biomechanical analysis of lateral lumbar interbody …biomechanical analysis of lateral lumbar...

Original Article

Biomechanical Analysis of Lateral Lumbar Interbody Fusion Constructs with Various
Fixation Options: Based on a Validated Finite Element Model
Zhenjun Zhang1,2, Guy R. Fogel3, Zhenhua Liao2, Yitao Sun4, Weiqiang Liu1,2

-BACKGROUND: Lateral lumbar interbody fusion usingcage supplemented with fixation has been used widely inthe treatment of lumbar disease. A combined fixation (CF)of lateral plate and spinous process plate may providemultiplanar stability similar to that of bilateral pediclescrews (BPS) and may reduce morbidity. The biomechan-ical influence of the CF on cage subsidence and facet jointstress has not been well described. The aim of this studywas to compare biomechanics of various fixation optionsand to verify biomechanical effects of the CF.

-METHODS: The surgical finite element models withvarious fixation options were constructed based oncomputed tomography images. The lateral plate and pos-terior spinous process plate were applied (CF). The 6 mo-tion modes were simulated. Range of motion (ROM), cagestress, endplate stress, and facet joint stress werecompared.

-RESULTS: For the CF model, ROM, cage stress, andendplate stress were the minimum in almost all motionmodes. Compared with BPS, the CF reduced ROM, cagestress, and endplate stress in all motion modes. The ROMwas reduced by more than 10% in all motion modes exceptfor flexion; cage stress and endplate stress were reducedmore than 10% in all motion modes except for rotation-left.After interbody fusion, facet joint stress was reduced

Key words- Biomechanics- Finite element analysis (FEA)- Facet joint stress (FJS)- Internal fixation- Lumbar interbody fusion- Range of motion (ROM)- Subsidence

Abbreviations and AcronymsBPS: Bilateral pedicle screwsCF: Combined fixationFE: Finite elementFEA: Finite element analysisFJS: Facet joint stressIDP: Intervetebral disc pressureIPS: Ipsilateral pedicle screws

e1120 www.SCIENCEDIRECT.com WORLD NE

substantially compared with the intact conditions in allmotion modes except for flexion.

-CONCLUSIONS: The combined plate fixation may offeran alternative to BPS fixation in lateral lumbar interbodyfusion.

INTRODUCTION

umbar interbody fusion has been used in the treatment oflumbar disease such as spondylolisthesis, trauma, and
Ldegenerative disc degeneration. Successful clinical out-
comes depend on fusion healing. The best opportunity for healingmay be the anterior interbody fusion, with better loading of thegraft and the largest surface area for fusion.1-4 Laterally insertedinterbody cages significantly decrease range of motion (ROM)compared with other cages.5-8 The interbody cage fusion improvesthe loading capacity of the anterior column.2,3 To achieve effectivefusion with an interbody cage, supplemented internal fixationoften is used. The supplemental fixation favorably influences thehealing of the lumbar fusion.4

It was known that some factors may affect the risk of cage sub-sidence, such as fusion constructs, bone quality of vertebraltrabecular and endplate, and preparation of endplate. According tothe existing literature, the biomechanical effects of various fixationmethods on subsidence are not understood fully. Bilateral pedicle

LP: Lateral plateROM: Range of motionSPP: Spinous process plate

From the 1Department of Mechanical Engineering, Tsinghua University, Beijing, China;2Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University inShenzhen, Shenzhen, China; 3Spine Pain Begone Clinic, San Antonio, Texas, USA; and4Haicheng City Central Hospital, Haicheng, China

To whom correspondence should be addressed: Weiqiang Liu, Ph.D.[E-mail: [email protected]]

Citation: World Neurosurg. (2018) 114:e1120-e1129.https://doi.org/10.1016/j.wneu.2018.03.158

Journal homepage: www.WORLDNEUROSURGERY.org

Available online: www.sciencedirect.com

1878-8750/$ - see front matter ª 2018 Elsevier Inc. All rights reserved.

UROSURGERY, https://doi.org/10.1016/j.wneu.2018.03.158

http://crossmark.crossref.org/dialog/?doi=10.1016/j.wneu.2018.03.158&domain=pdf

mailto:[email protected]

https://doi.org/10.1016/j.wneu.2018.03.158

http://www.WORLDNEUROSURGERY.org

www.sciencedirect.com/science/journal/18788750



ORIGINAL ARTICLE

ZHENJUN ZHANG ET AL. INTERBODY FUSION WITH VARIOUS FIXATION OPTIONS

screw (BPS) fixation has been used widely to supplement interbodycage because it can provide multiplanar stability.5,9-11 It may be notnegligible to account for one of the primary advantages of pediclescrew fixation, which is for compression dorsal to the instantaneousaxis of rotation to increase segmental lordosis. However, the fixa-tion of BPS requires an additional posterior procedure, which mayincrease risk and morbidity of complications.12-16

Compared with BPS, lateral plate (LP) fixation and spinous pro-cess plate (SPP) fixation have similar advantages of minimallyinvasive surgery, such as single-position lateral procedure, shorteroperative times, and less blood loss. Recent studies have indicatedthat both of thefixation options could provide lumbar stability5,6,17,18

and reduce morbidity.19-21 In the previous in vitro study, Fogel et al.4

proposed combined constructs with lateral and posterior platefixation, which could provide stability similar to BPS fixation.However, the influence of the combined fixation on cagesubsidence and facet joint stress (FJS) has not been investigated.Using a finite element (FE) model to systematically study the

biomechanical effects of various fixation options may be valuable.Further information to be determined is the influence of variousfixation options on the subsidence at surgical level, as well asdamage to the adjacent levels induced by the increased stiffness inthe index disc space associated with the interbody cage andsupplemented fixation options. The aim of this study was toinvestigate the biomechanical properties of cage subsidence andFJS with lumbar fusion constructs with various fixation optionsusing finite element analysis (FEA) and to verify the biomechanicaleffects of the combined fixation.

MATERIALS AND METHODS

The FE model of the intact lumbar spine employed in this studywas developed and validated in our previous study.22 Computed

Figure 1. Finite element model o

WORLD NEUROSURGERY 114: e1120-e1129, JUNE 2018

tomography images of intact lumbar spine with intervals of 0.7mm were obtained from a 36-year-old woman (weight 52 kg,height 158 cm, excluded from lumbar disease based on visual andradiographic examination). A total of 492 computed tomographyimages were imported into Mimics (Materialise Inc., Leuven,Belgium). The 3-dimensional geometry structure and the meshstructure were constructed by the use of Mimics and Hypermesh(Altair Technologies Inc., Fremont, California, USA), respectively.The mesh model was imported into Abaqus (Simulia Inc, Provi-dence, Rhode Island, USA) to perform FEA. The computer for thesimulation is ThinkStation (Lenovo, Beijing, China) configuredwith 64 GB memory and 24 processors.Figure 1 shows the FE model of lumbar spine L1eL5. The

vertebral body was composed of cancellous bone, cortical bone,and posterior bone. The intervertebral disc was composed ofnucleus pulposus and annulus fibrosus. The model included 7ligaments: anterior longitudinal ligament, posterior longitudinalligament, ligamenta flava, interspinal ligament, supraspinalligament, intertransverse ligament, and capsular ligament. Thecortical bone was 1.0 mm thick, and the endplate was 0.5 mmthick.11 All the ligaments were modeled with tension-only trusselements (2-node 3-dimensional truss element). The FE modelwas meshed using the 3-dimensional tetrahedral elements exceptfor the ligaments. There were 195,533 nodes and 841,038 elementsin the intact model.The interbody cage was modeled based on Nuvasive cage

(Nuvasive, Inc., San Diego, California, USA). The standard cagewas 15� lordosis, 10 mm high anteriorly, and 4 mm posteriorly.The cage was made of polyetheretherketone. The bilateral pediclescrew system was modeled based on the EXPEDIUM 5.5 System(DePuy Synthes Spine, Inc., Raynham, Massachusetts, USA). Thediameter of pedicle screw was 5.5 mm. The material of the pediclescrews was titanium alloy (Ti6Al4V). The LP was modeled based

f the intact lumbar spine.

www.WORLDNEUROSURGERY.org e1121


ORIGINAL ARTICLE


on Nuvasive Decade plate, and the diameter of the LP bolts was 5.5mm. The SPP was modeled based on Nuvasive Affix plate, and thesize of the plate was 45 mm. Both of the plates were made oftitanium alloy (Ti6Al4V). The material properties of componentswere shown in Table 1.23-31

To validate the intact FE model, the analysis study included 2steps of simulation. First, the ROM of intact lumbar spine L1eL5under pure moment was predicted. The ROM of the lumbar spinewas compared with previous in vitro results.26,32 Then, thecompression displacement and intervetebral disc pressure (IDP) ofthe motion segment L4eL5 under pure compression were calcu-lated. The compression displacement and IDP of L4eL5 werecompared with previous results.32-34

For simulation of the surgical models, the segment L2eL5 waschosen to predict the biomechanical changes of surgical level andadjacent levels. The interbody cage was inserted at the L3eL4 discspace laterally. The surgical conditions were as follows: intact(Intact), stand-alone cage (Cage), cage supplemented with LP,cage supplemented with ipsilateral pedicle screws (IPS), cagesupplemented with SPP, cage supplemented with LP and SPP(combined fixation, CF), and cage supplemented with BPS. Forthe 2 models with SPP fixation (SPP and CF), the interspinousligament and supraspinous ligament were resected. The FEmodels of interbody fusion constructs with various fixation op-tions were shown in Figure 2. All the surgical FE models wereconstructed based on the validated intact model. The surfacecontact between the vertebrae and discs and the contact

Table 1. Material Properties Used in the Finite Element Models

ComponentsYoung’s

Modulus, MPaPoissonRatio

Cortical bone 12,000 0.3

Cancellous bone 100 0.2

Posterior bone 3500 0.25

Endplate 4000 0.3

Annulus fibrosus 4.2 0.45

Nucleus pulposus 1 0.49

Anterior longitudinal ligament 20 0.3

Posterior longitudinal ligament 20 0.3

Ligamentum flavum 19.5 0.3

Interspinous ligament 11.6 0.3

Supraspinous ligament 15 0.3

Transverse ligament 58.7 0.3

Capsular ligament 32.9 0.3

Cage (PEEK) 3500 0.3

Pedicle screws (titanium alloy) 110,000 0.3

Lateral plate (titanium alloy) 110,000 0.3

Spinous process plate (titanium alloy) 110,000 0.3

PEEK, polyetheretherketone.


between the facet joints were consistent with that of thevalidated model. The interfaces of vertebrae and cages wereassigned to tie constraints. The bottom of L5 was fixed in alldirections. The compressive load of 280 N and the moment of7.5 Nm were applied to the upper surface of L2 as in previousliterature.35,36 The compressive load of 280 N corresponded tothe partial weight of a human body, and the moment of 7.5 Nmsimulated the motion modes occurred in different conditions suchas flexion, extension, lateral bending, and axial rotation.Considering the asymmetry of the LP fixation, this study

simulated the biomechanical properties of surgical FE models in 6motion modes: flexion, extension, bending-left, bending-right,rotation-left, and rotation-right. The ROM, cage stress, IDP,endplate stress, and FJS were analyzed and exported. The pre-dicted results of LP, SPP, and CF were compared with that of BPS.The ROM data were normalized to the intact ROM data.4 Underthe combined loading, the intact L2eL5 model was recalculated.In total, 42 simulation calculations for 7 models and 6 motionmodes were performed. Simulation results were in accordancewith the requirements of visualization, and mechanics data wereexpressed with Von Mises stress contours.

RESULTS

Model ValidationThe FE model of the intact lumbar spine employed in this studywas validated in our previous study.22 Under the pure moment, the

Cross-SectionalArea, mm2 References

— Shirazi-Adl et al., 1986,23 Zhong et al., 200624



— Schmidt et al., 200725


— Dreischarf et al., 2014,26 Ayturk et al., 201127

63.7 Zhong et al., 2006,24 Faizan et al., 201428

20 Zhong et al., 2006,24 Faizan et al., 201428




3.6 Zhong et al., 2006,24 Faizan et al., 201428

60 Zhong et al., 200624 Faizan et al., 201428

— Xiao et al., 2012,29 Vadapalli et al., 200630

— Xiao et al., 2012,29 Chosa et al., 200431






Figure 2. Finite element models of interbody fusion constructs with variousfixation options: (A) Cage: stand-alone cage; (B) LP: cage with lateral plate;(C) IPS: cage with ipsilateral pedicle screws; (D) SPP: cage with spinous

process plate; (E) CF: cage with lateral plate and spinous process plate; and(F) BPS: cage with bilateral pedicle screws.

ORIGINAL ARTICLE


L1eL5 ROM was within the range of the previous FE and in vitroexperimental studies.26,32 The loadedeflection curves were com-parable with the existing results of previous studies.26,32 Thecompressionedisplacement curves and compressioneIDP curvesalso were compared with the previous FE and in vitro experimentalstudies.32-34

Range of MotionUnder the combined loading of 280 N and 7.5 Nm, the ROM ofsurgical models is shown in Figure 3. After the interbody cage wasinserted, the predicted ROM at surgical level L3eL4 decreased inall motion modes. ROM of IPS was slightly less than that of Cage.ROMs of LP, SPP, and CF were compared with that of BPS. LPreduced ROM in bending and rotation, whereas it increasedROM in flexion and extension. SPP reduced ROM in extensionand rotation, whereas it did not substantially alter ROM inflexion and bending. CF reduced ROM in all motion modes.Compared among all the surgical models, ROM for CF was theminimum in all motion modes. Compared with BPS, ROMs for


CF were reduced by 4.20% in flexion, 12.87% in extension,34.98% in bending-left, 57.15% in bending-right, 64.27% inrotation-left, and 37.28% in rotation-right, respectively.

Cage Stress and IDPThe maximum stress in cage (cage stress) is displayed inFigure 4A. Cage stress of IPS was slightly less than that of Cage.Cage stresses of LP, SPP, and CF were compared with that ofBPS. LP increased cage stress in all motion modes except forbending. SPP did not substantially alter cage stress in all motionmodes. CF reduced cage stress in all motion modes. Comparedamong all the surgical models, cage stress for CF was theminimum in all motion modes except for flexion and rotation-right. Compared with BPS, cage stresses for CF were reduced by10.97% in flexion, 17.06% in extension, 62.76% in bending-left,11.91% in bending-right, 2.39% in rotation-left, and 13.46% inrotation-right, respectively. Figure 4B showed the contour plots ofVon Mises stress in the cage for CF in different motion modes.The IDP at adjacent levels is displayed in Figure 5. After



Figure 3. Range of motion at surgical level with variousfixation options in 6 motion modes. Cage, stand-alonecage; LP, cage with lateral plate; IPS, cage with

ipsilateral pedicle screws; SPP, cage with spinousprocess plate; CF, cage with lateral plate and spinousprocess plate; BPS, cage with bilateral pedicle screws.

ORIGINAL ARTICLE


interbody fusion, the IDP at adjacent level L2eL3 increased inextension and bending-right, whereas it changed very little inflexion and rotation. Compared among the surgical models, TheIDP at adjacent levels was not substantially changed with variedfixation options except for SPP in bending-right. The IDP for CFwas similar to that for BPS.

Endplate StressFigure 6A depicts the maximum stress in endplates (endplatestress) at surgical level. After interbody fusion, the predictedendplate stresses at surgical level L3eL4 increased in all motionmodes except for LP and CF in bending-left. Endplate stress ofIPS was slightly less than that of Cage. Endplate stresses of LP,SPP, and CF were compared with that of BPS. LP increased end-plate stress in flexion and extension, whereas it decreased that inbending-left. SPP did not substantially alter endplate stress in allmotion modes. CF reduced endplate stress in all motion modes.Compared among all the surgical models, endplate stress for CFwas the minimum in all motion modes except for flexion. Inflexion, endplate stress for CF was slightly more than that for SPP.Compared with BPS, endplate stresses for CF were reduced by12.11% in flexion, 20.90% in extension, 57.13% in bending-left,9.97% in bending-right, 2.64% in rotation-left, and 14.00% inrotation-right, respectively. Figure 6B showed the contour plots ofVon Mises stress in the L3 bottom endplate for CF in differentmotion modes.

Facet Joint StressIn Figure 7, the FJS of intact and surgical models is displayed.After interbody fusion, FJS at surgical level L3eL4 decreased inall motion modes except for flexion. Compared among all thesurgical models, FJS for various fixation options was notsubstantially changed in all motion modes except for flexionand bending-right. Compared with BPS, SPP and CF increasedFJS in flexion and bending-right. However, FJS for all the fixationoptions was much smaller than that for the intact conditions in all


motion modes except for flexion. Compared with the case of intactconditions, the average FJS for CF and BPS was reduced by 51%and 56%, respectively.

DISCUSSION

The predicted ROMs with various fixation options were normalizedto the intact ROM data.4 In addition, the current study showed thecage stress, IDP, endplate stress, and FJS. As was displayed inFigure 3, the ROM decreased at surgical level after the cage wasinserted at L3eL4 in all motion modes. Compared among all thefixation options, ROM for the CF was the minimum in all motionmodes. As is displayed in Figures 4 and 5, the cage stress wassensitive to the various fixation options, whereas the IDP atadjacent levels was not substantially changed with various fixationoptions. Compared among all the fixation options, cage stress forCF was the minimum in all motion modes except for flexion androtation-right. Figure 6 shows that the endplate stress increasedat surgical level after the cage was inserted at L3eL4 in all motionmodes. Compared among all the fixation options, endplate stressfor CF was the minimum in all motion modes except for flexion.As is displayed in Figure 7, FJS decreased at surgical level after thecage was inserted at L3eL4 in all motion modes except forflexion. The average FJS for CF and BPS was reduced to about onehalf of that for the intact conditions. There was not a substantialdifference in FJS between CF and BPS.The ROM, cage stress, and endplate stress at L3eL4 were

directly affected in all motion modes and changed with variousfixation options (Figure 2). By comparing the biomechanics oflumbar fusion with different fixation options, it was shown thatthe CF displayed advantages at surgical level L3eL4, such as theminimum ROM in all motion modes, the minimum cage stressexcept for flexion and rotation-right, and the minimum endplatestress except for flexion. Compared with BPS, the combination ofLP and SPP reduced ROM in all motion modes, which was notavailable when using LP or SPP alone. The CF reduced the ROM,which may provide better multiplanar stability than BPS,




Figure 4. Maximum stress in the cage with various fixation options in (A) 6motion modes and (B) contour plots of Von Mises stress in the cage for CF.Cage, stand-alone cage; LP, cage with lateral plate; IPS, cage with

ipsilateral pedicle screws; SPP, cage with spinous process plate; CF, cagewith lateral plate and spinous process plate; BPS, cage with bilateralpedicle screws; L, left; R, right.

ORIGINAL ARTICLE


particularly in low-demand patients. The CF reduced the cagestress and endplate stress, which may decrease the risk of subsi-dence of the cages into the endplate and the adjoining vertebralbone over time.30 It was indicated that in performing laterallumbar interbody fusion, the combination of LP and SPP mayoffer an alternative to BPS in low-demand situations.Biomechanics of lateral lumbar interbody fusion was sensitive

to the different fixation options. The previous studies have shownthat LP may increase stiffness in bending and rotation whereas it


had little effect in flexion and extension.5,6,37 The predicted ROMin the current study was comparable with the previous in vitroexperiments. In addition, the predicted results in the current studyhave shown that LP reduced cage stress and endplate stress inbending while changing little in other motion modes. From abiomechanical standpoint, LP had advantages in bending androtation. Some studies have shown that SPP may reduceflexioneextension motion but is less effective in other motionmodes.6,17,18,38,39 The predicted ROM in the current study was



Figure 5. IDP at adjacent levels with various fixation options in flexion (A),in extension (B), in bending (C), and in rotation (D). D2, disc between L2

and L3; D4, disc between L4 and L5; BL, bending-left; BR, bending-right;RL, rotation-left, RR, rotation-right.

ORIGINAL ARTICLE


comparable with the previous in vitro experiments except forrotation. In addition, the predicted results in the current studyhave shown that SPP reduced cage stress and endplate stress in allmotion modes. From a biomechanical standpoint, SPP had ad-vantages in flexion, extension, and rotation. Because the LP andSPP showed biomechanical advantages in different motion modes,a combination of these plates may provide better biomechanicalproperties in all motion modes.The basic idea of lumbar interbody fusion is to stabilize the

lumbar spine by reducing the ROM at surgical level. The previousliterature has shown that lumbar fusion may accelerate thedegeneration of intervertebral discs at adjacent levels.38-41 InFigure 5, the IDP at adjacent level L2eL3 increased after interbodyfusion in extension and bending-right, whereas that at adjacentlevels changed very little in flexion and rotation. In addition, thesame load condition was considered in the present study, the IDPwas not substantially increased at adjacent levels. However, toachieve the desired total ROM, patients after interbody fusion willincrease the driving force naturally, which may further increase therisk of degeneration of intervertebral discs at adjacent levels.


In the current study, the 15� lordosis cage was chosen ac-cording to the foraminal height and disc space angle of the pre-sent lumbar model. In this study, the combined anterioreposterior fixation of LP and SPP was compared with BPS fixa-tion. As was predicted in Figures 3, 4, and 6, the CF has advan-tages in ROM, cage stress, and endplate stress, which mayprovide better stability and lead to a smaller risk of endplateinjury.30 In clinical practice, the CF can be placed in asingle-position used for lateral procedure, avoiding an addi-tional posterior procedure, which may be associated with shorteroperative times, less invasiveness, and less blood loss.There are some limitations in the present study, such as using a

unique lumbar model, simplifying the material properties of sometissues, and ignoring the role of muscles. One limitation is theFEA standard technique of using a unique lumbar model. Thegeometric model of lumbar spine varies from person to person,such as the intervertebral disc space and the gaps between facetjoints. However, only one model of lumbar spine was chosen inthis study. Furthermore, the material properties were simplified,as linear elastic though the components of lumbar spine is




Figure 6. Maximum stress in the endplate at surgical level with variousfixation options in (A) 6 motion modes (B) and contour plots of Von Misesstress in L3 bottom endplate for CF. Cage, stand-alone cage; LP, cage with

lateral plate; IPS, cage with ipsilateral pedicle screws; SPP, cage withspinous process plate; CF, cage with lateral plate and spinous processplate; BPS, cage with bilateral pedicle screws; L, left; R, right.

ORIGINAL ARTICLE


nonlinear in reality. However, many FEAs on lumbar spine haveassumed that the components of spine were linear to improve thecalculation efficiency.24,30,36,42,43 In addition, the muscles were notconsidered in the present study although the muscles play animportant role in supporting the stability of lumbar spine.


However, the tendency of predicted results with various fixationoptions would not be substantially changed depending on theindividual geometric model and simplified material properties.According to the predicted results using FEA, it was indicated

that fixation options can affect the biomechanics of lumbar



Figure 7. Facet joint stress (FJS) at surgical level withvarious fixation options in 6 motion modes. Cage,stand-alone cage; LP, cage with lateral plate; IPS, cage

with ipsilateral pedicle screws; SPP, cage with spinousprocess plate; CF, cage with lateral plate and spinousprocess plate; BPS, cage with bilateral pedicle screws.

ORIGINAL ARTICLE


interbody fusion noticeably. Compared among the surgical modelswith different fixation methods, a CF of LP and SPP showed ad-vantages in biomechanics such as ROM, cage stress, and endplatestress. Compared with BPS fixation, the CF has advantages in


biomechanics and may have advantages in lower-demand patientsin clinical practice. An in vitro biomechanical testing or furtherclinical studies will be necessary to validate the observations ofthis FE study.

REFERENCES

1. Oxland TR, Lund T. Biomechanics of stand-alonecages and cages in combination with posteriorfixation: a literature review. Eur Spine J. 2000;9:S95-S101.

2. Phillips FM, Cunningham B, Carandang G,Ghanayem AJ, Voronov L, Havey RM, et al. Effectof supplemental translaminar facet screw fixationon the stability of stand-alone anterior lumbarinterbody fusion cages under physiologiccompressive preloads. Spine. 2004;29:1731-1736.

3. Tsantrizos A, Andreou A, Aebi M, Steffen T.Biomechanical stability of five stand-alone ante-rior lumbar interbody fusion constructs. Eur SpineJ. 2000;9:14-22.

4. Fogel GR, Parikh RD, Ryu SI, Turner AW.Biomechanics of lateral lumbar interbody fusionconstructs with lateral and posterior plate fixa-tion: laboratory investigation. J Neurosurg Spine.2014;20:1-7.

5. Cappuccino A, Cornwall GB, Turner AW,Fogel GR, Duong HT, Kim KD, et al. Biome-chanical analysis and review of lateral lumbarfusion constructs. Spine. 2010;35:S361-S367.

6. Laws CJ, Coughlin DG, Lotz JC, Laws CJ,Coughlin DG, Lotz JC, et al. Direct lateralapproach to lumbar fusion is a biomechanicallyequivalent alternative to the anterior approach: anin vitro study. Spine. 2012;37:819-825.

7. Perez-Orribo L, Kalb S, Reyes PM, Chang SW,Crawford NR. Biomechanics of lumbar corticalscrew-rod fixation versus pedicle screw-rod

fixation with and without interbody support. Spine.2013;38:635-641.

8. Pimenta L, Turner AW, Dooley ZA, Parikh RD,Peterson MD. Biomechanics of lateral interbodyspacers: going wider for going stiffer. Scienti-ficWorldJournal. 2012;2012:381814.

9. Kornblum MB, Turner AW, Cornwall GB,Zatushevsky MA, Phillips FM. Biomechanicalevaluation of stand-alone lumbar polyether-ether-ketone interbody cage with integrated screws.Spine J. 2013;13:77-84.

10. Slucky AV, Brodke DS, Bachus KN, Droge JA,Braun JT. Less invasive posterior fixation methodfollowing transforaminal lumbar interbody fusion:a biomechanical analysis. Spine J. 2006;6:78-85.

11. Ambati DV, Wright EK, Lehman RA, Kang DG,Wagner SC, Dmitriev AE. Bilateral pedicle screwfixation provides superior biomechanical stabilityin transforaminal lumbar interbody fusion: a finiteelement study. Spine J. 2015;15:1812-1822.

12. Amato V, Giannachi L, Irace C, Corona C. Accu-racy of pedicle screw placement in the lumbosa-cral spine using conventional technique:computed tomography postoperative assessmentin 102 consecutive patients. Clinical article.J Neurosurg Spine. 2010;12:306-313.

13. Lau D, Terman SW, Patel R, La MF, Park P.Incidence of and risk factors for superior facetviolation in minimally invasive versus open pediclescrew placement during transforaminal lumbarinterbody fusion: a comparative analysis. Clinicalarticle. J Neurosurg Spine. 2013;18:356-361.

14. Lieberman IH, Hardenbrook MA, Wang JC,Guyer RD. Assessment of pedicle screw

UROSURGERY, http

placement accuracy, procedure time, and radia-tion exposure using a miniature robotic guidancesystem. J Spinal Disord Tech. 2012;25:241-248.

15. Lotfnia I, Sayahmelli S, Gavami M. Postoperativecomputed tomography assessment of pediclescrew placement accuracy. Turk Neurosurg. 2010;20:500-507.

16. Wang MY, Anderson DG, Poelstra KA,Ludwig SC. Minimally invasive posterior fixation.Neurosurgery. 2008;63:197-203.

17. Kaibara T, Karahalios DG, Porter RW,Kakarla UK, Reyes PM, Choi SK, et al. Biome-chanics of a lumbar interspinous anchor withtransforaminal lumbar interbody fixation. WorldNeurosurg. 2010;73:572-577.

18. Karahalios DG, Kaibara T, Porter RW,Kakarla UK, Reyes PM, Baaj AA, et al. Biome-chanics of a lumbar interspinous anchor withanterior lumbar interbody fusion. Laboratoryinvestigation. J Neurosurg Spine. 2010;12:372-380.

19. Pradhan BB, Turner AW, Zatushevsky MA,Cornwall GB, Rajaee SS, Bae HW. Biomechanicalanalysis in a human cadaveric model of spinousprocess fixation with an interlaminar allograftspacer for lumbar spinal stenosis. Laboratoryinvestigation. J Neurosurg Spine. 2012;16:585-593.

20. Rodgers WB, Gerber EJ, Rodgers JA. Lumbarfusion in octogenarians: the promise of minimallyinvasive surgery. Spine. 2010;35:S355-S360.

21. Youssef JA, McAfee PC, Patty CA, Raley E,DeBauche S, Shucosky E, et al. Minimally invasivesurgery: lateral approach interbody fusion: resultsand review. Spine. 2010;35:S302-S311.

s://doi.org/10.1016/j.wneu.2018.03.158

http://refhub.elsevier.com/S1878-8750(18)30640-5/sref1




































































































ORIGINAL ARTICLE


22. Zhang ZJ, Li H, Fogel GR, Liao ZH, Li Y, Liu WQ.Biomechanical analysis of porous additive manu-factured cages for lateral lumbar interbody fusion:a finite element analysis.World Neurosurg. 2018;111:E581-E591.

23. Shirazi-Adl A, Ahmed AM, Shrivastava SC. Me-chanical response of a lumbar motion segment inaxial torque alone and combined with compres-sion. Spine. 1986;11:914-927.

24. Zhong ZC, Wei SH, Wang JP, Feng CK, Chen CS,Yu CH. Finite element analysis of the lumbarspine with a new cage using a topology optimi-zation method. Med Eng Phys. 2006;28:90-98.

25. Schmidt H, Heuer F, Drumm J, Klezl Z, Claes L,Wilke HJ. Application of a calibration methodprovides more realistic results for a finite elementmodel of a lumbar spinal segment. Clin Biomech.2007;22:377-384.

26. Dreischarf M, Zander T, Shirazi-Adl A,Puttlitz CM, Adam CJ, Chen CS, et al. Comparisonof eight published static finite element models ofthe intact lumbar spine: predictive power ofmodels improves when combined together.J Biomech. 2014;47:1757-1766.

27. Ayturk UM, Puttlitz CM. Parametric convergencesensitivity and validation of a finite element modelof the human lumbar spine. Comput Methods Bio-mech Biomed Engin. 2011;14:695-705.

28. Faizan A, Kiapour A, Kiapour AM, Goel VK.Biomechanical analysis of various footprints oftransforaminal lumbar interbody fusion devices.J Spinal Disord Tech. 2014;27:E118-E127.

29. Xiao ZT, Wang LY, Gong H, Zhu D. Biomechan-ical evaluation of three surgical scenarios of pos-terior lumbar interbody fusion by finite elementanalysis. Biomed Eng Online. 2012;11:31.

30. Vadapalli S, Sairyo K, Goel VK, Robon M,Biyani A, Khandha A, et al. Biomechanical ratio-nale for using polyetheretherketone (PEEK)

WORLD NEUROSURGERY 114: e1120-e1

spacers for lumbar interbody fusion-A finiteelement study. Spine. 2006;31:992-998.

31. Chosa E, Goto K, Totoribe K, Tajima N. Analysisof the effect of lumbar spine fusion on the supe-rior adjacent intervertebral disk in the presence ofdisk degeneration, using the three-dimensionalfinite element method. J Spinal Disord Tech. 2004;17:134-139.

32. Schmidt H, Galbusera F, Rohlmann A, Zander T,Wilke HJ. Effect of multilevel lumbar discarthroplasty on spine kinematics and facet jointloads in flexion and extension: a finite elementanalysis. Eur Spine J. 2012;21:S663-S674.

33. Berkson MH, Nachemson A, Schultz AB. Me-chanical properties of human lumbar spine mo-tion segments—Part II: responses in compressionand shear; influence of gross morphology.J Biomech Eng. 1979;101:53-57.

34. Brinckmann P, Grootenboe H. Change of discheight, radial disc bulge, and intradiscal pressurefrom discectomy. An in vitro investigation onhuman lumbar discs. Spine. 1991;16:641-646.

35. Rohlmann A, Neller S, Claes L, Bergmann G,Wilke HJ. Influence of a follower load on intra-discal pressure and intersegmental rotation of thelumbar spine. Spine. 2001;26:E557-E561.

36. Choi J, Shin D, Kim S. Biomechanical effects ofthe geometry of ball-and-socket artificial disc onlumbar spine: a finite element study. Spine. 2017;42:E332-E339.

37. Bess RS, Cornwall GB, Vance RE, Bachus KN,Brodke DS. Biomechanics of lateral arthrodesis.In: Goodrich JA, Volcan IJ, eds. Extreme LateralInterbody Fusion (XLIF). St. Louis, MO: QualityMedical Publishing; 2008:31-40.

38. Techy F, Mageswaran P, Colbrunn RW,Bonner TF, Mclain RF. Properties of an inter-spinous fxation device (ISD) in lumbar fusion

129, JUNE 2018 www.

constructs: a biomechanical study. Spine J. 2013;13:572-579.

39. Wang JC, Spenciner D, Robinson JC. SPIREspinous process stabilization plate: biomechanicalevaluation of a novel technology. J Neurosurg Spine.2006;4:160-164.

40. Kim HJ, Kang KT, Chang BS, Lee CK, Kim JW,Yeom JS. Biomechanical analysis of fusionsegment rigidity upon stress at both the fusionand adjacent segments: a comparison betweenunilateral and bilateral pedicle screw fixation.Yonsei Med J. 2014;55:1386-1394.

41. Zhang ZJ, Sun YT, Li Y, Liao ZH, Liu WQ. Recentadvances in finite element applications in artificiallumbar disc replacement. J Biomed Sci Engin. 2016;9:1-8.

42. Kim KT, Lee SH, Suk KS, Lee JH, Jeong B.Biomechanical changes of the lumbar segmentafter total disc replacement: Charite�, Prodisc�and Maverick� using finite element model study.J Korean Neurosurg Soc. 2010;47:446-453.

43. Grauer JN, Biyani A, Faizan A, Kiapour A,Sairyo K, Ivanov A, et al. Biomechanics of two-level Charité artificial disc placement in compar-ison to fusion plus single-level disc placementcombination. Spine J. 2006;6:659-666.

Conflict of interest statement: This study was supported bythe National Key Research and Development Plan (GrantNumber 2016YFC1102002).

Received 8 February 2018; accepted 22 March 2018

Citation: World Neurosurg. (2018) 114:e1120-e1129.https://doi.org/10.1016/j.wneu.2018.03.158

Journal homepage: www.WORLDNEUROSURGERY.org

Available online: www.sciencedirect.com

1878-8750/$ - see front matter ª 2018 Elsevier Inc. Allrights reserved.

WORLDNEUROSURGERY.org e1129














































































































biomechanical analysis of lateral lumbar interbody …biomechanical analysis of lateral lumbar...

Documents