Tapered cages in anterior lumbar interbody fusion: biomechanics of segmental reactions

2006 ◽  
Vol 5 (4) ◽  
pp. 330-335 ◽  
Author(s):  
Jason Moore ◽  
Narayan Yoganandan ◽  
Frank A. Pintar ◽  
Jason Lifshutz ◽  
Dennis J. Maiman
Keyword(s):  
Interbody Fusion ◽  
Anterior Lumbar Interbody Fusion ◽  
Lumbar Interbody Fusion ◽  
Lateral Bending ◽  
Related Data ◽  
Flexion Extension ◽  
Before And After ◽  
Bending Modes ◽  
Lumbar Spinal

Object The aim of this study was to determine the in vitro biomechanical responses of lumbar spinal segments after implantation of tapered cages. Methods Range of motion (ROM)– and stiffness-related data were determined in 10 human cadaveric T12–S1 columns subjected to flexion, extension, and lateral bending modes before and after anterior lumbar interbody fusion in which stand-alone LT-CAGE devices were used. The overall column showed no significant changes in ROM or stiffness. At the instrumented level, stiffness increased significantly (p < 0.05) in flexion and lateral bending modes. Indications of instability in extension were present, but these values were not statistically significant. There was no evidence of adjacent-level instability at any level in any mode, except for the segment superior to the fixation level in flexion; here there was a significant increase in ROM (p < 0.05) and a decrease in stiffness. Conclusions The anatomical conformity and bilateral placement of cages provide ample stability and rigidity at the treated level, comparable to that of other cage systems. Because hypermobility is traditionally related to early degenerative changes, the present results appear to suggest that cages do not significantly contribute to such alterations.

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.

Augmentation of an anterior lumbar interbody fusion with an anterior plate or pedicle screw fixation: a comparative biomechanical in vitro study

2007 ◽  
Vol 6 (3) ◽  
pp. 267-271 ◽  
Author(s):  
Tann A. Nichols ◽  
Brenda K. Yantzer ◽  
Suzanne Alameda ◽  
Wesley M. Johnson ◽  
Bernard H. Guiot
Keyword(s):  
Pedicle Screw ◽  
Interbody Fusion ◽  
Screw Fixation ◽  
Pedicle Screw Fixation ◽  
Anterior Lumbar Interbody Fusion ◽  
Lumbar Interbody Fusion ◽  
Lateral Bending ◽  
Anterior Plate ◽  
Elastic Zone ◽  
Flexion Extension

Object Posterior pedicle screw (PS) instrumentation is often used to augment anterior lumbar interbody fusion (ALIF) but at the cost of an increase in the morbidity rate due to the second approach and screw placement. If anterior plates were found to be biomechanically equivalent to PS fixation (PSF) after ALIF, then this second approach could be avoided without decreasing vertebral stability. Methods Eight cadaveric L5–S1 spinal segments were tested under four conditions: intact, following anterior discectomy and interbody spacer placement, after placement of an anterior plate, and following PSF. The elastic zone and stiffness were calculated for axial compression, flexion/extension, lateral bending, and torsion. Neither anterior plate stabilization nor PSF showed significant intergroup differences in stiffness or the elastic zone. Both exhibited greater stiffness in flexion than the intact specimens (p < 0.001). Pedicle screw fixation was associated with a decreased elastic zone in lateral bending compared with the intact specimen (p < 0.04). Conclusions Anterior plate fixation is biomechanically similar to PSF following ALIF. Surgeons may wish to use anterior plates in place of PSs to avoid the need for a posterior procedure. This may lead to a decrease in operative morbidity and improved overall outcomes.

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.

Adjacent-segment effects of lumbar cortical screw–rod fixation versus pedicle screw–rod fixation with and without interbody support

2021 ◽  
pp. 1-7
Author(s):  
Piyanat Wangsawatwong ◽  
Anna G. U. Sawa ◽  
Bernardo de Andrada Pereira ◽  
Jennifer N. Lehrman ◽  
Luke K. O’Neill ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Interbody Fusion ◽  
Lumbar Fusion ◽  
Statistical Significance ◽  
Adjacent Segment ◽  
Lumbar Interbody Fusion ◽  
Lateral Bending ◽  
Single Level ◽  
Cortical Screw ◽  
Flexion Extension

OBJECTIVE Cortical screw–rod (CSR) fixation has emerged as an alternative to the traditional pedicle screw–rod (PSR) fixation for posterior lumbar fixation. Previous studies have concluded that CSR provides the same stability in cadaveric specimens as PSR and is comparable in clinical outcomes. However, recent clinical studies reported a lower incidence of radiographic and symptomatic adjacent-segment degeneration with CSR. No biomechanical study to date has focused on how the adjacent-segment mobility of these two constructs compares. This study aimed to investigate adjacent-segment mobility of CSR and PSR fixation, with and without interbody support (lateral lumbar interbody fusion [LLIF] or transforaminal lumbar interbody fusion [TLIF]). METHODS A retroactive analysis was done using normalized range of motion (ROM) data at levels adjacent to single-level (L3–4) bilateral screw–rod fixation using pedicle or cortical screws, with and without LLIF or TLIF. Intact and instrumented specimens (n = 28, all L2–5) were tested using pure moment loads (7.5 Nm) in flexion, extension, lateral bending, and axial rotation. Adjacent-segment ROM data were normalized to intact ROM data. Statistical comparisons of adjacent-segment normalized ROM between two of the groups (PSR followed by PSR+TLIF [n = 7] and CSR followed by CSR+TLIF [n = 7]) were performed using 2-way ANOVA with replication. Statistical comparisons among four of the groups (PSR+TLIF [n = 7], PSR+LLIF [n = 7], CSR+TLIF [n = 7], and CSR+LLIF [n = 7]) were made using 2-way ANOVA without replication. Statistical significance was set at p < 0.05. RESULTS Proximal adjacent-segment normalized ROM was significantly larger with PSR than CSR during flexion-extension regardless of TLIF (p = 0.02), or with either TLIF or LLIF (p = 0.04). During lateral bending with TLIF, the distal adjacent-segment normalized ROM was significantly larger with PSR than CSR (p < 0.001). Moreover, regardless of the types of screw-rod fixations (CSR or PSR), TLIF had a significantly larger normalized ROM than LLIF in all directions at both proximal and distal adjacent segments (p ≤ 0.04). CONCLUSIONS The use of PSR versus CSR during single-level lumbar fusion can significantly affect mobility at the adjacent segment, regardless of the presence of TLIF or with either TLIF or LLIF. Moreover, the type of interbody support also had a significant effect on adjacent-segment mobility.

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.

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.

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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