非骨水泥股骨假体选择

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1、CementlessFemoralFixationinTotalHipArthroplastyAnumberofcementlessfemoralstemsareassociatedwithexcellentlong-termsurvivorship.Cementlessdesignsdifferfromoneanotherintermsofgeometryandthemeansofobtaininginitialfixation.Strictclassificationofstemdesignsisimport

2、antinordertocompareresultsamongseries.Looseningandthighpainarelessprevalentwithmodernstemdesigns.Stress-shieldingispresentinmostcases,evenwithnewerstemdesigns.In1995,theNIHConsensusDevelopmentPanelhybridfixation----acementedstemandanoncementedcup.Today,60%to90

3、%ofthe200,000THAyearlyintheUnitedStatesinvolvebothacementlesscupandstem.Thisreviewdoesnotincludeprosthesesthatweredesignedforfixationinthefemoralneck.Osteointegration:1981,Albrektsson,-----theattachmentoflamellarbonetoimplantswithoutinterveningfibroustissue.Th

4、isprocess,approximatelyfourtotwelveweeksafterimplantationandmaycontinueforuptothreeyears.Micromotionof>150mmleadstofibroustissueformationbetween40and150mmleadstoacombinationofbonefibroustissueformation,and<20mmresultsinpredominantlyboneformation.Initialfixatio

5、nisobtainedbypress-fittingaslightlyoversizedcomponent.factorsthatinfluencetheinitialstabilityorprimaryfixation:geometry,roughnessandcoatingofthestem,techniqueofpreparation,andbonequality.Ingrowthoccurswhenbonegrowsinsideaporoussurface.Ongrowthoccurswhenbonegro

6、wsontoaroughenedsurface.surfacecharacteristicsIngrowthrequiresaporesizebetween50and400mmthepercentageofvoidswithinthecoatingshouldbebetween30%and40%tomaintainmechanicalstrengthsinteredbeadsFibermeshPorousmetalsZIMMERTANCAPOngrowthsurfacesarecreatedbygritblasti

7、ngorplasmaspraying.Hydroxyapatiteisacalciumphosphatecompoundthatisplasmasprayeddirectlyontheimplantaloneoroveraporouscoating.osteoconductiveandenhancesgrowthofmineralizedboneontotheimplantInterfacedegradationcouldleadtoimplantloosening31-33.Theoptimalthickness

8、ofthecoatingis50mm,whichdoesnotcompromiseitsstrengthfixationsurfacesneedtobecircumferentialandcontinuousEnhancemetaphysealosseointegrationandproximalstresstransferanddecreasebonelo