Rev. bras. ortop. vol.50 número1

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

Original

article

Femoropatellar

radiographic

alterations

in

cases

of

anterior

cruciate

ligament

failure

夽

Diego

Protásio

de

Vasconcelos

,

Alan

de

Paula

Mozella

,

Pedro

Guilme

Teixeira

de

Sousa

Filho

_,

_Gustavo

_Cardilo

_Oliveira

_,

Hugo

Alexandre

de

Araújo

Barros

Cobra

a_{OrthopedicsandTraumatologyService,UniversityHospital,FederalUniversityofSergipe,Aracaju,SE,Brazil} b_{KneeSurgeryCenter,NationalInstituteofTraumatologyandOrthopedics(INTO),RiodeJaneiro,RJ,Brazil}

a

r

t

i

c

l

e

i

n

f

o

Articlehistory:

Received8September2013 Accepted17October2013 Availableonline31January2015

Keywords:

Jointinstability

Anteriorcruciateligament Patellofemoraljoint

a

b

s

t

r

a

c

t

Objective:Tomakeacomparativeanalysisonthreefemoropatellarradiographicparameters, betweenkneeswithchronicfailureoftheanteriorcruciateligament(ACL)andnormalknees.

Methods:ThirtyvolunteerpatientswithadiagnosisofunilateralisolatedchronicACLinjury formorethanoneyearandanormalcontralateralkneewereselected.Digitalradiographs wereproducedforallthepatients,onbothkneesinabsolutelateralviewat30◦_of

flex-ion,withandwithoutload-bearingononeleg,andinaxialviewofthepatellaat30◦_.The

Caton–Deschampspatellarheightindex,MerchantpatellarcongruenceangleandLaurin lat-eralpatellartiltangleweremeasuredontheradiographsobtainedfromthenormalknees andkneeswithACLinjuries,andcomparativeanalysiswasperformedbetweenthesetwo groups.

Results:Thepatellarheightwasstatisticallysignificantlylower(p<0.001)inthekneeswith ACLfailurethaninthenormalknees,bothonradiographswithoutloadingandonthose withsingle-footloading.TheMerchantpatellarcongruenceanglewassignificantlysmaller (p<0.001)inthenormalkneesandthelateralpatellartiltanglewassmaller(p<0.001)inthe kneeswithACLfailure.

Conclusion: Chronic ACL failure gave rise to a statistically significant change in the femoropatellarradiographicvaluesstudied(p<0.001).Kneeswithinjuriestothisligament presentedlowerpatellarheightvalues,greatertiltandlateraldisplacementofthepatella, inrelationtothefemoraltrochlea,incomparisonwiththenormalcontralateralknees.

©2015SociedadeBrasileiradeOrtopediaeTraumatologia.PublishedbyElsevierEditora Ltda.Allrightsreserved.

夽

WorkdevelopedattheKneeSurgeryCenteroftheNationalInstituteofTraumatologyandOrthopedics(INTO),RiodeJaneiro,RJ,Brazil.

∗ _{Correspondingauthor.}

E-mail:[email protected](D.P.deVasconcelos).

http://dx.doi.org/10.1016/j.rboe.2015.01.005

Alterac¸ões

radiográficas

femoropatelares

na

insuficiência

do

ligamento

cruzado

anterior

Palavras-chave:

Instabilidadearticular Ligamentocruzadoanterior Articulac¸ãopatelofemoral

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e

s

u

m

o

Objetivo: Análisecomparativadetrêsparâmetrosradiográficosfemoropatelaresentre joel-hoscominsuficiênciacrônicadoligamentocruzadoanterior(LCA)ejoelhosnormais.

Métodos: Foramselecionados30pacientesvoluntárioscomdiagnósticodelesãocrônica isoladaunilateraldoLCAhaviamaisdeumanoejoelhocontralateralnormal.Todosos pacientesforamsubmetidosaradiografiasdigitaisdeambososjoelhosnasincidências emperfilabsolutoa30◦_{deflexão,comesemcargamonopodal,eaxialdepatelaa30}◦_.

Forammensurados,nasradiografiasobtidas,oíndicedealturapatelardeCaton-Deschamps, oângulodecongruênciapatelardeMerchanteoângulodeinclinac¸ãolateraldapatela, descritoporLaurin,nosjoelhosnormaisenosjoelhoscomlesãodoLCAefoifeitaanálise comparativaentreessesdoisgrupos.

Resultados: Aalturapatelarfoiinferior,deformaestatisticamentesignificante(p<0,001), nosjoelhoscominsuficiênciadoLCAemcomparac¸ãocomosjoelhosnormais,tantonas radiografiassemcargaquantonascomcargamonopodal.Oângulodecongruênciapatelar deMerchantfoisignificativamentemenor (p<0,001)nosjoelhosnormaiseoângulode inclinac¸ãolateraldapatelafoiinferior(p<0,001)nosjoelhoscominsuficiênciadoLCA.

Conclusão: AinsuficiênciacrônicadoLCAalteroudeformaestatisticamentesignificante (p<0,001)osvaloresdosparâmetrosradiográficosfemoropatelaresestudados.Joelhoscom lesãodesseligamentoapresentarammenoresvaloresdealturapatelar,maiorinclinac¸ãoe deslocamentolateraisdapatelaemrelac¸ãoàtrócleafemoralcomparadoscomosjoelhos contralateraisnormais.

©2015SociedadeBrasileiradeOrtopediaeTraumatologia.PublicadoporElsevier EditoraLtda.Todososdireitosreservados.

Introduction

Anteriorcruciateligament(ACL)injuriesareamongthe com-monest knee injuries, with growing incidence due to the increasinglylarge numberofindividuals involvedinsports activities.1_{Failureofthisligamentcausesanteriorand}

rota-tional instability of the knee, characterized by recurrent episodes ofanterior and rotational(i.e. internal rotational) subluxationofthetibiaoverthefemur.2_{Theseepisodesmay}

causefunctionallossesandlimitsportspracticesandcertain activitiesofdailyliving.3

Significantbiomechanicalandkinematicalterationshave beenrecognizedoverrecentdecades,inkneeswithACL fail-ure. Laboratory studies on gait analysis have shown that knees with ACL injuriespresent greater internalrotation,4

less external rotation5 _{and increased medial translation}

of the tibia over the femur,6 _{in comparison with normal}

knees,duringthestance and swingphases ofgait.Several authors7–10 _{havestatedthatACLfailuregivesrisetolossof}

tibiofemoralkinematicbalanceandcausesabnormal biome-chanicalbehavior,whichputsthekneeatriskofsecondary injuries.

Despitethelargenumberofstudiesthathaveexaminedthe effectsofACLinjuriesontibiofemoralkinematics,fewhave analyzedfemoropatellaralterationsinpatientswithfailure ofthisligament.9_Baugheretal.11_{demonstratedthatpatients}

withACLfailurepresentedirreversibleatrophyofthe quadri-cepsmuscleandwarnedofthepossibleconsequencesofthis forthepatellofemoraljoint.

According toHsiehet al.,12,13 _{alterations totibiofemoral}

kinematicsthatresultfromACLinjuriesaffectthekinematics ofthepatellofemoraljointandcauseimbalanceofthe exten-sormechanismandabnormaldistributionofforcesbetween the patella and the femoral trochlea. These authors12,13

showedthattherewere increasesinlateraltranslation and lateralinclinationofthepatellainrelationtothefemur,after resectionoftheACLinthekneesofcadavers.Invivo,Vande Veldeetal.14_{demonstratedthatACLfailurealtersthecontact}

areaandfemoropatellartracking.

Femoropatellarradiographicparametersmayaidin diag-nosingalterationsofthepatellofemoraljoint.Inthepresent study,wemadeacomparativeanalysisonthree femoropatel-lar radiographic parameters that are commonly used in clinicalpractice,withtheaimofdetectingdifferencesinthese parametersbetweenkneeswithchronicACLfailureand nor-malknees.

Methods

Table1–Inclusionandexclusioncriteriaofthesample.

Inclusioncriteria

1.Skeletallymatureindividualsundertheageof60years 2.DiagnosisofsingleunilateralACLinjurythathadoccurred morethan12monthsearlier

2.1.Anteriortranslationofthetibiaoverthefemurgreater than5mm,withoutanendpointinrelationtothe

contralateralknee,usingKT-1000.

2.2.Lachman,AnteriorDrawerandPivot-Shifttests positive

2.3.Otherligamentandmeniscustestsnegative

2.4.Magneticresonanceimaging(MRI)showingsingleACL injury

3.Contralaterallowerlimbandkneewithoutalterationson physicalexamination

4.Individualswhoagreedtoparticipateandsignedthefree andinformedconsentstatementofthestudy

Exclusioncriteria

1.Presenceofalterationsofanyorigin(congenital, traumatic,metabolic,inflammatoryordegenerative)that weregeneticallyinheritedoracquired,ineitherofthelower limbs,otherthanasingleACLinjuryinoneoftheknees 2.Presenceofadeformityofvarus,valgus,antecurvatum, recurvatumortorsionalnatureineitherofthelowerlimbs 3.Previoussurgeryineitherofthelowerlimbs

4.Pregnantwomen

lengthoftimewiththeACLinjurywas32months,ranging from14to70.

All the patients underwent digital radiography on both knees:thekneewithACLfailureandthenormalcontralateral knee.Five radiographswereproducedoneach patient:two (oneoneachknee)inabsolutelateralviewwithflexionof30◦_, withoutloadingonthelowerlimb,performedwiththepatient inlateraldecubitusontheradiographictable;two(oneoneach knee)inabsolutelateralviewwithflexionof30◦_,performed inanuprightstandingpositionwiththebodyweightborneon onefootonthesideradiographed;andoneaxialradiographof thepatella,coveringbothkneesinaccordancewiththe tech-niqueofMerchantetal.,15 _{butwiththekneesflexedat30}◦_,

insteadof45◦_.

Allthe150digitalradiographsobtainedwereanalyzedby thesame examiner,usingtoolsformeasuringdistancesin millimetersand angles,withinthe DicomViewer® _software

(Microdata,RiodeJaneiro,Brazil).

Thevaluesofthreefemoropatellarradiographic parame-terswererecorded:thepatellarheight,whichwasmeasured onthelateral-viewradiographsofthekneebymeansofthe methoddescribedbyCaton–Deschamps16_{(Fig.1);Merchant’s}

angleofpatellarcongruence,measuredonaxialradiographs ofthepatellaasdescribedbyMerchantetal.15_{(Fig.2);andthe}

angleoflateralinclinationofthepatella,measuredin accor-dancewiththetechniqueofLaurinetal.17_{(Fig.3),onaxial}

radiographsofthepatella.

Thevaluesofthefemoropatellarradiographicparameters obtainedfromthe kneeswithACL failure(case group)and fromthenormalcontralateralknees(controlgroup)were sub-jectedtotheKolmogorov–SmirnovandShapiro–Wilknormal distributiontests,andwerecomparedusingthepaired Stu-dent’sttesttoevaluatethestatisticalsignificance(p<0.05). Pearson’scorrelationtestwasusedtoassessthecorrelations

Left

A/B = 1.07

A B

Fig.1–Caton–Deschampspatellarheightindex(A/B)from radiographsofthekneeinabsolutelateralview:(A) distancebetweentheanteriormarginofthejointsurfaceof thetibiaandthelowerlimitofthejointsurfaceofthe patella;(B)distancebetweentheupperandlowerlimitsof thejointsurfaceofthepatella.

between thetime elapsedsinceACL injury andthe values forthepatellarheight,Merchant’scongruenceangleandthe lateralinclinationangleofthepatella.

Results

Among the 30 volunteers, 57% (n=17) were men and 43% (n=13)werewomen.Themeantimethathadelapsedsince theligamentinjurywas32±14months,witharangefrom14 to70.Thesubjects’meanagewas28±7.6years,rangingfrom 17to46.TheACLinjuriesweredistributedequallyonthetwo sides:50%(n=15)intherightkneeand50%(n=15)intheleft knee.Thetraumamechanismthatcausedtheligamenttear wasindirectin83%(n=25)anddirectin17%(n=5).The com-monestcausesweresoccerpractice(57%,n=17),fallsfroma height(16.5%,n=5),trafficaccidents(16.5%,n=5)andmartial artspractice(10%,n=3).

Themeanvaluesforthepatellarheightinthetwogroups, withoutweight-bearingonthelowerlimbandwith weight-bearingonasinglefoot,areshowninFigs.4and5.Thepatellar heightvalueswerestatisticallysignificantlysmaller(p<0.001) intheknees withACL failure(casegroup)than inthe nor-malknees(controlgroup),bothontheradiographswithout weight-bearingandinthosewithweight-bearingonasingle foot.Single-footweight-bearinggaverisetoastatistically sig-nificanceincrease(p<0.001)inthepatellarheightvaluesin thetwogroupsinasimilarmanner(Fig.5).

BÂC = + 4.7º _{BÂC = + 13.2º}

B

D

 Â

D

E

D E

C C B

Fig.2–Merchant’spatellarcongruenceangle(BÂC).LineCbisectstheangleDÂE,whichistheangleofthetrochlearsulcus. LineBjoinsthevertexoftheangleDÂEtothelowestpointofthepatellarcrest.BÂC=+4.7◦_{inthenormalkneeand}

BÂC=+13.2◦_{intheleftkneewithananteriorcruciateligamentinjury.}

 = 10.4º  = 6.9º

D

Fig.3–Lateralinclinationangle(Â)ofthepatellaasdescribedbyLaurinetal.,17_{formedbyalinethatjoinstheanterior} limitsofthemedialandlateralfemoralcondylesandanotherlinetangentialtothelateralfacetofthepatella.Â=10.4◦_in

thenormalrightkneeandÂ=6.9◦_{intheleftkneewithananteriorcruciateligamentinjury.}

kneeswas−2.57◦_±5.86◦_{.Thisvaluewasstatistically}

signifi-cantlylower(p<0.001)thanthatofthekneeswithACLfailure (+2.08◦_±6.16◦_{),asshowninFig.6.}

The mean value of the lateral inclination angle of the patella in the group of knees with ACL injuries was 6.70◦_±4.86◦_{,andthisvaluewassignificantlylower(p<0.001)}

than thatofthenormalknees (11.25◦_±4.54◦_{),asshown in}

Fig.7.Table3presentsthemean,standarddeviationand max-imumandminimumvaluesofthelateralinclinationangleof thepatellaineachgroup.

2

1.5

Mean (M) and standard deviation (SD) of the patellar height without weight-bearing on the lower limbs in the two groups (p<0.001)

0.5

1.05

0.97 Normal knees

Knees with ACL injury

Patellar height without weight-bearing 0 1

Fig.4–Meanandstandarddeviationofthepatellarheight withoutweight-bearingonthelowerlimbsinthetwo groups.

Pearson’scorrelationtestdidnotshowanysignificant cor-relation(r=0.14)betweenthetimethathadelapsedsincethe ligamentinjuryandthevaluesforthepatellarheight, Mer-chant’spatellarcongruenceangleandthelateralinclination angleofthepatellainthekneeswithACLfailure.

Discussion

TheeffectsofACLfailureontibiofemoralkinematicsarewell documented in the literature. Rotational alterations4,5 _and

translationalalterations6_{tothetibiofemoraljointduringthe}

2

1.5

Mean (M) and standard deviation (SD) of the patellar height with weight-bearing on one foot only in the two groups (p<0.001)

0.5

1.11

1.03

Normal knees

Knees with ACL injury

Patellar height without weight-bearing 0 1

10 8 6 4 2 –2 –4 –6 –8 –10

Mean (M) and standard deviation (SD) of merchant’s congruence angle in the two groups

–2.57

2.08 Normal knees

Knees with ACL injury

Merchant’s congruence angle

0

Fig.6–MeanandstandarddeviationofMerchant’s congruenceangleinthetwogroups.

18 15 12 9 6 3 –3

Mean (M) and standard deviation (SD) of the lateral inclination angle of the patella in the two groups

11.25

6.70

Normal knees

Knees with ACL injury

Lateral inclination angle of the patella

0

Fig.7–Meanandstandarddeviationofthelateral inclinationangleofthepatellainthetwogroups.

stance and swing phasesof gait havebeen demonstrated. AccordingtoHsiehetal.,13_{alterationstotibiofemoral}

kine-maticsinevitablycause changestothefemoropatellarjoint andmodifyitsnormalfunctioning.

Usingradiographicparametersthatarecommonlyapplied in clinical practice, we sought to detect these possible femoropatellaralterationsinkneeswithchronicACLinjuries alonethathadoccurredmorethan12monthsearlier.Forthis,

Table2–Mean,standarddeviation(SD)andminimum

andmaximumvaluesforMerchant’spatellar

congruenceangleinthetwogroups.

Merchant’spatellarcongruenceangle

Mean SD Min Max

Normalknees −2.57 5.86 −13.90 7.80

KneeswithACLinjuries 2.08 6.16 −13.20 13.20

Table3–Mean,standarddeviation(SD)andminimum

andmaximumvaluesforthelateralinclinationofthe patellainthetwogroups.

Lateralinclinationangleofthepatella

Mean SD Min Max

Normalknees 11.25 4.54 0.00 21.00

KneeswithACLinjuries 6.70 4.86 −4.80 14.80

weusedthenormalcontralateralkneeofthecamepatientas thecontrol.

Inanalyzingthepatellarheight,wefoundasignificantly lowervalue(p<0.001)inthegroupofkneeswithACLinjuries thaninthegroupofnormalknees.Ontheradiographswithout weight-bearing,theCaton–Deschampspatellarheightindex forthekneeswithACLinjurieswas0.97±0.11,whileitwas 1.05±0.09forthe normalknees(Fig.4).These valueswere verysimilartothoserecordedbyLinetal.,18_whocompared

thepatellarheightwithoutweight-bearingonthelowerlimbs usingtheInsall-Salvatipatellarheightindex,inkneeswith ACL injury(0.99±0.11)and withoutACLinjury(1.05±0.12). Furthermore,theseauthors,andalsoAgliettietal.,19_found

significantlylowerpatellarheightvaluesinmalepatientswith ACLinjuriesandconcludedthatalowpatellaisariskfactorfor ligamentinjury.Inoursample,wedidnotobserveany statis-ticallysignificantdifference(p>0.05)inpatellarheightvalues betweenmenandwomen.Moreover,sinceweusedthe con-tralateralnormalkneeofthesamepatientasthecontrol,we cannotsaywhetherthelowervaluesforpatellarheightthat wefoundinthekneeswithACLinjuryareariskfactorfor lig-amentinjury,orwhethertheyareaconsequenceofchronic injury.

Weight-bearingonasinglefootstatisticallysignificantly increasedthepatellarheightvaluesinbothgroups(p<0.01) (Fig. 5). Yiannakopouloset al.20 _{observedthat there was a}

meanincreaseintheCaton–Deschampspatellarheightindex of0.11whenbodyweightwasbornebynormalknees.These authors suggested that the increasein patellar heightdue to proximal translation of the patella through contraction ofthequadricepswhenweightisbornebythelowerlimbs mightbegreaterinkneeswithligamentfailure.VandeVelde etal.14_{detectedrelativestretchingofthepatellartendonin}

knees with ACL injury, which could theoretically cause an evengreaterincreaseinpatellarheightintheseknees dur-ingquadricepscontraction.However,inourstudy,themean increase in patellarheight was the same (0.06)in the two groups.

Merchant’spatellarcongruenceanglereflectstheposition ofthe patellainrelationtothe trochlearsulcus.Itsvalues canbenegative,whichindicatesthatthecrestofthepatella islocatedmediallytothetrochlearsulcus;orpositive,when the crest ofthe patella islocatedlaterally tothe trochlear sulcus.15_{Thus,themorepositivethevalueoftheangleis,the}

greaterthelateraldisplacementofthepatellainrelationtothe femoraltrochleawillbe;andthemorenegativeitis,thegreater themedialdisplacementwillbe.Inourstudy,themeanvalue ofthisangleinthenormalkneeswas−2.57◦_±5.86◦_,versus

+2.08◦_±6.16◦_{(p<0.001)inthekneeswithACLfailure,which}

indicatesthatthepositioningofthepatellawasmorelateralin relationtothetrochlearsulcusinthegroupofkneeswith liga-mentlesions.Thisfindingisconcordantwithwhatwasfound byVandeVeldeetal.,14_{whorecordedgreaterlateral}

displace-mentofthepatellainmillimeters,inrelationtothetrochlear sulcus,inkneeswithACLinjuriesatflexionsbetween0◦_and

30◦_{.Onaverage,thelateraldisplacementofthepatellafound}

bytheseauthors14_{was1.7mmgreater(p<0.001)inkneeswith}

ACLfailurethaninnormalknees.Hsiehetal.13_alsorecorded

 = – 4.8º _{ = + 5.9º}

D

Fig.8–Negativelateralinclinationangle(Â)ofthepatella(Â=−4.8◦)intherightkneewithACLinjuryandpositiveangle (Â=+5.9◦_{)inthenormalleftknee.}

flexionsbetween0◦ _{and 90}◦_{, inthe kneesofcadaverswith}

ligamentinjuries.

As the patella tilts laterally, there is a decrease in the lateralinclinationangleofthepatella,asdescribedby Lau-rinetal.17_{Thisoccursbecausethelinethatistangentialto}

thelateralfacetofthepatellabecomesmoreparalleltothe linethat joinsthe anteriorlimitsofthe medialand lateral femoralcondyles.Incasesofseverelateraltilting,inversion of this angle may occur, thus becoming negative through medialopening,instead ofthrough lateral opening(Fig. 8). Inoursample,this inversionoftheangleonlyoccurred in two knees with ACL injuries (−2.2◦ _{and −4.8}◦_{) and it was}

notrecorded inany ofthe normalknees. Themean value ofthe lateral inclinationangle ofthe patella in the knees withACLinjurieswas6.70◦_±4.86◦_{,whichwas significantly}

smaller (p<0.001) than what was measured in the normal knees (11.25◦_±4.54◦_{). These results reveal that there was}

greater lateral tilting of the patella inthe knees withACL injuries,whichwasonaverage4.55◦_{greaterthaninthe}

nor-malknees.SimilarvalueswerealsoreportedbyVandeVelde etal.,14_{whorecordedameanincreaseinlateraltiltingof5.2}◦_,

forthepatellaeofkneeswithACLinjuriesoverthefirst30◦_of

flexion.

Thereisnoconsensusintheliteratureregardingwhether femoropatellar alterationsmightbe reversiblethroughACL reconstruction.Inthekneesofcadavers,Hsiehetal.12,13_found

thatafterACLreconstruction, thepatellartilt,contactarea andfemoropatellarcontactpressurereturnedtovaluesclose tothoseofnormalknees.Ontheother hand,inaninvivo

study,VandeVeldeetal.14_{documentedthatthesealterations}

persistedevenafterligamentreconstruction,whichsuggested thatthis procedure alone wouldnot becapableof correct-ingthem.Furtherresearchwillbeneededinordertoconfirm thesehypotheses.

Small changes to patella orientation in relation to the femoral trochlea may cause significant changes to femoropatellar biomechanics.14 _{According to some}

authors,14,21,22 _{thegreater displacement and greater lateral}

inclination ofthe patella found in knees with ACL failure mightberelated tothe appearanceofanterior paininthe kneeandfemoropatellararthrosis.

Webelievethatfemoropatellaralterationsinkneeswith ACLinjuriesorinthosethatundergoreconstructionofthis ligament are oftenunderdiagnosed in clinical practice. An appropriateradiological examinationwithdetailed analysis onthefemoropatellarradiographicparametersmightaidin

recognizingthesealterationsandenablerationaltherapeutic approaches.

Conclusion

In oursample,chronicACLfailurestatisticallysignificantly alteredthevaluesofthefemoropatellarradiographic param-etersevaluated(p<0.001).Kneeswithchronicinjuriestothis ligamentpresentedlowervaluesforpatellarheight,greater tiltingandgreaterlateraldisplacementofthepatellain rela-tiontothefemoraltrochlea,incomparisonwiththenormal contralateralknees.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

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