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OutcomesofAdultSpinalDeformitySurgery
Several studies have reported various outcomes for the operative and nonoperative
management of adult spinal deformity. Estimates of the prevalence of adult spinal
deformityintheUnitedStatesrangefrom2.5to25%
7
However,manyofthesepatientsdo
notseekmedicalcarefortheircondition,andofthosewhodo,manymayhavesuccessful
managementoftheirsymptomswithoutsurgery.Nonoperativecaremayincludephysical
therapy, core strengthening, weight loss/aerobic activity, pain medications, steroid
injections,andalternativemodalitiessuchasacupunctureandchiropracticcare.Formost
patients, a trial of nonoperative care should be initiated before surgery is considered.
Exceptionsincludepatientswithneurologicdeficitsorsignificantinstability.Surgerymay
also beindicated in patientswith progressive curves, substantialdeformity-related pain,
and thosewho have failed appropriatenonoperative treatment. Studiesofoperative and
nonoperativemanagementofadultspinaldeformityhavedemonstratedimprovedpatient-
reportedoutcomeswithsurgicalmanagement.
8–12
Inareviewarticleonadultspinaldeformity,Youssefetal
13
summarizethefindingsof
49 studies reporting outcomes for various surgical strategies including decompression
alone versus decompression with fusion; anterior, posterior, or combined surgical
approaches; the use of vertebral osteotomies; and levels of instrumented vertebrae. A
varietyofoutcomemeasurementsarereportedforeachtechnique.
RadiographicOutcomes
Asystematic reviewofadult scoliosisoutcomesby Yadlaet al
14
found arangeinCobb
angle correction from 9.1 to 53.9 degrees (mean 26.6 degrees, representing an average
40.7%curvecorrection)inaseriesof49articlespublishedbetween1950and2009with
minimum2-yearfollow-up.
Radiographic outcomes have also been compared between different surgical
approaches. Crandall and Revella
15
found no significant difference in coronal curve
correctionbetweenpatientsundergoingposteriorinstrumentedfusioninadditiontoeither
anterior lumbar interbody fusions (ALIF), with an average correction 69.5%, or
transforaminal lumbar interbody fusion (TLIF), with an average correction 68.7%. A
literaturereviewbyMundisetal
16
reportedimprovedcoronalandsagittalcorrectionwith
a lateral transpsoas approach compared with open anterior procedures. A retrospective
reportby Pateder etal
17
comparing patients whounderwent posterioronly surgery(n=
45)versuscombinedanterior-posteriorsurgery(n=35)foundnosignificantdifferencein
coronalorsagittalcurvecorrectionbetweenthetwogroups.
Youssef et al
13
also reviewed radiographic outcomes for different types of posterior
osteotomies including Smith-Petersen osteotomy (SPO), pedicle subtraction osteotomy
(PSO), and vertebral column resection (VCR). These techniques are used to achieve
varying degreesof lordosis correction andrestoration of sagittalbalance.SPO provides
the smallest degree of curve correction, achieving up to 10 degrees of lordosis per
vertebral level;however, multilevelosteotomies may achieve alarge overall correction.
ReportsofPSOhavedemonstratedanaverage30degreesoflordoticcorrectionperlevel.
In a comparison of SPO and PSO, Cho et al
18
found an average total correctionof33
degrees for patients undergoing three or more SPOs and 31.7 degrees for patients
undergoingPSO, but asignificantly lower improvementin sagittalbalancefor theSPO
groupthanforthePSOgroup.VCRachievesthehighestdegreeofcurvecorrection.Suk
etal
19
reportedameandeformitycorrectionof59%(109.0degreesto45.6degrees)in16
patientswhounderwentposteriorVCR.Papadopoulosetal
20
reportedthatof45patients
whounderwentposteriorVCR,theaveragecorrectionofkyphosiswasfrom108degrees
to60degreeswithonepatientsustainingacompletespinalcordinjury.
Complications
Theincidenceofcomplicationsisanimportantqualitymeasureinadultspinaldeformity.
Reported complication rates for spinal deformity surgery are high, but a standardized
definition or classification for reporting complications in the literature has not been
established. Complication rates have been classified in various ways, including major
versusminorcomplications,early versuslatecomplications,andsurgicalversus medical
complications. Reported complications in deformity surgery include pseudarthrosis,
adjacent segment disease, dural tears, superficial or deep wound infections, implant
complications, neurologic deficits, epidural hematoma, wound hematoma, pulmonary
embolism, deep vein thrombosis, systemic complications, and death. The incidence of
complicationsmay be influencedby patientfactors (e.g.,age, comorbidities,severity of
deformity)orsurgicalfactors (e.g.,approachtype,need forosteotomy,numberoflevels
fused).
The49articlesreviewedbyYadlaetal
14
reportcomplicationratesrangingfrom0to53%,
witha combinedtotal of897 complicationsamong 2,175patients (41.2%).Charosky et
al
31
reportedanoverall39%complicationrateamong306patientsoverage50undergoing
adultdeformitysurgerywitheitherananterioronly,posterioronly,orcombinedapproach.
Sansuretal
22
reviewed atotalof 4,980cases ofadultscoliosis fromthe SRSmorbidity
andmortality databaseand foundan overallcomplicationrate of13.4% anda mortality
rate of 0.3%. Significantly higher complication rates resulted from revision surgeries,
osteotomies,andcombinedanterior-posteriorsurgery.
Youssef et al
13
summarized several studies reporting complication rates of various
procedures. Transfeldt et al
23
report a 10% complication rate among adult deformity
patients who underwent decompression alone compared with 56% in patients who
underwent decompression and fusion. Burneikiene et al
24
reported a 31% incidence of
systemic complications and 49% hardware or surgical technique complications in 29
patients undergoing TLIF. Complications of ALIF may include vascular injuries,
ilioinguinal and iliohypogastric nerve injuries, damage to the bladder or ureters,
pseudarthrosisandsubsidence,ileus,lymphocele,andretrogradeejaculation.
13,25
Mostof
thesecomplicationsareuncommon,althoughratesofmajorandminorcomplicationsvary
intheliterature.Inastudyof447patients,McDonnelletal
26
foundacomplicationrateof
11% for major complications and 24% for minor complications. Complications of the
lateral transpsoasapproach are often related tomanipulation of the lumberplexus. In a
prospective multi-center evaluation of 107 adult degenerative scoliosis patients
undergoing extreme lateral interbody fusion, Isaacs et al
27
reported a 12.1% major
complicationrate.
Reoperations
Scheer et al
28
analyzed data from a prospective, multicenter adult spinal deformity
database,and examinedthe rates,indications, timing,andrisk factorsfor reoperationas
wellas the effectofreoperation on HRQOLmeasures. In acohort of352 patients(268
withatleast1-yearfollow-up),theyfoundatotalreoperationrateof17%,themajorityof
whichoccurred within 1year ofthe index operation.The mostcommon indicationsfor
reoperationincludedinstrumentationcomplicationsandradiographicfailure.
There was a19% reoperation rate for patients undergoinga three-column osteotomy
anda 16%reoperation ratefor patientsnotrequiringthree-columnosteotomy; however,
three-column osteotomy was not significantly predictive of reoperation at 1 year. The
uppermost instrumented vertebrawas also not predictive of reoperation. Therewere no
significant differences in the American Society of Anesthesiologists (ASA) grade,
Charlson comorbidity index rating, preoperative body mass index (BMI), or smoking
historybetweenpatientswhodidnotundergoreoperationandthosewhodid.Patientswho
neededreoperationwithin1year hadworseODIandSRS-22scores at1-yearfollow-up
thandidpatientsnotneedingreoperation.However,therewasnosignificantdifferencein
HRQOLscoresat2years betweenpatients whorequiredreoperationat1yearandthose
whodidnot.
Other studies have demonstrated similar reoperation rates, ranging from 10 to
21%.
21,29–31
Reasonsforrevisionsurgeryinadultspinaldeformityincludepseudarthrosis,
curve progression, infection, painful/prominent implants, adjacent segment disease
implantfailure,andneurologicdeficits.
29,30
HRQOLOutcomesinAdultSpinalDeformity
Despitehighcomplicationandreoperationratesinadultspinaldeformitysurgery,patient
satisfaction with these proceduresis high. Both condition-specific and general HRQOL
outcomes that can be converted to utility scores and compared across the literature are
importantprerequisitesfordeterminingthevalueofspinaldeformitysurgery.
Several prospective multicenter studies have demonstrated the benefits of operative
treatmentofadultspinaldeformitycomparedwithnonoperativecareinregardtopatient-
reportedhealthmeasuresincludingODI,SRS-22,EQ-5D,andnumericratingscalescores
forlegandbackpain.
8–12
Yadlaetal
14
reportedthatinthe49studiesincludedintheirsystematicreview,ODIand
SRS werethe most commonly usedpatient-based outcome instruments,with 11studies
reporting pre- and postoperative ODI scores and 10 studies reporting pre- and
postoperativeSRSscores.Therewasanaveragedecreaseof15.7points(range3.1–32.3)
inODIscoreamong911patients.Thisimprovementindisabilityoutcomecorrelateswith
previousreportsof significantclinicalimprovementof ODIscoresrangingfrom 4to15
points.
32
Of the 999 patients with pre- and postoperative SRS scores in Yadla et al’s
review,therewasa meanincreaseinSRSscoresof23.1points,wellabovethe minimal
importantdifferenceforSRSscoresof13pointsreportedbyBagóetal.
33
Youssef et al
13
summarized the results of studies reporting HRQOL outcomes for
patients undergoing various surgical approaches. Crandall and Revella
15
found
nonsignificant differences in VAS and ODI outcomes between patients undergoing
posterior fusionwith either ALIFor TLIF.Mundis et al
16
found significantlyimproved
VAS and ODI scores in a literature review of the lateral approach for adult spinal
deformity. Various studies have reported improved patient-reported outcomes following
PLIF,includingimprovedODI,SF-36,andVASscores.
34–36
Goodetal
37
reportedsimilar
SRS and ODI scores for both posterior only and combined fusions, with both having
improvementsat2-yearfollow-up.
CostandValueinAdultSpinalDeformity
Severalrecent articleshavereported onthe costsofadult spinaldeformity surgery. Mc-
Carthy et al
38
studied the total costs of 484 patients undergoing operative treatment of
adultspinaldeformitywithanaveragefollow-upof4.8years,andfoundanaveragetotal
hospital cost of $120,394. Total cost for primary surgery averaged $103,143, which
increased to $111,807 at 1-year follow-up and $126,323 at 4-year follow-up. Hospital
readmissions wererequiredin 130 patients (27%), withan average readmission cost of
$67,262. Another cost analysis by McCarthy et al
39
found higher direct costs with
increasingage,lengthofhospitalstay,lengthoffusion,andfusionstothepelvis.
Cost-utility studies of adult spinal deformity are lacking in the literature. Although
several recently published systematic reviews report on cost-utility analyses in spine
care,
40,41
noneofthereviewedarticlesincludevalueassessmentsinadultdeformity.One
studybyGlassmanetal
42
examinedthecostsandbenefitsofnonoperativecareforadult
scoliosis, and questioned the value of nonoperative treatment given their findings of a
$10,815meantreatmentcostovera2-yearperiodwithnosignificantchangeinHRQOL.
ImprovingOutcomesinDeformitySurgery
Measurementofclinicaloutcomesandvalueisanimportantgoalinspinesurgeryandis
criticalinestablishingaccountabilityfor theendresultofcare.ErnestA.Codmanwasa
surgeonintheearly20thcenturyandapioneerinadvocatingoutcomemeasurementand
reporting.He proposedan “endresults system”in whichpatients’symptoms, diagnosis,
treatment,andoutcomeswouldbetrackedovertimeinanefforttoreducecomplications
andimprove quality ofcare. Atthe time,Codman’sideas wereseen asradicaland met
withstrongresistance,leadingtohisdismissalfromhisfacultypositionatMassachusetts
General Hospital. Although great strides have been made since Codman’s time in
recognizing the importance of outcome measurement, there is still much room for
improvement in the effort to establish regular and reliable systems for outcome
measurementandreporting.
There is a high variability in spine surgery with regard to surgical rates, surgical
strategies, and costs.
43–45
High variability indicates a lack of consensus on the optimal
treatment strategy and a need for further comparative effectiveness research. Reducing
variability in spine surgery requires an evidence-based approach to care. The
establishment of large multicenter procedural and diagnosis-based registries for spine
surgery has been an important step to improving outcome measurement and reporting.
These registries provide a reliable system for the reporting of complications, clinical
outcomes,andHRQOLoutcomes,andfacilitatetheevaluationofalternativeinterventions
incomparativeeffectivenessresearch. Withthe accuratemeasurement of complications,
quality may be improved through the establishment of clinical protocols based on
standards of care in an effort to reduce complications. The widespread use of patient-
reportedoutcometoolsthatmaybetranslatedtoautilityscoreisnecessarytoaddressthe
lack of cost-utility analyses and value-based assessments in adult spinal deformity. An
increased emphasis on measuring and improving value in spine care will result in
improvedoutcomesandreducedcostsovertime.Althoughwesupportanefforttoreduce
variabilityinspinesurgerythroughanevidence-basedapproachtocare,wealsorecognize
that care isnot monolithic, and patient and physicianpreference must be considered to
obtainoptimaloutcomes.
ChapterSummary
Surgicaltreatment of adult spinaldeformity is a high-costintervention that consistently
drawstheattentionofthelaypressandthemedicalprofessionduetoaperceivedlackof
effect. In the evolving health care economy, demonstration of value, through cost data
coupledwithpatient-reported outcomes,will be criticalin maintainingpatient access to
care. Tobestprotect our patients’ ability toreceivecare that can effect changein their
healthstatus,itisimperativeforspinalsurgeonstounderstandandcollectpatientreported
outcomes. Surgical treatment of adult spinal deformity has been shown to have a
significant effect on patient-reported outcomes. Although the initial cost of spinal
deformitysurgeryishigh,thecost perQALYdecreaseswithincreasingdurabilityof the
intervention. Thus,it is imperative that weas a profession continue totrack and report
secondaryinterventionsandcomplicationsofcare,sothatoptimalinterventionstrategies
canbecreated.Determinationofappropriatequalitymetricsandprocessmeasuresforthe
deliveryofspinecarecanhelpachieveimprovedpatientoutcomesand potentiallylower
cost,thusmaximizingsocietalreturnoninvestmentforthecareofadultspinaldeformity.
Pearls
In a value-based health care economy, measures of cost and clinical outcome are important to define cost-
effectiveinterventions.
Patient-centeredmeasuresofoutcomesprovidethemostusefulassessmentofvalueofinterventionsindeformity
surgery.
Utilityscoresareausefulmeasureofgeneralhealthstatuspreferencethathasadefinableunitofwell-yearsof
life/year.
Cost per QALY isa measure of value that is sensitive to the magnitude ofthe health status change and the
durabilityofchange.
Selectionofdisease-specific,patient-reportedoutcomeshouldconsidervalidatedmetricsthatcanpotentiallybe
convertedtoautilityscore.
Pitfalls
Sole focus on quality metrics and process measures creates adissociation betweeninterventions and patient-
centeredoutcomes.
Optimizing quality and process metricsin theabsence ofpatient-centered informationmay incorrectlyguide
evidence-basedcare,andprovideincentivesforinappropriatecare.
Cost-minimizationstrategiesorfocusoncostwithoutregardtoeffectoftreatmentonpatientreportedoutcomes
willnotbeavalue-optimizingstrategy.
References
FiveMust-ReadReferences
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Econ2002;21:271–292PubMed
2.Berven S, DevirenV, Demir-Deviren S, HuSS,BradfordDS. Studies inthemodifiedScoliosis Research Society
Outcomes Instrument in adults: validation, reliability, and discriminatory capacity. Spine 2003; 28:2164–2169,
discussion2169PubMed
3.BridwellKH,BervenS,GlassmanS,etal.IstheSRS-22instrumentresponsivetochangeinadultscoliosispatients
havingprimaryspinaldeformitysurgery?Spine2007;32:2220–2225PubMed
4. Bridwell KH, Cats-BarilW, HarrastJ, et al. The validity of theSRS-22 instrumentin an adult spinal deformity
population compared with the Oswestry andSF-12: astudy of response distribution, concurrent validity, internal
consistency,andreliability.Spine2005;30:455–461PubMed
5. Brazier JE, Roberts J. The estimation of a preference-based measure of health from the SF-12. Med Care
2004;42:851–859PubMed
6.CarreonLY,GlassmanSD,McDonoughCM,RampersaudR,BervenS,ShainlineM.PredictingSF-6Dutilityscores
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PubMed
7. United States Bone and Joint Initiative. The Burden of Musculoskeletal Diseases in the United States, 2nd ed.
Rosemont,IL:AmericanAcademyofOrthopaedicSurgeons;2011
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Suppl):S130–S134PubMed
9.SmithJS,ShaffreyCI,BervenS,etal;SpinalDeformityStudyGroup.Improvementofbackpainwithoperativeand
nonoperativetreatmentinadultswithscoliosis.Neurosurgery2009;65:86–93,discussion93–94PubMed
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quality of life in patients with adult symptomatic lumbar scoliosis: a prospective multi-center evidence-based
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9
Junctional Issues Following Adult Deformity
Surgery
HanJoKim,SravishtIyer,andChristopherI.Shaffrey,Sr.
Introduction
Proximaljunctionalkyphosis(PJK)wasfirstdefinedandcharacterizedintheliteratureby
Glattes and colleagues.
1
These authors presented a retrospective series of 81 adult
deformitypatients anddefinedabnormal PJKusing twocriteria:(1) proximaljunctional
sagittal Cobb angle ≥ 10 degrees (Fig. 9.1) and (2) postoperative proximal junctional
sagittalCobbangleatleast10degreesgreaterthanthepre-operativemeasurement.They
reported an incidenceof PJK of 26%,
1
and have been supported by subsequentstudies
reporting rates of PJK ranging from 17 to 61.7%.
2,3
Although PJK is generally
asymptomatic,thereisasubsetofpatients(1.4–4%)whopresentwithsymptomsrequiring
furthersurgery.
4,5
Risk factors for the development of PJK include advanced age, surgical approach,
greater rigidity of construct, greater magnitude of sagittal correction, the presence of
preexistingproximalkyphosis,damage totheposteriorligamentouscomplex, damageto
theadjacentfacetwheninstrumentingtheupperinstrumentedvertebra(UIV),fixationto
the ilium, type of instrumentation (hooks versus pedicle screws), and the presence of
osteoporosis.
1,2,6
Giventhelargenumberofidentifiedriskfactors,theetiologyofPJKis
mostlikelymultifactorialinnature.Nonetheless,advancedageisafactorthatseemstobe
uniformacrossthemajorityofstudies.Inaddition,thecurrentliteraturesuggeststhatPJK
maybemoreprevalentthantheratesinitiallyreported20yearsago.
Thischapter synthesizesour currentunderstanding ofPJKin adultsby reviewingthe
literature underlying the various etiologies of PJK, discussing the impact of PJK on
clinical outcomes, examining the risk factors that lead to revision surgery due to PJK,
providing consensus expert opinion on possible methods for minimizing PJK
development,anddescribingindicationsforsurgicaltreatment.
EtiologyandRiskFactorsforProximalJunctional
Kyphosis
Theetiologyof PJKismultifactorialand canbedividedinto surgical,radiographic, and
patient-relatedfactors.These aresummarizedin Table 9.1.Wewill closelyexaminethe
literatureaboutthesevariouscauses.
SurgicalFactors
DisruptionofthePosteriorSoftTissues
In their classic paper, Panjabi and White
7
high-lighted the role of the posterior spinal
ligamentsin preventingexcessivemotion betweenthe vertebrae.Giventhese ligaments’
role asa stabilizer in thespine, the disruptionof posterior soft tissueshas always been
viewedasapotentialcontributortothedevelopmentofPJK.
Fig.9.1a,bTheproximaljunctionalsagittalCobbmeasurement(proximaljunctionalangle).ThisisdefinedastheCobb
anglebetweenthe inferior endplateoftheupper instrumented vertebraandthesuperiorend plateofthevertebratwo
levelsabove.(a)Postoperativeradiograph.(b) Radiograph at6monthsthatmeetsbothcriteriaofproximal junctional
kyphosis(PJK):proximaljunctionalangle>10degreesandaprogressionoftheproximaljunctionalangle>10degrees.
Therelativecontributionoftheposteriorsofttissueshasbeenexaminedinacadaveric
model.
8
The authors of this study performed one of several procedures on motion
segments obtained from six human cadavers. These procedures included bilateral
transverse hook site preparation, sublaminar hook site preparation, pedicle screw
placement, supra-and interspinous ligament transection,and transection of all posterior
structures. Following these interventions, the authors measured the torque needed to
produce2.8degreesofangulardisplacement,and,basedonthismeasurement,calculated
the total flexionstiffness of the motionsegment. Their data showed that sectioningthe
supra-andinterspinousligamentsledtoasignificant(p= 0.02)lossof flexionstiffness.
Theyfoundthat theposteriorligamentouscomplexcontributed6.59%tothestiffnessof
the motion segment and that thestiffness loss could roughly double (12.62%) with the
exposurerequiredforplacementofinstrumentationatthesamemotionsegment.
Table9.1ASummaryofVariousRiskFactorsforPJKProposedintheLiterature
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