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Surgical Radiographic Patient-Specific
•Disruptionofposteriorsoft
tissues
•Rigidityofinstrumentation
• Combined anterior-
posteriorapproach/fusion
• Upper instrumented
vertebrae in the upper
thoracicspine
•Fusiontothesacrum
•Degreeofcorrection
Increasedlumbarlordosis
HighSVAcorrection
Failure to respect global
sagittalalignment
• Increased preoperative
thoracickyphosis
• Increased preoperative
proximaljunctionalangle
•Advancedage
•HighBMI
•Osteoporosis
Abbreviations:BMI,bodymassindex;SVA,sagittalverticalaxis.
Similarly,abiomechanicalmodeldevelopedbyCammarataetal
6
showedthatcomplete
facetectomyand posterior ligamentresection bothindependently increased theproximal
junctional kyphotic angle; combining the two procedures resulted in an even greater
increaseinthekyphoticangle.
Denisetal
9
presentedaseriesof67patientswithScheuermann’skyphosistreatedwith
an instrumented fusion. They highlighted the importance of the posterior ligamentous
structures in theirseries. They separated their cohort ofpatientswith PJK into a group
wherethefusionstoppedshortoftheproximalendvertebraaswellasagroupwherethe
proximalendvertebrawasincludedinthefusion.Thelattergrouphadthreepatientswho
developed PJK. All three were noted to have disruption of the junctional ligamentum
flavum with sublaminar hooks or sublaminar wires. In all, the authors noted that
disruptionoftheposteriorligamentswasimplicatedin25%(5/20)casesofPJKobserved
intheirseries.
Althoughthe abovefindings allhint attheimportance ofthe posteriorstructures, the
trueimpactofposteriordissectionhasbeendifficulttoisolateinclinicalstudies.Although
all surgeons would agree that disruption of the muscular,ligamentous, and bony tissue
likelyoccurscephaladtotheUIV,thedegreeofdisruptionisdifficulttoquantify,letalone
standardize.
2
Despitethislimitation,thespinalreconstructivecommunitygenerallyagrees
thatdamagetotheposteriorsofttissueslikelycontributestothedevelopmentofPJK.
2
RigidityofInstrumentation
In additionto theposteriorsoft tissues,numerousinvestigators havecommented on the
rigidityofinstrumentationasariskfactorfordevelopmentofPJK.Thishasbeenafocus
inthefield,particularlyinlight ofthemore rigid,all-pediclescrewconstructs thathave
gainedinpopularityoverthepasttwodecades.
The biomechanical study by Cammarata et al
6
described in the prior section nicely
highlights the impact of increasing construct rigidity on the proximal junctional angle.
Similarly,Thawranietal
10
usedaporcinecadavermodeltoshowthattransverseprocess
hooksprovideddecreasedstiffnesscomparedwithanallpediclescrewconstruct.Intheall
pedicle screw group, the majority of the motion occurred at the motion segment
immediately proximal to the UIV, whereas this transition was more gradual in the
transverseprocessgroup.
However, clinical studies have not clearly affirmed the findings of the above
biomechanical studies.
5,11,12
Y.J. Kim et al
12
found that the use of all pedicle screw
constructs wasassociated with an increased rateof PJK compared withhybridor hook
constructs(p=0.04),butthisdifferencedidnotremainsignificantwhenadjustingforage
(p = 0.33). Similarly, other published series of adult scoliosis patients have not
demonstratedthatallpediclescrewconstructsweremorelikelytobeassociatedwithPJK
than were hybrid screw–hook constructs.
5
Hassanzadeh and colleagues
11
published a
seriesof47consecutive adultpatientswith2-yearfollow-upwhounderwentlongspinal
fusionwithhooksorscrewsattheUIV.TheyfoundnoinstancesofPJKinthe20patients
treatedwithahookattheUIVcomparedwitha29.6%(8/27patients)rateofPJKinthe
screwsgroup(p=0.01).
SurgicalApproach
Some types of surgical approach have also been associated with PJK. Y.J. Kim and
colleagues
12
foundthat acombinedanteriorand posteriorapproachwasa riskfactorfor
development of PJK, even when adjusted for age (p = 0.04). This finding has been
consistentlyshownto bethecaseinotherseriesas well.
13,14
In aretrospectiveseries of
249patients(adultsandadolescents)whounderwentsurgeryforidiopathicscoliosis,H.J.
Kimetal
14
performedamultivariateanalysistoidentifyriskfactorsforthedevelopment
ofPJK.Theyfoundthatpatientswhounderwentananterior-posteriorapproachwerethree
times as likely (odds ratio [OR], 3.04; 95% confidence interval [CI], 1.56–5.93) to
develop PJK compared with individuals who underwent posterior-only fusion.
Additionally,acombinedanteriorandposteriorapproachwasoneofthefewfactorsthat
couldbeconsistentlyidentifiedasariskinasystematicreviewofthefield.
2
UpperInstrumentedVertebrae
The contribution of the UIV to the development of PJK was suggested in the initial
descriptionofthephenomenon.Glattesandcolleagues
1
foundasignificantlyhigherlevel
ofPJKwhentheinstrumentationstoppedatT3(53%)whencomparedwithT4(12.5%)(p
= 0.02). A subsequent larger series from the same institution did show that an upper
thoracicUIV(T2–6)demonstratedahigherprevalenceofPJK(33.67%,33/98)compared
withlowerthoracicandupperlumbarUIV(p=0.036).
12
However,thisdifferencedidnot
remainsignificantwhenadjustingforage(p=0.65).
12
TheUIV,alongwithacombined
anterior-posteriorapproach,wasonlyoneoftwoindependentriskfactorsassociatedwith
thedevelopmentofPJKinaseriesof249patients.
14
Bridwelletal
15
foundthatpatientswithmoreadvancedPJK(PJK≥20degrees)were
morelikelytohavealowernumberoflevelsfused(8versus11)andweremorelikelyto
have aUIV inthe lowerthoracicspine (p< 0.001). Haet al
16
examinedthe difference
between aUIV inthe lower andupperthoracic spine andfound that themechanism of
failurewasdifferent betweenthe twoscenarios.Failure occurredsooner (p <0.01) and
wasmorelikelytooccurduetofractureinthelowerthoracicspine,whereassubluxation
wasmoreprevalentintheupperthoracicspine.
Other series,however, failedto identify the UIVas a risk factor fordevelopment of
PJK.
5,17
Asystematic reviewfoundlow-levelevidencethat theUIVwasamongtherisk
factorsassociatedwiththedevelopmentofPJK.
2
The mechanism of how the UIV might contribute to the development of PJK is
incompletely understood. Proposed theories include both damage to the adjacent facet
joint that can occur more easily in the upper thoracic spine
18
as well as the interface
betweenthemobilecervicalandrelativelystaticthoracicspine.
1
InstrumentationtotheSacrum/Ilium
Incases ofadultscoliosis, extensionofthe fusiontothe sacropelvisandthe subsequent
increaseinstiffnessoftheconstructhasbeenthoughttocontributetothedevelopmentof
PJK.Intheirseriesofadultpatients,Y.J.Kimandcolleagues
12
foundahigherrateofPJK
inpatientswhoselowerinstrumentedvertebra(LIV)wasS1comparedwithpatientswith
anLIVofL5orabove(51%vs30%,p=0.009).Thisremainedastrongtrend(p=0.059)
evenafteradjustingforage.Yagietal
5
observedasimilartrend;intheirseries,fusionto
the sacrum was associatedwith a significantly higher incidence of PJK (anincrease of
27.6%,p=0.02).AmorerecentclinicalseriesalsofoundthatpatientswithPJKrequiring
revision were more likely to have fusions extending to the pelvis (74% vs 91%, p =
0.02).
19
Fusiontothesacrumwasalsoassociatedwithanincreasedriskofprogressionof
PJKtogreaterthan20degrees.
15
MagnitudeofCorrection
More recently, as we have begun to understand the importance of global sagittal
alignment, investigators have sought to determine if parameters of sagittal alignment
correlate with the incidence of PJK. In general, studies have found that an increase in
sagittal balance correction and an increase in lumbar lordosis correlate with the
development of PJK.
5,17,19,20
The mechanism underlying this increased rate of PJK is
unknown. In their retrospective series, H.J. Kim et al
19
found that patients requiring
revisionsurgeryforPJKhadalumbarlordosis(LL)thatwasclosertothepelvicincidence
(PI),whereasthosewithoutPJKhadaLLmuchlowerthanPI.Theirfindingsaresimilar
tothoseofMaruoandcolleagues,
17
whoshowedthatincreasingLLmorethan30degrees
wasassociatedwithasignificantlyhigherincidenceofPJK(58%vs28%,p=0.003).
Similarly, patients requiring revision surgery with PJK had a lower postoperative
sagittalverticalaxis(SVA)(0.8vs4.1cm)and ahigher magnitudeofSVAcorrection(9
vs4cm)comparedwiththosewithoutPJK.
19
Thesefindingsaregenerallyinkeepingwith
thoseofYagiandcolleagues,
5
whosawthataSVAcorrectiongreaterthan5cmledtoa
50%incidenceofPJK(p=0.01).Anotherseriesof54patientsdemonstratedthattherisk
ofPJKdecreasesby30%foreverycentimeterincreaseintheC7-plumbline.
20
Inthesame
series,theC7-plumblinehadreturnedclosertoitspreoperativepositioninallpatientsby
finalfollow-up(average2.23years).
Theinterplaybetweenthoracickyphosisandlumbarlordosis,thatis,theglobalsagittal
alignment (GSA), is also becoming an increasingly important conceptinunderstanding
PJK. In the same study where they looked at sagittal correction, Yagi and colleagues
5
showedthatanonidealpostoperativeGSA(thoracickyphosis[TK]+LL+PI>45°)led
to a 70% rate of PJK(p < 0.001). Maruo et al
17
also showed that ideal global sagittal
alignmentprotectedagainstthedevelopmentofPJK.Theimportanceofspinalbalanceis
also highlighted by Mendoza-Lattes and colleagues,
20
who found that the difference
betweenTKandLLwasinverselyproportionaltotheriskofdevelopingPJK.
Taken together, these studies add to our growing understanding of global sagittal
balance.TheysuggestthatthegoalofrestoringtheSVAto0cmmaynotbeoptimalfor
allpatients.Indeed,studiesofasymptomaticvolunteershaveconsistentlyshownincreased
agetobecorrelatedwithgreaterSVA.
21,22
Theyalsohighlighttheneedforfurtherstudies
toestablishthe optimalspinopelvicparameters forsurgeonstotarget(i.e., tounderstand
thedifferencebetweenLL+9°andLL–9°).
19
RadiographicFactors
PreoperativeThoracicKyphosis
HighpreoperativeTKmaypredispose toPJKinbothadultand pediatricpopulations.In
theadultpopulation,Maruoandcolleagues
17
showedthatpreoperativeTKgreaterthan30
degrees was a risk factor for developing PJK (62% vs 29%, p = 0.002). Similarly,
Mendoza-Lattes and colleagues
20
found that patients with PJK had a larger difference
between TK and LL at baseline (p = 0.012). These patients also presented with lower
sacralslopeandsignsofpelvicretroversion.
ProximalJunctionalAngle
Leeand colleagues,
23
one ofthefirstgroupsto describePJKin patientswith idiopathic
scoliosis,found thatapreoperative PJanglegreater than5degrees wasarisk factorfor
developmentofsubsequentjunctionalkyphosis.ThisworkhasbeensupportedbyDeniset
al’s
9
seriesofScheuermannpatients.ThelargemajorityofcasesofPJKobservedinthat
series were noted when the proximal extent of the fusion did not include the kyphotic
proximalendvertebra.Maruoandcolleagues
17
wereabletodemonstratethataproximal
junctionalangle(PJA)greaterthan10degrees(p=0.016),inadditiontoaPI>55°(p=
0.037),wasariskfactorforthedevelopmentofPJK.
17
PatientFactors
Patient-specificfactorssuchasadvancedage,highbodymassindex(BMI),thepresence
ofosteoporosis,smoking,andthepresenceofothercomorbiditiesarealwaysimportantto
considerpriortospinesurgery.Notsurprisingly,manyofthesefactorshavebeenlinkedto
thedevelopment ofPJK.In theadult literature,increasing agehas beenassociated with
theincidenceofPJKandPJKrequiringrevisioninnumerouscaseseries.
1,2,15,19,24
Interestingly,thelinkbetweenhighBMIandthedevelopmentofPJKislessclearinthe
literature.Bridwelletal
15
wereabletoshowthathigherBMI(p=0.015)andthepresence
of a comorbidity (p = 0.001) were associated with the development of PJ angle > 20
degrees.However,otherseriesfromthesameinstitutionhavefailedtoshowthesamelink
between high BMI and PJK (defined in the traditional manner using 10 degrees as a
cutoff).
19,24
Given that a large proportion of PJK occurs due to fracture at the UIV,
17
it is not
surprisingthatosteoporosisplaysacriticalroleinthedevelopmentofPJK.Inoneseries,
osteoporoticpatientsovertheageof65whounderwentaminimumfive-levelfusionwere
foundtohavepedicleandcompressionfracturesatarateof13%,withPJKoccurringin
26%ofpatients.
25
Inasmallseriesof10adultpatients,Watanabeandcolleagues
26
found
that osteopenia and pre-operative comorbidities were common among patients with
proximalvertebralfractureandsubluxation.Caseseriesinadultpatientshavefoundthat
osteoporosisismuchmoreprevalentinindividualswithPJKthaninthosewithout.
24
TimingofProximalJunctionalKyphosis
The majorityof the cases ofPJK are identifiedwithinthe first yearpostoperatively.
5,14
ThepatientswhodogoontodevelopPJKprogresstoaboutonehalf(53%)oftheirtotal
degreeof PJKby 3 months.
5
Similarly,Y.J. Kimand colleagues
12
reported that59%of
progressionofthePJAoccurswithinthefirst8weeks.Maruoetal
17
reportedthat62%of
cases with PJK were identified within 8 weeks, with fracture being the most common
cause.
ClinicalOutcomesAfterProximalJunctionalKyphosis
Clinicaloutcomesafter PJKaresummarized inTable9.2. Ingeneral,most studieshave
shown that most cases of PJK are asymptomatic, and that this condition does not
substantially alterclinical outcome. There are, however, two recentseries that do show
that patientswith PJK have increasedpain levels compared withthosepatients without
PJK.
19,24
Thedifferenceinpainlevelsbetweenthetwogroupsmettheminimalclinically
importantdifference.
24
Theincidenceofsymptomaticpain(i.e.,upperbackpainreported
bythe patientat follow-up)wasalsomarkedlyhigher inthe groupwith PJK(29.4%vs
0.9%,p < 0.001). These more recent results highlight the importance of furthering our
understandingofPJK;asweshallseeinthefollowingsections,theearlydescriptionsof
PJK as a radiographic finding that warrants follow-up might be understating the true
impactofthecondition.
Investigators arenow turning acloser eye tothe concept ofsymptomatic PJK tosee
how these cases might impact clinical outcomes. Yagi and colleagues
5
found that their
patientswithsymptomaticPJKhadasignificantlyhigherOswestryDisabilityIndex(ODI)
scorecomparedwithpatientswithoutPJK.
5
Similarly,H.J.Kimetal
19
foundlowerODI
andpainscoresinpatientswithPJKandlowerpainscoresinpatientsundergoingrevision
for PJK. Importantly, they found lower outcomes across all domains of the Scoliosis
ResearchSociety(SRS)questionnaireinpatientswithPJK,thoughtheseoutcomesdidnot
reachstatisticalsignificance.
RevisionSurgeryforProximalJunctionalKyphosis
ThemajorityofcasesofPJKareasymptomaticanddonotrequireintervention.Reported
rates of revision due to PJK have ranged from 1.4 to 11.2% with pain being the most
commonreasonforrevision.
4,19,27,28
SeverecasesofPJKcanleadtosignificantsagittalimbalanceanddisability.Inasmall
series of 10 patients, Watanabe et al
26
reported vertebral subluxation and severe
neurologicdeficitintwooftheir10patientsasaresultofprogressionofPJK.
Hartetal
28
reportedonacaseseriesfromtheInvasiveSpeciesSpecialistGroup(ISSG)
database.Their definition ofproximal junctionalfailure (PJF)was “severePJK,” which
wasfurtherdefinedasachangeofmorethan10degreesofkyphosisbetweentheUIVand
thevertebratwolevelsabovetheUIV(UIV+2),alongwithoneormoreofthefollowing:
fractureofthevertebralbodyofUIVorUIV+1,posteriorosseoligamentousdisruption,or
pullout ofinstrumentation at the UIV. Intheir series, they identified57 patients from a
seriesof1,218consecutiveadultpatientswhometthisdefinitionofPJF(4.68%).Ofthe
57casesof PJF,27 (47.4%)underwent revision surgerywithin 6months of theirindex
operation.OfthecausesofPJF,fracturewasthe mostcommon(56%),followedbysoft
tissue failure (35%) and screw pullout (9%). Of the risk factors identified for revision
surgery,acombinedanterior/posteriorapproach(p=0.001)andhigherPJKangulation(p
=0.034)werefoundtobesignificant.Ofthevariousmodesoffailure,onlythepresence
of traumatic mechanism of failure, which occurred in six patients, was deemed to
predisposepatientsto arevision(p =0.019).AhigherSVAalso trendedtowardbeing a
significantpredictorofrevision(p=0.090)alongwithfemalesex(p=0.066).Theoverall
rateofrevisionsurgerywas2.21%.
Asimilarstudywas conductedbyYagi andcolleagues
4
aspartoftheComplex Spine
StudyGroup.Theyutilizedaconsecutiveseries of1,668patientstreatedforadultspinal
deformityandgreaterthanfivelevelsoffusion.Theirserieshadlongerfollow-up(2to12
year, mean 4.3 years), and they also focused on patients older than 50 at the time of
surgery.TheydefinedPJFasPJKrequiringrevisionandidentified23patients(1.4%).The
largemajorityofthese 23patients(17patients, 74%)hadbeenrevisionsurgerycasesat
the time of their long segment fusion and all had received posterior pedicle screw
constructs. Osteopenia was prevalent (10/23, 43%), but, interestingly, none of these
patientshad osteoporosis. Sixteenpatients wererevised forintolerable pain,anothersix
foraneurologicdeficit,andoneforheadptosis.Theauthorsfoundthatamajorityofthese
failuresoccurredearly,withameantimetoPJF(revision)of10.5±9.3months;87%had
been revised within 2 years of surgery. H.J. Kim et al
19
reported that a higher lumber
lordosisand an increasedSVAcorrection arerisk factorsforrevision dueto PJK.They
reportedarevisionrateof10.7%.
Moving forward,importantwork remains to bedone regarding our understanding of
PJF.Aclassificationsystem forPJK andaclear definitionof PJFare neededbeforewe
progresstowarddefiningthe riskfactorsforPJF.Additionally,theoptimal magnitudeof
correctionalsoremainstobedetermined.
PreventingProximalJunctionalKyphosis
To date, no definitive methods have been described to prevent PJK, although several
approacheshavebeensuggested.Twostudieshavereportedontechnicaltrickstoreduce
theincidenceofPJK.
11,29,30
Hassanzadehetal
11
foundnoinstancesofPJKin20patients
treated with a hook at the UIV compared with a 29.6% (8/27 patients) rate of PJK in
patientswhoweretreatedwithapediclescrewattheUIV(p= 0.01).Additionally,they
foundthat patientswith hookshad significantlyhigher functionalscores comparedwith
thosewithscrews(p<0.01).Thesedatahavenotbeenreplicatedtodate.
Given that vertebral fractures represent a common etiology for PJK and PJF,
investigators have also studied the impact of prophylactic one- and two-level
vertebroplasty above long fusions. Results reported include both biomechanical
29
and
clinical
30
data.Inabiomechanicalmodelusing18cadavericspines,Kebaishetal
29
were
able to show a significant reduction in vertebral compression fractures when two-level
vertebroplasty (UIV and UIV +1) was compared with one-level (UIV only) or no
vertebroplasty.Aclinicalseriesfromthesamegroupfollowed38patientswithtwo-level
vertebroplasty(UIVandUIV+1)for2years.
30
TheyreportedalowerrateofPJKorPJF
(PJK8%, PJF 5%,combined 13%)than previouslypublished rates.Their studydid not
includea controlcohort(i.e., patientswhohad notreceivedvertebroplasty), anddidnot
showanysignificantdifferencesinclinicaloutcomesbetweenthegroupswithandwithout
PJKorPJF.
Finally, Yanik et al
31
reported on a series of 60 patients treated for Scheuermann
kyphosis. To reduce the stiffness of the proximal construct, they studied the impact of
leavingtwoscrewthreads outoftheposteriorcortexwhen placingpediclescrewsatthe
UIV. They theorized that this would reduce the stiffness at the proximal aspect of the
construct.Atanaverageof2-yearfollow-up,theyfoundthatthescrewswiththreadsleft
outofthecortexhadalowerPJangle(4.44±1.55degreesvs8.08±2.96degrees)when
comparedwithstandardpediclescrewinsertion(p=0.001).Thisgroupalsohadnocases
ofPJK,comparedwitha17.2%(5/29,p=0.02)ratewiththestandardscrew technique.
Finally, they werealso able to show an improvementin the physical component of the
ShortForm36scoreinthegrouptreatedwiththemodifiedscrewinsertion.
RevisionStrategies
TheapproachtothepatientwithPJKissimilartothe approachtothepatientwithother
sagittalplanedeformities.Ourindicationsforarevisionoperationareasfollows:
1.Progressivedeformity
2.Painthathasfailednonoperativemeasuresformanagement
3.Implantprominencewithimminentskinbreakdown
4.Neurologicdeficitorcordcompression
The decisionabout the UIVlevel selection isbasedon several factors,but generally
speaking,PJKcaseswithaUIVinthelowerthoracicspineshouldbeextendeduptothe
upperthoracicspine,andcaseswithaUIVintheupperthoracicspineshouldbeextended
uptoT1–2orintothecervicalspine.
Osteotomies may also be necessary in the treatment of PJK. Osteotomy selection is
based ontherigidity of PJK. FlexiblePJK (Fig. 9.2)can usually be treated withoutan
osteotomy, or with a posterior column only osteotomy (Fig. 9.2d), whereas rigid
deformities(Fig.9.3)maynecessitateathree-columnosteotomy(i.e.,pediclesubtraction
osteotomy or vertebral column resection) (Fig. 9.3c). Flexibility can be assessed with
hyperextension or supine radiographs as well as the scout images on some computed
tomography(CT)scans(aslongasaheadsupportwasnotusedduringthescan).
For cases where a neurologic deficit or symptomatic cord compression is present, a
vertebralcolumnresection maybenecessarytodecompressthekyphoticareawhere the
cordcompressionislikelytobepresent.Anatomicrealignmentisessentialtorelievethe
cordcompression.
The goal for the revision operation should avoid the temptation for overcorrection;
instead, the goal should be an SVA close to 4 to 5 cm. Overcorrection can lead to a
recurrenceofPJKandnecessitateadditionaloperationsandunnecessaryriskforpatients.
ChapterSummary
Proximaljunctionalkyphosisisdefinedusingtwocriteria:(1)proximaljunctionalsagittal
Cobbangle≥10degrees,and(2)postoperativeproximaljunctionalsagittalCobbangleat
least 10 degrees greater than the preoperative measurement.
1
PJK is generally an early
postoperativephenomenon,andmostcasestypicallyarerecognizedinthefirstyearafter
surgery.
5,14
RatesofPJKreportedintheliteraturerangefrom17to61.7%.
2,3
Proximal junctional kyphosis is likely multifactorial in origin. Risk factors for the
development of PJK can be categorized as surgical, radiographic, and patient-related
factors.Advancedageappearstobethemostimportantpatient-relatedriskfactor.Surgical
risk factors to consider include greater magnitude of sagittal correction, damage to the
adjacentfacetwheninstrumentingtheUIV,damagetotheposteriorligamentouscomplex,
a combined anterior and posterior approach, fixation to the ilium, and certain types of
instrumentation.Oftheabove,themagnitudeofcorrectionisparticularlyimportant,asan
SVAof0 cmmaynot beoptimal forallpatients.
21,22
Ahigherpostoperative LLand an
SVAcorrection ofgreaterthan5cmhaveboth beenassociatedwiththe developmentof
PJK.
17,19
To date, no definitive methods have been described to prevent PJK. Some
investigatorshavedescribedtechnicaltrickstoreducetheincidenceofPJK.
11,31
PatientswithPJKaregenerallyasymptomatic.However,recentstudieshaveshownthat
thesepatientsmayhaveincreasedpainlevelsandworsefunctionaloutcomemeasures.
19,24
Inthesubsetofpatientswhoaresymptomatic,painisthemostcommoncomplaintandthe
mostcommonreason forrevision.Reportedratesfor revisionforPJKrangefrom 1.2to
11.4%.
4,19,27,28
Patients requiringrevision forPJK aregenerallyapproached similarlyto
patients with other sagittal plane deformities. Osteotomies may be necessary and are
chosen based on the rigidity of the PJK. When revising PJK, the temptation for
overcorrectionshouldbeavoided.
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