Abstract: ObjectiveToexplorethemethodtoestablishanimalmodelofearlyosteonecrosisofthefemoralhead(ONFH)inducedby steroid.Methods20healthymaleBeagleswererandomlydividedintocontrolgroupandexperimentalgroupwith10dogsineachgroup. Theexperimentalgroupwasinjectedlipopolysaccharide10μg/kgandmethylprednisolone20mg/kgfor3daysconsecutively.Thecontrol groupwasinjectednormalsaline.2monthsand4monthsafteradministration,bothgroupswereperformedmagneticresonanceimaging (MRI).5animalsweresacrificedrespectivelyat2monthsand4monthsafteradministrationineachgroup,andbilateralfemoralheadspeci-menswereobtainedtoperformhistologicalexamination.Plasmaprothrombintime(PT),activatedpartialthromboplastintime(APTT),anti-thrombinIII(AT-III)weretestedbeforeand24hafteradministration.ResultsIntheexperimentalgroup,thepathologicalresultsshowed thattherewere4ONFH2monthsand6ONFH4monthsafteradministrationandMRIdidnotshowanyabnormality.Comparedwiththe controlgroup,thePT,APTT,AT-IIIintheexperimentgroupshortenedsignificantlyafteradministration(P<0.001).ConclusionModified steroid-inducedmethodcanestablishtheanimalmodelofearlyONFH.Hypercoagulationandlowfibrinolysismaybethereasonofste-roid-inducedosteonecrosis.

Key words: osteonecrosisofthefemoralhead, earlystage, modifiedsteroid-inducedmethod, animalmodel, Beagles