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ThepurposeofthisstudywastocomparethebiomechanicalpropertiesoftibialistendonsandBTBssterilizedwithgammairradia-tiontoaseptictendons.IntroductionGammairradiationhasanextensivehistoryouseorsterilizingsottissueallograts.Earlyresearchshowingdose-dependentre-ductionsinmusculoskeletaltissuebiomechanicsathighgammadoses3.0mRad1-3haspromptedtissuebankstoemploylowerdosesthatremainextremelyefcientindeactivatingmicroor-ganismswhileminimizingtissuedamage.Recentstudieshaveshownthatlowdosegammairradiationlooselydenedasap-proximately1.5-2.0mRaddoesnotalterthebiomechanicalprop-ertiesobone-patellartendon-boneBTBtibialisandsemiten-dinosustendonallograts4-5.StillclinicalstudiesreportinghigherailureratesinACLreconstructionsusingallogratsespeciallyinyoungerpatients6-8haveimplicatedgammairradiationasaprimarycauseorailurewithoutaullunderstand-ingopotentialailuremechanisms9-10.Thisnegativeperceptionhasspurredincreaseduseoasepticgratstosae-guardbiomechanicalintegritybutitcomesattheriskoimplantinganon-sterilegrat.Furtherresearchisneed-edtosupportgammairradiationuseatappropriatedosesthatdonotaectthegratsbiomechanicalintegrity.StudyObjectiveThepurposeothisstudywastocomparethebiomechanicalpropertiesoanteriorposteriortibialistendonsandBTBssteril-izedwithgammairradiationatadoseo1.7-2.1mRadtoasepti-callyprocessednon-irradiatedtendons.Ourhypothesiswasthatgammairradiatedtendonswouldbebiomechanicallyequivalenttoasepticcontrols.SpecimenPreparationPairedbisectedBTBsromagroupo10donors6maleand4e-malemeanage57.8yearsagerange49-72yearsoldandpairedanteriorandposteriortibialistendonsromadierentgroupo10donors5maleand5emalemeanage65.1yearsagerange40-74yearsoldwereasepticallyrecoveredandprocessedasresh-rozengratspercurrentstandardmanuacturingproceduresthatincludedaproprietarymethodthathasbeenvalidatedtoaSteril-ityAssuranceLevelSALo10-6.Tendonswererandomlyselectedandeithergammairradiatedondryiceata1.7-2.1mRaddoseorletuntreatedtoserveasasepticcontrols.BiomechanicalTestingTissueswerestoredat-65Cuntiltestingatwhichtimetheywerethawedinawaterbathsettophysiologictemperature37C.Allspecimensweretrimmedtoaminimumgagelength-to-widthratioo31andthecross-sectionaldimensionsandini-tialgagelengthsweremeasuredintheunloadedstateusingalasermicrometerandcalipersrespectively.ForBTBsthetibialboneblockswerepottedusingBondobodyllerresinincustommolds.Fortibialistendonstheendswereoldedinsandpapertopreventslippage.BothendsoeachspecimenweresecuredinpneumaticclampsandtestingwasconductedusingamaterialstestingsystemInstronElectroPulsE3000NorwoodMA.Eachtendonwaspreconditionedviacyclictensileloadingrom0-20Nat0.5Hzor10cycles.Thegratswerethensubjectedto2000cy-clesocyclictensileloadingatarateo2Hzwithloadssinusoidallyrampedbetween0Nand200Ninloadcontrol11.Specimenswereunloadedandallowedtorelaxorvemin-utesollowingthecyclicsub-ailuretesting.Lastlythespecimenswereloadedintensiontoailureatadisplacementrateo100initialgagelengthpersecond12-13.Alltestingwasconductedinacustomenvironmentalchamberthatmaintainedphysiologictemperature372CandconstantlymistedthespecimenswithsalinetomaintaintissuehydrationDataAnalysisTotaltendonelongationorthecyclictestwasexpressedasaper-centageanddenedasthestraindierenceollowingcompletionothesub-ailureloading.Structuralandmaterialpropertieswerecalculatedromailureload-displacementcurvesandstress-straincurvesrespectively.Nominalstrainwasdeterminedromtheratioogrip-to-gripdisplacementtotheinitialspecimenlength.Sti-nesswascalculatedastheslopeothelinearportionotheload-displacementcurvestypicallydenedbetween2080otheabsolutepeakorce.Similarlytheelasticmoduluswascalculatedromthestress-straincurvesotheailuretests.Maximumloadmaximumdisplacementailurestressandailurestrainwerealldenedatthebreakingpointontheailuretestcurves.Meanandstandarddeviationwerecalculatedoreachbiomechanicalprop-ertyandastudentt-testwasusedtodetectdierencesbetweengammairradiatedandasepticallypreparedtendonsandallre-portedp-valuesaretwo-tailedwith0.05signicancelevel.GammaIrradiatedSotTissueAllogratsareBiomechanicallyEquivalenttoAsepticNon-SterilizedTissues