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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.