Rev. bras. ortop. vol.51 número3

SOCIEDADE BRASILEIRA DE ORTOPEDIA E TRAUMATOLOGIA

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

Original

Article

Anthropometric

study

of

the

knee

and

its

correlation

with

the

size

of

three

implants

available

for

arthroplasty

夽

Fabrício

Bolpato

Loures

,

Rogério

Franco

de

Araújo

Góes

,

Idemar

Monteiro

da

Palma

,

Pedro

José

Labronici

_,

_José

_Mauro

_Granjeiro

_,

_Beni

_Olej

a_{HospitalSantaTeresa,Petrópolis,RJ,Brazil}

b_{InstitutoNacionaldeTraumatologiaeOrtopedia(INTO),RiodeJaneiro,RJ,Brazil}

c_{UniversidadeFederalFluminense,Niterói,RJ,Brazil}

d_{InstitutoNacionaldeMetrologia,QualidadeeTecnologia(Inmetro),RiodeJaneiro,RJ,Brazil}

a

r

t

i

c

l

e

i

n

f

o

Articlehistory: Received9May2015 Accepted2July2015 Availableonline8April2016

Keywords: Arthroplastyknee Anthropometry Femur

Tibia

a

b

s

t

r

a

c

t

Objective:TodefinetheanthropometricprofileofthekneeinaBrazilianpopulationwith gonarthrosisusingintraoperativemeasurements;andtoevaluatethecompatibilityofthree implantsavailablefortotalkneearthroplasty.

Methods:Morphometricdatawerecollectedprospectivelyfrom117subjectswith gonarthro-sis.Sixdimensionsinthedistalfemurandtwointheproximaltibiaweredocumentedin118 kneeswhileperformingtotalarthroplasty.Thesedatawerecomparedwiththedimensions ofthreeimplantsavailablefortotalkneearthroplasty.

Results:Thestatisticalanalysisshowedthatmorethanaquarterofthepatientspresented anunsatisfactoryrelationshipbetweenthekneeandprosthesis.

Conclusion:TheimplantsevaluatedneedtobeadjustedtobetterfitBrazilianpatients. ©2015SociedadeBrasileiradeOrtopediaeTraumatologia.PublishedbyElsevierEditora

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

Estudo

antropométrico

do

joelho

e

sua

correlac¸ão

com

o

tamanho

de

três

implantes

disponíveis

para

artroplastia

Palavras-chave: Artroplastiadojoelho Antropometria Fêmur Tíbia

r

e

s

u

m

o

Objetivo:Definiroperfilantropométricodojoelhoempopulac¸ãobrasileiraportadorade gonartrose,comousodamensurac¸ãointraoperatória,eavaliaracompatibilidadedetrês implantesdisponíveisparaartroplastiatotaldojoelho.

Métodos:Foramcoletados,deformaprospectiva,osdadosmorfométricosde117pacientes portadoresdegonartrose.Documentaram-seseisdimensõesnofêmurdistaleduasnatíbia

夽

StudyconductedatHospitalSantaTeresadePetrópolis,RJ,Brazil.

∗ _{Correspondingauthor.}

E-mail:[email protected](F.B.Loures). http://dx.doi.org/10.1016/j.rboe.2015.07.009

proximalem118joelhos,duranteaartroplastiatotal.Essesdadosforamcomparadoscom asdimensõesdostrêsimplantesdisponíveisparaartroplastiatotaldojoelho.

Resultados: Aanáliseestatísticarevelouquemaisdeumquartodospacientesapresentou relac¸ãoinadequadaentreosjoelhoseaspróteses.

Conclusão:Osimplantesavaliadosnecessitamdeajustesparamelhoratenderaospacientes brasileiros.

©2015SociedadeBrasileiradeOrtopediaeTraumatologia.PublicadoporElsevier EditoraLtda.EsteéumartigoOpenAccesssobalicençadeCCBY-NC-ND (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Introduction

Osteoarthrosis (OA) is the main cause of musculoskeletal disability in the elderly and the main cause of total knee arthroplasty(TKA).1 _{Theagingprocess,the geneticburden,} andfemalegenderarenon-modifiablefactorsassociatedwith theoriginofthedisease.2_{Obesityandactivitieswithloadalso} haveadirectparticipationinthisdisease.IntheBrazilian pop-ulationabove19 yearsofage, 5.2%ofthe individuals have sometypeofarthrosis (nearly10million individuals). This numberwillprobablyincreaseandreach12.4millionin2015.3 OAincidencehasadirectrelationwithage,affecting85%of thepopulationabove75years.4_{Accordingtoprojectionsof} theBrazilianInstituteofGeographyandStatistics(Instituto BrasileirodeGeografiaeEstatística[IBGE]),in2030Brazilwill probablyhavethesixtholdestpopulationintheworld,5_afact that,associatedwiththeincreaseofobesityrates,will signif-icantlyincreasetheprevalenceofthisdisease.

Even though thereare noofficial statistics for Brazil,it isestimatedthat 70,000knee arthroplastiesare performed yearly.6_{TheincreaseoftheBrazilianmeanincomehas} facil-itated the access to healthcareservices and increasedthe numberofTKAcandidates,seekingbetterqualityoflifeand higherphysicalcapacity.7

Prosthesisimplantationisasurgeryofprecision,andthe similarity between the implant and the resected bone is essentialforagood clinicalresultand thedurabilityofthe replacement.8 _{Theknee anatomy presents greatvariability} regardinggender,8–14_ethnicity,10,15–20_andbodytype.21

AfterresearchingtheliteratureinPortugueseandEnglish language,theauthorsdidnotretrievestudiesdefiningknee dimensions in the Brazilian population with gonarthrosis. Thus,prosthesesdevelopedforCaucasianswereintroduced inthecountrywithoutanymodification.Apossible incompat-ibility,evenifpartial,increasesthecomplexityofthesurgery andhinderstheappropriatematchingoftheimplantwiththe bone.

Thisstudyaimedtodefinetheanthropometrickneeprofile intheBrazilianpopulationwithgonarthrosisusing intraoper-ativemensuration,andtocomparethebonedimensionswith threeavailableimplantsforarthroplasties.

Material

and

methods

Afterapprovalofthestudybytheinstitution’sResearchEthics Committee,underNo.CEP68542,118kneesof117patients whounderwentTKAbetweenAugust2012andDecember2013

were prospectivelystudied.Thestudy includedall patients whoacceptedtoparticipatebysigningtheinformedconsent form. Caseswith history ofprior knee fracture or surgery, patientswhopresentedbonelossesthatneededgrafting,and thosewithvarusorvalgusdeformitygreaterthan15◦ _were excluded.

Three metal pachymeters were purchased and sent to the National Institute of Metrology, Quality, and Technol-ogy(InstitutoNacionaldeMetrologia,QualidadeeTecnologia [Inmetro]),whichconfirmedtheprecisionoftheinstruments. During the surgicalprocedure, the leadsurgeonconducted sixmensurationsofthefemur:heightandwidthofthe lat-eralandmedialcondyles,totalmediolateralandintercondyle width(Fig.1A),andtwoonthetibia:mediolateraland antero-posterior width(Fig. 1B).Thedimensions wererecorded in millimeters,aftertwomeasurementsperformedbythemain investigator,inordertoavoidanyinterobserveralteration.The arithmeticmeanwasusedforanalysis.

Prior to the measurements, the distal cut ofthe femur and the proximalcut ofthe tibia were performed, and all osteophyteswere removed.This maneuverallowedforthe identificationoftheactualdimensionsofthebonesurfaces thatwouldbeincontactwiththeimplant.Themediolateral femoraldistancewasmeasured atthelevel ofthe surgical transepicondylaraxis.Thewidthofeachfemoralcondylewas measuredat8mmoftheposteriorarticularsurfaceofthe lat-eralcondyleandat10mmoftheposteriorarticularsurfaceof the medialcondyle,simulating theexternalrotationofthe femur. The anteroposteriormeasurements were performed priortothecuts,inordertoassesswhetheroverstuffingwould occur.Theanteroposteriorwidthofthetibiawasmeasured fromthecenteroftheposteriorcruciateligament(PCL)tothe medialthirdofthepatellartendon.Themediolateralwidth wasthelargestperpendiculardistancetothefirst measure-ment.

Theimplantswerechosenbythesimilaritywiththeheight ofthelateralcondyleanditswidthcomparedwiththetotal width of the femurafterthe distal cut.Therelative index (RI)betweentotalwidthandheightofthelateralcondyle,as describedbyHittetal.,wasalsoassessed.9

Considering the objective of the study, the following assumptionsweremadeforthecalculationofthesamplesize: significancelevel of5%(˛),statistical power of80% (1₋␤),

Fig.1–Intraoperativemeasurement(A)rightdistalfemur:1–heightofthelateralcondyle;2–heightofthemedialcondyle; 3–totalwidthofthefemur;4–widthofthelateralcondyle;5–widthofthemedialcondyle;6–intercondylarfossa;(B)right proximaltibia:1–anteroposteriorwidth;2–mediolateralwidth.

Thedescriptiveanalysiswaspresentedontablesand illus-trativecharts.Theobserveddata wereexpressed asmean, standard deviation, median, minimum, and maximum for numericaldata,byfrequency(n)andpercentage(%)for cat-egoricaldata.

The intraclass correlation coefficient (ICC_{) was used to} assessthecompatibilityofthreeimplantsfrequentlyavailable inBrazil:Scorpio®_{(StrykerHowmedicaOsteonics),NexGen}® (Zimmer,Warsaw,Indiana),andNativeKnee®_(Zimmer, War-saw,Indiana).TheMcNemartest wasusedtocomparethe threeimplantsbrands.

Non-parametricmethodswereused,asthevariablesdid notpresentaGaussiandistributionasshownbytherejection oftheShapiro–Wilksnormalitytest.Theadoptedsignificance criterion was the level of 5%. Statistical analysis was per-formedusingthestatisticalsoftwareSAS®_version6.1.

Results

Thestudyincluded118kneesfrom117patients;33patients weremaleand84werefemale.Onefemalepatientunderwent bilateralTKA.Table1presentsthedistributionofthesample regardinggender,operatedside,andethnicity.

Theanalysisofthedistalfemurdatashowedsignificantly greaterabsolutevaluesformalepatients.TheRIbetweentotal widthofthefemurandheightofthelateralcondylewas sim-ilarforbothgenders(Table2).

Similarlytothedistalfemur,thetibialmeasurespresented significantlygreatervaluesformalepatients.TheRIbetween themediolateral andanteroposterior widthwasgreater for femalepatients.Thatsuggeststhatthesetibiasmaybewider. However,thisdifferencewasnotsignificant(p=0.26;Table3). Therewasgreatvariationoftherelationbetweenthetotal width of the femur and the height of the lateral condyle, regardlessofthesizeofthefemur(patientheight).

Figs.2and3showtherelationoftheprosthesiswiththe bonesurfacesalreadypreparedtoreceivetheimplant.

Table1–Samplecharacterization.

Variable Numberofknees Percentage

Gender

Male 33 28.0%

Female 85 72.0%

Side

Right 60 50.8%

Left 58 49.2%

Ethnicity

White 105 89.0%

Mixed-race 9 7.6%

Black 4 3.4%

Source:Datafromtheinstitution.

Thecorrelationofthefemoralimplantswiththeresected bonesreceivedgreaterattention,asthesearedirectlyrelated toappropriatejointbalanceandnormalgait.Toassessthis relation,theICCwasused,whichrevealedasignificant,albeit moderate,conformityofthreeimplantstothedistalfemurof thestudiedsample(p<0.0001,Table4).

Adifferenceequaltoorgreaterthan3mmwasconsidered unbearableforimplantover-orunderhanginthe mediolat-eralsense.Thisstudyobservedthat29.7%ofthepatientswho usedScorpio®_{,28.8%ofthosewhousedNexGen}®_,and27.9%of thosewhousedNativeKnee®_{presentedinadequacies.} Under-hangwasthemostfrequentproblem,presentin20.9%ofthe patients,anditwastwiceascommonamongmalepatients. Mediolateraloverhangwaspresentin7.9%ofthepatientsand wasthreetimesascommonamongfemalepatients.The dis-tributionofincompatibilitiesequaltoorgreaterthan3mmis presentedinTable5.

Table2–Distalfemur.

Gender Numberofknees Totalwidtha _{Heightofthelateralcondyle}a _{Relativeindex}

Male 33 77.7(±4.9) 70.3(±4.7) 111%(±7.1%)

Female 85 67.8(±4.0) 61.5(±4.9) 111%(±10.4%)

Total 118 70.6(±6.1) 64.0(±6.3) 111%(±9.6%)

Source:Datafromtheinstitution. a _{Measurementsinmillimeters.}

Table3–Proximaltibia.

Gender Numberofknees Mediolateralwidtha _{Anteroposteriorwidth}a _{Relativeindex}

Male 33 79.8(±5.8) 53.9(±6.1) 150%(±22.1%)

Female 85 69.6(±4.3) 46.0(±4.0) 152%(±15.3%)

Total 118 72.4(±6.6) 48.2(±5.9) 152%(±17.4%)

Source:Datafromtheinstitution. a _{Measurementsinmillimeters.}

90

85

75

65

55

50

60 50

45 40

Lateral condyle height (mm)

Total femoral length (mm)

80

70 75

65 55

60 70 80

Male Female NexGen® _{Natural Knee}® _Scorpio®

Fig.2–Relationbetweenimplantsanddistalfemur. Source_{:Datafromtheinstitution.}

Discussion

Brazilhasbeenpresentingtypicalsocialchangesof develop-ingcountries,suchaspopulationaging23_{andthegrowthof} obesity.24_{Thesefactorsaredirectlyconnectedtothegenesisof} osteoarthrosis,whichallowsustopredictthatthedemandfor jointreplacementswillgrowexponentiallyinthenearfuture. FollowingtheprinciplesofTKAandimplantingthe appro-priateprosthesissizearefundamentalfactorsforthesuccess ofjointreplacementsurgery.Correct ligamentbalance and maximum bone coverage by the implant are pursued, in order to reduce the stress on the bone–implant surface.15 Mismatchingsinthisrelationincreasethecomplexityofthe surgery.19

Table4–Relationbetweendistalfemurandimplants.

Prosthesis ICC 95%CI p-value

Scorpio® _{0.592 0.462–0.698 <0.0001}

NaturalKnee® _{0.534 0.392–0.651 <0.0001}

NexGen® _{0.547 0.407–0.661 <0.0001}

Source:Datafromtheinstitution.

ICC,intraclasscorrelationcoefficient;CI,confidenceinterval.

95

90

85

75

65

55

50

45 40

35 50 60

30 25

Anteroposterior length (mm)

Mediolateral length (mm)

65 55

60 70 80

Male Female NexGen® _{Natural Knee}® _Scorpio®

Fig.3–Relationbetweenimplantsandproximaltibia. Source_{:Datafromtheinstitution.}

Table5–Distributionoftheincompatibilities≥3mm.

Gender Male Female

Prosthesis/incompatibility Underhanga _Overhanga _Underhanga _Overhanga

Scorpio® _{9 1 18 7}

NexGen® _{13 1 12 8}

NaturalKnee® _{9 1 13 10}

Total 31(31.3%) 3(3%) 43(16.9%) 25(9.8%)

Source:Datafromtheinstitution. a _{Numberofpatients.}

bonedimensionsthatwouldbeincontactwiththeimplants. Additionally,everypatientofthesamplepresentedtheclinical andradiographicdiagnosisofkneeosteoarthrosis,and there-forepresentedthetypicalanatomicalchangesofthisdisease. Theseaspectsincreasedthereliabilityofthestudy,sincethe dimensionsofosteoarthritickneesaredifferentfromthoseof normalknees.8

ThemeanRIofthefemuramongmalepatientswas111%, rangingfrom 101%to124%. Femalepatientspresentedthe samemean,howeverwithamuchwiderrange,from90%to 143%.Thisfactrevealsthegreateranatomicalvariabilityof thedistalfemurinthisgender. Thisvalueisinagreement withthedimensionsfoundforKoreans(111%)19_;howeverthey are larger than those of the Chinese (109%)10 _{and smaller} thanthoseoftheJapanese(129%)populations.19_Thestudied implantspresentedanRIvariationbetween105%and112%, indicatingthattherecanbebothunder-andoverhang.

Ha et al.19 _{found a tendency of underhang forsmaller} femurs,andofoverhangforlargerfemurs.Thistendencywas notobservedinthepresentsample.Agreatvariabilityofthe totalwidthofthefemurwasobservedforthesame height ofthelateralcondyle.Thestudiedimplants presentedonly onewidthforeachheight,whichappearsnottobetheideal format.

Table6–Comparisonbetweentheimplants.

Prosthesis p-valuea

Scorpio®_vs.NexGen® _0.88 Scorpio®_vs.NaturalKnee® _0.23 NexGen®_vs.NaturalKnee® _0.15

Source:Datafromtheinstitution. a _{p-valuefor5%.}

Table7–Comparisonbetweenthefemoralmeasurements.

Authors Population Method LTF ACL RI

Menschetal. (1975)27

American CadaversandX-rays 69.7±2.7(F) 81.1±3.4(M)

69.9±2.6(F) 67.9±3.3(M)

99% 119% Vaidyaetal.

(2000)18

Indian CT 55.58(F)

61.09(M)

Hittetal.(2003)9 _{American Intraoperative 72.4}±8.3 64.3±4.7 112% Hoetal.(2006)10 _{Chinese Intraoperative 70.2}±5.4 63.7±5.1 109% Lonneretal.

(2008)28

American Intraoperative 67.49(F)

76.92(M)

66.79(F) 74.22(M)

101% 104% Eweetal.(2009)20 _{Chinese.Malaysian.}

andIndian Intraoperative (navigation) 63.83(F) 72.45(M) 59.14(F) 64.55(M) 108% 109% Chaichankul

etal.(2010)15 a

Thai MRI 59.9±3.7(F)

70.1±3.8(M)

43.3±3.6(F) 48.5±3.7(M)

138% 144% Kwaketal.

(2010)16

Korean CTincadavers 65.9(F)

74.4(M)

41.2(F) 46.2(M)

160% 161% Chinetal.29

2011b

Chinese,Malay, Indian,andothers

Intraoperative 63.0(F) 73.0(M) 66.5(F) 71.3(M) 95% 102% Yueetal.(2011)30 _Chineseand

American

CT MRI

72.8±2.6(CF) 76.4±4.0(AF) 82.6±3.6(CM) 86.0±5.6(AM)

58.8±2.5(CF) 59.7±2.6(AF) 65.0±2.8(CM) 67.5±3.6(AM)

124% 128% 127% 128% Dargeletal.

(2011)12

German Cadavers 61.5±3.39(F)

70.5±3.79(M)

63.1±3.82(F) 69.3±2.50(M)

97% 102% Haetal.(2012)19 _{Korean Intraoperative 68.2(F)}

74.8(M)

60.8(F) 66.3(M)

112% 113% Guyetal.(2012)13 _{English Intraoperative 64.1}±2.6(F)

74.9±3.9(M)

65.5±5.32(F) 73.5±4.5(M)

98% 102% Terzidisetal.

(2012)31

Caucasian (Greeks)

Cadaves (drybones)

78.5±3.0(F) 88.6±4.2(M)

55.4±2.1(F) 61.1±3.3(M)

142% 145% Lietal.(2014)32 _Chineseand

American

MRI 64.4±2.6(CF)

72.7±3.8(CM) 65.4±1.4(AF) 74.6±3.9(AM)

52.8±2.6(CF) 56.5±2.5(CM) 55.4±2.8(AF) 59.6±3.2(AM)

122% 129% 118% 125% Presentstudy 2012 2013

Brazilian Intraoperative 67.8±4.0(F) 77.7±4.9(M)

61.5±4.9(F) 70.3±4.7(M)

111% 111%

F,female;M,male;AF,Americanfemale;CF,Chinesefemale;AM,Americanmale;CM,Chinesemale. a _{Chaichankuldidnotusethesameanatomicalparameters.}

b _{APmeasurementafterthetrochlearcut.}

Thestudiedimplantsweredevelopedbasedon anthropo-metricstudiesinCaucasianpopulations.Theauthors’initial hypothesiswas that valuesforknee anthropometry inthe Brazilianpopulationwouldbedifferentfromthatother pop-ulation.Whenthemeasurementsofthepresentstudywere compared with other studies that assessed different eth-nicities, the mean Brazilian values were similar to those describedforCaucasians,whichleadstothebeliefthatthe incompatibilities are not a consequence of ethnic differ-ences.Theconflictbetween the small number ofavailable implants and the great anatomical variability of the dis-tal femurcan bethe cause ofthese incompatibilities. The main assessedanthropometric studies are summarized in Table7.9,13,15,17–20,27–32

Thegreatnumberofpatientswhoself-declaredaswhite mightbeafactor.Penaetal.33_{conductedageneticstudyof} theBrazilianpopulationanddemonstratedthattheAfrican ancestryinwhitesubjectsfromtheBrazilianSoutheastwas upto32%,whiletheEuropeanancestryinblacksubjectsfrom

thatregionreachedupto49%.Thatprovesthattherelation betweenskincolorandgeneticinheritanceinBrazilisvery weak. Afterfive centuriesof racial mixing, the phenotypic manifestationofskincolorhaslittleornovalueinmedical practice.

highertibialcoverage,thecorrectrotationalalignmentoccurs more frequently in asymmetrical implant, as the match-ing betweenrotationand coverage iseasierinthis typeof prosthesis.

Conclusions

AsignificantnumberofpatientswhoundergoTKAinBrazil presentdifferencesabovetheacceptablebetweenthe dimen-sionsofthekneesandofthestudiedimplants,whichmay compromise the clinical result and the durability of the surgeryresults.Thestudy indicatesthat adjustmentsneed tobemadesothattheimplantscanappropriatelymeetthis growingdemand.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

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