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会计学Itisestimatedthat20000to30000newpatientsarediagnosedwithosteonecrosis（股骨头坏死(huàisǐ)）annuallyaccountingforapproximately10%ofthe250000totalhiparthroplasties(THA)doneannuallyintheUnitedStates.Thelackoflevel1evidenceintheliteraturemakesitdifficulttoidentifyoptimaltreatmentprotocols（协议）tomanagepatientswithpre-collapseavascularnecrosisofthefemoralhead,andearlyinterventionpriortocollapseiscriticaltosuccessfuloutcomesinjointpreservingprocedures.Therehavebeenavarietyoftraumaticandatraumaticfactorsthathavebeenidentifiedasriskfactorsforosteonecrosis,buttheetiologyandpathogenesisstillremainsunclear.Generally,thefirstradiographicchangesseenbyradiographwillbecysticandscleroticchangesinthefemoralhead.Althoughthediagnosismaybemadebyradiograph,plainradiographsaregenerallyinsufficientforearlydiagnosis,thereforeMRIisconsideredthemostaccuratebenchmark（标准(biāozhǔn)）.Treatmentoptionsincludepharmacologicagents（药剂）suchasbisphosphonates（磷酸盐）andstatins,biophysicaltreatments,aswellasjoint-preservingandjoint-replacing.Ingeneral,FHSP(femoralheadsparingprocedures)areindicatedatpre-collapsestageswithminimalsymptomswhereasFHRP(femoralheadreplacementprocedures)arepreferredatpost-collapsesymptomaticstages.Currentosteonecrosisdiagnosisisdependentuponplainanteroposteriorandfrog-leglateralradiographsofthehip,followedbymagneticresonanceimaging(MRI).ItisdifficulttoknowwhetheranytreatmentmodalitychangesthenaturalhistoryofcoredecompressionsincethetruenaturalhistoryofcoredecompressionhasnotbeendelineatedIntroductionETIOLOGYANDPATHOGENESISMoststudieshaveattributedthediseaseprocesstothecombinedeffectsofgeneticpredisposition（遗传(yíchuán)易感性）,metabolicfactors（代谢因素）,andlocalfactorsaffectingbloodsupplysuchasvasculardamage,increasedintraosseouspressure,andmechanicalstress.Thisresultsinboneischemiaandinfarctionleadingtobonedeath.Theprecipitatingmechanismwhichleadstothispathwayisvariablethough.Ischemiacanresultfromexternalorinternalvascularinsult（血管损伤）typicallycausedbydirecttrauma,vascularocclusion（闭塞）,directc
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