ORIGINALARTICLETreatmentofdegenerativespondylolisthesis:potentialimpactofdynamicstabilizationbasedonimaginganalysisThomasW.LawhorneIIIÆFedericoP.GirardiÆCurtisA.MinaÆIaonnisPappouÆFrankP.CammisaJrReceived:19March2008/Revised:19February2009/Accepted:5March2009/Publishedonline:28March2009�Springer-Verlag2009AbstractIntraspinousandpediclescrew-based(PSB)dynamicinstrumentationsystemshavebeeninuseforadecadenow.Bydirectorindirectdecompression,thesedevicestheoreticallyestablishlesspainfulsegmentalmotionbydiminishingpathologicmotionandunloadingpainfuldisks.Ideally,dynamicsshouldaddressinstabilityintheearlystagesofdegenerativespondylolisthesisbeforeexcessivetranslationoccurs.EvidencetodateindicatesthatGradeIIorlargerslipsrequiringdecompressionshouldbefused.Inaddition,multiplesegmentlisthesis,severecoronalplanedeformities,increasingage,andosteoporosishaveallbeenlistedaspotentialcontraindicationstodynamicstabilization.Wereviewedtheexclusionandinclusioncriteriafoundinvariousdynamicstabilizationstudiesandinvestigationaldrugexemption(IDE)proto-cols.Wesummarizethereportedlimitationsforbothpedicle-andintraspinous-basedsystems.Wethencon-ductedaretrospectivechartandimagingreviewof100consecutivecasesundergoingfusionfordegenerativespondylolisthesis.Allpatientsinourcohorthadbeenindicatedforandeventuallyunderwentdecompressionoflumbarstenosissecondarytospondylolisthesis.Weesti-matedhowmanypatientsinourpopulationwouldhavebeencandidatesfordynamicstabilizationwitheitherinterspinousorpedicle-basedsystems.Usingthecriteriaforinstabilityoutlinedintheliterature,32patientsdem-onstratedtranslationrequiringfusionsurgeryand24patientshadinstabilityunsuitablefordynamicstabiliza-tion.Sixpatientshadtwo-levelslipsandwereexcluded.Twopatientshadcoronalimbalancetoogreatfordynamicsystems.Twelvepatientswereovertheageof80and16demonstratedosteoporosisasdiagnosedbybonescan.Finally,wefoundtwoofourpatientstohavevertebralcompressionfracturesadjacenttothesiteofinstrumenta-tion,whichisastrictexclusioncriteriainalldynamictrials.Thirty-fourpatientshadzeroexclusioncriteriaforintraspinousdevicesand23patientshadnoneforPSBdynamicstabilization.Therefore,weestimatethat34and23%ofdegenerativespondylolisthesispatientsindicatedforsurgerycouldhavebeentreatedwitheitherintraspinousorpedicle-baseddynamicdevices,respectively.KeywordsDynamicstabilization�Degenerativespondylolisthesis�Dynamics�SpinalfusionIntroductionKirkaldy-Willisdividedthespectrumofdegenerativechangesinthelumbarspineintothreedistinctphases:(1)temporarydysfunction;(2)instability;and(3)re-stabi-lization.Stage1degenerationislikelytorespondtoconservativemeasures.Intermsofacceptedtreatmentguidelines,treatmentofearlystage2diseasehasbeenagrayareainwhichconservativemeasureshavebeenthetreatmentofchoice,buthaveadiminishingeffect.Latestage2casesaremostlikelytobetreatedwithstabiliza-tion/fusionsurgery.Finally,instage3theroleofT.W.LawhorneIIISpineService,RushUniversityMedicalCenter,1653W.CongressParkway,Chicago,IL,USAF.P.Girardi�C.A.Mina(&)�I.Pappou�F.P.CammisaJrSpineService,HospitalforSpecialSurgery,535E.70thStreet,NewYork,NY,USAe-mail:minac@hss.eduT.W.LawhorneIII�F.P.Girardi�C.A.Mina�I.Pappou�F.P.CammisaJrDepartmentofOrthopedics,WeillMedicalCollegeofCornellUniversity,NewYork,NY,USA123EurSpineJ(2009)18:815–822DOI10.1007/s00586-009-0941-9decompressionwithoutfusionserv...
