Postoperative Sagittal Balance has Only a Limited Role in the Development of Adjacent Segment Disease after Lumbar Spine Fusion for Degenerative Lumbar Spine Disorders : A Subanalysis of the 10-year Follow-up Study

This is a sel -a chi ed e sion o an o iginal a icle. This e sion may di e om he o iginal in pagina ion and ypog aphic de ails. Au ho (s): Ti le: Yea : Ve sion: Copy igh : Righ s: Righ s u l: Please ci e he o iginal e sion: CC BY-NC-ND 4.0 h ps://c ea i ecommons.o g/licenses/by-nc-nd/4.0/ Pos ope a i e Sagi al Balance has Only a Limi ed Role in he De elopmen o Adjacen Segmen Disease a e Lumba Spine Fusion o Degene a i e Lumba Spine Diso de s : A Subanalysis o he 10-yea Follow-up S udy © 2022 The Au ho (s). Published by Wol e s Kluwe Heal h, Inc. Published e sion Toi onen, Lee i A.; Män ymäki, Heikki; Häkkinen, A ja; Kau iainen, Hannu; Ne a, Ma ko H. Toi onen, L. A., Män ymäki, H., Häkkinen, A., Kau iainen, H., & Ne a, M. H. (2022). Pos ope a i e Sagi al Balance has Only a Limi ed Role in he De elopmen o Adjacen Segmen Disease a e Lumba Spine Fusion o Degene a i e Lumba Spine Diso de s : A Subanalysis o he 10-yea Follow-up S udy. Spine, 47(19), 1357-1361. h ps://doi.o g/10.1097/BRS.0000000000004400 2022 SURGERY Pos ope a i e Sagi al Balance Has Only a Limi ed Role in he De elopmen o Adjacen Segmen Disease A e Lumba Spine Fusion o Degene a i e Lumba Spine Diso de s: A Subanalysis o he 10-yea Follow-up S udy Lee i A. Toi onen, MD, a Heikki Män ymäki, MD, PhD, a A ja Häkkinen, PhD, b Hannu Kau iainen, PhD, c and Ma ko H. Ne a, MD, PhD a S udy Design. Re ospec i e addi ional analysis o a p ospec i e ollow-up s udy. Objec i es. We aimed o find ou whe he poo pos ope a i e sagi al alignmen inc eases e isions o adjacen segmen disease (ASD) a e lumba spine usion (LSF) pe o med o degene a i e lumba spine disease. Summa y o Backg ound Da a. Re isions o ASD accumula e o e ime a e LSF o degene a i e lumba spine disease. The e iology o ASD is conside ed mul i ac o ial. Ye , he ole o pos - ope a i e sagi al balance in his p ocess emains con o e sial. Ma e ials and Me hods. A o al o 215 consecu i e pa ien s who had unde gone an elec i e LSF su ge y o spinal s enosis wi h (80%) o wi hou (20%) spondylolis hesis we e analyzed. Spinal eope a ions we e collec ed om he hospi al eco ds. P eope a i e and pos ope a i e sagi al alignmen we e e alua ed om s anding adiog aphs. The isk o e isions o ASD was e alua ed by Cox p opo ional haza ds eg ession models. Resul s. We did no find he poo pos ope a i e balance [pel ic incidence−lumba lo dosis (LL) >9°] o significan ly inc ease he isk o e isions o ASD. c ude haza d a io (HR) =1.5 [95% confidence in e al (CI): 0.8–2.7], adjus ed (by age, sex, pel ic incidence, usion leng h, and he le el o he caudal end o usion): HR =1.7 (95% CI: 0.9–3.3). We ound highe LL ou side he usion segmen (LL−segmen al lo dosis) o dec ease he isk o e isions o ASD: HR =0.9 (95% CI: 0.9–1.0). Conclusion. Poo sagi al balance has only a limi ed ole as a isk ac o o he e isions o ASD among pa ien s wi h degene a i e spinal disease. Howe e , he isk o ASD migh be he g ea es among pa ien s wi h educed spinal mobili y. Key wo ds: lumba spine usion, degene a i e spinal disease, sagi al balance, e isions, adjacen segmen disease, adjacen segmen pa hology Le el o E idence: 3 Spine 2022;47:1357–1361 Lumba spine usion (LSF) su ge y is a common p ocedu e in he ea men o se e al spinal pa holo- gies. Degene a i e lumba spine diso de s (DLSDs) a e he mos common eason o LSF, while is hmic spondylo- lis hesis (IS) co e s up o 20% o he cases.1,2 LSF su ge ies occasionally become complica ed by he need o epea su ge ies.3,4 Adjacen segmen disease (ASD) is a majo eason o la e eope a ions a e LSF.5By defini ion, ASD is a degene a i e condi ion ha pos ope a i ely de elops o he disk le el nex o he usion segmen and causes symp oms ia ins abili y o neu al comp ession.6ASD is he mos equen among he pa ien s wi h DLSD whe e eop- e a ions accumula e by ime, on con as o he pa ien s wi h IS, who in equen ly acqui e his complica ion.4,7,8 DOI: 10.1097/BRS.0000000000004400 F om he a Depa men o O hopaedics and T auma, Facul y o Medicine and Li e Sciences and Tampe e Uni e si y Hospi al, Uni e si y o Tampe e, Tampe e, Finland; b Facul y o Spo and Heal h Sciences, Uni e si y o Jy äskylä, Jy äskylä, Finland; and c P ima y Heal h Ca e Uni , Kuopio Uni e si y Hospi al, Kuopio, Finland; Folkhälsan Resea ch Cen e , Helsinki, Finland. Acknowledgmen da e: Decembe 8, 2021. Fi s e ision da e: Ma ch 1, 2022. Accep ance da e: Ma ch 14, 2022. Suppo ed by he Compe i i e S a e Financing o he Expe Responsibili y A ea o Tampe e Uni e si y Hospi al. The au ho s epo no conflic s o in e es . This is an open access a icle dis ibu ed unde he e ms o he C ea i e Commons A ibu ion-Non Comme cial-No De i a i es License 4.0 (CCBY- NC-ND), whe e i is pe missible o download and sha e he wo k p o ided i is p ope ly ci ed. The wo k canno be changed in any way o used comme cially wi hou pe mission om he jou nal. Add ess co espondence and ep in eques s o Lee i A. Toi onen, MD, Depa men o O hopaedics and T auma, Tampe e Uni e si y Hospi al, Elämänaukio 2, Tampe e 33520, Finland; E-mail: lee i. oi onen@pshp.fi SPINE Volume 47, Numbe 19, pp 1357–1361 © 2022 The Au ho (s). Published by Wol e s Kluwe Heal h, Inc. Spine www.spinejou nal.com 1357 E iology o ASD is hough o be mul i ac o ial. Ye , he de ailed pa hogenesis emains no ho oughly cla ified. On he one hand, LSF su ge y may con ibu e o he pa ho- genesis by al e ing he adjacen le el biomechanics. On he o he hand, he ongoing degene a i e p ocess ou side he usion i sel seems o ha e a significan ole, as well.9 Se e al po en ial isk ac o s a e linked o he p og ession o ASD, bu hei significance a ies in he li e a u e.5,10 Sag- i al alignmen a e LSF is gene ally conside ed ele an he e, so ha ailu e o es o e no mal lo dosis o loss o lo dosis in LSF inc eases he isk o ASD.5,11 I he pos - ope a i e balance can be linked o he occu ence o ASD, his would also suppo he ole o su ge y in he pa hogenesis o ASD. In a 10-yea p ospec i e ollow-up s udy o elec i e LSF su ge ies pe o med in a single uni e si y cen e , we ound e isions o ASD o accumula e o e ime among pa ien s wi h DLSD while hey we e spo adic wi h IS. He e, we pe - o med addi ional analysis among he DLSD pa ien s o find ou whe he poo pos ope a i e sagi al alignmen inc eases he e isions o ASD in a 10-yea ollow-up a e LSF. MATERIALS AND METHODS Pa ien s Be ween 2008 and 2012, all elec i e LSF pa ien s in Tampe e Uni e si y Hospi al we e ec ui ed in o a p ospec i e ollow- up s udy. In Finland, a single public uni pe o ms LSF su ge ies and eope a ions o a ce ain popula ion. Hence, he s udy popula ion ep esen s a ce ain geog aphical ca chmen a ea. A he baseline, su geons and s udy pe - sonnel filled in he demog aphic and su gical da a, and he pa ien s answe ed he ollowing ques ionnai es: Oswes y Disabili y Index, Dep ession Scale, and a Visual Analog Scale o back and leg pain. All pa ien s signed w i en consen , and he Tampe e Uni e si y Hospi al E hics Commi ee ap- p o ed he s udy (R07108). As ASD is mainly ela ed o degene a i e spinal dis- o de s, we excluded pa ien s wi h IS he e. Ou p e ious ollow-up showed de o mi y pa ien s o esemble DSLS pa ien s demog aphically and in e ms o e isions o ASD.4Howe e , gi en hei condi ion which po en ially equi es mo e ex ensi e su ge y and indi idual judgemen , we excluded pa ien s wi h de o mi y he e o acili a e an- swe ing o he p esen ques ion. Hence, ou exclusion c i e ia we e: (1) usion eaching he ho acic spine, (2) o me spine su ge y, (3) IS, (4) de o mi y, (5) ac u e, o (6) umo . Ou whole s udy popula ion su e ed om degene a i e lumba spine pa hology wi h ela ed neu al comp ession, ha is, spinal s enosis wi h (80%) o wi h- ou (20%) spondylolis hesis. Fusion was implemen ed o add ess he spondylolis hesis o o acili a e o aminal decomp ession. All su ge ies we e ins umen ed pos e o- la e al usions om midline incision wi h o wi hou in e body usion ( ans o aminal lumba in e body usion/pos e io lumba in e body usion) combined wi h necessa y decomp ession. We in es iga ed all spinal eope a ions om he pa ien eco ds. Dea h o eope a ion o ASD ended he ollow-up o a single pa ien —o he wise, he ollow-up con inued o June o 2020. Spinopel ic Pa ame e s Lumba lo dosis (LL), pel ic incidence (PI), sac al slope, pel ic il , and segmen al lo dosis (SL) o he usion segmen we e de e mined om sagi al s anding lumba spine a- diog aphs be o e and 3 mon hs a e su ge y. The p e- ope a i e s anding adiog aph was missing om 7 pa ien s — hey we e excluded om he analysis. Figu e 1 shows he defini ions o hese pa ame e s. PI is ega ded a cons an alue de e mined by indi idual pel ic ana omy. We de e mined LL as an angle be ween he uppe endpla es o L1 and S1 e eb ae. Schwab e al12 pos ula ed a o mula LL =PI ±9° in he no mal popula ion. Acco ding o ha , he pa ien can be conside ed hypolo do ic in spine su ge y se ings wi h PI−LL >9°. The op imal a ge lo dosis in LSF, howe e , dec eases wi h he pa ien ’s age.13,14 A single h eshold was chosen o s a is ical analysis. Fu he , analyses we e pe o med sepa a ely o he pa ien s unde and o e 65 yea s o a oid he po en ial e ec o he di e ence be ween he age-app op ia e h eshold and he fixed cu o o 9°. Sac al slope desc ibes he pel ic alignmen , and pel ic il indica es he amoun o pel ic e o e sion which is needed o main ain a s anding pos u e. A e LSF, LL−SL ep esen s he mobile segmen o he lumba spine. LL SS PI PT SL Figu e 1. Lumba spinopel ic pa ame e s: lumba lo dosis (LL), pel ic incidence (PI), sac al slope (SS), pel ic il (PT), and segmen al lo dosis (SL) o he usion segmen . Values a e p esen ed in deg ees. SURGERY Sagi al Balance and ASD •Toi onen e al 1358 www.spinejou nal.com Oc obe 2022 S a is ics The desc ip i e s a is ics a e p esen ed as means wi h SD, as medians wi h in e qua ile ange o as coun s wi h pe cen- ages. Cox p opo ional haza ds eg ession models we e used o es ima e he adjus ed haza d a ios (HRs) and hei 95% confidence in e als (CIs). Age, sex, usion leng h, and he le el o he caudal end o usion we e used as co a ia es in hese models. The possible nonlinea ela ionship be- ween LL and SL and he isk o e ision o ASD was modeled using es ic ed cubic splines wi h 4 kno s a he fi h, 35 h, 65 h, and 95 h pe cen iles. Spline unc ions we e es ima ed using mul i a iable Cox p opo ional haz- a d eg ession models, including age, sex, usion leng h, and he le el o he caudal end o usion as a co a ia e. All analyses we e pe o med using STATA so wa e, e sion 16.1 (S a aCo p LP, College S a ion, TX). RESULTS A o al o 215 pa ien s (mean age: 66 y , SD: 10 y ) me he inclusion c i e ia. Mos o hem we e women (76%) who mos commonly unde wen wo-segmen usion in he lowe lumba spine (Table 1). Du ing he ollow-up wi h a median o 9.2 yea s, 43 (20%) pa ien s unde wen a e ision o ASD. The spinopel ic pa ame e s o he pa ien s we e equal p eope a i ely and pos ope a i ely (Table 2). By mean, he di e ence PI−LL anged in no mal lo dosis be o e and a e su ge y. Howe e , 83 (39%) pa ien s we e hypolo do ic a e su ge y acco ding o he misma ch o PI−LL >9°. The pos ope a i e imbalance (PI−LL >9°) did no esul in a significan ly inc eased isk o e ision o ASD ac- co ding o he Cox mul i a ia e model. The c ude HR o 1.5 (95% CI: 0.8–2.7) and adjus ed (by age, sex, PI, usion leng h, and he le el o he caudal end o usion) HR o 1.7 (95% CI: 0.9–3.3) emained s a is ically insignifican . HR was he same, insignifican , i pa ien s unde and o e 65 yea s we e analyzed sepa a ely. Pos ope a i e segmen al hypolo dosis migh lead o hy- pe lo dosis ou side he usion segmen (LL−SL) as a com- pensa o y mechanism. Ne e heless, we ound highe LL −SL o esul in less e isions o ASD: HR =0.9 (95% CI: 0.9–1.0). The e ec o con inuous di e ence LL−SL on e- isions o ASD is shown in Figu e 2 ein o ced his finding. DISCUSSION Among pa ien s who unde wen LSF su ge y o DLSD, we did no find pos ope a i e hypolo dosis (by PI−LL >9°) o esul in a significan inc ease o he isk o e ision o ASD du ing a 10-yea ollow-up. Howe e , misma ch o 9° does no always ep esen a clinical h eshold o sa - is ac o y and poo alignmen . Olde age g oups epo edly ole a e lowe lo dosis and g ea e misma ch han younge pa ien s.13,14 Ne e heless, one fixed cu o was used o di e en ia e good and poo alignmen in s a is ical analysis. As p e iously indica ed, e isions o ASD a e in equen a e LSF o IS.4Con a y o ha , hey accumula e almos linea ly o e ime among pa ien s ha ha e unde gone LSF o TABLE 1. The Baseline Demog aphic Da a, Sel - epo ed (*) Symp oms and Como bidi ies, and he Type o P ima y Su ge y N=215 Women [n (%)] 164 (76) Age [mean (SD)] 66 (10) BMI [mean (SD)] 28.6 (4.4) Smoking* [n (%)] 12 (6) Educa ion yea s [mean (SD)] 11.1 (3.9) Physical ac i i y* [mean (SD)] (h/wk) 4 (2, 9) Du a ion o he spinal p oblem* [median (IQR)] (y) 9 (4, 20) Back pain* VAS [mean (SD)] 61 (26) Leg pain* VAS [mean (SD)] 68 (23) ODI* [mean (SD)] 45 (15) DEPS* [mean (SD)] 10.5 (6.1) Como bidi ie* [n (%)] Ca dio ascula 118 (60) Diabe es 24 (12) Psychia ic diso de 5 (3) Pulmona y 11 (6) Neu ological 5 (3) Rheuma oid 14 (7) Indica ion o su ge y Spinal s enosis wi h spondylolis hesis [n (%)] 172 (80) Spinal s enosis wi hou spondylolis hesis [n (%)] 43 (20) Fusion Le el o he lowe end [n (%)] L3 o L4 9 (4) L5 o L6 114 (53) S1 92 (43) Leng h, le els [n (%)] 1 59 (27) 2 84 (39) 3 54 (25) 4 17 (8) 5 1 (0) In e body cage (TLIF/PLIF) [n (%)] 23 (11) BMI indica es body mass index; DEPS, Dep ession Scale; IQR, in e qua ile ange; ODI, Oswes y Disabili y Index; PLIF, pos e io lumba in e body u- sion; TLIF, ans o aminal lumba in e body usion; VAS, Visual Analog Scale. SURGERY Sagi al Balance and ASD •Toi onen e al Spine www.spinejou nal.com 1359 DLSD. This phenomenon highligh s he ole o he ongoing degene a i e p ocess in he spine in he de elopmen o ASD. Gene ally, he e ec o pos ope a i e sagi al alignmen on clinical ou come is es ablished, bu i s ole in he p e en ion o ASD is mo e unclea .15,16 In he li e a u e, he case-con ol s udy o Dju aso ic and colleagues is o en e e ed o as a p oo o an associa ion be ween pos - ope a i e hypolo dosis and he inc eased e isions o ASD.5,11,17 In ha s udy, he mean in e al be ween he ini ial su ge y and he e ision was 58 mon hs, while he mean ollow-up pe iod o con ols was only 55 mon hs, which we conside ela i ely sho . As e isions accumula e o e ime, and secondly, pa ien s may die du ing he ollow- up, we conside he Kaplan-Meie me hod an app op ia e way o assess his phenomenon. Kim e al18 e ospec i ely analyzed 69 pa ien s who unde wen L4–L5 usion o IS o degene a i e spondylo- lis hesis. They concluded ha main aining a segmen al lo - dosis o 20° o mo e was impo an in he p e en ion o ASD. Bae e al,19 in hei e ospec i e analysis, sugges ed ha es o a ion o segmen al lo dosis is impo an in he p e en ion o ASD. Ne e heless, hey ound only a s a is- ically insignifican di e ence o 3° be ween ASD and non- ASD g oups. In a p ospec i e 5-yea ollow-up a e LSF, Anandjiwala e al20 ound p eexis ing adjacen segmen degene a ion, no pos ope a i e balance, o be a isk ac o o adiological ASD. Fu he mo e, hey ound no co ela- ion be ween he clinical ou come and adiological ASD. In a e ospec i e 10-yea ollow-up o pos e io lumba in- e body usion su ge ies, Nakashima e al21 ound high PI, no LL, a significan isk ac o o ea ly-onse ASD. In a e ospec i e analysis o Alen ado e al,10 SL and LL we e no significan isk ac o s o ASD. Despi e a ela i ely la ge s udy popula ion and a long ollow-up, we did no find a s a is ically significan e ec o poo pos ope a i e balance on he a e o e isions o ASD. Hence, we pos ula e ha alignmen plays a less significan ole in he mul i ac o ial pa hogenesis o ASD han com- monly p oposed. We conside he ongoing degene a i e spinal disease he mos impo an single ac o in his en i y. Poo segmen al alignmen equi es compensa o y mech- anisms om he pa ien o main ain global balance. Hy- pe lo dosis in he mobile segmen o he lumba spine, usually abo e he used segmen , is one o he compensa o y mechanisms a e LSF.22 Thus, we expec ed highe LL−SL o ela e o inc eased e isions o ASD caused by he in- c eased s ess a he adjacen segmen s. Howe e , he con- nec ion was he opposi e. This may indica e ha he pa ien s wi h mobile spine p esen mo e capaci y o com- pensa e and hus less s ess o he adjacen segmen s. Mo eo e , Figu e 2 indica ed a s ong e ec om he change in LL−SL on he e isions o ASD. Ou da a p o ide no defini i e answe whe he his, in ac , mo e eflec s he indi idual alignmen o mobili y in he mobile segmen . I is also possible ha some o he pa ien s had an un ulfilled need o compensa ion be o e and a e su ge y due o a s i spine. Ea lie , di use idiopa hic skele al hype os osis, a condi ion esul ing in se e ely es ic ed spinal mobili y, is epo ed as a significan isk ac o o ASD a e sho segmen LSF.23 We assume ha he benefi o easonable segmen al lo dosis in he p e en ion o ASD migh be he mos impo an wi h educed spinal mobili y. Du ing he da a collec ing pe iod, use o in e body cage was less common han nowadays. The main indica ion o in e body cage hen was o aminal decomp ession o s eng hening he usion o p e en ins umen a ion ailu es. TABLE 2. The Spinopel ic Pa ame e s (°) Be o e and A e Lumba Spine Fusion Su ge y Mean (SD) P eope a i e Pos ope a i e LL 50 (13) 49 (12) PI 56 (10) — PI−LL 6.7 (11.1) 6.7 (11.1) PT 20 (8) 21 (7) SS 37 (9) 36 (8) SL 29 (14) 27 (12) LL−SL 21 (14) 22 (13) LL indica es lumba lo dosis; PI, pel ic incidence; PT, pel ic il ; SL, segmen al lo dosis; SS, sac al slope. LL-SL pos -100 10203040506070 F equency, % 0 1 2 3 4 5 6 7 8 Adjus ed Haza d Ra io (95% CI) 0,02 0,05 0,2 0,5 1 2 5 10 Figu e 2. Highe lo dosis in he mobile segmen o he lumba spine (LL−SL) a e lumba spine usion was linked o dec eased e isions o adjacen segmen disease. Re e ence le el (haza d a io =1) o LL−SL was he e se o 21°. CI indica es con idence in e al; LL, lumba lo dosis; SL, segmen al lo dosis. SURGERY Sagi al Balance and ASD •Toi onen e al 1360 www.spinejou nal.com Oc obe 2022 The use o ans o aminal lumba in e body usion in he co ec ion o sagi al alignmen has inc eased he ea e . The e o e, we did no assess he ole o he in e body cage in he p e en ion o ASD he e. Al hough he connec ion be ween pos ope a i e sagi al alignmen and he occu ence o ASD seems less s aigh - o wa d as occasionally p oposed, he pu sui o no mal alignmen is impo an , especially o he clinical ou come. In his s udy, we ha e no in es iga ed how pos ope a i e sagi al balance a ec s he unc ionali y o he heal h- ela ed quali y o li e. Mo eo e , ending up in kyphosis du ing LSF su ge y usually hampe s u u e e ision su ge ies, whe e es o ing no mal balance may equi e conside ably hea ie su ge y. All his migh ha e he g ea es impac wi h limi ed spinal mobili y. This s udy does no p o e ha sagi al alignmen has no e ec on he de elopmen o ASD. Howe e , ou esul s ein o ce he pe cep ion om he li e a u e ha sagi al alignmen has only a limi ed e ec on he p og ession o ASD. CONCLUSION Poo sagi al alignmen (misma ch PI−LL >9°) did no significan ly inc ease e isions o ASD in a 10-yea ollow- up o he pa ien s who unde wen LSF o DLSD. Achie ing app op ia e segmen al lo dosis in LSF migh be he mos impo an in pa ien s wi h educed spinal mobili y. ➢Key Poin s ❑We pe o med a e ospec i e addi ional analysis o e alua e he effec o sagi al alignmen on he isk o e isions o adjacen segmen disease a e LSFs. ❑The s udy popula ion had been p ospec i ely ollowed up o 10 yea s a e ha ing unde gone LSF o a degene a i e spinal diso de (s enosis wi h o wi hou spondylolis hesis). ❑We did no find poo pos ope a i e balance o significan ly inc ease he isk o e isions o ASD. Re e ences 1. S omq is B, F i zell P, Hagg O, Jonsson B, Sanden B. Swedish Socie y o Spinal Su geons. Swespine: he Swedish Spine Regis e : he 2012 epo . Eu Spine J. 2013;22:953–74. 2. Pekkanen L, Ne a MH, Kau iainen H, Ky ola K, Ma inen I, Hakkinen A. Changes in heal h u ili y, disabili y, and heal h- ela ed quali y o li e in pa ien s a e spinal usion: a 2-yea ollow-up s udy. Spine (Phila Pa 1976). 2014;39:2108–14. 3. 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O suki B, Fujibayashi S, Takemo o M, Kimu a H, Shimizu T, Ma suda S. Di use idiopa hic skele al hype os osis (DISH) is a isk ac o o u he su ge y in sho -segmen lumba in e body usion. Eu Spine J. 2015;24:2514–9. SURGERY Sagi al Balance and ASD •Toi onen e al Spine www.spinejou nal.com 1361