Rev. bras. ortop. vol.52 número2

SOCIEDADE BRASILEIRA DE ORTOPEDIA E TRAUMATOLOGIA

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

Original

article

Do

patients

lose

weight

after

total

knee

replacement?

夽

Carlos

Roberto

Schwartsmann

a,b,∗

,

Alexandre

Moreira

Borges

b

,

Geraldo

Luiz

Schuck

de

Freitas

b

_,

_Eduardo

_Zaniol

_Migon

b

_,

_Gustavo

_Kaempf

_de

_Oliveira

b

_,

Marcos

Wainberg

Rodrigues

b

a_{UniversidadeFederaldeCiênciasdaSaúdedePortoAlegre(UFCSPA),PortoAlegre,RS,Brazil}

b_{ComplexoHospitalardaSantaCasadePortoAlegre,PortoAlegre,RS,Brazil}

a

r

t

i

c

l

e

i

n

f

o

Articlehistory:

Received4November2015 Accepted29March2016 Availableonline24January2017

Keywords:

Obesity

Kneearthroplasty Bodymassindex

a

b

s

t

r

a

c

t

Objective:Severalstudiesshowthatpatientsundergoingtotalkneearthroplasty(TKA)tend tomaintainorgainweightaftertheprocedure,whichwouldresultinincreasedwearofthe prosthesisandnewsurgicalinterventionsinasmallerperiodoftimeincomparisonwith patientswithadequatebodymassindex(BMI).Theaimofthisstudywastoinvestigatethe effectofTKAsurgeryonthesepatients’BMI.

Methods:Initiallytherecordswereanalyzed,chosenatrandomfrom91patientsundergoing TKAduringtheperiodfromAugust2011toJuly2013.PatientswerestratifiedbyBMIas normalweight(BMIbetween20and25),overweight(BMIbetween25and30),andobesity (BMI>30).Theywerere-evaluatedinaminimumperiodof18months.

Results:Themeanageofthesamplepopulationwas68.1years;69.1formenand67.2for women.ThemeanpreoperativeBMIwas27.24kg/m2_{.Amongthestudyparticipants,inthe}

preoperativeperiod,17patientshadnormalweight,65wereoverweight,andninewere obese.Postoperativeanalysisshowedweightlossin41patients(46%),andweightgainin 50patients(54%).ThemeanpostoperativeBMIwas27.16kg/m2_{,ingeneral,experiencinga}

slightdeclineinthemeanBMIof0.08kg/m2_.

Conclusion: PatientswhounderwentTKAdidnotachievesignificantreductioninBMIafter surgery.

©2017PublishedbyElsevierEditoraLtda.onbehalfofSociedadeBrasileiradeOrtopedia eTraumatologia.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense(http:// creativecommons.org/licenses/by-nc-nd/4.0/).

夽

StudyconductedattheSantaCasadePortoAlegre,Servic¸odeOrtopediaeTraumatologia,PortoAlegre,RS,Brazil.

∗ _{Correspondingauthor.}

E-mail:[email protected](C.R.Schwartsmann). http://dx.doi.org/10.1016/j.rboe.2017.01.003

Os

pacientes

emagrecem

após

artroplastia

total

de

joelho?

Palavras-chave:

Obesidade

Artroplastiadojoelho Índicedemassacorporal

r

e

s

u

m

o

Objetivo: Diversosestudosdemonstramquepacientessubmetidosàartroplastiatotaldo joelho(ATJ)tendemamanterouaganharpesocorporalapósoprocedimento,oque acar-retaria aumentonodesgasteda próteseenovasintervenc¸õescirúrgicasemumtempo inferioràquelesquesemantémemíndicedemassacorporal(IMC)adequado.Oobjetivo desteestudofoiinvestigaroefeitodacirurgiadeATJnoIMCdessespacientes.

Métodos:Inicialmenteforamanalisadososprontuários,escolhidosaoacaso,de91pacientes submetidosàATJdeagostode2011ajulhode2013.Ospacientesforamestratificadospelo IMCcomopesonormal(IMCentre20-25),sobrepeso(IMCentre25-30)eobesidade(IMC>30) ereavaliadosem18mesesnomínimo.

Resultados: Amédiadeidadedapopulac¸ãoamostralfoide68,1anos,69,1parahomense 67,2paramulheres.OIMCmédiopré-operatóriofoide27,24kg/m2_{.Entreosparticipantesdo}

estudo,noperíodopré-operatório,17pacientesapresentavampesonormal;65,sobrepesoe nove,obesidade.Aanálisepós-operatóriademonstroudiminuic¸ãonopesoem41pacientes (46%)eganhoponderalem50(54%).OIMCmédiopós-operatóriofoide27,16kg/m2_,de

formageral,ocorreuumaligeiraquedadoIMCmédioem0,08kg/m2_.

Conclusão: OspacientessubmetidosàATJnãoobtiveramreduc¸ãosignificativadoIMCapós oprocedimentocirúrgico.

©2017PublicadoporElsevierEditoraLtda.emnomedeSociedadeBrasileirade OrtopediaeTraumatologia.Este ´eumartigoOpenAccesssobumalicenc¸aCCBY-NC-ND (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Introduction

Obesityisaseriousprobleminbothdevelopedanddeveloping countries.Itislikelyoneofthefactorsthatismostassociated withtheincreaseinthemorbimortalityoftheglobal popula-tionnowadays.1_{Theincreaseinobesitywilllikelycausean}

increaseintheincidenceofkneeosteoarthritisandhencein thenumberoftotalkneearthroplasties(TKA).2

EvidenceindicatesthattherelativerisktoundergoaTKA variesfrom3.20foroverweightindividuals to32.73in indi-vidualswithmorbidobesitygradeIII_.3_{Highbodymassindex}

(BMI)hasbeenshowntobeariskfactorforworseningofknee osteoarthritis.1–5 _{Therelationshipbetweenarthroplastyand}

increasedBMIisthereforeincreasinglyimportantinrelation totheoutcomesinthepostoperativeperiodandthe expecta-tionsofpatients.5

Todate,the gold standard treatmentforobese patients withkneeosteoarthritisremainsthesubjectofdebate,since patients with a high BMI (>30kg/m2_{) are at higher risk of}

developingcomplicationsafterTKA.6_{Kerkhoffsetal.}7_suggest

thatthesepatientsshouldfirstundergoabodyweightcontrol programinordertoreducetheriskofpostoperative compli-cations,whichiswhymanysurgeonsarereluctanttoperform TKAinthispopulation.8_{TheimpactofbodyweightonTKA}

hasnotbeenfullyexplored.Clinicallysignificantbodyweight gainafterTKAcouldposepotentiallyharmfulhealthrisks.9

However, preoperative weight loss inTKA is an impor-tant measure that should be strongly encouraged, since highBMIhasbeenshowntobeariskfactorforworsening kneeosteoarthritis.10–15 _{Thebenefitsofweightlossinclude}

decreasedsurgicalriskandincreasedlongevityofthe pros-theticimplant.However,severalstudieshavedemonstrated

thatpatientswhoundergoTKAtendtomaintainorgainbody weightafterthesurgicalprocedurewhencomparedwiththe periodbeforethe placementoftheprosthesis,whichleads toanacceleratedincreaseinprosthesiswear.Therefore,the obesepatientwillhavetoundergoanewsurgicalintervention inashortertimeintervalthanthosewithanadequateBMI.1,3,4

The rate of obesity among the adult population has increased inepidemic proportions. Statistical datasupport thehypothesisthatobesityrateswillcontinuetogrowuntil 2030.16_{Accordingtothemedicalliterature,theobeseand}

over-weightpopulations,assessedbyBMI,aremorelikelytohave conditions such as knee osteoarthritis.1–3,14 _{In the present}

study,itwasobservedthatthevastmajorityofpatientseligible forTKAareabovetheiridealweight(82%).

Thesignificantimprovementinjointpainandfunctional limitations after TKA14,15 _{does not change the patients’}

lifestylehabits.17–20

Theresultsofthesestudiesarealarming,sincethenumber ofyoungpatientsundergoingkneearthroplastyisgradually increasing.13,16 _{Furthermore,ahigher-than-ideal BMIraises}

concernsregardingthelowerdurabilityoftheprosthesis.13,20

ThepresentstudyaimedtoinvestigatetheeffectofTKA ontheBMIofpatientsundergoingthisprocedure.

Material

and

methods

whounderwentkneearthroplasty,withaminimum1.5years ofpost-operativefollow-up.Patientswithincompletedataand recordsandthosewhowerenotweighed(ineitherthe pre-orpostoperativeperiods) wereexcluded.Ofthe100records analyzed,91 met the aforementioned criteria. Ofthese, 21 (24%)were menand 70(76%)werewomen.Inthe preoper-ativeperiod,themeanageofthesamplepopulationwas68.1 years(SD±2);69.1±2formenand67.2±2forwomen.

Bothweightand heightinthe preoperativeperiodwere measuredonaconventionalscalewithaheightgauge.BMI wascalculatedusingthebodymass/height2_formula.The

cur-rentweightofthe patientswas assessedagain atleast1.5 yearsaftersurgery.PatientswerestratifiedbyBMIasfollows: normalweight(between20and25),overweight(between25 and30),andobese(over30),asproposedbytheWorldHealth Organization.11,12

Datawere analyzedbySPSSsoftwareforWindows, ver-sion17;descriptivestatisticsandfrequencydistributionwere observed.Groupswere correlatedusing theMann–Whitney test.BMIvariationswerecomparedbetweenmaleandfemale patients,andacomparisonofthegroupsstratifiedaccording toBMIwasalsomade.

Results

MeanpreoperativeBMIwas27.24kg/m2_{.AsshowninTable1,}

inthepreoperativeperiod17patientshadnormalweight(BMI 20–25),65wereoverweight(25–30),andninewereobese(>30). Postoperativeanalysisshowedadecreaseinweightin41 patients(46%)andweightgainin50(54%).Meanpostoperative BMIwas27.16kg/m2_{;overall,aslightdecreaseof0.08kg/m}2

wasobserved.Therefore,meanBMIofthestudypopulation remainedpracticallyunchanged.

Fig.1presentstheBMIvariationwithineachgroup.Inthe groupwithpreoperativeBMIfrom20to24.9,aslighttendency towardincreasedBMIwasobserved,withariseof0.04kg/m2

(23.91vs.23.95).Thesamepatternwasobservedinthegroup withBMIfrom 25 to 29.9;the preoperativemean was 27.1 and the postoperative mean was 27.12, i.e. an increase of 0.02kg/m2_{. Conversely,adownward trend wasobserved in}

those withpreoperative BMIgreater than 30kg/m2_{, with a}

fallof0.42kg/m2_{(31.66vs.31.24).Onceagain,themeanBMI}

remainedpracticallyunchanged.

Table1–Stratificationofpatientsbypre-and post-operativebodymassindex.

Pre-operativeclassification Post-operativeclassification

Normalweight (20–25kg/m2_):

17

Normalweight(20–25kg/m2_):

15

Overweight(25–30kg/m2_):2

Obese(>30kg/m2_):0

Overweight(25–30kg/m2_):

65

Normalweight(20–25kg/m2_):2

Overweight(25–30kg/m2_):61

Obese(>30kg/m2_):2

Obese(>30kg/m2_):

9

Normalweight(20–25kg/m2_):0

Overweight(25–30kg/m2_):2

Obese(>30kg/m2_):7

BMI range ; 20-24.9(Pre); 23.91 ; 20-24.9(Post); 23.95 ; 25-29.9(Pre); 27.1 ; 25-29.9(Post); 27.12 ; >30(Pre);

31.66 ; >30(Post); 31.24

IMC

Fig.1–Comparisonbetweenpre-andpostoperativebody massindex(BMI).

Discussion

As observedin thepresent study, therewas no significant reductioninbodymassaftersurgery,and54%ofthepatients presentedweightgain.Ofthe threegroups,onlythegroup ofpatientswithpreoperativeBMIabove30kg/m2_presenteda

trendofbodymassreduction.Somestudiesreportedthata post-operativeweightgainofmorethan5%–10%hada nega-tiveimpactonpainandfunction.21,22_{AccordingtoTeichtahl}

etal.,22_{asignificantpredictorofpostoperativeweightlossis}

worsepreoperativefunction.Thepresent studyisin agree-ment with a study published byZeni et al., in which 47% ofthepatientsstudiedpresentedweightgainoneyearafter thesurgicalprocedure.23 _{Asimilartrendofmaintenanceof}

BMIlevelsabovetheidealwasobservedinmenandwomen. Otherstudieshaveobservedagreatertendencyofwomento loseweightpost-surgeryandalowerpropensityformento eitherloseorgainweightinboththepre-andpostoperative periods,inadditiontoalowerpropensityforweightgainin older patients.24,25 _Stetsetal.26 _{alsofoundthat only21.5%}

oftheirpatientspresentedareductioninBMI;intheother patients,weightwasmaintained(59.2%)orincreased(19.9%). Regardingobesepatients,Järvenpääetal.27_{observedalower}

lossofperiprostheticbonemineraldensityinthe postopera-tiveperiod,probablyrelatedtoagreaterinducedstressdueto highbodyweight.

Thepresent study corroboratesthe findings retrievedin the literature, in which no significant decrease in BMI is observed.17,18,20

Thelimitationsobservedinthepresentstudyincludethe lackofacontrolgroupanddataonnutrition,physicalactivity level,socioeconomicprofile,andeducationallevelofthe stud-iedpatients.Althoughsomestudiesdidnotshowsignificant differenceintheimpactofpreoperativeweightlosson surgi-calsiteinfectionandhospitalreadmissionrates,28_thepresent

study showsthe importanceofthe decreaseinBMI imme-diatelyinthepreoperativeperiod,sincethereisatendency toincreaseormaintainweightamongpatientssubmittedto kneereplacement.5,6

anthropometricmeasurementsinpatientswithBMIbetween 20and30kg/m2_{;however,inpatientswhowereobesepriorto}

surgery,therewasaslighttrendtowardareductioninBMI. The reasons why patients undergoing TKA cannot lose weightneedtobebetterevaluatedandmaybethesubject offuturestudies.

Conclusion

Patients who underwent TKA did not obtain a significant reductionofBMIafterthesurgicalprocedure.Ofthese,46% lostand54%gainedweightinthepostoperativeperiod.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

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