Biomechanical analysis of stand-alone lumbar interbody cages versus 360° constructs: an in vitro and finite element investigation

2021 ◽  
pp. 1-9
Keyword(s):  
Interbody Fusion ◽  
Posterior Instrumentation ◽  
Axial Rotation ◽  
Posterior Fixation ◽  
Interbody Cage ◽  
Lateral Bending ◽  
Flexion Extension ◽  
Lateral Interbody ◽  
Flexion And Extension

OBJECTIVE Low fusion rates and cage subsidence are limitations of lumbar fixation with stand-alone interbody cages. Various approaches to interbody cage placement exist, yet the need for supplemental posterior fixation is not clear from clinical studies. Therefore, as prospective clinical studies are lacking, a comparison of segmental kinematics, cage properties, and load sharing on vertebral endplates is needed. This laboratory investigation evaluates the mechanical stability and biomechanical properties of various interbody fixation techniques by performing cadaveric and finite element (FE) modeling studies. METHODS An in vitro experiment using 7 fresh-frozen human cadavers was designed to test intact spines with 1) stand-alone lateral interbody cage constructs (lateral interbody fusion, LIF) and 2) LIF supplemented with posterior pedicle screw-rod fixation (360° constructs). FE and kinematic data were used to validate a ligamentous FE model of the lumbopelvic spine. The validated model was then used to evaluate the stability of stand-alone LIF, transforaminal lumbar interbody fusion (TLIF), and anterior lumbar interbody fusion (ALIF) cages with and without supplemental posterior fixation at the L4–5 level. The FE models of intact and instrumented cases were subjected to a 400-N compressive preload followed by an 8-Nm bending moment to simulate physiological flexion, extension, bending, and axial rotation. Segmental kinematics and load sharing at the inferior endplate were compared. RESULTS The FE kinematic predictions were consistent with cadaveric data. The range of motion (ROM) in LIF was significantly lower than intact spines for both stand-alone and 360° constructs. The calculated reduction in motion with respect to intact spines for stand-alone constructs ranged from 43% to 66% for TLIF, 67%–82% for LIF, and 69%–86% for ALIF in flexion, extension, lateral bending, and axial rotation. In flexion and extension, the maximum reduction in motion was 70% for ALIF versus 81% in LIF for stand-alone cases. When supplemented with posterior fixation, the corresponding reduction in ROM was 76%–87% for TLIF, 86%–91% for LIF, and 90%–92% for ALIF. The addition of posterior instrumentation resulted in a significant reduction in peak stress at the superior endplate of the inferior segment in all scenarios. CONCLUSIONS Stand-alone ALIF and LIF cages are most effective in providing stability in lateral bending and axial rotation and less so in flexion and extension. Supplemental posterior instrumentation improves stability for all interbody techniques. Comparative clinical data are needed to further define the indications for stand-alone cages in lumbar fusion surgery.

Immediate Stiffness of the C5–C6 Segment after Discectomy with the Cloward Technique: An in Vitro Biomechanical Study on a Human Cadaveric Model

Neurosurgery ◽  
2001 ◽  
Vol 49 (6) ◽  
pp. 1399-1408 ◽  
Author(s):  
Andrzej Maciejczak ◽  
Michał Ciach ◽  
Maciej Radek ◽  
Andrzej Radek ◽  
Jan Awrejcewicz
Keyword(s):  
Interbody Fusion ◽  
Spinal Instrumentation ◽  
Axial Rotation ◽  
Postoperative Management ◽  
Biomechanical Study ◽  
Lateral Bending ◽  
Cervical Discectomy ◽  
Cloward Procedure ◽  
Flexion Extension

ABSTRACT OBJECTIVE To determine whether the Cloward technique of cervical discectomy and fusion increases immediate postoperative stiffness of single cervical motion segment after application of interbody dowel bone graft. METHODS We measured and compared the stiffness of single-motion segments in cadaveric cervical spines before and immediately after interbody fusion with the Cloward technique. Changes in range of motion and stiffness of the C5–C6 segment were measured in a bending flexibility test (flexion, extension, lateral bending and axial rotation) before and after a Cloward procedure in 11 fresh-frozen human cadaveric specimens from the 4th through the 7th vertebrae. RESULTS The Cloward procedure produced a statistically significant increase in stiffness of the operated segment in flexion and lateral bending when compared with the intact spine. The less stiff the segment before the operation, the greater the increase in its postoperative flexural stiffness (statistically significant). The Cloward procedure produced nonuniform changes in rotational and extensional stiffness that increased in some specimens and decreased in others. CONCLUSION Our data demonstrate that Cloward interbody fusion increases immediate postoperative stiffness of an operated segment only in flexion and lateral bending in cadaveric specimens in an in vitro environment. Thus, Cloward fusion seems a relatively ineffective method for increasing the stiffness of a construct. This may add to discussion on the use of spinal instrumentation and postoperative management of patients after cervical discectomy, which varies from bracing in hard collars through immobilization in soft collars to no external orthosis.

Biomechanics of lateral lumbar interbody fusion constructs with lateral and posterior plate fixation

2014 ◽  
Vol 20 (3) ◽  
pp. 291-297 ◽  
Author(s):  
Guy R. Fogel ◽  
Rachit D. Parikh ◽  
Stephen I. Ryu ◽  
Alexander W. L. Turner
Keyword(s):  
Interbody Fusion ◽  
Plate Fixation ◽  
Spinous Process ◽  
Pedicle Screws ◽  
Axial Rotation ◽  
Interbody Cage ◽  
Lateral Bending ◽  
Lateral Plate ◽  
Flexion Extension ◽  
Supplemental Fixation

Object Lumbar interbody fusion is indicated in the treatment of degenerative conditions. Laterally inserted interbody cages significantly decrease range of motion (ROM) compared with other cages. Supplemental fixation options such as lateral plates or spinous process plates have been shown to provide stability and to reduce morbidity. The authors of the current study investigate the in vitro stability of the interbody cage with a combination of lateral and spinous process plate fixation and compare this method to the established bilateral pedicle screw fixation technique. Methods Ten L1–5 specimens were evaluated using multidirectional nondestructive moments (± 7.5 N·m), with a custom 6 degrees-of-freedom spine simulator. Intervertebral motions (ROM) were measured optoelectronically. Each spine was evaluated under the following conditions at the L3–4 level: intact; interbody cage alone (stand-alone); cage supplemented with lateral plate; cage supplemented with ipsilateral pedicle screws; cage supplemented with bilateral pedicle screws; cage supplemented with spinous process plate; and cage supplemented with a combination of lateral plate and spinous process plate. Intervertebral rotations were calculated, and ROM data were normalized to the intact ROM data. Results The stand-alone laterally inserted interbody cage significantly reduced ROM with respect to the intact state in flexion-extension (31.6% intact ROM, p < 0.001), lateral bending (32.5%, p < 0.001), and axial rotation (69.4%, p = 0.002). Compared with the stand-alone condition, addition of a lateral plate to the interbody cage did not significantly alter the ROM in flexion-extension (p = 0.904); however, it was significantly decreased in lateral bending and axial rotation (p < 0.001). The cage supplemented with a lateral plate was not statistically different from bilateral pedicle screws in lateral bending (p = 0.579). Supplemental fixation using a spinous process plate was not significantly different from bilateral pedicle screws in flexion-extension (p = 0.476). The combination of lateral plate and spinous process plate was not statistically different from the cage supplemented with bilateral pedicle screws in all the loading modes (p ≥ 0.365). Conclusions A combination of lateral and spinous process plate fixation to supplement a laterally inserted interbody cage helps achieve rigidity in all motion planes similar to that achieved with bilateral pedicle screws.

Revision of transforaminal lumbar interbody fusion using anterior lumbar interbody fusion: a biomechanical study in nonosteoporotic bone

2010 ◽  
Vol 12 (1) ◽  
pp. 82-87 ◽  
Author(s):  
Avraam Ploumis ◽  
Chunhui Wu ◽  
Amir Mehbod ◽  
Gustav Fischer ◽  
Antonio Faundez ◽  
...  
Keyword(s):  
Interbody Fusion ◽  
Posterior Instrumentation ◽  
Transforaminal Lumbar Interbody Fusion ◽  
Anterior Lumbar Interbody Fusion ◽  
Posterior Fixation ◽  
Lumbar Interbody Fusion ◽  
Mineral Density ◽  
Normal Bone Mineral Density ◽  
Flexion Extension

Object Transforaminal lumbar interbody fusion (TLIF) is a popular fusion technique for treating chronic low-back pain. In cases of interbody nonfusion, revision techniques for TLIF include anterior lumbar interbody fusion (ALIF) approaches. Biomechanical data of the revision techniques are not available. The purpose of this study was to compare the immediate construct stability, in terms of range of motion (ROM) and neutral zone (NZ), of a revision ALIF procedure for an unsuccessful TLIF. An in vitro biomechanical comparison of TLIF and its ALIF revision procedure was conducted on cadaveric nonosteoporotic human spine segments. Methods Twelve cadaveric lumbar motion segments with normal bone mineral density were loaded in unconstrained axial torsion, lateral bending, and flexion-extension under 0.05 Hz and ± 6-nm sinusoidal waveform. The specimens underwent TLIF (with posterior pedicle fixation) and anterior ALIF (with intact posterior fixation). Multidirectional flexibility testing was conducted following each step. The ROM and NZ data were measured and calculated for each test. Results Globally, the TLIF and revision ALIF procedures significantly reduced ROM and NZ compared with that of the intact condition. The revision ALIF procedures achieved similar ROM as the TLIF procedure. Conclusions Revision ALIF maintained biomechanical stability of TLIF in nonosteoporotic spines. Revision ALIF can be performed without sacrificing spinal stability in cases of intact posterior instrumentation.

Assessment of L5–S1 anterior lumbar interbody fusion stability in the setting of lengthening posterior instrumentation constructs: a cadaveric biomechanical study

2021 ◽  
pp. 1-9
Keyword(s):  
Interbody Fusion ◽  
Posterior Instrumentation ◽  
Pedicle Screws ◽  
Axial Rotation ◽  
Anterior Lumbar Interbody Fusion ◽  
Posterior Fusion ◽  
Lumbar Interbody Fusion ◽  
Lateral Bending ◽  
Fusion Construct ◽  
Flexion Extension

OBJECTIVE Excessive stress and motion at the L5–S1 level can lead to degenerative changes, especially in patients with posterior instrumentation suprajacent to L5. Attention has turned to utilization of L5–S1 anterior lumbar interbody fusion (ALIF) to stabilize the lumbosacral junction. However, questions remain regarding the effectiveness of stand-alone ALIF in the setting of prior posterior instrumented fusions terminating at L5. The purpose of this study was to assess the biomechanical stability of an L5–S1 ALIF with increasing lengths of posterior thoracolumbar constructs. METHODS Seven human cadaveric spines (T9–sacrum) were instrumented with pedicle screws from T10 to L5 and mounted to a 6 degrees-of-freedom robot. Posterior fusion construct lengths (T10–L5, T12–L5, L2–5, and L4–5) were instrumented to each specimen, and torque-fusion level relationships were determined for each construct in flexion-extension, axial rotation, and lateral bending. A stand-alone L5–S1 ALIF was then instrumented, and L5–S1 motion was measured as increasing pure moments (2 to 12 Nm) were applied. Motion reduction was calculated by comparing L5–S1 motion across the ALIF and non-ALIF states. RESULTS The average motion at L5–S1 in axial rotation, flexion-extension, and lateral bending was assessed for each fusion construct with and without ALIF. After adding ALIF to a posterior fusion, L5–S1 motion was significantly reduced relative to the non-ALIF state in all but one fused surgical condition (p < 0.05). Longer fusions with ALIF produced larger L5–S1 motions, and in some cases resulted in motions higher than native state motion. CONCLUSIONS Posterior fusion constructs up to L4–5 could be appropriately stabilized by a stand-alone L5–S1 ALIF when using a nominal threshold of 80% reduction in native motion as a potential positive indicator of fusion. The results of this study allow conclusions to be drawn from a biomechanical standpoint; however, the clinical implications of these data are not well defined. These findings, when taken in appropriate clinical context, can be used to better guide clinicians seeking to treat L5–S1 pathology in patients with prior posterior thoracolumbar constructs.

In vitro biomechanical comparison of an anterior and anterolateral lumbar plate with posterior fixation following single-level anterior lumbar interbody fusion

2007 ◽  
Vol 7 (3) ◽  
pp. 332-335 ◽  
Author(s):  
Wesley M. Johnson ◽  
Tann A. Nichols ◽  
Deepika Jethwani ◽  
Bernard H. Guiot
Keyword(s):  
Interbody Fusion ◽  
Plate Fixation ◽  
Anterior Lumbar Interbody Fusion ◽  
Posterior Fixation ◽  
Lumbar Interbody Fusion ◽  
Lateral Bending ◽  
Anterior Plate ◽  
Axial Torsion ◽  
Flexion Extension

Object Anterior lumbar interbody fusion (ALIF) is often supplemented with instrumentation to increase stability in the spine. If anterior plate fixation provided the same stability as posterior pedicle screw fixation (PSF), then a second approach and its associated morbidity could be avoided. Methods Seven human cadaveric L4–5 spinal segments were tested under three conditions: ALIF with an anterior plate, ALIF with an anterolateral plate, and ALIF supplemented by PSF. Range of motion (ROM) was calculated for flexion/extension, lateral bending, and axial torsion and compared among the three configurations. Results There were no significant differences in ROM during flexion/extension, lateral bending, or axial torsion among any of the three instrumentation configurations. Conclusions The addition of an anterior plate or posterior PS/rod instrumentation following ALIF provides substantially equivalent biomechanical stability. Additionally, the position of the plate system, either anterior or anterolateral, does not significantly affect the stability gained.

scholarly journals Biomechanical evaluation of the ProDisc-C stability following graded posterior cervical injury

2018 ◽  
Vol 29 (5) ◽  
pp. 515-524
Author(s):  
Michael D. Staudt ◽  
Doron Rabin ◽  
Ali A. Baaj ◽  
Neil R. Crawford ◽  
Neil Duggal
Keyword(s):  
Axial Rotation ◽  
Control Group ◽  
Lateral Bending ◽  
Cervical Injury ◽  
Cervical Arthroplasty ◽  
Posterior Surgery ◽  
Flexion Extension ◽  
Posterior Element ◽  
And Control ◽  
Flexion And Extension

OBJECTIVEThere are limited data regarding the implications of revision posterior surgery in the setting of previous cervical arthroplasty (CA). The purpose of this study was to analyze segmental biomechanics in human cadaveric specimens with and without CA, in the context of graded posterior resection.METHODSFourteen human cadaveric cervical spines (C3–T1 or C2–7) were divided into arthroplasty (ProDisc-C, n = 7) and control (intact disc, n = 7) groups. Both groups underwent sequential posterior element resections: unilateral foraminotomy, laminoplasty, and finally laminectomy. Specimens were studied sequentially in two different loading apparatuses during the induction of flexion-extension, lateral bending, and axial rotation.RESULTSRange of motion (ROM) after artificial disc insertion was reduced relative to that in the control group during axial rotation and lateral bending (13% and 28%, respectively; p < 0.05) but was similar during flexion and extension. With sequential resections, ROM increased by a similar magnitude following foraminotomy and laminoplasty in both groups. Laminectomy had a much greater effect: mean (aggregate) ROM during flexion-extension, lateral bending, and axial rotation was increased by a magnitude of 52% following laminectomy in the setting of CA, compared to an 8% increase without arthroplasty. In particular, laminectomy in the setting of CA introduced significant instability in flexion-extension, characterized by a 90% increase in ROM from laminoplasty to laminectomy, compared to a 16% increase in ROM from laminoplasty to laminectomy without arthroplasty (p < 0.05).CONCLUSIONSForaminotomy and laminoplasty did not result in significant instability in the setting of CA, compared to controls. Laminectomy alone, however, resulted in a significant change in biomechanics, allowing for significantly increased flexion and extension. Laminectomy alone should be used with caution in the setting of previous CA.

Biomechanics of a lumbar interspinous anchor with anterior lumbar interbody fusion

2010 ◽  
Vol 12 (4) ◽  
pp. 372-380 ◽  
Author(s):  
Dean G. Karahalios ◽  
Taro Kaibara ◽  
Randall W. Porter ◽  
Udaya K. Kakarla ◽  
Phillip M. Reyes ◽  
...  
Keyword(s):  
Interbody Fusion ◽  
Plate Fixation ◽  
Pedicle Screws ◽  
Axial Rotation ◽  
Anterior Lumbar Interbody Fusion ◽  
Lumbar Interbody Fusion ◽  
Lateral Bending ◽  
Anterior Plate ◽  
Foraminal Height ◽  
Flexion And Extension

Object An interspinous anchor (ISA) provides fixation to the lumbar spine to facilitate fusion. The biomechanical stability provided by the Aspen ISA was studied in applications utilizing an anterior lumbar interbody fusion (ALIF) construct. Methods Seven human cadaveric L3–S1 specimens were tested in the following states: 1) intact; 2) after placing an ISA at L4–5; 3) after ALIF with an ISA; 4) after ALIF with an ISA and anterior screw/plate fixation system; 5) after removing the ISA (ALIF with plate only); 6) after removing the plate (ALIF only); and 7) after applying bilateral pedicle screws and rods. Pure moments (7.5 Nm maximum) were applied in flexion and extension, lateral bending, and axial rotation while recording angular motion optoelectronically. Changes in angulation as well as foraminal height were also measured. Results All instrumentation variances except ALIF alone reduced angular range of motion (ROM) significantly from normal in all directions of loading. The ISA was most effective in limiting flexion and extension (25% of normal) and less effective in reducing lateral bending (71% of normal) and axial rotation (71% of normal). Overall, ALIF with an ISA provided stability that was statistically equivalent to ALIF with bilateral pedicle screws and rods. An ISA-augmented ALIF allowed less ROM than plate-augmented ALIF during flexion, extension, and lateral bending. Use of the ISA resulted in flexion at the index level, with a resultant increase in foraminal height. Compensatory extension at the adjacent levels prevented any significant change in overall sagittal balance. Conclusions When used with ALIF at L4–5, the ISA provides immediate rigid immobilization of the lumbar spine, allowing equivalent ROM to that of a pedicle screw/rod system, and smaller ROM than an anterior plate. When used with ALIF, the ISA may offer an alternative to anterior plate fixation or bilateral pedicle screw/rod constructs.

Biomechanical Consequences of Cervical Spondylectomy Versus Corpectomy

2008 ◽  
Vol 63 (suppl_4) ◽  
pp. ONS303-ONS308 ◽  
Author(s):  
Şeref Doğan ◽  
Seungwon Baek ◽  
Volker K.H. Sonntag ◽  
Neil R. Crawford
Keyword(s):  
Range Of Motion ◽  
Axial Rotation ◽  
Posterior Fixation ◽  
Spinal Stability ◽  
Angular Range ◽  
Anterior Instrumentation ◽  
Lateral Bending ◽  
Cervical Corpectomy ◽  
Flexion Extension ◽  
Anterior Plating

Abstract Objective: To evaluate the differences in spinal stability and stabilizing potential of instrumentation after cervical corpectomy and spondylectomy. Methods: Seven human cadaveric specimens were tested: 1) intact; 2) after grafted C5 corpectomy and anterior C4–C6 plate; 3) after adding posterior C4–C6 screws/rods; 4) after extending posteriorly to C3–C7; 5) after grafted C5 spondylectomy, anterior C4–C6 plate, and posterior C4–C6 screws/rods; and 6) after extending posteriorly to C3–C7. Pure moments induced flexion, extension, lateral bending, and axial rotation; angular motion was recorded optically. Results: After corpectomy, anterior plating alone reduced the angular range of motion to a mean of 30% of normal, whereas added posterior short- or long-segment hardware reduced range of motion significantly more (P &lt; 0.003), to less than 5% of normal. Constructs with posterior rods spanning C3–C7 were stiffer than constructs with posterior rods spanning C4–C6 during flexion, extension, and lateral bending (P &lt; 0.05), but not during axial rotation (P &gt; 0.07). Combined anterior and C4–C6 posterior fixation exhibited greater stiffness after corpectomy than after spondylectomy during lateral bending (P = 0.019) and axial rotation (P = 0.001). Combined anterior and C3–C7 posterior fixation exhibited greater stiffness after corpectomy than after spondylectomy during extension (P = 0.030) and axial rotation (P = 0.0001). Conclusion: Circumferential fixation provides more stability than anterior instrumentation alone after cervical corpectomy. After corpectomy or spondylectomy, long circumferential instrumentation provides better stability than short circumferential fixation except during axial rotation. Circumferential fixation more effectively prevents axial rotation after corpectomy than after spondylectomy.

Anterior cervical fusion: a biomechanical comparison of 4 techniques

2008 ◽  
Vol 9 (5) ◽  
pp. 444-449 ◽  
Author(s):  
Fabio Galbusera ◽  
Chiara M. Bellini ◽  
Francesco Costa ◽  
Roberto Assietti ◽  
Maurizio Fornari
Keyword(s):  
Randomized Clinical Trials ◽  
Locking Plate ◽  
Axial Rotation ◽  
Finite Element Models ◽  
Interbody Cage ◽  
Lateral Bending ◽  
Flexion Extension ◽  
Pure Moment ◽  
Fixation Type ◽  
Biomechanical Comparison

Object Cervical instrumented fusion is currently performed using several fixation methods. In the present paper, the authors compare the following 4 implantation methods: a stand-alone cage, a cage supplemented by an anterior locking plate, a cage supplemented by an anterior dynamic plate, and a dynamic combined plate–cage device. Methods Four finite element models of the C4–7 segments were built, each including a different instrumented fixation type at the C5–6 level. A compressive preload of 100 N combined with a pure moment of 2.5 Nm in flexion, extension, right lateral bending, and right axial rotation was applied to the 4 models. The segmental principal ranges of motion and the load shared by the interbody cage were obtained for each simulation. Results The stand-alone cage showed the lowest stabilization capability among the 4 configurations investigated, but it was still significant. The cage supplemented by the locking plate was very stiff in all directions. The 2 dynamic plate configurations reduced flexibility in all directions compared with the intact case, but they left significant mobility in the implanted segment. These configurations were able to share a significant part of the load (up to 40% for the combined plate–cage) through the posterior cage. The highest risk of subsidence was obtained with the model of the stand-alone cage. Conclusions Noticeable differences in the results were detected for the 4 configurations. The actual clinical relevance of these differences, currently considered not of critical importance, should be investigated by randomized clinical trials.

Stabilizing effect of posterior lumbar interbody fusion cages before and after cyclic loading

2000 ◽  
Vol 92 (1) ◽  
pp. 87-92 ◽  
Author(s):  
Annette Kettler ◽  
Hans-Joachim Wilke ◽  
Rupert Dietl ◽  
Matthias Krammer ◽  
Christianto Lumenta ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Interbody Fusion ◽  
Posterior Lumbar Interbody Fusion ◽  
Axial Rotation ◽  
Lumbar Interbody Fusion ◽  
Lateral Bending ◽  
Content Type ◽  
Flexion Extension ◽  
Stabilizing Effect ◽  
Fine Print

Object. The function of interbody fusion cages is to stabilize spinal segments primarily by distracting them as well as by allowing bone ingrowth and fusion. An important condition for efficient formation of bone tissue is achieving adequate spinal stability. However, the initial stability may be reduced due to repeated movements of the spine during everyday activity. Therefore, in addition to immediate stability, stability after cyclic loading is of remarkable relevance; however, this has not yet been investigated. The object of this study was to investigate the immediate stabilizing effect of three different posterior lumbar interbody fusion cages and to clarify the effect of cyclic loading on the stabilization. Methods. Before and directly after implantation of a Zientek, Stryker, or Ray posterior lumbar interbody fusion cage, 24 lumbar spine segment specimens were each evaluated in a spine tester. Pure lateral bending, flexion—extension, and axial rotation moments (± 7.5 Nm) were applied continuously. The motion in each specimen was measured simultaneously. The specimens were then loaded cyclically (40,000 cycles, 5 Hz) with an axial compression force ranging from 200 to 1000 N. Finally, they were tested once again in the spine tester. Conclusions. In general, a decrease of movement in all loading directions was noted after insertion of the Zientek and Ray cages and an increase of movement after implantation of a Stryker cage. In all three cage groups greater stability was demonstrated in lateral bending and flexion than in extension and axial rotation. Reduced stability during cyclic loading was observed in all three cage groups; however, loss of stability was most pronounced when the Ray cage was used.

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