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ClassificationOfAnnularTears:ACriticalProspectiveStudyInTheSurgicalTreatmentOfTheVariousTypesOfTearsAnthonyT.Yeung,M.D.Patho-PhysiologyOfLowBackPainThepatho-anatomyandphysiologyofchronicbackpainisthoughttobeduetoacombinationofcomplexconditionsthatresultinpainfromchemicalaswellasmechanicalfactorsarisingfromthediscandannulus.Thediscisaninnervatedstructurethatiscapableofpaingenerationfromtheendplate,outeronethirdoftheannulus,andtheposteriorlongitudinalligament.Theposteriorlongitudinalligamentandannuluscontainunmyelinatedpainnociceptorsthattransmitandrelayafferentpainsignalsthroughthedorsalrootganglion.SubstancePisreleasedbythedegeneratingdiscthroughannulartearsthatcancausechemicalirritationofmyelinatedspinalnerves,resultinginsciaticaandwithbackpain.Theseannulartearsallowtheingrowthofgranulationtissueandsmallunmyelinatednervefibersintothenucleus,theoreticallydifferentiatingthepainfuldegenerativediscfromanasymptomaticdegenerativedisc.However,thepainpattern,whennotinadermatomalpattern,ispoorlyunderstood,andpatientswithdiscogenicpainarefrequentlyfrustratedbytheirphysician'sfocusonfunctionalcauseswhentheirsciaticaisnotcorrelatedwithknowndermatomalpatterns.BackgroundStudiesPioneeringworkonsheepandpostmortemstudiesonhumanlumbardiscsbyOstiandFrasersuggestthatperipheralannularlesionshavearoleindiscdegenerationandinthepathogenesisofdiscogenicpain.Althoughwenowhaveextensiveevidenceofthebiologyofdiscdegeneration,verylittleisknownabouthowthatdegenerativeconditioncauseschronicpaininsomepeoplebutnotothers.Adamsclassifiedfivelevelsofdiscdegenerationbyitsconfigurationondiscography.Fromourknowledgeofannularinnervation,thetypeIVandVconfigurationsarethereforeexpectedtocreatepainduetoitsinvolvementoftheouterannulus.Annulartearsarecurrentlyclassifiedbyitsextentandconfiguration.TheDallasclassificationgradestheextentofradialtearsbythedegreeofextensiontotheouterannulus.GradeIIIandIVtears,reachingtheinnerandouterannularfibers,arethereforeanticipatedtobepainful.Annulartearsarefurtherclassi
