Rev. bras. ortop. vol.51 número4

SOCIEDADE BRASILEIRA DE ORTOPEDIA E TRAUMATOLOGIA

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Original

article

Safety

zone

for

posterosuperior

shoulder

access:

study

on

cadavers

夽

Miguel

Pereira

Costa,

Sandro

Baraldi

Moreira,

Gustavo

Costalonga

Drumond

_,

Fernanda

de

Marchi

Bosi

Porto,

Fabiano

Rebouc¸as

Ribeiro,

Antonio

Carlos

Tenor

Junior

HospitaldoServidorPúblicoEstadualdeSãoPaulo,SãoPaulo,SP,Brazil

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Articlehistory: Received21May2014 Accepted30June2014 Availableonline8June2016

Keywords:

Shoulder/anatomyandhistology Shoulder/innervation

Acromioclavicularjoint/surgery Operativesurgicalprocedures

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Objective:Theposterosuperiorshoulderaccessusedinsurgicaltreatmentfor acromioclavic-ulardislocationwasconstructedthroughdissectionof20shouldersfrom10recentlychilled adultcadavers,andthedistancesfromthisroutetothenearbyneurovascularstructures wereanalyzed.

Methods:AKirschnerwirewasintroducedintothetopofthebaseofthecoracoidprocess throughtheposterosuperiorshoulderaccess,intheareaoftheoriginoftheconoidand trapezoidligaments,thusreproducingthepathforinsertingtwoanchorsforanatomical reconstructionofthecoracoclavicularligaments.Thesmallestdistancefromtheinsertion pointoftheKirschnerwiretothesuprascapularnerveandartery/veinwasmeasured. Results:Themeandistancefromthesuprascapularnervetotheoriginofthe coracoclavicu-larligamentsatthetopofthebaseofthecoracoidprocesswas18.10mm(range:13.77–22.80) intherightshoulderand18.19mm(range:12.59–23.75)intheleftshoulder.Themean dis-tancefromthesuprascapularartery/veintotheoriginofthecoracoclavicularligaments was13.10mm(range:9.28–15.44)intherightshoulderand14.11mm(range:8.83–18.89)in theleftshoulder.Comparisonbetweenthecontralateralsidesdidnotshowanystatistical difference.

Conclusion: Theposterosuperiorshoulderaccessrouteforanatomicalreconstructionofthe coracoclavicularligamentsintreatingacromioclaviculardislocationshouldbeperformed respectingtheminimumlimitof8.83mmmedially.

©2016SociedadeBrasileiradeOrtopediaeTraumatologia.PublishedbyElsevierEditora Ltda.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense(http:// creativecommons.org/licenses/by-nc-nd/4.0/).

夽

StudyconductedattheHospitaldoServidorPúblicoEstadualdeSãoPaulo,Servic¸odeOrtopediaeTraumatologia,GrupodeOmbroe Cotovelo,SãoPaulo,SP,Brazil.

∗ _{Correspondingauthor.}

E-mails:gustavocdrumond@gmail.com,marateko@hotmail.com(G.C.Drumond). http://dx.doi.org/10.1016/j.rboe.2016.06.001

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Zona

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seguranc¸a

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acesso

posterossuperior

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ombro:

estudo

em

cadáver

Palavras-chave:

Ombro/anatomiaehistologia Ombro/inervac¸ão

Articulac¸ão

acromioclavicular/cirurgia Procedimentoscirúrgicos operatórios

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Objetivo: Osautores fizeramoacessoposterossuperiordoombrousadonotratamento cirúrgicodaluxac¸ãoacromioclavicular,apartirdadissecc¸ãode20ombrosde10cadáveres adultosrecém-resfriados,eanalisaramasdistânciasdaviaàsestruturasneurovasculares próximas.

Métodos: Introduziu-seumfiodeKirschnernotopodabasedoprocessocoracoidepelo acessoposterossuperiordoombro,naáreadeorigemdosligamentosconoideetrapezoide, parareproduzirotrajetodainserc¸ãodeduasâncorasparareconstruc¸ãoanatômicados ligamentoscoracoclaviculares.Mediu-seamenordistânciadopontodeinserc¸ãodofiode Kirschneraonervoeàartéria/veiasupraescapular.

Resultados: Amédiadadistânciadonervosupraescapularatéaorigemdosligamentos coracoclavicularesnotopodabasedoprocessocoracoidefoide18,10mm(13,77a22,80) noombrodireitoe18,19mm(12,59a23,75)noombroesquerdo.Amédiadadistânciada artéria/veiasupraescapularatéaorigemdosligamentoscoracoclavicularesfoide13,10mm (09,28a15,44)noombrodireitoe14,11mm(08,83a18,89)noombroesquerdo.Nãohouve diferenc¸aestatísticacomparativaentreosladoscontralaterais.

Conclusão: Aviadeacessoposterossuperiordoombroparareconstruc¸ãoanatômicados ligamentoscoracoclavicularesnotratamentodasluxac¸õesacromioclavicularesdeveser feitacomrespeitoaolimitede08,83mmmedialmente.

©2016SociedadeBrasileiradeOrtopediaeTraumatologia.PublicadoporElsevier EditoraLtda.Este ´eumartigoOpenAccesssobumalicenc¸aCCBY-NC-ND(http:// creativecommons.org/licenses/by-nc-nd/4.0/).

Introduction

Acromioclaviculardislocationisacommoninjuryin ortho-pedicpractice.1 _{Themostcommon mechanismofinjury is} falling on the adductedshoulder, with force being applied directlytotheacromion.2_{Thisinjuryoccursmorefrequently} amongyoungindividualsandisassociatedwithimpactsports andhighspeedvehiclesaccidents.3,4_{Rockwood,apudLemos}2 andMouhsineetal.,5_{classifiedacromioclaviculardislocations} insix types: typesI _and II_{, considered as mild, with}

non-operativetreatment;typesIV_,V_,andVI_{,severe,withsurgical}

treatment6_;andtypeIII_{,moderate,whichhascontroversial}

treatment,dependentonfactorssuchasage,sportsactivity, anddeformity.

There are over 75 described techniques for the surgi-cal treatment of acromioclavicular dislocations, but none is considered to be the gold standard.7 _{The techniques} includethe following: acromioclavicularjoint fixation with wire or plate8,9_{; coracoacromial ligament transfer}10_; cora-coacromial interval fixation with screw; use of anchors at the topofthe baseofthe coracoidprocess or subcoracoid suture loop11,12_{; and tendon reconstruction with autograft} fromthecoracoclavicularandacromioclavicularligaments.13 The modifications of the techniques that secure the clav-icle to the coracoid process range from the use of screws (orsubcoracoid loops) tothe use ofanchorsand materials suchastheEndobuttonTM _(flip-buttonTM_{).Thesetechniques}

canbedone throughopen,minimallyinvasive,14 _or arthro-scopicsurgery.15,16 _{Theadvantageinthe use ofanchors is} itsplacement closertotheanatomical insertionsiteofthe coracoclavicularligaments.17

Theposterosuperiorshoulderapproachforthetreatment ofacromioclaviculardislocationswas presentedduringthe 34th Brazilian Congress of Orthopedics and Traumatology (2002) and received the Professor Orlando Pinto de Souza Award forCreativity.Developedbythe ShoulderandElbow Groupofourdepartment,thisapproachaimstofacilitatethe accesstothetopofthebaseofthecoracoidprocess;more anatomicallyreducetheacromioclavicularjoint;andpreserve theanteriorportionofthedeltoidmuscle,allowingforabetter functionalrecoveryoftheshoulder.

Thisstudyaimedtoreproducetheposterosuperior shoul-der access for the surgical treatment of acromioclavicular dislocationsincadaversandtoevaluatetheriskof neurovas-cularinjury.

Methods

Thestudydissected20shouldersin10recently-chilledadult cadavers(threewomenandsevenmen),meanageof61years (43–79),withnocongenitalabnormalities,signsoftrauma,or previoussurgeryontheshoulder.Dataonheight,gender,and agewerecollected.Thesamegroupofresearcherswas respon-sible foralldissections. Apilotstudy (usingtwoshoulders fromtwocadavers)wasmadeinadvancebeforethestartof datacollection,forbetterunderstandingandassessmentof thelocalanatomy.

Fig.1–Markingofboneprotusionsofthedistalclavicle,the coracoidprocess,theacromioclavicularjoint,theacromion, thescapularspine,andposterosuperiorshoulderapproach.

and for marking the posterosuperior shoulder approach (Fig.1).

Then,theskinincisionwasmadeandthesuperficialplane was dissected, exposing the deltotrapezial fascia. The fas-ciawasdetachedfromthedistalclavicleandscapularspine, makingitpossibletoexposethedeepplane,comprisingthe supraspinatusmusclebellyinferiorly,theacromioclavicular jointlaterally,andthetopofthebaseofthecoracoidprocess anteriorly.Followingtheexposureofthisareaandgood visi-bilityofthebaseofthecoracoidprocess,thecoracoclavicular andacromioclavicularligamentsaswellastheclaviclecould beidentifiedanddetached.Withtheclaviclestillreducedto theacromion,aKirschnerwirewasintroducedintothetopof thebaseofthecoracoidprocess,posteriorlytotheclavicle,to simulatetheintroductionofanchorsintheinsertionspotof thecoracoclavicularligaments(Fig.2).

After anterior dislocation of the distal clavicle, dissec-tioncontinuedfromthebaseofthecoracoidprocesstothe scapularnotch,identifyingthesuprascapularartery/vein,the suprascapularligamentandthesuprascapularnerve(Fig.3). Thestructuresweremarkedwithcoloredmarkersandthe dis-tancesfromthemtotheKirschnerwireweremeasured.The measurementsweremadewithaKingtools®150mmdigital caliper.

Foreachshoulder,twomeasuresweremadeandrecorded (Table1).Thefirstcorrespondedtothesmallestdistancefrom theKirschnerwiretothesuprascapularnerveandthesecond, tothedistancefromthewiretothesuprascapularartery/vein. StatisticalanalysiswasperformedusingthepairedWilcoxon test.Thesignificancelevelwassetat5%,andSASsoftware, version9.2,wasused.

Fig.2–Markingofthedistalthirdoftheclavicle.Pink marker:suprascapularnerve;bluemarker:trapezoid ligament;purplemarker:bordersoftheacromioclavicular joint.Thepincerindicatesthedirectionandtheinsertionof theKirschnerwireintothecoracoidprocess.

Results

ThemeandistancefromtheKirschnerwiretothe suprascapu-larnervewas18.10mmintherightshoulderand18.19mmin theleftshoulder.ThemeandistancefromtheKirschnerwire tothe suprascapularartery/veinwas13.10mminthe right shoulderand14.11mmintheleftshoulder(Table1).

In all dissected shoulders, no anatomic variationswere observedregardingthelocationandrouteofthe neurovascu-larstructuresrelativetothesuperiortransverseligamentof

Fig.3–Markingofshouldersuperolateralstructureswith theclavicleposteriorlydislocated.Pinkmarker:

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Table1–ShortestdistancefromtheKirschnerwireto thesuprascapularnerve(firstvalue)andthedistance fromtheKirschnerwiretothesuprascapularartery/vein (secondvalue).

Cadaver Rightshoulder Leftshoulder

1 20.20/15.44mm 23.75/18.89mm

2 16.30/13.08mm 12.59/8.83mm

3 22.80/13.60mm 18.90/14.62mm

4 13.77/12.03mm 15.45/12.36mm

5 17.60/11.79mm 19.96/13.97mm

6 16.44/14.54mm 17.82/15.65mm

7 15.43/13.65mm 16.65/15.54mm

8 15.08/9.28mm 18.22/12.52mm

9 15.55/10.87mm 16.65/14.77mm

10 18.78/12.65mm 17.46/14.98mm

MeasurestakenwithaKingtools®_{150mmdigitalcaliper.}

thescapula:thesuprascapularnervewasundertheligament andthesuprascapularartery/vein,aboveit.

Discussion

Theneurovascularstructuresclosesttotheshoulder postero-superiorapproachandtotheintroductionofanchorsatthe topofthebaseofthecoracoidprocesswerethesuprascapular nerveandthesuprascapularartery/vein.Thesuprascapular nerve arises from the upper trunk ofthe brachial plexus, passesunderneaththeomohyoidmuscletowardthesuperior notchofthescapula,andthenunderthesuperiortransverse scapular ligament, which connects its two bone edges. At thislevel,itsendsnervemotorbranchestothe supraspina-tusmuscleandfollowstowardthespinoglenoidnotch,where itinnervatestheinfraspinatusmuscle.18

Thesuprascapulararteryoriginatesfrom the thyrocervi-caltrunk,abranchofthesubclavianarteryintheneck,and passesbehindtheclavicletosupplythemusclesofthe pos-terioraspectofthescapula.Thesuprascapulararteryfollows thesuprascapularnerve,butseparatesfromitnearthe supe-riortransverseligamentofthescapulaandpassesabovethe ligament.Itanastomosestothedorsalscapularand circum-flexscapulararteries,formingacollateralcirculationaround thescapula.Therefore,thesuperiortransverseligamentofthe scapulaseparatesthearterysuprascapularfromthe supras-capularnerve.18

Thegoal ofthe surgical treatment of acromioclavicular dislocationis to obtain anatomical reductionto allowsoft tissuehealingandrecoveryofpriorjointfunction. Biomechan-icalstudieshavedemonstratedthattheconoidandtrapezoid ligamentsareimportantstaticstabilizersofthe acromioclav-icularjoint.Theyhavealsoindicatedthat,amongthedifferent reconstruction techniques of these ligaments, anatomical reconstructionhasbiomechanicalpropertiessuperiortothose ofnon-anatomictechniques.19–25_{Thefixationoftheclavicle} tothecoracoidprocesswithsutureanchorshasfacilitatedthe surgicaltechnique.However,theanteriorapproachrequires dissectionoftheanteriorportionofthedeltoidmuscleand maintainsresidualsubluxationoftheclavicle,asitdoesnot restoretheforcevectorofthecoracoclavicularligaments.The shoulderposterosuperiorapproachprovidesadirectaccessto

thetopofthebaseofthecoracoidprocessnotdamagingthe anteriordeltoidmuscle,andcanmaintainthejointreduction moreanatomically,restoringjointstabilitybypositioningthe anchorsintheanatomicallocationofthetorncoracoclavicular ligaments.

Molinetal.26_{presented84casesofpatientstreatedwith} the posterosuperior shoulder approach for placement of sutureanchorsatthebaseofthecoracoidprocess.The tech-niquewasshowntobeeasytolearnandreproduce,yielding resultssimilartothetechniquesdescribedintheliterature, withalowrateofpostoperativecomplications.

DieterKohnet al.14_{reproducedincadaversaminimally} invasiveendoscopictechniquefortheanatomical reconstruc-tionofcoracoclavicularligamentsandanalyzedthepotential riskofneurovascularinjury.Theanchorswerecorrectly pos-itionedatthecenterofthebaseofthecoracoidprocessand thesutureforcevectornearedtheanatomicalposition.The meandistancefromthecoracoidprocesstothe suprascapu-larnervewas1.8cm(1.5–2.2),andfromthecoracoidprocessto thesuprascapulararterywas1.5cm(1.3–1.9).However,those authorsdidnotcomparetothecontralateralside.

In the present study,the mean distancefrom the cora-coid process to the suprascapular nerve reached 1.81cm (1.37–2.28)intherightshoulderand1.81cm(1.25–2.37)inthe leftshoulder.Fromthecoracoidprocesstothesuprascapular artery/vein,themeandistancereached1.31cm(0.92–1.54)in therightshoulderand1.41cm(0.83–1.88)ontheleft shoul-der.Nosignificantdifferencesfromthelefttotherightsides wereobserved.Noneofthetwentyshouldersdissected pre-senteddamagetoneurovascularstructuresandsupraspinatus musclewiththeintroductionoftheKirschnerwire.

Conclusion

Itcanbeconcludedthattheinsertionofanchorsatthebase ofthecoracoidprocessthroughtheposterosuperiorshoulder approach foranatomical reconstruction ofcoracoclavicular ligamentsinthetreatmentofacromioclaviculardislocations shouldrespectthelimitof8.83mm,medially.

Conflicts

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interest

Theauthorsdeclarenoconflictsofinterest.

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