Rev. bras. ortop. vol.51 número2

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

Original

Article

Evaluation

of

the

acromiohumeral

distance

by

means

of

magnetic

resonance

imaging

umerus

夽

Flávio

de

Oliveira

Franc¸a

_,

_André

_Couto

_Godinho,

_Elísio

_José

_Salgado

_Ribeiro,

Lorenzo

Falster,

Lucas

Emanuel

Gava

Búrigo,

Rafael

Berenstein

Nunes

HospitalOrtopédicoBH,BeloHorizonte,MG,Brazil

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Articlehistory:

Received6May2015 Accepted11June2015

Availableonline4February2016

Keywords:

Rotatorcuff

Magneticresonanceimaging Acromion

Humerus

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s

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t

Objective:Todemonstratetherelationshipbetweenthesize,degreeofretractionand

topog-raphyofrotatorcuffinjuriesandthedegreeofriseofthehumeralhead,andtoevaluatethe influenceofgravity,usingmagneticresonanceimaging(MRI).

Methods:Weevaluated181shoulderMRIsfrom160patientsagedover45years,between

November2013andJuly2014.Thepatientsweredividedintotwogroups:onecontrol(no lesionorpartialdamagetotherotatorcuff);andtheotherwithcompletetearsoftherotator cuff.Wemeasuredtheacromiohumeraldistanceinthesagittalplane,andestablishedthe shortestdistancebetweentheapexoftheheadandtheacromion.

Results:Inthisstudy,96examinationsonfemalepatients(53.04%)and58onmalepatients

(46.96%)wereevaluated.Themeanagewas63.27years:inthecontrolgroup,61.46;and inthegroupwithinjuries,65.19.Fromanalysisonthemeasurementsofthesubacromial space,weobservedsignificantlyhighervaluesinthecontrolgroup(7.71mm)thaninthe groupwithinjuries(6.99).Incomparingthecontrolgroupwithsomespecificsubgroup, i.e.posterosuperior(6.77),anteroposterior-superior(4.16)andretractionPatteIII(5.01),we confirmedtheimportanceoftopographyanddegreeofretractioninrelationtotheriseof thehumeralhead.

Conclusion: Theriseofthehumeralheadwasdirectlyrelatedtothesize,degreeofretraction

andtopographyoftherotatorcuffinjuries,withgreaterdegreesofriseincasesofsuperior andposteriorlesionsandanteroposterior-superior(massive)lesions.Theassessmentusing MRIwasnotinfluencedbytheforceofgravity.

©2016SociedadeBrasileiradeOrtopediaeTraumatologia.PublishedbyElsevierEditora Ltda.Allrightsreserved.

夽

WorkperformedintheShoulderGroup,HospitalOrtopédicoBH,BeloHorizonte,MG,Brazil.

∗ _{Correspondingauthor.}

E-mails:[email protected],[email protected](F.deOliveiraFranc¸a). http://dx.doi.org/10.1016/j.rboe.2016.01.008

Palavras-chave:

Bainharotadora Imagemderessonância magnética

Acrômio Úmero

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e

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Objetivo:Demonstrararelac¸ãoentreotamanho,grauderetrac¸ãoetopografiadaslesõesdo

manguitorotadorcomograudeascensãodacabec¸aumeraleavaliarainfluênciadaforc¸a dagravidadenaressonânciamagnética.

Métodos:Avaliamos181ressonânciasmagnéticasdeombrode160pacientescommaisde45

anos,entrenovembrode2013ejulhode2014.Ospacienteseramdivididosemdoisgrupos, umdecontrole(semlesãooucomlesãoparcialdoMR)eoutrocomlesãocompletadoMR. Fizemosamensurac¸ãodadistânciaacrômio-umeralnoscortessagitaisefoiestabelecidaa menordistânciaentreoápicedacabec¸aeoacrômio.

Resultados: Foramavaliadosnesteestudo96(53,04%)examesdepacientesdosexo

fem-ininoe58 depacientesdosexomasculino(46,96%).Aidademédia foi63,27anos,ado grupocontrole61,46eadogrupocomlesão65,19.Aoanalisarasmedidasdoespac¸o sub-acromial,observamosvaloressignificativamentemaioresnogrupocontrole(7,71mm)do quenogrupocomlesão(6,99).Quandocomparamosogrupocontrolecomalguns subgru-posespecíficos,posterossuperior(6,77),anteroposterossuperior(4,16)eretrac¸ãoPatteIII (5,01),confirmamosaimportânciadatopografiaegrauderetrac¸ãoparaascensãodacabec¸a umeral.

Conclusão:Aascensãodacabec¸aumeraltemrelac¸ãodiretacomotamanho,grauderetrac¸ão

eatopografiadaslesõesdomanguitorotador,comgrausmaioresdeascensãonaslesões posterossuperioreseanteroposterossuperiores(extensas).Aavaliac¸ãofeitapela ressonân-ciamagnéticanãosofreinfluênciadaforc¸adagravidade.

©2016SociedadeBrasileiradeOrtopediaeTraumatologia.PublicadoporElsevier EditoraLtda.Todososdireitosreservados.

Introduction

The rotator cuff acts as a compressor of the head of the humerusagainsttheglenoid,thusenablingshoulder move-mentsindifferentspatialplanes.Diseaseoftherotatorcuff maycausethisequilibriumtobebrokenandmayculminatein moreadvancedstagesofinjurywithconsequentascensionof thehumeralhead.1–4_{Thisphenomenoncanbequantifiedby}

measuringthedistancefromthehumerustotheacromion.5

Themechanismforascensionofthehumeralheadisstill notcompletelyclear.Itisbelievedthatthetractionexertedby thedeltoidmusclewithoutthestabilizingactionoftherotator cuffmightexplainthesefindings.5_{Inthisregard,failureofthe}

infraspinatusandthedepressorfunctionofthehumeralhead wouldallowascensionbymeansofaninjuredsupraspinatus thatwouldnotoccupythesubacromialspace.6–9

Clinically,thismeasurementcanbeusedtoevaluatethe functionoftherotatorcuffandaidinchoosingthetypeof therapytobeused.10,11_{Adistancefromthehumerustothe}

acromionoflessthanorequalto7mmmeasuredon radio-graphsinanteroposteriorviewsuggeststhattherotatorcuff injuryislarge,whichdiminishesthelikelihoodofsuccessful surgicaltreatment.10,12_{Ithasalsobeenshownthatthe}

ascen-sionofthehumeralheadisrelatedtofattydegenerationof therotatorcuff.11–13

Useofmagneticresonanceimaging(MRI)forestimating theascensionofthehumeralheadiscurrentlyundergreat discussion.Oneofthemainissuesinvolvedisthefactthat MRI is performed in dorsal decubitus. It is believed that

thereductionoftheforceofgravityonthelimbduringthe examinationmightoverestimatethisradiologicalfinding.

Theobjectivesofthisstudywere:(1)todemonstratethat thedegreeofascensionofthehumeralheadisrelatedtothe sizeoftherotatorcuffinjuryanditsdegreeofretraction;(2) toevaluatewhetherthe ascensionofthehumeralheadon MRI hasany relationship withgravity; and (3) toascertain whetherthelocationoftheinjuryinfluencesthisascension ofthehumeralhead.

Materials

and

methods

ThisstudywasapprovedbytheResearchEthicsCommittee of our institution. Prospective evaluations were conducted on181MRIsoftheshoulder, from160patientswho under-wentthisexaminationbetweenNovember2013andJuly2014. Theseevaluationswereperformedinaradiologyclinic.

Forinclusioninthisstudy,thepatientsneededtobemore than45yearsofageandtohaveundergoneMRIfor investiga-tionofnon-traumaticpathologicalconditionsoftheshoulder. Patients withhistories of fractures or previous surgery on the shoulder thatwas now undergoingexamination,cases involvingmagneticresonancearthrographyandpatientswith glenohumeralarthrosisthathadalreadybecomeestablished wereexcluded.

Fig.1–Apexofthehumeralhead,seenonacoronalslice(imageonleft).Measurementoftheshortestdistancebetween theapexofthehumeralheadandtheacromion,seenonasagittalslice(imageonright).

subdividedaccordingtothelocationoftheinjury (anterosupe-rior,superior,posterosuperiororanteroposterosuperior)and thedegreeoftendonretractionaccordingtotheclassification ofPatte.14

All the examinations were performed inMRI machines of1.5T.Theexaminationswereevaluatedandthe measure-ments were made bytwophysicians undergoingspecialist trainingintheshouldersurgeryservice,withassistancefrom a radiologist who was a specialist in osteomuscular MRI. Themeasurementsonthedistancefromthehumerustothe acromionweremadeonsagittalslicesandtheshortest dis-tancebetweentheapexoftheheadandthe acromionwas established(Fig.1:howthemeasurementwasmade).Through thismeasurement,theaimwastomaketheexaminationas reproducibleaspossibleinconsultationoffices.

Thestatisticalanalysisrelatingtothesizeofthelesionwas doneusingtheANOVAparametrictest.

Toevaluatethedifferencesbetweenthegroupsoflesion sizeandthevariableofsubacromialspace,whichcomprised morethanthreegroups,eithertheANOVAparametrictestor Student’st testforindependentsampleswasusedto com-parethemeansbetweenthegroups.Thisanalysiswasalso performedforthesubacromialspaceinrelationtothedegree oftendonretractionaccordingtotheclassificationofPatte(I_, II_orIII_).

ThedataofthisstudywereprocessedusingthePredictive AnalyticsSoftware(PASW18).Inallthestatisticaltests,the significancelevelwastakentobe5%.

Results

Amongthe181shouldersevaluated(160patients),88(48.6%) presentedcompleterotatorcufftearsandformedtheinjury group,while93(51.3%)formedthecontrolgroup.

Injurygroup

Thepatients’meanagewas65years,andtheagerangewas from 45 to 89 years. There were 43 males (48.8%) and 45 females(51.1%);55rightshoulderswereaffected(62.5%)and sevenpatientswereaffectedbilaterally(7.95%).

Regarding the locations of the injuries, 40 shoulders (45.45%) were injured in a superior location, eight (9.09%) anterosuperior,27 (30.68%) posterosuperiorand 13 (14.77%) anteroposterosuperior. The mean ages in these subgroups were63,66,65and70years,respectively(Table1).

Inanalyzingtheinjuriesregardingtheirdegreeof retrac-tion, based on the classification of Patte,14 _{there were 29}

shoulders(32.95%)withgradeI_{,32(36.36%)withgrade}II_and 27 (30.68%)withgradeIII_{.Themeanagesinthesubgroups} were,respectively,62,64and69years(Table2).

Controlgroup

Thepatients’meanagewas61yearsandtheagerangewas from 45to79.Therewere 42males(45.1%)and51 females

Table1–Demographicsoftheinjurygroup.

n(%) Meanage(range) Meansubacromialspace(range)

Injurygroup 88(100) 65.19(36–89) 6.97(1.81–13.5)

Superior 40(45.45) 63.47(36–89) 7.78(4.15–11.58)

Anterosuperior 8(9.09) 66.25(51–85) 8.28(5.73–13.5)

Posterosuperior 27(30.68) 65.03(51–88) 6.77(5.04–9.91)

n(%) Meanage(range) Meansubacromialspace(range)

Injurygroup 88(100) 65.19(36–89) 6.97(1.81–13.5)

PatteI _{29(32.95) 62.31(36–78) 8.56(4.22–13.5)}

PatteII _{32(36.36) 64.28(51–89) 7.23(4.19–11.73)}

PatteIII _{27(30.68) 69.37(51–88) 5.01(1.81–10.11)}

Table3–Correlationofsubacromialspacebetweenthecontrolandinjurygroups.

Group N Meansubacromialspace SD ttest p-Value

Control 93 7.71 1.58 2.418 0.017a

Injury 88 6.99 2.37

a _{Theprobabilitiesofsignificance(p-values)refertoStudent’sttestforindependentsamples.}

Table4–Comparisonbetweenmeansubacromialspacemeasurementsintheinjurysubgroupsandinthecontrolgroup.

Group N Meansubacromialspace SD ttest p-Value

Controlgroup 93 7.71 1.57

Superior 40 7.8 1.75 −0.298 0.766

Anterosuperior 8 8.29 2.82 −0.92 0.36

Posterosuperior 27 6.77 1.85 2.622 0.010a

Anteroposterosuperior 13 4.16 2.57 6.97 0.000a

a _{Theprobabilitiesofsignificance(p-values)refertoStudent’sttestforindependentsamples.}

(54.8%).Therightshoulderwasevaluatedin49cases(52.6%) andbothshoulderswereusedintheevaluationin13cases (13.9%).

Incomparing the meansubacromial space betweenthe injury and control groups, it was foundto be significantly largerinthecontrolgroup(7.71)thanintheinjurygroup(6.99), withp<0.05(Table3).

Amongthesubgroupsofpatientswithinjuries(superior, anterosuperior,posterosuperiorandanteroposterosuperior), itwasseenthatthemeansubacromialspace wasdifferent betweenthefoursubgroups.Itwaspossibletomake compar-isonsbetweenpairsofsubgroupsinordertoidentifythereal differencebetweenthem.

In analyzing the difference inmean subacromial space measurements between these subgroups and the control group,no statistical differences betweenthe controlgroup andthepatientswitheithersuperiororanterosuperiorlesions wereobserved(p>0.05).Ontheotherhand,inrelationtothe individualswithposterosuperiorandanteroposterosuperior, it was noted that the subacromial space was statistically smaller than in the individuals inthe control group or in the subgroups with superior and anterosuperior injuries. In comparing the differences in mean measurements of

the subacromial space between the subgroups of postero-superior andanteroposterosuperior injuries,which showed lower means than the other subgroups, we observed that the subgroupofanteroposterosuperiorinjuriespresenteda significantly lower mean (4.16) (p<0.05), in relation to the subgroupofposterosuperiorinjuries(6.77)(Table4).

Inrelationtotheanalysisonthemeanmeasurementson thesubacromialspacebetweentheinjurysubgroups classi-fied inaccordance with Patte and the controlgroup, there wasastatisticaldifference(p<0.05)inrelationtoPatte sub-group I_{, which presenteda largersubacromial space (8.57)} thanthecontrolgroup(7.71);andinrelationtoPattesubgroup III_{,inwhichthemeansubacromialspacemeasurementwas}

smaller(5.01)than inthe controlgroup(7.71).Thepatients withinjuriesclassifiedasPatteIIpresentedamean subacro-mialspacemeasurementof7.23,whichwasnotstatistically differentfromthecontrolgroup(Table5).

In evaluating thesesubgroupsinrelation toeach other, it was observedthat the individuals withPatte III _injuries presentedmeansubacromialspacemeasurementsthatwere smaller than those ofindividuals with Patte I _{and Patte II} injuries. Likewise,the subacromial space in individuals in PattesubgroupII_{wassmallerthanthespaceinindividuals}

Table5–ComparisonbetweenmeansubacromialspacemeasurementsinthePattesubgroupsandinthecontrolgroup.

Group N Meansubacromialspace SD ttest p-Value

Controlgroup 93 7.71 1.58

PatteI _{29 8.57 1.91} −2.425 0.017a

PatteII _{32 7.23 1.55 1.484 0.14}

PatteIII _{27 5.01 2.25 7.063 0.000}a

Table6–Pair-by-paircomparisonofmeansubacromialspacemeasurementsinrelationtothePatteclassification.

Group N Meansubacromialspace SD ttest p-Value

I _{29 8.57 1.91 3.009 0.004}a

II _{32 7.23 1.55}

I _{29 8.57 1.91 6.386} 0.000a

III _{27 5.01 2.25}

II _{32 7.23 1.55} −4.472 0.000a

III _{27 5.01 2.25}

a _{Theprobabilitiesofsignificance(p-values)refertoStudent’sttestforindependentsamples.}

withPatte I injuries. Both ofthese comparisonspresented statisticallysignificantdifferences(p<0.05)(Table6).

Inevaluating the subacromial space ofindividuals with posterosuperiorinjuriesand comparingtheminrelationto the Patte classification, it was observed that those with posterosuperior injuries classified as Patte III presented a mean subacromial space measurement of5.74,which was significantlysmallerthanthespaceinindividualswith pos-terosuperiorinjuriesclassifiedasPatteI_andII_(7.48).

Discussion

Evaluationofthe subacromialspace bymeans ofMRImay provideinformationonthebiomechanicsoftheshoulderand the prognosisforrotator cuffinjuries. In astudy inwhich subacromialspacemeasurementsfromconventionalX-rays andmagneticresonancearthrographywerecompared,Saupe etal.5_{concludedthatthereductionindistancewas}

associ-atedwithrotatorcuffinjuriesandfattydegenerationofthe tendons.Thesameauthorsconcludedthatinvolvementofthe infraspinatustendoncausedgreatervariationinthe subacro-mialspace. Inourstudy,patientswithrotator cuffinjuries presented decreased distances from the humerus to the acromion,incomparisonwiththecontrolgrouppatients,with astatisticallysignificantdifference.Incomparingthe subacro-mialspaceinpatientswithrotatorcuffinjuriesindifferent locationswithpatientsinthecontrolgroup,wefoundthat thesubacromialspacewassmallerinpatientswithinjuriesin theposterosuperiorandanteroposterosuperiorregions,witha statisticallysignificantdifference.Thesefindingsshowedthe importanceofthetendonoftheinfraspinatusinmaintaining thesubacromialspace.

Inthestudies byPatte14 _{andGerber etal.,}15_the

biome-chanicalfunctionoftorn,retractedanddegeneratedtendons maybeimpaired,therebyenablingascensionofthehumeral head.15,16_{Throughcomparingthevariationofthesubacromial}

spacewiththeextentoftherotatorcuffinjuryaccordingto Patte’sclassification,itwasconcludedfromthepresentstudy thatPatte IIIinjuriesevolvedwithgreater ascensionofthe humeralhead.TheassociationbetweenPatte’sclassification andfattydegenerationiswellknown.

Theprognosticvalueofthedistancebetweenthehumerus andtheacromioniswellknown andcanbeusedtoaid in therapeuticdecision-making.WeinerandMacnab17_werethe

firsttodescribeanassociationbetweenreductionofthe sub-acromialspaceandrotatorcuffinjuries.Theyobservedthat if the distancewas ≤7mm on conventional radiographs, a

completetendontearwouldbepresent.Subsequently,itwas observed that this measurement ofthe subacromial space might alsobeassociated witha lower successrate in sur-gical treatment.18,19 _{Werner etal.}20 _{believedthatthecutoff}

point forevaluating theascension ofthe humeralheadon MRIshouldbe≤6mm,i.e.lowerthanonconventional radio-graphs.Theyattributedthistogeometricalattributesandto the patient’s positionduringtheexamination,which could causealterationstomuscletonus.21_{Thepresentstudyfounda}

meansubacromialspacemeasurementof7.71mminthe con-trolgroup,whichdoesnotcorroboratethefindingsofWerner etal.,20_{and6.97mminpatientswithrotatorcuffinjuries.IN}

evaluatingthetendongroupsaffected,weobservedthatonly the patients who presented anteroposterosuperior injuries hadsubacromialspaces≤6mm(meanof4.15mm).

Conclusions

Ascension ofthe humeral head (reduction ofthe subacro-mial space)isdirectly relatedtothelocationand extentof theinjuries.Thus,extensiveinjuriesorthoseina posterosu-periorlocationpresentascension ofthehumeralhead, and thisworsenswhenitisassociatedwithadvanceddegreesof tendonretraction.

TheascensionofthehumeralheadassessedthroughMRI doesnotinfluencetheseveritybut,rather,thelocationand extentofrotatorcuffinjuries.

Posterosuperiorandanteroposterosuperiorinjuries (exten-siveinjuries)presentascensionofthehumeralheadonMRI. Thegreaterthedegreeoftendonretractionassociatedwith theseinjuriesis,thegreatertheascensionwillbe.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

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