Rev. bras. ortop. vol.52 número1

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SOCIEDADE BRASILEIRA DE ORTOPEDIA E TRAUMATOLOGIA

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

Original

article

Arthroscopic

subcapital

realignment

osteotomy

in

chronic

and

stable

slipped

capital

femoral

epiphysis:

early

results

夽

Bruno

Dutra

Roos

∗

_,

_Marcelo

_Camargo

_de

_Assis,

_Milton

_Valdomiro

_Roos,

Antero

Camisa

Júnior,

Ezequiel

Moreno

Ungaretti

Lima,

Rodolfo

Cavanus

Pagani

UniversidadedePassoFundo,FaculdadedeMedicina,HospitalOrtopédicodePassoFundo,PassoFundo,RS,Brazil

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Articlehistory:

Received1February2016 Accepted29March2016

Availableonline29December2016

Keywords:

Epiphyses,slipped Hip

Femurhead Arthroscopy Child

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b

s

t

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t

Objective:Thisstudyaimedtoevaluatetheclinicalandradiographicoutcomes,aswellas

thecomplicationsofarthroscopicsubcapitalrealignmentosteotomyinchronicandstable slippedcapitalfemoralepiphysis(SCFE).Asindicatedbytheliteraturereview,thisisthe firsttimethistypeofarthroscopicosteotomywasdescribed.

Methods:BetweenJune2012andDecember2014,sevenpatientsweresubmittedto

arthro-scopicsubcapitalrealignmentosteotomyinchronicandstableSCFE.Themeanagewas11 yearsand4months,andthemeanfollow-upperiodwas16.5months(6–36).Clinicalresults wereevaluatedusingtheModifiedHarrisHipScore(MHHS),whichwasmeasuredpre-and postoperatively.RadiographswereevaluatedusingtheSouthwickquantitativeclassification andtheepiphysis–diaphysisangle(pre-andpostoperatively).Complicationswereassessed.

Results:The meanpreoperativeMHHSwas35.8points,and97.5pointspost-operatively

(p<0.05).Radiographically,fivepatientswereclassifiedasSouthwickclassificationgrade II_and_two_as_gradeIII_._The_mean_correction_of_the_{epiphysis-diaphysis}_angle_was₄₀◦_._No

immediatepostoperativelycomplicationswereobserved.Onepatientpresentedfemoral headavascularnecrosis,withoutcollapseorchondrolysisatthemostrecentfollow-up(22 months)

Conclusion: Thearthroscopictechniquepresentedforsubcapitalrealignmentosteotomyin

chronicandstableSCFEshowedsatisfactoryclinicalandradiographicoutcomesina16.5 monthsfollow-upperiod.

夽

StudyconductedattheHospitalOrtopédicodePassoFundo(HOPF),CirurgiadoQuadril,PassoFundo,RS,Brazil.

∗ _{Corresponding}_author_.

E-mail:[email protected](B.D.Roos). http://dx.doi.org/10.1016/j.rboe.2016.12.007

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Osteotomia

artroscópica

de

realinhamento

subcapital

no

tratamento

da

epifisiólise

proximal

do

fêmur

crônica

e

estável:

resultados

precoces

Palavras-chave:

Epífisedeslocada Quadril

Cabec¸adofêmur Artroscopia Crianc¸a

r

e

s

u

m

o

Objetivo: Avaliaros resultados clínicos e radiográficos,bem como as complicac¸ões da

osteotomiaderealinhamentosubcapitalporviaartroscópicaparatratamentodaepifisiólise proximaldofêmur(EPF)crônicaeestável,relativosaumasérieinicialdepacientes. Con-formeanálisedaliteratura,oestudoapresentaaprimeiradescric¸ãodetécnicaartroscópica dessetipodeosteotomia.

Métodos: Entre junhode2012a dezembrode2014,sete pacientesforamsubmetidos à

osteotomiaderealinhamentosubcapitalporviaartroscópicaparatratamentodaEPFcrônica eestável.Aidademédiadospacientesfoide11anosequatromeses.Oseguimentomínimo foideseisa36meses(médiade16,5meses).Ospacientesforamavaliadosclinicamente deacordocomoHarrisHipScoremodificadoporByrderadiograficamenteconformea classificac¸ãoquantitativadeSouthwickeoânguloepifisio-diafisário.Complicac¸ões pós-operatóriasforamanalisadas.

Resultados: Comrelac¸ãoàavaliac¸ãodoescoreclínicoHarrisHipScoreModificadoporByrd,

observou-semédiapré-operatóriade35,8pontosepós-operatóriade97,5pontos(p<0,05). Radiograficamente,cincopacientesforamclassificadoscomograuII_e_dois_como_grauIII deSouthwick.Observou-secorreçãomédiadoânguloepifisio-diafisáriode40o_._Não_houve complicaçõespós-operatóriasimediatas.Umpacienteevoluiucomnecroseavascularda cabeçafemoral,semcolapsooucondrólisenoúltimoseguimento(22meses).

Conclusão:AtécnicaartroscópicaapresentadapelosautoresparatratamentodaEPFcrônica

eestávelresultouemmelhoriaclínicaeradiográficadospacientesnestasérieinicial. ©2016SociedadeBrasileiradeOrtopediaeTraumatologia.PublicadoporElsevier EditoraLtda.Este ´eumartigoOpenAccesssobumalicenc¸aCCBY-NC-ND(http:// creativecommons.org/licenses/by-nc-nd/4.0/).

Introduction

Slippedcapitalfemoralepiphysis(SCFE)isthemostcommon diseaseoftheadolescenthip, withanestimatedfrequency of10.8per100,000individuals.1_Recent_studies_on_the

biome-chanicsoffemoroacetabularimpingement(FAI)indicatethat small anatomical deformities that may arise from SCFE potentiallycausepermanentacetabularchondraldamage,2,3

leadingtoearlyosteoarthritis.

ThereisnoconsensusregardingthebestSCFEtreatment option,especiallyconsideringhigh-gradeslips(gradesIIand IIIofthe Southwick classification).4 _Some_authors _indicate

treatmentwithinsitufixationinthesecases,becausethis procedure has a low complication rate. They believe that the residual hip deformity remodelsduring growth allow-ingproperfunction.5,6_Others,_including_the_present_authors,

indicatecorrectingthedeformitysite(subcapitalrealignment osteotomy)inorder to achieve ananatomical reductionof theepiphysisanddecreasetheriskofsubsequentchondral degeneration.7

Themaincriticism oftheauthorscontrarytotheuseof thesubcapitalrealignmentosteotomytechniqueistheriskof complicationssuchasavascularnecrosis(AVN)ofthefemoral headandchondrolysis,whichcanoccurinupto28%ofcases.8

However,thegrowingnumberofstudiesinthisareahasled toareductionincomplications.Itisessentialtoobserve tech-nicaldetailstopreservethevascularsupplyoftheepiphysis duringtheprocedure.7

Thisstudyaimedtoassess theclinicalandradiographic results and the complications of arthroscopic subcapital realignmentosteotomyasatreatmentforchronicandstable SCFEinaninitialseriesofpatients.

Accordingtoourliteraturesearch,thisisthefirst descrip-tionofarthroscopicsubcapitalrealignmentosteotomyforthe treatmentofchronicandstableSCFE.

Materials

and

methods

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Proximal

B

A

L

H

FN

Lateral

Distal Medial

Medial

H

FN

D

Fig.1–(A)IntraoperativeimageofhiparthroscopyforsubcapitalrealignmentinthetreatmentofchronicandstableSCFE, disclosingtheexposureofthelabrum(L),femoralhead(H),andfemoralneck(FN).(B)Axialcharacterizationofthelefthip showingthefemoralhead(H),femoralneck(FN),andCAM-typedeformityofthefemoralneck(D)resultingfromthe chronicityoftheSCFE.

Regardingclinicalaspects,thepatientswereevaluated pre-andpostoperativelyaccordingtotheHarrisHipScoremodified byByrd(MHHS)apudGuimarãesetal.9

Thecaseswere radiographicallyevaluated in the pelvic anteroposteriorandfroglegviews.Todeterminethedegree ofpreoperativeslippage,the Southwick4 _criteria_were_used

andthecaseswereclassifiedasgradeI_(up_to₃₀◦_),_gradeII (30◦_–60◦_),_or_gradeIII_(above₆₀◦_)._The_degree_of_slip_correction wasalsodetermined,bycomparingthepre-and postopera-tivemeasuresoftheepiphyseal-diaphysealangle4_(EDA)_in_the

froglegview.Duringfollow-up,thepresenceofAVNand/or chondrolysiswasanalyzed.

The statistical method used for the analysis of paired variables(MHHS,EDA)wastheWilcoxontest,considered sta-tisticallysignificantatp<0.05.

Surgical

technique

Generalanesthesiawithfemoralnerveblockwasusedtoall cases.Physicalexaminationofthehipwiththepatientunder anesthesia was used to passively assess bilateral range of motion.

Thepatientwasplacedinthesupinepositionona radiolu-centtable.Theorthopedictractiontablewasnotused,due tothe needforgreater hipmobility forthemultiple intra-operative maneuvers. The pelviswas slightly tilted to the contralateralside,andaradiolucentcushionwasplacedunder theaffectedhemipelvis.

Theanatomicalreferencesweremarkedwithan appropri-atepen.Averticallinewasdrawn fromtheanterosuperior iliacspinetowardthecenterofthepatella.Theanterior, pos-terior,andproximalbordersofthegreatertrochanterofthe femurwere marked. Theportals were positioned withthe assistanceoffluoroscopy.Thefirstportalwasthemid-anterior (MAP),whichisusedforthecamera.Subsequently,the proxi-malmid-anteriorportal(PMAP),whichistheworkingportal,is

positionedtoprovideaparallelaccesstotheproximalfemoral physis.

Thearthroscopicapproachusedforsubcapitalrealignment was extracapsular,10 _following_the _access_to_the _peripheral

jointcompartmentdescribedbySampson.11

Withtheaffectedlimbinaneutralpositionandafter estab-lishingthearthroscopicportals,theanteriorjointcapsuleand the iliocapsularmuscleweredissectedwithradiofrequency andshavertoobtainproperexposure.Then,aT-capsulotomy of the femoral neck was made, which could be extended as required. Subsequently, capsulectomy was made until a proper exposure of the anterior metaphysis and epiph-ysisoftheproximalfemurinits mid-lateralextensionwas obtained.Withradiofrequency,thelongitudinalopeningofthe periosteumanditsdetachmentfromthefemoralneckwere made,formingaretinacularflaptogetherwiththeepiphysis (Fig.1).

After proper exposure, an osteochondroplasty of the femoral neck-head transition is made, which allows the resection of a CAM-type deformity originated by the SCFE chronicity; it also allows a better identification of physis (Fig.2).Inmoreseveredegreesofslippage,externalrotation andlimbextensionmayberequiredtoexposetheepiphyseal plate.Theosteotomyisperformed2mmdistaltothegrowth plate(tofacilitateasubsequentneckshortening)witha spe-cificcurvedosteotomeatdifferentlocationsoftheepiphyseal plate, until the epiphysis and metaphysis are completely separated.Allpatientshadopenepiphysealplate,andno dif-ficultieswereobservedatthissurgicalstep(Fig.3).

Whenthefemoralmetaphysiswasseparatedfromthe epi-physis,thehipwasexternallyrotatedandgentlytractionedto enabletheshorteningoftheneckandgrowthplateresection usingarthroscopiccurette(Fig.4).Subsequently,thehipwas adductedtoremovethe neoformedbonetissueinthe pos-teromedialfemoralneckregion,whichcanbeanobstacleto subsequentreduction.

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Proximal

B

A

H

FN Lateral

Lateral

Distal Medial

Medial

H

FN

Fig.2–(A)IntraoperativeimageofthelefthipafterfemoralneckosteochondroplastyforthecorrectionofCAM-type deformityshowingthefemoralhead(H)andfemoralneck(FN).(B)Axialcharacterizationofthelefthip,showingthe femoralhead(H)andfemoralneck(FN)afterfemoralneckosteochondroplastyforthecorrectionofCAM-typedeformity.

Proximal

B

A

CO

FN

Lateral

Distal Medial

Medial

FN

GP

Fig.3–Intraoperativeimageofthelefthipshowingthefemoralneck(FN)andthecurvedosteotome(CO)duringneck osteotomyatthelevelofthegrowthplate.(B)Axialcharacterizationofthelefthipshowingthefemoralhead(H),femoral neck(FN),thegrowthplate(GP),andthecurvedosteotome(CO)positionedforneckosteotomy.

Proximal

B

A

AC

FN

Lateral

Distal Medial

Medial

H FN

AC

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Lateral Medial

FN

Fig.5–Axialcharacterizationofthelefthipshowingthe femoralhead(H)andfemoralneck(FN)afterosteotomy reduction.

partially threaded cancellous screw was used for percuta-neousfixation(Figs.6–8).

Toreducethe riskofavascularnecrosisoftheproximal femoralepiphysis, atthe time ofthe neck osteotomyit is essentialtoavoiddirectingtheosteotometowardthe postero-superiorretinaculum(whichcontainstheterminalbranches ofthe medialcircumflexartery)andtowardthe lower reti-nacularartery(whichisdirectedtowardtheepiphysisoutside theretinaculartissueofthefemoralneckinthemedial Weit-brechtligament),whicharenotvisualizedduringarthroscopy. Likewise, shortening of the femoral neck and appropriate

resectionoftheposteromedialboneformationareessentialto avoidexcessivetensioningofthevesselsduringtheosteotomy reductionmaneuver.

Postoperatively, patients were hospitalized for 24h for observation ofclinical outcome.Naproxenwasused for30 days toprevent heterotopic ossification; patients were ori-entedtousecrutcheswithoutweightbearingontheoperated limbforthesameperiod,withoutrestrictionstothehiprange ofmotion.At30postoperativedays,controlradiographswere madeandfullweightbearingwasauthorized.

Results

RegardingtheassessmentoftheMHHSscore,themean pre-operativescorewas35.8points(SD=4.1,range=30.8–41.8)and themeanpostoperativescore,97.5(SD=2.9,range=93.5–100), withameanpostoperativeincreaseof61.7.Therewasa sta-tisticallysignificantdifference(p<0.05)whencomparingthe pre-andpostoperativeMHHS.9

Regardingtheradiographicevaluation,fivepatientswere preoperatively classifiedasSouthwick4 _gradeIIand twoas gradeIII_._The_mean_{pre-operative}_EDA4_was_51.2◦ _(SD₌_12.4, range=32◦_–68◦₎ _and _{postoperative,} _11.2◦ _(SD₌_5.1, _range₌ 6◦_–18◦_),_with_a_mean_{postoperative}_correction_of₄₀◦_._A sta-tisticallysignificant differencewasobserved(p<0.05)when comparingthepre-andpostoperativeEDA4₍_Table₁_).

There were no immediate postoperative complications. Onepatient(case2)evolvedwithAVN60daysaftersurgery, withoutcollapseorchondrolysisuntilthelastfollow-up(22 months).Thiscasehadalargeposteromedialboneformation

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Fig.7–Femalepatientaged12yearsandtwomonths.Paininthelefthipforonemonth,wasabletowalkwithoutcrutches. HiplockedinIR,90◦_of_flexion._(A)_and_(B)_Preoperative_radiographs_showing_Southwick_grade_II_SCFE_to_the_left,_EDA₄₅◦_._(C) and(D)Postoperativeradiographsatsixmonthsoffollow-updisclosingdeformitycorrection,EDA6◦_.

inthefemoralneck,whichtheauthorsbelievetohavebeen insufficientlyresected.

Discussion

SCFEisthemostcommondiseaseoftheadolescenthip, esti-matedat10.8per100,000individuals.1_Recent_studies_on_the

biomechanicsofFAIindicatethatsmallanatomical deformi-tiesofthehipthatmayarisefromSCFEareapotentialcause ofpermanentacetabularchondraldamage2_and_lead_to_early

osteoarthritis.

The anterior displacement of the femoral meta-physis caused by mild or moderate slips (Southwick classification)4 _leads _to _CAM-type _FAI _and _generates _a

progressive injury on the chondrolabral junction due to excessive shear stress on the structure. In severe SCFE, the degenerative biomechanical mechanism is PINCER-type FAI, since the large deformity generates compression and primary failure of the acetabular labrum, as well as contrecoup injury in the posteroinferior cartilage of the acetabulum.8

Leunig et al.2 _evidenced _labral _and _chondral _acetabular

injuries in14 patientswith unstable SCFE3 _during_surgery

using the surgical dislocation of the hip technique; they observed that these injuries occurred when the femoral metaphysiswasatorextendedbeyondtheepiphysealline. Likewise, Sink et al.,12 _using _the _same _technique,

demon-stratedthepresenceofintra-articularinjuriesin39patients withSCFE,34labraland33chondral.

Table1–Operatedcases,description,andmeanmeasurements.

Patient Gender Age(months) Side Follow-up (months)

MHHS pre-op

MHHS post-op

EDA pre-op

EDA post-op

Complications

1 M 147 L 36 30.8 93.5 62 18

2 M 130 R 22 30.8 93.5 42 6 AVN

3 M 132 R 20 34.1 100 54 8

4 M 133 L 12 37.4 97.9 56 12

5 F 134 L 10 38.5 97.9 68 18

6 M 135 L 10 41.8 100 32 11

7 F 146 L 6 37.4 100 45 6

Mean 136.7 16.5 35.8 97.5 51.2 11.2

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Anterior X X Proximal Posterior Distal

∗

Fig.8–Aspectoftheincisionsshowingthearthroscopic portals(X)andtheincisionforpercutaneousfixationofthe femoralneck(*).

Dunn’s original procedure for the treatment of SCFE, describedin1964,consistedofatrapezoidalproximalfemoral neck osteotomy for further reduction and fixation of the slippage.13_Their_results_were_first_published_in_1978,

compris-ing78hips(25acuteand48chronic);ninecasesprogressedto AVN(twocaseswithcompleteepiphysealnecrosis).14

Ganzetal.15_described _the_use _of_the_surgical_hip

dislo-cationtechniqueinamodifiedDunnosteotomy(subcapital realignmentosteotomy)inthetreatmentofhigh-gradeSCFE.4

Accordingtotheauthors,thisapproachprovidesaccesstothe hip,preservestheepiphysealvascularsupply,andallows ade-quateresectionoftheposteromedialboneformationinthe femoralneckandsatisfactoryreductionoftheepiphysis.This makesitpossibletorestoretheanatomyoftheproximalfemur withatechniquethatreducestheriskofAVN.15

Leunigetal.16_published_the_first_results_of_this_technique_in

2007,with30hipstreatedandameanfollow-upof55months. Ofthese,24caseswereconsideredchronicslips,andnocase progressedtoAVN.Twocases(6.66%)underwentreoperation due tofailure ofthe fixation withscrews. Ziebarthet al.7

alsoretrospectivelyevaluatedthistechniquein40patients, dividedinto twocohortsfrom differentcenters,withmean follow-upsof5.4and2.2years.Thealphaangleandtheslip anglewerenormalizedinallcases,withnocasesofAVNor chondrolysis.7

Otherauthorswhohavepublishedtheirresultsontheuse ofthetechniquedescribedbyGanzshowedagreaternumber ofcomplications.Sankaretal.,17_in_a_multicenter_study_that

evaluated27patientswithunstableSCFE3_in_mean_follow-up

of22.3months,observedfourpatients(15%)requiring reope-rationforfailure offixationand sevencases(26%) ofAVN. Themeanpostoperativecourseuntilosteonecrosiswas21.4 weeks;patientswhodidnotdevelopthiscomplication pre-sented asignificantly lower clinical painscore and greater postoperativesatisfaction.17 _Upasani _et _al.18 _presented_the

resultsof43patientstreatedwiththistechnique;60%ofcases patientshadunstableSCFE,3_40%_were_considered_acute,_and

86%wereclassifiedassevereslip.4_Those_authors_observed₂₂

complicationsin16patients;therewere15reoperationsdue

toAVN,fixationfailure,andpostoperativehipdislocation.Two patientsreceivedindicationfortotalhiparthroplasty.

TwoBrazilianstudiesreportedthearthroscopictreatment ofchronic-acutizedSCFE(unstable).3_Akkari_et_al.19_presented

theresultsoffivecasestreatedwitharthroscopictrapezoidal osteotomywithameanpreoperativeEDA4_of₈₂◦_and_a_mean postoperativeEDAof14◦_;_one_case_developed_AVN.19_Dobashi etal.20_presented_a_case_report_of_a_12-year-old_patient_who

underwentaDunn-typearthroscopicfemoralneckosteotomy; theslippagewascorrectedfrom70◦_to₃₀◦_.

The present study presented an alternative to classical techniques of subcapital realignment for the treatment of chronicandstableSCFE3_that_allows_adequate_access_to_the

hip joint andappropriatereductionofthe slippage,witha theoretical advantageofrapidrehabilitation.Theperiodof slippageevolutionisnotalimitingfactorfortheapplication ofthistechnique;nonetheless,itwasonlyindicatedincases withopenepiphysealplate.

Accordingtoaliteraturesearch,thisisthefirstdescription ofanarthroscopicsubcapitalrealignmentosteotomyforthe treatmentofchronicandstableSCFE.Theauthorsreiterate that,priortotheperformanceofthearthroscopictechnique described,itisessentialthatthesurgeonreceivesadequate traininginhiparthroscopy,aswellasexperienceinopen sub-capitalosteotomy,duetothemultipletechnicaldifficultiesof treatment.

Conclusion

Thearthroscopictechniquepresentedbytheauthorsforthe treatmentofchronicand stableproximalfemoral epiphysi-olysis resultedinclinicaland radiographicimprovementof patientsinthisinitialseries,withameanfollow-upof16.5 months.OnecaseofAVN,withoutcollapseorchondrolysis, wasobservedat22monthsoffollow-up.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

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