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Original

article

The

pectoralis

major

footprint:

An

anatomical

study

夽

,

夽夽

Eduardo

Antônio

de

Figueiredo

∗

_,

_Bernardo

_Barcellos

_Terra,

_Carina

_Cohen,

Gustavo

Cará

Monteiro,

Alberto

de

Castro

Pochini,

Carlos

Vicente

Andreoli,

Moises

Cohen,

Benno

Ejnisman

SportsTraumatologyCenter,DepartmentofOrthopedicsandTraumatology,EscolaPaulistadeMedicina,UniversidadeFederaldeSão Paulo,SãoPaulo,SP,Brazil

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f

o

Articlehistory:

Received27June2012 Accepted8February2013

Keywords:

Pectoralismuscles/surgery Pectoralis/anatomy&histology Cadaver

a

b

s

t

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c

t

Objective:Tostudytheinsertionofthepectoralismajortendontothehumerus,through knowledgeofitsdimensionsinthecoronalandsagittalplanes.

Methods:Twentyshouldersfrom10cadaversweredissectedandthepectoralismajortendon insertiononthehumeruswasidentifiedandisolated.Thedimensionsofits“footprint” (proximaltodistalandmedialtolateralborders)andthedistancefromthetopedgeofthe pectoralismajortendontoapexofthehumeralheadstructuresweremeasured.

Results:Theaverageproximaltodistalborderlengthwas80.8mm(range:70–90)andthe medial-to-lateralborderlengthwas6.1mm(5–7).Theaveragedistance(andrange)from theapexofthepectoralismajortendontothehumeralheadwas59.3mm.

Conclusions: Wedemonstratethattheinsertionofthepectoralismajortendonislaminar, andthepectoralismajortendonhasanaveragefootprintheightandwidthof80.8mmand 6.1mm,respectively.

Footprint

do

tendão

do

peitoral

maior:

Estudo

anatômico

Palavras-chave:

Músculospeitorais/cirurgia Músculospeitorais/anatomiae histologia

Cadáver

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e

s

u

m

o

Objetivo:Estudarainserc¸ãodotendãodopeitoralmaiornoúmero,pormeiodo conheci-mentodesuasdimensõesnosplanoscoronalesagital.

Métodos:Foramdissecados20ombrosdedezcadáveresfrescos(cincohomensecinco mul-heres).Todososcadáveresencontravam-seembomestado,semcicatrizesousinaisde traumaprévios.Fez-seoestudopormeiodaviadeltopeitoralestendidaefoiidentificadae isoladaainserc¸ãodotendãodopeitoralmaiornoúmero.Mensuraram-seasdimensõesdo

footprintpormeiodasaferic¸õescomumpaquímetromilimetrado,deseuslimitesde proxi-malparadistalemedialparalateral.Foiaferidaadistânciadabordasuperiordotendãodo peitoralmaioraoápicedacabec¸aumeral.

夽_Work_performed_at_the_Sports_Traumatology_Center,_Department_of_Orthopedics_and_{Traumatology,}_Escola_Paulista_de_Medicina,

UniversidadeFederaldeSãoPaulo,SãoPaulo,SP,Brazil.

夽夽

Pleasecitethisarticleas:deFigueiredoEA,TerraBB,CohenC,MonteiroGC,deCastroPochiniA,AndreoliCV,etal.Footprintdotendão dopeitoralmaior:estudoanatômico.RevBrasOrtop.2013;48:519–523.

∗ _{Corresponding}_author_.

E-mail:eduardoafigueiredo@terra.com.br(E.A.deFigueiredo).

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Resultados: Emtodososcadáveresopeitoralmaiorapresentouumainserc¸ãoúnica.O com-primentomédiodeproximalparadistalfoide80,8mm(70-90)edelateralparamedialde 6,1mm(5-7).Jáadistânciamédiadoápicedotendãodopeitoralmaioraoápicedacabec¸a umeralfoide59,3mm(55-64).

Conclusões: Otendãodomúsculopeitoralmaiorapresentainserc¸ãolaminar.Ofootprinttem aalturaealarguramédiade80,8mme6,1mm,respectivamente.

Introduction

Injuriestothepectoralismajormuscleareinfrequent,1_with

approximately200casesreportedintheliteraturesincethe firstdescriptionbyPatissierin1822.2

They most frequently affect young and active patients, especiallyweightlifterswhilepracticingsupinemovements.3,4

Tearingofthetendonofthepectoralismajormuscleisa sit-uation forwhich surgeryis indicated amongathletes, and primaryrepairoftheseinjurieshastypicallybeendone by meansofanchorsorbonetunnels.5_However,_placement_of

a torn tendon in its anatomical position may be difficult, because this requires accurate identification of its inser-tion in the humerus. If there are no residual fibers in its insertion,knowledgeoftheanatomicalrelationshipsatthe proximalextremityofthehumerusisrequiredforthesurgical treatment.6

The present study had the objectives ofdescribing the insertionofthetendonofthepectoralismuscleand measur-ingits limits,inordertoobtain acorrectparameterforits treatment.

Methodology

This anatomicalstudy was conducted atthe Death Inves-tigation ServiceofHospital dasClínicas de SãoPaulo after obtainingapprovalfromits reviewboard.Twentyshoulders from10freshcadavers(fivemenandfivewomen)ofmean age65.4years(range:51–75years)weredissected.Allofthe cadaverswereingoodcondition,withoutscarringorsignsof previoustrauma.

The study was conducted by means of the extended deltopectoral route, and the tendon insertion of the pec-toralis major in the humerus was identified and isolated. Afterhighlightingtheinsertion,thefootprintofthetendon ofthe pectoralis majoron the humerus was identified. Its dimensionsweremeasuredusingapachymetercalibratedin millimeters(proximaltodistalandmedialtolateral limits)

(Figs.1–6).

Following this, with the arm in neutral rotation and extendedat45◦_,_the_distance_from_the_top_edge_of_the

pec-toralis major tendon on the humerus to the apex of the humeralheadabovethetendonofthesupraspinatusmuscle wasidentifiedandmeasured(Fig.7).

Statistical analysis was performed using Pearson correlation tests, and the significance level was set at p<0.01. The SPSS 17.0 software was used for the analysis.

Fig.1–Instrumentusedtopositionthecadaver.

Results

The mean proximal to distal border length was 80.8mm (range: 70–90) and the medial-to-lateral border length was 6.1mm(5–7).Themeandistancefromtheupperborderofthe pectoralismajortendontotheapexofthehumeralheadwas 59.3mm(range:55–64)(Table1).

Inallthecadaversdissected,thefootprintofthetendonof thepectoralismajormuscleoccurredjustlaterallytothelong headofthebiceps,anditslaminarinsertionwascomposedof asinglelayer.Asananatomicalrelationshipofimportanceas aparameterinsurgicalprocedures,itcouldbeseenthatthe heightofthefootprintofthetendonofthepectoralismajor musclewasaround1.36timesgreaterthanthedistancefrom

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Table1–Summarymeasurements(mean,standarddeviation,median,minimumandmaximum).

Variable Mean SD Median Minimum Maximum N

Heightoffootprint 80.80 7.14 83.5 70 90 20

Widthoffootprint 6.10 0.72 6 5 7 20

Humeralhead 59.30 2.70 59 55 64 20

Table2–Simplelinearregressionforestimatingtherelationshipbetweentheheightofthefootprintandthedistance fromtheupperedgeoftheinsertionofthepectoralismajortotheapexofthehumeralhead.

Factor Coefficient Standarderror tvalue p R2

Humeralhead 1.363 0.02 66.648 <0.001 0.996

Fig.3–Deltopectoralrouteinprogress,withinsertionof thetendonofthepectoralismajoridentifiedandisolated.

Fig.6–Footprintofthetendonofthepectoralisbeing

measuredbymeansofapachymetercalibratedin

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Apex of humeral head

Apex of tendon of pectoralis major

Fig.7–Drawingillustratinghowthedataweremeasured.

theupperedgeofthefootprinttotheapexofthe humeral

head(Table2andFig.8).

Discussion

Thepectoralismajormuscleoccupiesalargeareaonthe ante-riorchestwallanditsfunctionconsistsbasicallyofproviding adductionandmedialrotationoftheshoulder.4,6,7

Footprint “width”

Footprint “height”

Fig.9–Drawingdemonstratingtherestorationofthefootprint,whichwaspossiblebymeansofasinglerowofanchors.

60 65 70 75 80 85 90 95

64 63 62 61 60 59 58 57 56 55 54

Upper edge of the footprint

height

Fig.8–Linearregressionontheheightofthefootprintof thepectoralismajoranditsdistancefromtheapexofthe humeralhead.

Itistraditionallydividedintotwoportions:clavicularand sternal.However,therearefewdescriptionsintheliterature regardingitssurgicalanatomy.6

Lately,injurytothismuscleanditssurgicaltreatmenthave becomemorefrequent.Inaprospectivestudypublishedin 2009,suchinjuriesweredescribedin20patients.8_However,_a

subsequentstudyreportedthattherewasnosignificant differ-enceinstrength,assessedthroughisokinetictests,between surgicalandnonsurgicaltreatments.9

Thedifficultiesencounteredinsurgicaltreatmentforthese patients, especiallyinsituationsofretractionofthe medial stumpandabsenceoffibersattheinsertion,provided moti-vationforconductingthisanatomicalstudy.

Fungetal.7_,_in_2009,_described_two_separate_layers

(ante-riorandposterior),whichwereinsertedinthehumerus,with proximal-to-distallengthsof66mmand77mm.However,we agreewithCarey andOwens6 _who _in₂₀₁₀_reported_that _it

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regionoftheinsertioninthehumerus.Theseauthorsfound, indissecting12shouldersoffreshcadavers,thatthemean proximal-to-distallengthwas72mm.Inadditiontothis mea-surement,theyfoundthatthemeandistancefromtheapex oftheupperedgeto thesuperomedial edgeofthe greater tuberclewas42mm.

Fromtheresultsdescribedabove,wecanconcludethatthe insertionofthetendonofthepectoralismajorinthehumerus isdonebymeansofanarrowlayer(approximately6mmon average)thatcannotbedistinguishedintoanteriorand pos-teriorportions,whichislocatedjustlateraltothelonghead ofthebiceps.Thus,wedisagreewithFungetal.7_and_Wolfe

etal.10_who_described_two_and_three_layers,_{respectively.}

Basedonthewidthoftheinsertionfootprintofthe pec-toralismajor,themeanmeasurementof6mmmaysuggest thatitsanatomicalrepaircanbedonebyusingasinglerow ofanchorsof5–5.5mm(Fig.9).Theschematicdrawingofthe insertionofthepectoralismajorshowsthereestablishment ofitsinsertionbyusingarowofanchors.

Oneweakpointofthisstudyisthatwebelievethatitwas conductedonapopulationofhigheragegroupthanthosewho generallyhavesuchinjuries.

Onthecontrary,thestrongpointthatwecanhighlightis theparametersforsurgicaltreatmentandtheanatomical cor-relationwithahighsignificancelevel(p<0.01)betweenthe heightofthefootprintandthedistancefromtheupperedgeof thetendoninsertionofthepectoralismajortotheapexofthe humeralhead.Therelationshipdescribedaboveisan impor-tantparametertobefollowedwhilerepairingsuchinjuries, particularlyinchroniccasesinwhichnofibersarepresentat theinsertion.Wealsobelievethatthisstudyprovides impor-tantdatanotonlyforrepairinginjuriestothepectoralismajor butalsoforcarryingoutseveralothersurgicalprocedureson theshoulder,suchasarthroplasty,fracturefixationand mus-cletransfer.

Conclusions

Thetendonofthepectoralismajormusclepresentedasingle laminarinsertioninthehumerus,inthecranial–caudal direc-tion,withameanof80.8mm(range:70–90mm)andnarrow widthwithameanof6.1mm(range:5–7mm).

Thereferencethattheheightofthefootprintofthe pec-toralismajoris1.36times(36%)greaterthanthedistancefrom theupperedgetotheapexofthehumeralheadcanbeused duringsurgicaltreatment.

Conflict

of

interest

Theauthorsdeclarenoconflictsofinterest.

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