CoreDecompressionforOsteonecrosisofthehipClinOrthop.2004;418:29-33DEVELOPMENTOFCOREDECOMPRESSIONOFTHEFEMORALHEADCoredecompressionofthehipisthemostcommonprocedurecurrentlyusedtotreattheearlystagesofONofthefemoralhead.FicatandArletthenhypothesizedthatONcouldbetreatedsuccessfullybydecompressingthefemoralhead.Thegoalofcoredecompressionwastodecompressthefemoralheadpressure,restorenormalvascularflows,andalleviatepaininthehip.Eventhoughnumerousstudieshavebeenpublishednogeneralconsensushasbeendevelopedregardingpatientselection,surgicaltechnique,classificationsystemsused,orpostoperativetreatmentofthesepatients.CLASSIFICATIONANDSTAGINGThepurposeofanyclassificationsystemistoprovideguidelinesfortreatmentandprognosis.Overtheyears,numerousdifferentclassificationssystemshavebeendevelopedtoevaluatepatientswithONofthefemoralheadbutcurrently,thereisnostandardunifiedclassificationsystemusedbyallinvestigators.ThereisgeneralagreementthattheprognosisforapatientwithONofthehipisinfluencedbytheextentandthelocationofthenecroticareainthefemoralheadandwhetherthereisinvolvementoftheacetabulum.FicatandArletoriginallydevelopedafour-stageclassificationsystembasedonradiographicchangesandthefunctionalexplorationofbonethatincludedintraosseousvenographyandmeasurementofbonemarrowpressure(Table1).TABLE1.RadiographicClassificationsofOsteonecrosisoftheFemoralHeadFicatandArletClassificationSystemStageCriteriaINormalIIScleroticorcysticlesionsIIISubchondralcollapseIVOsteoarthritiswithdecreasedarticularcollapseSincethattime,numerousdifferentclassificationsystemshavebeendevelopedbuttheUniversityofPennsylvaniaSystemofClassificationandStaginghasthemostpotentialasausefulclinicalandresearchtool.BecauseitincludedMRIevaluations,whichallowforthequantificationoftheextentoffemoralheadinvolvement(Table2).TABLE2.UniversityofPennsylvaniaSystemofclassificationandStagingStageCriteria0Normalornondiagnosticradiograph,bonescan,andMRIINormalradiograph;Abnormalbonescanand/orMRIIILucentandscleroticchangesinfemoralheadIIISubchondralcollapse(crescentsign)withoutflatteningIVFlatteningoffemoralheadVJointnarrowingand/oracetabularchangesVIAdvanceddegenerativechangesCOREDECOMPRESSIONTherehavebeennumerousextensiveliteraturereviewspublishedassessingtheclinicalresultsofcoredecompression.Smithetalreviewed12articlespublishedbetween1979and1991thatincluded702hipswithanaveragefollowupof38months.UsingtheUniversityofPennsylvaniaStagingSystem,successfulresultswerereportedasfollows:StageI,78%;StageII,62%;andStageIII,41%.Montandassociatesassessed42reportsinwhich1206hipsweretreatedbycoredecompressionand819hipsweretreatedbyvariousnonoperativemeans.nonoperativetreatmentwasnotsuccessful.Only23%ofhipsin21studieshadasatisfactoryclinicalresultwhentreatednonoperatively.In24studies,65%ofthehipstreatedwithcoredecompressionhadanoverallsatisfactoryclinicalresult.Furthermore,whenassessinghipstreatedbeforecollapse,goodresultswereobtainedin71%ofthehipstreatedwithcoredecompressionandin35%ofhipstreatednonoperatively.Stulbergetalcomparedcoredecompressionalonewithconservativetreatmentinaprospectiverandomizedstudythatincluded55hips.Coredecompressionwassuccessfulin70%ofthehipsthatwereeitherFicatStageI,II,orIII.Incontrast,therewaslimitedsuccesswithnonoperativetreatment(FicatStageI,20%;FicatStageII,0%;FicatStageIII,10%).ItwasconcludedthatcoredecompressionwasmoreeffectivethannonoperativetreatmentforpatientswithearlystagesofON.Kooandassociatesdidarandomizedtrialon71hipsthatweretreatedbycoredecompressionornonoperatively.Radiographicprogressionwasseenin72%ofthehipstreatedwithcoredecompressionandin79%ofthehipsthatweretreatedsymptomatically.Seventy-twopercentofthehipstreatedwithacoredecompressioneventuallyrequiredaTHAand68%ofthehipstreatedsymptomaticallyrequiredaTHA.TheinvestigatorsconcludedthattherewasnosignificantadvantageintheoutcomewhenpatientswithONofthefemoralheadweretreatedwithcoredecompression.Smithandassociatesevaluated114hipsandshowedthattherewasasignificantdecreaseinsatisfactoryresultswhenacrescentsignwaspresent.ThesuccessrateinhipswithFicatStageIONwas81%butinhipswiththecrescentsignordefinitivecollapseofthefemoralheadthesuccessrateswere20%and0%Steinberganalyzed205patients(297hips)withaminimum2-yearfollowup.Thestageofthehip,accordingtotheUniversityofPennsylvaniaClassificationSystem,andthelesionsiteclearlyinfluencedthesuccessratesofcoredecompression.headinvolvement15%headinvolvement15%requiredTHA22%(StageI-II)39%(StageI)40%(StageII)Aaronetal’evaluated118hipswithFicatStageIIorIllONwhichwastreatedwithcoredecompressionandcoredecompressionandhumanDBM.Survivalpercentisshowbelow:coredecompression(Group1)coredecompressionandhumanDBM(Group2)StageFollowup-40monthsFollowup-34monthsII72%83%III47%88%Therealsohasbeenaninterestincombiningcoredecompressionofthefemoralheadwithbonegraftingorelectricalstimulationorbothtoenhancebonerepairinthefemoralhead.Steinbergetalfoundnoadvantagetosupplementingcoredecompressionwitheitherdirectcurrentorcapacitativecoupling.Bozicetalstudied54hipsthathadONofthefemoralh