechanicallyEquivalenttoAchillesTendonAllograftsIsaacMabeM.S.andShawnA.HunterPh.D.AbstractQuadricepstendonwithapatellarboneblockmaybeaviablealternativetoAchillestendonoranteriorcruciateligamentreconstructionACL-Riitisataminimumabiomechanicallyequivalentgrat.TheobjectiveothisstudywastodirectlycomparethebiomechanicalpropertiesoquadricepstendongratstoAchillestendongrats.QuadricepsandAchillestendonpairsromninedonorsninemalesmeanage56.9yearsrange37-74yearsweretestedinaphysiologicenvironmentalchamberundersub-ailureandailureloadingregimes.Theresultsshowedthattherewerenostatisticaldierencesinsevenoeightstructuralandmechanicalpropertiesmaximumloadstinessmaxi-mumstressmaximumstrainstrainatmaximumstressmodulusoelasticityandcyclicelongationbetweenthetwotendontypes.Thesignifcantlyhigh-erdisplacementatmaximumloadobservedorquadricepstendonsmayberelatedtotheailuremode.Whilespecimensailedeitherbyboneavul-sionorrupturingothetendonmid-substanceAchillestendonshadahigheravulsionratethanthequadricepstendons89comparedto22respectively.Thiswaslikelyduetoobserveddierencesinboneblockdensitybetweenthetwotendontypes.ThisresearchsupportstheuseoquadricepstendonallogratsinlieuoAchillestendonallogratsorACL-R. QuadricepstendonuseorACL-Rwasfrstreportedinthe1980sandmorerecentstudieshaveshownthatquad-ricepsautogratsyieldclinicaloutcomesequivalenttothoseopatellartendonautograts.IntroductionAnteriorcruciateligamentACLrupturesoccuratanestimatedrateo1in3000resultinginapproximately100000ACLrecon-structionsACL-RperormedintheUnitedStatesannually1.ACLinjuriescanbetreatedbyreconstructingthedamagedligamentwithavarietyosottissueallograts2andallogratswithboneblocksareparticularlypopularbecausethebonyattachmentcanprovidebetterfxationandhealingwithinthebonetunnels.Pa-tellarandAchillestendonsarethemostcommontendon-boneallogratsusedorACL-R3butquadricepstendonsmayprovideaviablealternative.QuadricepstendonuseorACL-Rwasfrstreportedinthe1980s4andmorerecentstudieshaveshownthatquadricepsautogratsyieldclinicaloutcomesequivalenttothoseopatellartendonau-tograts5.Whilequadricepsautogratuseappearstobeincreas-ingcomparableinterestinquadricepsallogratshasnotbeenobserved.Alackoinormationregardingquadricepsallogratbiomechanicalpropertiesandclinicaloutcomesmaybeaactor.AlthoughsuchcomparisonsoAchillesorquadricepstendonstoothertendonssuchasBTBsaredocumentedinthescientifclit-eraturetoourknowledgetherehasnotbeenadirectcomparisonoAchillesandquadricepstendonspreparedusingtraditionaltis-suebankingprocessesandterminalsterilization.ThereoretopromotetheuseoquadricepstendonallogratsasanalternativetoAchillesgratsorACL-Rweperormedadirectbiomechanicalcomparisonothetwograttypes.StudyObjectiveThepurposeothisstudywastocomparethebiomechanicalpropertiesoasepticallypreparedterminallysterilizedquadri-cepstendonwithbonetoAchillestendonwithbone.Ourhypoth-esiswasthatthestructuralandmaterialpropertiesoquadricepstendonswouldnotbesignifcantlydierentromthoseoAchil-lestendons.SpecimenPreparationPairedAchillestendonswithboneblocksandquadricepstendonswithboneblockswereprocuredromnineresearch-consenteddonorsninemalesmeanage56.9yearsrange37-74yearsandasepticallyprocessedus-ingcurrentprocedures.Allspecimenswereterminallysterilizedvialow-dosegammairradiation.Tendonswerestoredat-65Candthenthawedina37Cwaterbathornomorethan15minutespriortotesting.Forbothtendontypesthecentral10mmothebone-tendoncomplexwasisolated6.Quadricepstendonswereurthertrimmedbysharpdissectiontoisolatethetightlyconnectedbundlesotherectusemorisandthevastusintermedius7.AllboneblockswerepottedinBondobodyfllertoincreasethegripsuracetopreventslippage.BiomechanicalTestingTendoncrosssectionalareawasmeasuredinanunloadedstateusingdigitalmicrometers.Thespecimenwasthenplacedinanenvironmentaltestingchamberthatmaintainedaphysiologictemperatureat372Candmistedthespecimenwithsalineorthetestingduration.Specimensweresecuredinpneumaticgripsandaninitialgagelengthwasmeasuredbetweenthetopedgesoeachgripusingaruler.Allspecimensweregrippedtomaintainaconsistentlength-to-widthratiooapproximately51.QuadricepsTendonAllogratsareBiomechanicallyEquivalenttoAchillesTendonAllogratsTestingwasperormedusingamaterialstestingsystemElectro-PulsE3000InstronNorwoodMA.Tomimicdierentphysiologicloadingscenariosathree-phaseuniaxialtensionloadingproto-colwasusedthatwascomprisedoaload-controlledsinusoidalwaveormcycledbetween0-200Nata2Hzrequencyor2000cyclesafveminutestationaryrestortendonrecoveryandaramptoailureatadisplacement-controlledrateo100strainpersecond8.Failuremodewasrecorded.DataAnalysisStructuralandmaterialpropertieswerecalculatedromload-dis-placementandstress-straincurvesrespectively.Maximumloadanddisplacementatthemaximumloadwerere-cordedandstinesswascalculatedasthelinearportionotheloaddisplacementcurveintheailurephaseotesting.Stresswascalculatedastheorceappliedtothetendondividedbythemeasuredcrosssectionalarea.Themaximumstressandthecorrespondingstrainatmaximumstresswerereported.Failurestrainwascalcu-latedbydividingdisplacementbythesumma-tionotheinitialgagelengthplustheadditionalaccruedlengthromthecyclicphaseLLinitialLadditional.Modulusoelasticitywascalculatedasthelinearportionothestress-straincurveintheailurephase.CyclicelongationothetissueaterthecyclicphaseotestingwascalculatedasL2000L10L10100.Meanandstandarddeviationwerecalculatedorthemaximumloaddisplacementatmaximumloadstinessmaximumstressstrainstrainatmaximumstressmodulusoelasticityandcyclicelongationoreachtendontype.Apairedt-testwasusedtode-tectsignifcantdierencesbetweentendontypesusingstatisticalsotware.Adierencewasconsideredsignifcantithecalculatedp-valuewaslessthanatwo-tailedo0.05.Specimenbeingmistedwithsaline.Environmentaltestingchamber. 0102030AchillesQuadMaximumStressMPa0.00.51.01.5AchillesQuadMax.Strainmmmm0100200300AchillesQuadModulusMPa0.01.02.03.0AchillesQuadCyclicElongation050010001500AchillesQuadMaximumLoadN051015AchillesQuadDisp.atMaxLoadmm0100200300AchillesQuadStiffnessNmmp0.022ResultsAllspecimensailedeitherbyboneavulsioneightAchillesandtwoquadricepstendonsortendonmid-substanceruptureoneAchillesandsevenquadricepstendons.Noslippageorailureatthegripwasobserved.BiomechanicalresultsindicatedthattherewerenosignifcantdierencesinmaximumloadstinessstressmaximumstrainstrainatmaximumstressmodulusoelasticityandcyclicelongationbetweenthequadricepsandAchillesten-dons.QuadricepstendonhadsignifcantlygreaterdisplacementatmaximumloadthanAchillestendonsp0.022.QuadricepsTendonAllogratsareBiomechanicallyEquivalenttoAchillesTendonAllogratsConclusionsThisdirectbiomechanicalcomparisonoquadricepsandAchillestendonallogratsshowednostatisticallysignifcantdierencesinsevenoutoeightstructuralandmaterialproperties.Thedier-enceindisplacementatmaximumloadmaybeattributabletodensityvariationsinthebonyattachmentsothetwotendonsasthecancellousboneothepatellaisgenerallythickerandmorecompactthanthatothecalcaneus.Thismayalsoexplaina22boneavulsionrateorquadricepstendonscomparedtoan89avulsionrateorAchillestendonswhichsuggestsastrongpatel-la-quadricepstendoninteracethatshitedtheailureinitiationtothetendon.Ourresultsalsorepresentonlytwobundlesothequadricepstendon.Shouldclinicianschoosetoutilizetheentiretendontheincreasedtissuemasscouldbolsteritsbiomechanicalcapabilities.BasedonourbiomechanicalresultswerecommendquadricepstendonallogratsoruseinACL-RasanalternativetoAchillestendonallograts. Reerences1.FreedmanKDAmatoMNedefDKazABachB.ArthroscopicandteriorcruciateligamentreconstructionAmetaanalysiscomparingpatellartendonandhamstringtendonautograts.TheAmericanJournaloSportsMedicine20033112-11.2.WestRHarnerC.GratSelectioninanteriorcruciateligamentreconstruction.JAmAcadOrthopSurg200513197-207.3.WrenTLindseyDBeaupreGCarterD.Efectsocreepandcyclicloadingonthemechanicalpropertiesandailureohumanachillestendon.AnnalsoBiomedicalEngineering200331710-7.4.StaubliHSchatzmannLBrunnerPRinconLNolteL.Quadricepstendonandpatellarligamentcryosectionalanatomyandstructuralpropertiesinyoungadults.KneeSurgSportsTraumatolArthrosc19964100-10.5.GeibTSheltonWPhelpsRClarkL.AnteriorCruciateLigamentReconstructionUsingQuadricepsTendonAutogratIntermediate-TermOutcome.ArthroscopyTheJournaloArthroscopicRelatedSurgery2009December200925121408-14.6.HarrisLSmithDLamoreauxLPurnellM.Centralquadricepstendonoranteriorcruciatereconstruction.TheAmericanJournaloSportsMedicine199725123-8.7.SieboldRBuelowJUBosLEllermanA.PrimaryACLreconstructionwithresh-rozenpatellarversusAchillestendonallograts.ArchOrthopTraumaSurg2003123180-5.8.HoburgATKeshlaSSchmidtTSmithMGohsUPerkaCetal.Efectoelectronbeamirradiationonbiomechanicalpropertiesopatellartendonallogratsinanteriorcruciateligamentreconstruction.AmJSportsMed2010Jun3861134-40.CenterforTissueInnovationandResearch2900CollegeDriveKetteringOhio454201-800-684-7783www.communitytissue.orgREV01SM-700-F-09