Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6051_Библиотеки_им_академика_М_И_Перельмана
.pdf
adultdegenerativescoliosis:stoppingatT10versusL1.Spine2006;31(19,Suppl):S185–S194PubMed
minimumfive-yearanalysisoffiftypatients.Spine2008;33:1478–1483PubMed
andfusiontothesacrum:prevalenceandriskfactoranalysisof144cases.Spine2006;31:2329–2336PubMed
3
The Use of Osteotomies for Rigid Spinal
Deformities
StephenJ.LewisandSimonA.Harris
Introduction
The use of spinal osteotomies in severe spinal deformities has enabled corrections that
were not considered possible in the past. With advanced posterior-based techniques,
excellentcorrectionsare achievedthrough a singleapproach, shorteningthe duration of
surgeryandreducingtheneedformultiplepositionchangesduringsurgery.Althoughthe
majority of corrections can be performed from the posterior direction, selective
deformitiesmayrequirecombinedanteriorprocedures.
With the improvement in surgical techniques and neuromonitoring modalities,
obtaining corrections of severe spinal deformities is now both possible and reasonably
safe.
1
Thorough knowledge of advanced anatomy, careful preoperative planning, and
specialized instrumentation and implants provide the necessary tools for successful
surgery.Thischapterreviewsthevariousosteotomies,theindicationsfortheiruse,aswell
as the methods of maximizing corrections and minimizing both short-and long-term
complications.
PlanningtheDeformityCorrection
Although deciding whether or not to operate is the first main decision to be made,
planningthefinerdetailsoftheprocedurewillhelpensureasmootherflowofthesurgery.
The main planning should be done preoperatively, and an algorithm for key decisions
should be established preoperatively and discussed with the patient and family. For
example, if the patient does not wish to assume the increased risk associated with
achieving a morecomplete deformity correction, it isimportantto discuss what can be
achievedwithlesserreleases.Conversely,ifcorrectionisakeycomponentofthepatient’s
expectationsandthesurgicalteamcanreliablyachievethesegoalssafely,athree-column
osteotomycanbeperformediflesserosteotomiesareunsuccessful.
DeterminingtheFlexibilityoftheDeformity
Using the least risky procedure to obtain a correction is key to the safe outcome of
deformity surgery. If a similar correction can be obtained through multiple posterior
column releases, a three-column osteotomy may not be necessary. Determining the
flexibility of the curve can often be difficult, and intraoperative adjustments may be
requiredincaseswherethecurveismorestifforlessstiffthanexpected.
Helpfulcluestocurveflexibilityincludethepresenceofwidediskspaces,diskspaces
thatopenandcloseonbendingfilms,andcurvemagnitudesthatdecreasewhenthepatient
is in the prone position or with traction views. If computed tomography (CT) imaging
demonstrates anterior fusions, either congenital or from previous surgery, these fusions
willnotcorrectwithposteriorreleases,andthree-columnosteotomieswillberequired.In
contrast, good corrections can be achieved with posterior column releases through
previousposteriorfusionmassesthathavenotundergonepreviousanteriorfusions.Proper
preoperativeworkupwithlong-cassetteanteroposterior(AP)andlateralsidebenders,CT
scan,and magneticresonance imaging(MRI) shouldbedone preoperatively,so thatthe
bestpossiblepreoperativeplancanbemade.Newertechnologieswiththree-dimensional
(3D)printerscan providesurgeonswithpreoperativemodels ofthespine,to evenbetter
preparefortheultimateprocedure.
Exposure
Excellent exposure is an essential component of the procedure. Severe deformities can
make thismorechallenging; however,taking the time to obtainthenecessary exposure
willgreatlyfacilitateimplantinsertion,andgenerallyimprovetheflowoftheprocedure.It
is important to identify the spine levels, areas with previous decompressions, fusion
masses, and previous implants. In cases of revisions, knowledge of previous spinal
instrumentationwillensurethattherequiredinstrumentsareavailabletofacilitateimplant
removal.
SpinalCordBloodFlow
The blood flow to the spinal cord enters the dura through vessels that travel with the
exiting nerve root. Although nerve roots are commonly sacrificed in thoracic-level
osteotomies,taking anerveroot atthelevel oftheartery ofAdamkiewiczcould leadto
significantdetrimenttothespinalcordcirculation.
2
Thisarteryhasvariableanatomy,but
ispresentbetweenT8andL1ontheleftsideinthemajorityofpeople.Whenconsidering
osteotomiesaroundthethoracolumbarjunction,protectingandsavingthenerverootsmay
preservekeysourcesofbloodflow.
For thoracolumbar three-column osteotomies, preoperative angiography can be
performedtodeterminetheexactlocationofthearteryofAdamkiewicz.Thearteryrunsa
characteristicintradural“hairpin”loopon imaging
3
(Fig.3.1). Thelocationof theartery
mayinfluence thechoiceof levelofthe osteotomy,andthe surgeonmaychoose alevel
otherthantheapexifthearteryispresentattheapex.Injuringthisvessel,especiallyinthe
presence of hypotension, can lead to a loss of intraoperative motor evoked potential
(MEP)monitoringthatisoftendelayedfromthetimeofinjury.Withspinalcordinfarction
asone ofthemain risksofspinal cordlevelosteotomies, knowledgeofand attentionto
this artery may help prevent this devastating complication, especially in patients with
previousanteriorprocedures,wheresegmentalvesselsmayhavebeenligated.
Fig. 3.1a,b Spot image (a) and inverse (b) shots of angiography of the left T11 segmental artery showing the
characteristicintraduralhairpinloop (whitearrow),representing the arteryofAdamkiewicz.Inthispatient, the vessel
entersthe dura through theleftT11foramenand forms the loopthatextendsup to T10. With the vessel arisingtwo
levelsproximaltotheapex,avertebralcolumnresectionwasperformedatL1withoutincident.
Fixation
Achievingadequateandstablefixationisessentialtoobtainingandmaintainingdeformity
correction.Although thepediclescrew isthe mainanchor inthe majorityof constructs,
alternativessuchashooks,laminarscrews,fusionmassscrewsorhooks,wires,andbands
should be considered when pedicle screw fixation is not possible.
4
Obtaining adequate
proximal anchors is generally the key determinant of successful constructs in thoracic
osteotomies. Osteotomies should not be attempted unless solid proximal and distal
fixationisestablished.Carefulplanningfromthepreoperativeimageswillhelptoidentify
andselecttheappropriateanchorforeachlevel.
During osteotomy closure, various methods can be utilized to protect the main
implants. Temporary devices orimplantscan be used to close the osteotomies, such as
centralrodconstructs,sparing themainscrews.
5
Theuse ofperiapicalreduction screws,
tubes, or other extenders on the screws, linking of multiple anchors to the rod before
cantileveringthereduction,andtheuseofathree-orfour-rodtechniquewithconnectors
canfacilitatereductionoftheosteotomyandcorrectionofthedeformitieswhileprotecting
themainanchors.
DeterminingtheDesiredCorrection
Theimagingshouldbecarefullystudiedtoidentifythedeformityanddeterminethetype
and magnitude of the desired correction. Careful understanding of the normal sagittal
alignment,thepelvicparameters,andthemagnitudeofthedeformitywillhelptoidentify
whichosteotomieswouldberequiredtogainthedesiredcorrection.
6,7
For fixed kyphotic deformities, correction will be achieved through anterior
lengthening, posterior shortening, or a combination of both. For coronal deformities,
correction will be achieved through concave lengthening, convex shortening, or a
combination of both. For fixed lordosis, correction can be achieved through anterior
shortening,posteriorlengthening,oracombinationofboth.Formultiplanardeformities,it
isimportantto identifytheprimary deformityordeformities,and tailoranosteotomy or
combination of maneuvers to achieve the desired correction. For example, for a fixed
kyphoticscoliosis,acombinationofposteriorshorteningandconvexshorteningcouldbe
the primary mode of correction. If a vertebral column resection (VCR) were to be
performed,alargeranteriorcageplacedontheconcavitycouldmaximizecorrection.For
fixed hyperlordosis, a formal anterior release or resection could be combined with
posteriorcolumnreleasestoachievethedesiredcorrection.
8
The magnitude of the deformity must be considered. Rough estimates of potential
correction through a single osteotomy include 10 degrees of sagittal or coronal plane
correctionthroughasingleposteriorcolumnrelease,30to35degreesofsagittaland10to
15degreesofcoronalplanethroughasinglepediclesubtractionosteotomy(PSO),and30
to50degreesofcorrectionthroughaVCRinthecoronalorsagittalplane.
9,10
ForaVCR,
morecorrectionwillbeachievedthroughadeformitywithoutapreviousfusioncompared
with one that is previously fused, as correction will be achieved only through the
osteotomysiteandnotthroughtheadjacentsegmentsincasesofpreviousfusionmasses.
Properly estimating the desired correction relative to the deformity will help plan the
numberandtypesofosteotomiesrequiredtoachievethedesiredcorrection.
11
DecidingtheLeveloftheOsteotomy
For posterior column releases (Smith Petersen, Ponte), multiple periapical osteotomies
will help achieve a gradual, multilevel correction for deformities with mobile anterior
columns.Forthree-columnosteotomies(PSO,PSOvariants,VCR),thepreferredvertebra
would be at the apex of the deformity, not tilted in the coronal or sagittal planes, and
would be appropriate for proximal and distal fixation. Other considerations include the
location of the artery of Adamkiewicz and the presence of pseudarthrosis in cases of
revisions, in which cases it would preferable be include the nonfused levels in the
osteotomy.
PlanninganOsteotomy
Puttingall theinformationtogetherwillhelp todetermine thebest optionfor deformity
correction.Arepresentativecaseisa66-year-oldwomanwithankylosingspondylitis(Fig.
3.2). Preoperative imaging with long-cassette radiographs and CT demonstrated the
autofusion of herspine. Her chief complaints aresagittal imbalance and difficultywith
forwardgaze.Herpelvicincidencemeasures55degrees,thelumbarlordosis10degrees,
withasacral slopeof5 degreesandapelvic tiltof50 degrees.Withthedesiredlumbar
lordosisbeing10degreeslessthanthepelvicincidence,andthedesiredpelvictilt being
lessthan25degrees,shewouldrequire~35degreesoflumbarlordosis.Thiscanbestbe
achievedthroughasinglelumbarPSO.
As for her thoracic spine, she has significant complaints related to her gaze. Her
thoracickyphosisfromT5toT12measures25degrees,whichiswithinthenormalrange.
Her T2-T5, however, measures 45 degrees, which is greater than the 10 to 15 degrees
expected for this region. A single PSO in this region would provide the necessary
correctiontoimprovehergaze.
Fig. 3.2a–d Representative case of a 66-year-old woman with ankylosing spondylitis as demonstrated on the
preoperativestandingposteroanteriorradiograph(a)andthesagittalCTreconstruction(b).Abnormalsagittalalignment
ischaracterizedbya low sacralslope(SS),highpelvictilt(PT) andinsufficientlumbarlordosis(LL, T12-S1) forthe
givenpelvicincidence(PI).TomaintainabalancedrelationshipofthePIandLL,anL2pediclesubtractionosteotomy
(PSO)wasperformed.ForwardgazewasimprovedwithaT3PSOtocorrecttheproximalthoracickyphoticdeformity.
StabilizationofthiscorrectionwasachievedwithaC2topelvisconstructasdemonstratedonthestandingpostoperative
long-cassetteposteroanterior(c)andlateral(d)radiographs.
ThispatientunderwentaT3andanL2PSOswithaC2-to-pelvisstabilizationthrougha
single-stage procedure, addressing both of her deformities and providing her with the
necessarysagittalbalance.
SingleProcedureorStaged
Althoughit maybe preferabletocompletethesurgery inonestage,certainfactors may
necessitate performing the procedure in two or more stages. These factors include
excessive bleeding,long duration of the surgery, medical comorbidities,and difficulties
withneuromonitoring.Recognizingthesedifficultiespreoperativelymayhelptoelectively
plan performingthese surgeriesover two separatedays. The benefitsof staging include
minimizingoperativeteamfatigue,postponingthebleedingportionoftheproceduretothe
secondday,and thepossibilityofobtainingproper imagingto checkthe positionof the
instrumentation prior to the second stage. The timing between stages is controversial.
Someadvocate ashort timeof 1to 2days, whereasothersrecommend1 to2weeks to
allow patients to achieve their normal nutritional status before proceeding. Logistical
issuesofoperativetimeandsurgicalteamavailability,aswellaspatientandfamilyissues,
alsoneedtobeconsideredinthedecision.
TheSurgicalTeam
Having a strong, cohesive surgical team with open communication is essential to the
successofthesecomplexreconstructions.Ideally,theteamshouldincludeanexperienced
spinesurgeonandanesthesiologist,skilledsurgicalassistants,anursingteamfamiliarwith
the instrumentation and procedure, an experienced neuromonitoring and radiology
technologist,andabloodconservationteam.Opencommunicationisimportant,andsuch
issues as blood pressure parameters, blood conservation strategies, neuromonitoring
changes,andinformationaboutthesurgicalfieldandthestageoftheprocedureshouldbe
reviewedfrequentlythroughoutthecase.
12
ObtainingFusionAcrosstheOsteotomy
Obtaining a solid fusion across the osteotomy is important in preventing early implant
failureat thelevel oftheosteotomy. Althoughmultiple rodscan increasethe rigidityof
theconstructs,having stableanteriorandposteriorcolumns withbridgedstructuralbone
acrossalldefectsiskeytoobtainingfusion.Anteriorgraftsarenotsufficienttoovercome
largeposteriorcolumndefects.Resectedribscanbepreservedintheprocedureandused
to bridge posterior column defects following osteotomy closure.
13
Techniques of
fashioningthe rib andthe hostbed, wiringribs in place,or usingmini-screws fromthe
craniofacial internal fixation sets to secure the ribs will help re-create the structural
continuityoftheposteriorcolumn.
OsteotomyOptions
Spinalosteotomiescanbedividedintosixmaintypes
14
(Fig.3.3):
Posteriorcolumn:
1.Partialfacet
2.Completefacet
Partialbody:
3.Pediclesubtractionosteotomy(PSO)
4.Transdiskalpediclesubtractionosteotomy
Completebody:
5.Vertebralcolumnresection(VCR)
Multiplevertebrae:
6.Multiplevertebralcolumnresection
Inthisclassification,theapproachmodifierwasadded.Iftheprocedurewasperformed
fromposteriorly,theosteotomywouldhavea“P”afterthenumber.Ifacombinedanterior
and posterior surgery was performed, an “A/P” would be added after the number. For
example, if a PSO was performed from posteriorly, it would be considered a type 3P
osteotomy.AVCRperformedthroughacombinedanteriorandposteriorapproachwould
beconsideredatype5A/P.
Fig.3.3a–fSchematicofthecomprehensiveanatomicspinalosteotomyclassificationproposedbySchwabetal.Inthis
classification,Type1 (a)is a partial facet resection,type 2 (b)is acomplete facet resection,type 3 (c) is apedicle
subtraction osteotomy, type 4 (d) is a transdiskal pedicle subtraction osteotomy, type 5 (e) is a vertebral column
resection,andtype6(f)isamulti-levelvertebrectomy.(FromSchwabF,BlondelB,ChayE,etal.Thecomprehensive
anatomicalspinalosteotomyclassification.Neurosurgery2014;74:112–120,discussion120.Reprintedwithpermission.)
Types1and2:PosteriorColumnOsteotomies
Release of the facet joints and the posterior ligamentous structures, including the
ligamentum flavum, provides significant mobility to the posterior column. For any
correction to occur, the anterior column has to be mobile. With the combination of a
mobile anterior column and a released posterior column, significant correction can be
achievedin boththe coronaland sagittalplanes (Fig.3.4).For kyphosiscorrection, this
osteotomyprovidesacombinationofposteriorshorteningandanteriorlengthening.
Type 1 osteotomies involve resection of the inferior facets. This can provide some
mobilityintheposteriorcolumn.Type2osteotomiesinvolveremovalofthesuperiorfacet
andligamentousstructures.Resectionofthesuperiorfacetisthekeytotherelease.This
can be achieved without resecting the inferior facets, especially when significant
distractionofthefacetsoccurs,asisthecasewithlargekyphoticdeformities.Preservation
of the inferior facet during the osteotomy can help to maintain posterior-column bone
stock, aiding in the posterior fusion. Use of a hook-based temporary central rod to
facilitateosteotomyclosurefollowingtheposteriorcolumnreleaseproduced~10degrees
ofcorrectionperosteotomylevelinthethoracicspine(Fig.3.5).
Fig. 3.4a–f Long cassette standing (a) posteroanterior, (b) lateral, and (c) sagittal computed tomography (CT)
reconstruction of a17-year-old boy withan L2 congenital kyphosis. Notethe global compensationof thedeformity
through thoracic and lumbarhyperlordosis. Posterior columnosteotomies were performedatL1-L2 and L2-L3,with
correctionofthe deformityandstabilizationfrom(d) L1 to L3, allowing for (e) thespontaneousnormalizationofthe
thoracickyphosisandadecreasein(f)thecompensatorylumbarhyperlordosis.
Fig.3.5a,b(a)Schematicofaposteriorcolumnosteotomywithresectionofthesuperiorfacets.(b)Osteotomyclosure
is achieved with a temporary central hook-rod construct reducing the inferior facet to the proximal surface of the
pedicle. Note the flexible anterior column allowing anterior lengthening with osteotomy closure. (From Lewis SJ,
GoldsteinS,BodrogiA,etal.ComparisonofpediclesubtractionandSmith-Petersenosteotomiesincorrectingthoracic
kyphosiswhenclosedwithacentralhook-rodconstruct.Spine2014;39:1217–1224.Reprintedwithpermission.)
Type3:PedicleSubtractionOsteotomy
ThePSOis aposterior-based closing-wedgeosteotomy.It isideally suitedfor kyphosis
correctionandcanreliablyproduce25to35degreesoflordosiseveninthepresenceofa
solidlyfusedanteriorcolumn
15
(Fig.3.6).PerformingthePSOasymmetricallycanenable
concomitantcoronal planecorrection.APSOcan beperformedin boththethoracic and
lumbarspines.Incasesofpelvicincidence(PI)andlumbarlordosis(LL)mismatchwith
anassociatedabnormallyhighPI, asacralPSOcanbeperformedto decreasethePIand
normalizethePI–LLrelationship.
16
ThemaincomplicationsassociatedwithPSOsarebleeding,potentialnerverootinjury
orentrapment,andpseudarthrosis.Thetechniqueisdiscussedbelow.Carefulattentionto
detailcanhelpminimizethepotentialmorbiditythatcanbeseenwiththesecases.
Technique
Multiple variations of the technique have been described, but the principles of the
procedurearecommontoallofthem.
Decompression
Following exposure and implant insertion, the pedicle is isolated from all of its bony
attachments: laterally, the transverse process; distally, the pars; and proximally, the
superiorfacet.Acompletelaminectomyof theinvolvedlevelis performedaswellas of
someoralloftheadjacentlevelstoensureadequatespacefortheduralsaccentrallyupon
closure.Completeresection ofthepedicleis requiredtocreatea singleforamenfortwo
nerveroots—thenerve rootofthe osteotomylevelaswell asthenerveroot ofthelevel
proximal.Thecompleteposterior elementsofthevertebraofthe osteotomylevelshould
beresected. Atriangular posterior-basedwedge ofbone isthenremoved fromthe body,
leavingasmallamountofanteriorboneofthevertebralbody.Theanteriorcolumnactsas
ahingeduringclosure.
Соседние файлы в папке Библиотека им академика М.И. Перельмана