Rev. bras. ortop. vol.50 número3

rev bras ortop.2015;50(3):270–273

w w w . r b o . o r g . b r

Original

Article

Safety

zone

for

surgical

access

in

the

middle

third

of

the

clavicle:

study

on

cadavers

夽

Fabiano

Rebouc¸as

Ribeiro,

Fernanda

de

Marchi

Bosi

Porto

_,

_Marcio

_Vieira

_Sanches

_Silva,

Antonio

Carlos

Tenor

Junior,

Miguel

Pereira

da

Costa,

Cantidio

Filardi

HospitaldoServidorPúblicoEstadualdeSãoPaulo,SãoPaulo,SP,Brazil

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r

t

i

c

l

e

i

n

f

o

Articlehistory:

Received3February2014 Accepted26May2014 Availableonline17June2015

Keywords:

Clavicle/surgery Clavicle/anatomy Cadaver

a

b

s

t

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a

c

t

Objective:Theaimofthisstudywastoestablishaneurovascularsafetyzoneforsurgical accessinthemiddlethirdoftheclavicle,bymeansofdissectiononcadavers.

Methods:Twentyshouldersweredissectedin10cadavers,withdeepdissectionofthemiddle thirdoftheclavicle.Thefollowingstructureswereidentified:subclavianvein,uppertrunk ofthebrachialplexus(anteriorandposteriordivisions)andsuprascapularnerve.These structuresweremarkedoutinordertomeasuretheirdistancesfromthemostproximal pointofthemiddlethirdoftheclavicle.

Results:Themeandistancesfromthemiddlethirdoftheclavicletothesuprascapularnerve, subclavianvein,uppertrunk,anteriordivisionoftheuppertrunkandposteriordivisionof theuppertrunkwererespectively,fortherightside:15.92cm,10.77cm,23.68cm,14.60cm and15.42cm;andfortheleftside:12.69cm;9.82cm;22.19cm;12.16cmand13.46cm.

Conclusion:Therewasastatisticaldifferenceinthedistancestothesuprascapularnerve andanteriordivisionoftheuppertrunk,incomparingbetweentherightandleftsides.The closestneurovascularstructurestothemiddlethirdoftheclaviclewerethesuprascapular nerveandsubclavianvein.

©2014SociedadeBrasileiradeOrtopediaeTraumatologia.PublishedbyElsevierEditora Ltda.Allrightsreserved.

Zona

de

seguranc¸a

no

acesso

cirúrgico

do

terc¸o

médio

da

clavícula:

estudo

em

cadáveres

Palavras-chave:

Clavícula/cirurgia Clavícula/anatomia Cadáver

r

e

s

u

m

o

Objetivo:Estabelecerumazonadeseguranc¸aneurovascularnoacessocirúrgicodoterc¸o médiodaclavículapordissecc¸ãoemcadáveres.

Métodos:Foramdissecados20ombrosde10cadáveres,foifeitaadissecc¸ãoprofundadoterc¸o médiodaclavículaeidentificaram-seasseguintesestruturas:veiasubclávia,troncosuperior doplexobraquial(divisãoanterioreposterior)enervosupraescapular.Essasestruturas foramdemarcadasparamensurac¸ãodesuasdistânciasatéospontosmaispróximosdo terc¸omédiodaclavícula.

夽

WorkdevelopedintheHospitaldoServidorPúblicoEstadualdeSãoPaulo,SãoPaulo,SP,Brazil.

∗ _{Correspondingauthor.}

E-mails:ferbosi@hotmail.com,ricapb@gmail.com(F.deMarchiBosiPorto).

http://dx.doi.org/10.1016/j.rboe.2015.06.005

rev bras ortop.2 0 1 5;50(3):270–273

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Resultados: Adistânciamédiadoterc¸omédiodaclavículaaonervosupraescapular,àveia subclávia,aotroncosuperior,àdivisãoanteriordotroncosuperioreàdivisãoposteriordo troncosuperiorfoi,respectivamente,doladodireito:15,92cm;10,77cm;23,68cm;14,60cm e15,42cm;doladoesquerdo:12,69cm;9,82cm;22,19cm;12,16cme13,46cm.

Conclusão: Houve diferenc¸aestatística entreasdistânciasdonervo supraescapularea divisão anterior do troncosuperior comparativaentre os lados direito e esquerdo. As estruturas neurovasculares maispróximas ao terc¸o médioda clavícula foram onervo supraescapulareaveiasubclávia.

©2014SociedadeBrasileiradeOrtopediaeTraumatologia.PublicadoporElsevier EditoraLtda.Todososdireitosreservados.

Introduction

Theclaviclehasimportantanatomicalrelationshipswiththe subclavianartery,subclavianveinandbrachialplexus, espe-ciallyinitsmiddlethird,wherethecurvatureisthereference pointusedforaccessingthesestructures.Incasesoftrauma and/orsurgeryinthemiddlethirdoftheclavicle,and espe-ciallyissituationsoffractures thatneedtobereducedand fixed bymeans ofopen surgery, Using synthesismaterial, thesestructuresmaybecomeinjuredbecauseoftheir anatom-icalproximity.1,2

ThebrachialplexusisformedbytherootsofC5,C6,C7, C8andT1.Itoriginatesfromthecervicalspine,headstoward theupperlimbsandpasses betweenthemiddle and ante-riorscalenemuscles.TherootsofC5andC6formtheupper trunk, from which the suprascapular nerve emerges. Each trunkdivides into anterior and posterior portions when it passesbelowtheclavicle.3

Theright subclavian artery is a branch ofthe brachio-cephalictrunkandthe leftsubclavianarteryisabranchof theaortic arch.Thereference anatomicalstructureforthe subclavianarteryistheanteriorscalenemuscle,andthiscan befoundattheposteromedialborderofthismuscleoratits lateralborder.Thesubclavianvein isa continuationofthe axillaryveinandextendsfromtheborderofthefirstribtothe medialborderoftheanteriorscalenemuscle,whereitjoins theinternaljugularveintoformthebrachiocephalicvein.The clavicleandthesubclavianmusclearelocatedanteriorlytothe subclavianvein.1

Theaimof this study was toestablish a neurovascular safetyzoneatthesurgicalaccesstothemiddlethirdofthe clavicle,bymeansofdissectionincadavers.

Methods

Ten recently chilled cadavers were selected. Three were femaleandsevenweremale.Theirmeanagewas63.6years (range:55–73),mean height1.67m(1.58–1.73),mean weight 62kg(40.4–77)andmeanBMI22.1kg/m2_{(16.1–25.65).Theydid}

notpresentanycongenitalabnormalities,signsoftraumaor previoussurgeryintheshouldersstudied.Allthedissections were performed bythe same group ofresearchers. A pilot studywas initiallyconductedonthefour shouldersoftwo

cadavers,beforedata-gatheringwasstarted,inordertostudy andgainbetterknowledgeofthelocalanatomy(Table1).

The procedures were performed with the cadaver in a standardizedhorizontaldorsaldecubitusposition,withapad undertheipsilateral scapulaand theupperlimbinneutral position.Usingasurgicalpen,thesuperficialanatomyofthe clavicleandtheacromioclavicularandsternoclavicularjoints wasmarkedoutontheskin.Atransverseincisionwasmadein theskinalongtheentirelengthoftheclavicleandthemuscle layersweredissected,withexposureofthesubclavianmuscle (originandinsertion).Itsrelationshipwiththemiddlethirdof theclaviclewasdemonstratedusingmarkersanteroinferiorly (Fig.1).

Afterexposureofthemuscle,theclaviclewasdividedinto threethirdsand deeperdissectionofthemiddle thirdwas performed. In this, the following neurovascular structures wereidentified:subclavianvein,uppertrunkofthebrachial plexus(anterior andposterior divisions)and suprascapular nerve.Thesestructuresweredemarcatedusingcolored mark-ersandthedistancestotheclosestpointofthemiddlethird oftheclaviclewasrecordedusingaKingtools®_150mmdigital

pachymeter(Fig.2).

Forthestatisticalanalysis,thepairedWilcoxontestwas used.Thesignificanceleveladoptedwas5%andthesoftware usedfortheanalysiswasSASversion9.2.

Results

Themeandistancesfromthemiddlethirdoftheclavicletothe suprascapularnerve, subclavianvein,uppertrunk,anterior

272

Table1–Descriptionofthesamples,ages,heights,weightsandBMI.

Sample Mean Standarddeviation Median

Age(years) 10 63.6 5.5 62.5

Height(m) 10 1.67 0.06 1.68

Weight(kg) 10 62.0 11.7 66.0

BMI(kg/m2_{) 10 22.1 3.5 22.9}

Fig.2–Pinkmarker:suprascapularnerve;greenmarker: uppertrunk;whitemarker:posteriordivisionoftheupper trunk;yellowmarker:anteriordivisionoftheuppertrunk; whitearrow:subclavianvein.

divisionoftheuppertrunkandposteriordivisionoftheupper trunkontherightsidewere,respectively:15.92cm;10.77cm; 23.68cm;14.60cm;and15.42cm;andontheleftside:12.69cm; 9.82cm;22.19cm;12.16cm;and13.46cm.

Table2presentstheresultsfromthemeasurementsmade

betweenthemiddlethirdoftheclavicleandtheneurovascular structuresstudied.

Discussion

Thenumberofindicationsforsurgicaltreatmentoffractures of the middle third ofthe clavicle has increasedover the years becauseofbetterunderstanding ofthe biomechanics andfunctionoftheclavicle,thegreaternumberofprospective studiesdemonstratingcomparativeresultsandthe modern-izationofsynthesismaterialsforfixationofthesefractures. Today,sometypesofshorteninganddeformitiesarenolonger acceptable.4–9

AccordingtoIannottietal.6_{treatmentoffracturesofthe}

middlethirdoftheclaviclethroughplacementofaplateon its uppersurface presentedbiomechanical advantagesand facilitated surgical access. However, Kloen et al.7

demon-stratedthatiatrogeniclesionsoftheneurovascularstructures belowtheclavicleoccurredmorefrequentlyinthesetypesof osteosynthesisandthattheriskdiminishedwhentheplate waspositionedanteroinferiorly.6,7

Labrocini etal.10 _{demonstratedthatthe branchesofthe}

suprascapular nerve, which are responsible for the sensi-tivity on the clavicle, and the anteromedial region of the shoulderandproximalregionofthechestarevulnerablein casesoffracturesoftheclavicleandtheirsurgicaltreatment. According toSinhaetal.4 _{thestructuresatgreatestriskof}

injuryduringosteosynthesisofthemiddlethirdofthe clav-icle are the subclavianvein,subclavian artery,the brachial plexusandthepulmonarypleura.Accordingtotheirstudy, thesubclavianveinwasclosertothemiddlethirdofthe clav-icle thanwas thebrachialplexus,withamean distanceof 12.45mm. In ourstudy, theright subclavian veinwas ata meandistanceof10.77mmandtheleftat9.82mmfromthe

Table2–Means,standarddeviations,mediansandpvaluesofthedistancesbetweentheanatomicalstructuresandthe

middlethirdoftheclavicle.

Sample Mean Standarddeviation Median pvalue

Rightsuprascapularnerve 10 15.92 5.32 15.53

Leftsuprascapularnerve 10 12.69 13.02

Difference 10 3.23 3.75 2.91 0.0273a

Rightsubclavianvein 10 10.77 3.23 10.49

Leftsubclavianvein 10 9.82 4.04 8.75

Difference 10 0.95 2.27 1.39 0.2754

Rightuppertrunk 10 23.68 6.04 22.38

Leftuppertrunk 10 22.19 6.41 20.10

Difference 10 1.50 2.61 1.74 0.1309

Rightanteriordivision 10 14.60 5.76 13.64

Leftanteriordivision 10 12.16 4.00 12.67

Difference 10 2.44 2.96 2.18 0.0371a

Rightposteriordivision 10 15.42 5.16 15.39

Leftposteriordivision 10 13.46 3.82 13.17

Difference 10 1.96 3.30 2.65 0.1055

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middlethirdoftheclavicleandwasalsotheclosestvascular structure.4,10

AccordingtoMouzopoulosetal.8_{theassociationbetween}

fracturesoftheclavicleandinjuriestothebrachialplexusis wellknownandusuallyoccursduetohigh-energy supraclav-iculartraction. Fracturesoftheclavicleareassociatedwith theseeventsbutarenotthecausalfactor.Inanotherstudy, byDellaSantaetal.9_{itwasdemonstratedthatdirecttrauma}

ofthe brachial plexus caused byfragments of the clavicle occurredatlowfrequency(1%).8,9

Jeyaseelanetal.11_{reportedthatinvolvementofthe}

supras-capularnerveisacommonfindinginfracturesoftheclavicle, becausethis is the structureofthe brachial plexusthat is closesttothemiddlethirdoftheclavicle.Shorteningofthe clavicleandmobilizationofthefragmentsofthefracture dur-ingfixationmaycausecompressionofthebrachialplexus,due tothedecreasedinfraclavicularspace.Inconservative treat-ment,thepresenceofthebonecallusmayalsobethecause oflesionsofthesuprascapularnerve,duetocompression.In ourstudy,thebrachialplexusstructurethatwasclosesttothe middlethirdoftheclaviclewasthesuprascapularnerve.11

Therefore,accordingtotheliteratureconsulted, periclavic-ularneurovascularlesionsaremoreassociatedwithsurgical iatrogeniclesionsthanwiththetraumaitself.Inourstudy, theneurovascular structuresclosest tothe middle thirdof theclavicularandthereforemostsusceptibletoinjuryinthis region were the suprascapular nerve and subclavian vein, respectively.Duringourdissections,itwasalsoobservedthat thesubclavianmuscleprovidedanterosuperiorprotectionfor the adjacent neurovascular structuresand that it could be usedasananatomicalreferencepointfordelimitinga“safety zone”.

Conclusion

Therewasastatisticaldifference inthedistancesfromthe suprascapularnerveand theanterior divisionofthe upper trunk,comparatively between the right and left. The neu-rovascularstructuresclosesttothemiddlethirdoftheclavicle werethesuprascapularnerveandsubclavianvein.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

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