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TheSpringLigament,PTTTear,andAdultAcquiredFlatfootDeformityOnMRI
(Part2) ByWilliamRenner,M.D.
This and other topics will be discussed in:
Theposteriortibialtendonistheprimarystabi- andstabilizesthetalocalcanealnavicularjoint.lizerofthefoot.Otherstabilizersincludethe Thetarsalsinusligaments(cervicalandinteros-springligament,thetarsalsinusligamentsand seousligaments)limitmedialdeviationoftheplantarfascia.Thespringligamentcomplex talarhead.Tosurgicallycorrectflatfootde-consistsofthetibio-springcomponentofthe formitybothPTTandSpringLigamentinjuriesdeltoidligamentandthecalcaneonavicularliga-mustbeaddressed.ment,whichlimitsplantarflexionofthetalus
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Thetibio-springligamentinblueisaportionofthedeltoidligament.TheSM-CNLband(red)oftheSpringLigmentisthemostimportantportionoftheligament.InferiortotheSM-CNLbandisthemedioplantarobliqueligament(pink)andmostinferioristheinferoplantarligament(brown)
Thetibio-springligamentisaportionofthedel-toidligamentandhasawideattachmenttotheSM-CNL.Thespringligament(navicularcalcanealligament)has3componentsthatextendfromthecalcaneustothenavicular.Thesuperiormedial(SM-CNL)bandisthemostimportantportionoftheligament.InferiortotheSM-CNLbandisthemedioplantarobliqueligamentandmostinferioristheinferoplantarligament.TheSM-CNListhestrongestcomponentandshouldbeemphasizedwhenreadingMRexams.TheSM-CNLextendsfromthesustentaculumtalitothedorsalaspectofthemedialnavicular.ImmediatelysuperiortotheSM-CNListheposteriortibialtendon.Athinsynoviallayerseparatesthespringligamentandtheposteriortibialtendonandthisiscalledtheglidezone.
Frequentlythereisacombinationofposteriortibialtendoninjury,springligamentinjuryandtarsalsinusligamentinjurythatleadstoflatfootdeformityinadultsandresultsinhindfootvalgusdeformity.
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CoronalMR:Thetibio-springligament(TS)isaportionofthedeltoidligament.Attachedtothetibio-springligamentinferiorlyistheCNL(springligament,medialtotheposteriortibialtendon(PTT).
CoronalDiagram:Thetibio-springligamentinblueisaportionofthedeltoidligament.Attachedtothetibio-springligmentinferiorlyistheSM-CNLbandinred,themostimportantportionofthespringligament.Thesupe-riormedialcalcanealnavicularligament(SM-CNL)formsaslingthatholdsthetalarheadinitscorrectposition.
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Axial
Diagram:SM-CNLbandoftheSpringLigment,inred,isthemostimportantportionoftheligament.Thiscanbeseenbetweenthetalarhead/neckandtheposteriortibialtendon(yellow).
Whenthesurgeonsarediscussingthespringliga-menttheyarefrequentlyreferringtothetibio-springligamentandtheSM-CNL,whichIcallthespringligamentcomplex.Infact,atearatthejunc-tionofthetibio-springligamentandtheSM-CNLisoneofthemorecommontearsandiscalledthe“springligamenttear”bythesurgeons.
ThebestMRsignsofclinicallyimportantspringliga-menttearsareincreasedsignalonPDorT2weightedimageswithintheligamentwiththickening
oftheligamentgreaterthan5mmorthinningoftheligamenttolessthan2mm.Partialorcompletetearsresultinagapwithfluidsignalwithintheligament.
InastudyofMRfindingsofspringligamenttears:100%hadincreasedsignalonT2-weightedimages,93%hadabnormalcaliber,79%hadagapwithintheligament,64%hadawavyligament,and93%hadassociatedPTTtears.
AxialMR:SM-CNLbandoftheSpringLigmentisthestrongestandmostimportantportionoftheligament.Thiscanbeseenbetweenthetalarhead/neckandtheposteriortibialten-don(PTT).
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ThisMRINewsletterispublishedonRadiusImaging
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T2FSCoronalMRImage:thickeningoftheSM-CNLgreaterthan5mmconsistentwithspringligamentinjury.
MRfindingsofspringligamentinjury:
TheSMbandismostcommonlyinjured.TheSMbandinjurymayshowthickeninggreaterthan5mmorbeatreticiflessthan2mm.Agapintheligamentwithfluidsignalwithinthebandisthestrongestfindingofatear.Tearsofthespringligamentareaccompaniedbyposteriortibialtendontearsin>90%ofcases,flatfootdeformity,andsinustarsussyndrome
Checklistforadultacquiredflatfootdeformity: Posteriortibialtendoninjury Springligamentcomplextearincludingtibialspringligament Sinustarsisyndrome Plantarfasciitis Tarsalcoalition:themostcommoncoalitionsarethecalcaneonavicularandthetalocalcanealcoalition
