Biomechanical comparison of anterior Caspar plate and three-level posterior fixation techniques in a human cadaveric model

1993 ◽  
Vol 79 (1) ◽  
pp. 96-103 ◽  
Author(s):  
Vincent C. Traynelis ◽  
Paul A. Donaher ◽  
Robert M. Roach ◽  
H. Kojimoto ◽  
Vijay K. Goel
Keyword(s):  
Cervical Spine ◽  
Repeated Measures ◽  
Plate Fixation ◽  
Axial Rotation ◽  
Posterior Fixation ◽  
Lateral Bending ◽  
Anterior Plate ◽  
Content Type ◽  
Cervical Spine Injuries ◽  
Flexion Extension

✓ Traumatic cervical spine injuries have been successfully stabilized with plates applied to the anterior vertebral bodies. Previous biomechanical studies suggest, however, that these devices may not provide adequate stability if the posterior ligaments are disrupted. To study this problem, the authors simulated a C-5 teardrop fracture with posterior ligamentous instability in human cadaveric spines. This model was used to compare the immediate biomechanical stability of anterior cervical plating, from C-4 to C-6, to that provided by a posterior wiring construct over the same levels. Stability was tested in six modes of motion: flexion, extension, right and left lateral bending, and right and left axial rotation. The injured/plate-stabilized spines were more stable than the intact specimens in all modes of testing. The injured/posterior-wired specimens were more stable than the intact spines in axial rotation and flexion. They were not as stable as the intact specimens in the lateral bending or extension testing modes. The data were normalized with respect to the motion of the uninjured spine and compared using repeated measures of analysis of variance, the results of which indicate that anterior plating provides significantly more stability in extension and lateral bending than does posterior wiring. The plate was more stable than the posterior construct in flexion loading; however, the difference was not statistically significant. The two constructs provide similar stability in axial rotation. This study provides biomechanical support for the continued use of bicortical anterior plate fixation in the setting of traumatic cervical spine instability.

Plate fixation in the cervical spine: traditional paramedian screw configuration compared with unique unilateral configuration

2013 ◽  
Vol 18 (6) ◽  
pp. 575-581 ◽  
Author(s):  
Prasath Mageswaran ◽  
Robert F. McLain ◽  
Robb Colbrunn ◽  
Tara Bonner ◽  
Elijah Hothem ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Plate Fixation ◽  
Axial Rotation ◽  
Torsional Stiffness ◽  
Fixation Strength ◽  
Rigid Fixation ◽  
Lateral Bending ◽  
Flexion Extension ◽  
Standard Plate ◽  
Cervical Plate

Object This study compared the fixing strength and stability achieved by a unilateral plate and screw configuration against a standard cervical fixation plate using a single-level corpectomy and allograft strut graft model. Methods Multidirectional in vitro flexibility tests were performed using a robotic spine testing system. Human cadaveric spines were assessed for spinal stability after vertebral corpectomy and anterior instrumentation. Specimens were mounted cranially and caudally on custom jigs that were then attached to load cells on the robotic system's end effector and base pedestal. C2–T1 spine specimens (n = 6) were tested intact; then after C-5 corpectomy (the vertebral body was excised), allograft placement and anterior plate fixation were performed. The surgeons performed a uniform corpectomy and reconstruction of each specimen in a protocol fashion. Two plates were compared: a unilateral 4-hole cervical plate designed to obtain rigid fixation using 4 convergent fixation screws all placed unilateral to the vertebral midline, and a standard cervical plate with bilateral plate screw configuration. The plate testing sequence was selected at random to limit bias. Fixation screws were matched for length and diameter. Pure moments were applied under load control (maximum 1.8 Nm) in flexion, extension, left/right lateral bending, and left/right axial rotation. Vertebral motion was measured using an optoelectronic system. The mean relative range of motion between C-4 and C-6 was compared among groups using repeated-measures ANOVA (significance level of 0.05). Results In comparing the intact construct and 2 different plates in all planes of motion, only motion in extension (intact vs unilateral plate, p = 0.003; intact vs standard plate, p = 0.001) and left axial rotation (intact vs unilateral plate, p = 0.019) were significantly affected. In terms of immediate cervical stability after 1-level corpectomy and placement of an allograft reconstruction, the unilateral plate showed comparable stiffness to the standard plate in all 3 motion planes (flexion [p = 0.993], extension [p = 0.732], left lateral bending [p = 0.683], right lateral bending [p = 0.546], left axial rotation [p = 0.082], and right axial rotation [p = 0.489]). The unilateral plate showed a trend toward improved stiffness in axial rotation. In no direction did the unilateral configuration prove significantly less stiff than the traditional configuration. Conclusions The unilateral plate design proposed here requires minimal dissection and retraction beyond the midline of tissues susceptible to scar, postoperative pain, and swelling. The authors' study suggests that a unilateral plate can be configured to provide comparable fixation strength and torsional stiffness compared with traditional, widely accepted plate designs.

SPIRE spinous process stabilization plate: biomechanical evaluation of a novel technology

2006 ◽  
Vol 4 (2) ◽  
pp. 160-164 ◽  
Author(s):  
Jeremy C. Wang ◽  
David Spenciner ◽  
James C. Robinson
Keyword(s):  
Pedicle Screw ◽  
Repeated Measures ◽  
Spinous Process ◽  
Axial Rotation ◽  
Biomechanical Properties ◽  
Posterior Fixation ◽  
Lateral Bending ◽  
Flexion Extension ◽  
Fixation Techniques ◽  
Unilateral Pedicle Screw

Object The authors studied the biomechanical properties of a novel spinous process stabilization plate (CD HORIZON SPIRE Spinal System) and present the results in comparison with those of other posterior fixation methods. Methods Ten functional cadaveric lumbar segments were subjected to nondestructive quasistatic loading forces in 10 different conditions: intact, destabilized (discectomy), fitted with spinous process plate (SPP) alone, with anterior-column support (ACS) alone, ACS with SPP, ACS with posterior translaminar facet screw (PTFS) fixation, ACS with unilateral pedicle screw and rod (UPSR) fixation, ACS with bilateral pedicle screw and rod (BPSR) fixation, UPSR alone, or BPSR alone. Stiffness and range of motion (ROM) data were compared using a repeated-measures, one-way analysis of variance. The construct with greatest mean limitation of flexion–extension ROM was ACS/SPP at 4.14° whereas it was 5.75° for ACS/UPSR fixation, 5.03° for ACS/BPSR fixation, and 10.13° for the intact spine. The SPIRE plate alone also provided greater flexion and extension stiffness, with less ROM than other posterior stabilization options. Fixation with BPSR with or without ACS resulted in the stiffest construct in lateral bending and axial rotation. The SPP and UPSR fixation groups were equivalent in resisting lateral bending and axial rotation forces with or without ACS. Conclusions The SPIRE plate effectively stabilized the spine, and the test results compare favorably with other fixation techniques that are more time consuming to perform and have greater inherent risks.

Initial stability of cervical spine fixation: predictive value of a finite element model

2002 ◽  
Vol 97 (1) ◽  
pp. 128-134 ◽  
Author(s):  
Tobias R. Pitzen ◽  
Dieter Matthis ◽  
Dragos D. Barbier ◽  
Wolf-Ingo Steudel
Keyword(s):  
Cervical Spine ◽  
Fe Model ◽  
Lateral Bending ◽  
Anterior Plate ◽  
Content Type ◽  
Flexion Extension ◽  
Loading Case ◽  
Left And Right ◽  
Fine Print

✓ The purpose of this study was to generate a validated finite element (FE) model of the human cervical spine to be used to analyze new implants. Digitized data obtained from computerized tomography scanning of a human cervical spine were used to generate a three-dimensional, anisotropic, linear C5–6 FE model by using a software package (ANSYS 5.4). Based on the intact model (FE/Intact), a second was generated by simulating an anterior cervical fusion and plate (ACFP) C5–6 model in which monocortical screws (FE/ACFP) were used. Loading of each FE model was simulated using pure moments of ± 2.5 Nm in flexion/extension, axial left/right rotation, and left/right lateral bending. For validation of the models, their predicted C5–6 range of motion (ROM) was compared with the results of an earlier, corresponding in vitro study of six human spines, which were tested in the intact state and surgically altered at C5–6 with the same implants. The validated model was used to analyze the stabilizing effect of a new disc spacer, Cenius (Aesculap AG, Tuttlingen, Germany), as a stand-alone implant (FE/Cenius) and in combination with an anterior plate (FE/Cenius+ACFP). In addition, compression loads at the upper surface of the spacer were investigated using both models. As calculated by FE/Intact and FE/ACFP models, the ROM was within 1 standard deviation of the mean value of the corresponding in vitro measurements for each loading case. The FE/Cenius model predicted C5–6 ROM values of 5.5° in flexion/extension, 3.1° in axial rotation (left and right), and 2.9° in lateral bending (left and right). Addition of an anterior plate resulted in a further decrease of ROM in each loading case. The FE/Cenius model predicted an increase of compression load in flexion and a decrease in extension, whereas in the FE/Cenius+ACFP model an increase of graft compression in extension and unloading of the graft in flexion were predicted. The current FE model predicted ROM values comparable with those obtained in vitro in the intact state as well as after simulation of an ACFP model. It predicted a stabilizing potential for a new cage, alone and in combination with an anterior plate system, and predicted the influence of both loading modality and additional instrumentation on the behavior of the interbody graft.

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.

Construct Stability of C2 Replacement Strategies

2003 ◽  
Author(s):  
Christian M. Puttlitz ◽  
Robert P. Melcher ◽  
Vedat Deviren ◽  
Dezsoe Jeszenszky ◽  
Ju¨rgen Harms
Keyword(s):  
Repeated Measures ◽  
Posterior Instrumentation ◽  
Statistical Significance ◽  
Axial Rotation ◽  
Posterior Fixation ◽  
Camera Motion ◽  
Anterior Plate ◽  
Intact Specimen ◽  
Strut Graft ◽  
Significant Difference

Reconstruction of C2 after tumor destruction and resection remains a significant challenge. Most constructs utilize a strutgraft with plate or screw fixation. A novel C2 prosthesis combining a titanium mesh cage with bilateral C1 shelves and a T-plate has been used successfully in 18 patients. Supplemental posterior instrumentation includes C0-C3 or C1-C3. Biomechanical comparisons of this C2 prosthesis with traditional fixation options have not been reported. Five fresh-frozen human cadaveric cervical spines (C0-C5) were tested intact. Next, the C2 prosthesis, and strut graft and anterior plate constructs were tested with occiput-C3 and C1-C3 posterior fixation. Pure moment loads (up to 1.5 N-m) were applied in flexion and extension, lateral bending, and axial rotation. C1-C3 motion was evaluated using 3 camera motion analysis. Statistical significance was evaluated using one-way repeated measures ANOVA with Student-Newman-Keuls post hoc pairwise comparisons. All constructs provided a statistically significant decrease in motion in this C2 corpectomy model as compared to the intact condition. There was no significant difference in C1-C3 motion between the 4 constructs, regardless of whether the occiput was included in the fixation. Under these loading conditions, both the C2 prostheisis and strut-graft-plate constructs provided initial C1-C3 stability beyond that of the intact specimen. The occiput does not need to be included in the posterior instrumentation.

The cervical end of an occipitocervical fusion: a biomechanical evaluation of 3 constructs

2008 ◽  
Vol 9 (3) ◽  
pp. 296-300 ◽  
Author(s):  
Michael A. Finn ◽  
Daniel R. Fassett ◽  
Todd D. Mccall ◽  
Randy Clark ◽  
Andrew T. Dailey ◽  
...  
Keyword(s):  
Tracking System ◽  
Plate Fixation ◽  
Axial Rotation ◽  
Lateral Mass ◽  
Lateral Bending ◽  
Cross Link ◽  
3D Tracking ◽  
Flexion Extension ◽  
Biomechanical Evaluation ◽  
Rotation Motion

Object Stabilization with rigid screw/rod fixation is the treatment of choice for craniocervical disorders requiring operative stabilization. The authors compare the relative immediate stiffness for occipital plate fixation in concordance with transarticular screw fixation (TASF), C-1 lateral mass and C-2 pars screw (C1L-C2P), and C-1 lateral mass and C-2 laminar screw (C1L-C2L) constructs, with and without a cross-link. Methods Ten intact human cadaveric spines (Oc–C4) were prepared and mounted in a 7-axis spine simulator. Each specimen was precycled and then tested in the intact state for flexion/extension, lateral bending, and axial rotation. Motion was tracked using the OptoTRAK 3D tracking system. The specimens were then destabilized and instrumented with an occipital plate and TASF. The spine was tested with and without the addition of a cross-link. The C1L-C2P and C1L-C2L constructs were similarly tested. Results All constructs demonstrated a significant increase in stiffness after instrumentation. The C1L-C2P construct was equivalent to the TASF in all moments. The C1L-C2L was significantly weaker than the C1L-C2P construct in all moments and significantly weaker than the TASF in lateral bending. The addition of a cross-link made no difference in the stiffness of any construct. Conclusions All constructs provide significant immediate stability in the destabilized occipitocervical junction. Although the C1L-C2P construct performed best overall, the TASF was similar, and either one can be recommended. Decreased stiffness of the C1L-C2L construct might affect the success of clinical fusion. This construct should be reserved for cases in which anatomy precludes the use of the other two.

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 < 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 < 0.05), but not during axial rotation (P > 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.

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.

Biomechanical comparison of anterior and posterior stabilization methods in atlantoaxial instability

2004 ◽  
Vol 100 (3) ◽  
pp. 277-283 ◽  
Author(s):  
Sung-Min Kim ◽  
T. Jesse Lim ◽  
Josemaria Paterno ◽  
Tae-Jin Hwang ◽  
Kun-Woo Lee ◽  
...  
Keyword(s):  
The Other ◽  
Atlantoaxial Instability ◽  
Fixation Method ◽  
Posterior Fixation ◽  
Lateral Bending ◽  
Biomechanical Stability ◽  
Transarticular Screw ◽  
Content Type ◽  
Flexion Extension ◽  
Fine Print

Object. The authors compared the biomechanical stability of two anterior fixation procedures—anterior C1–2 Harms plate/screw (AHPS) fixation and the anterior C1–2 transarticular screw (ATS) fixation; and two posterior fixation procedures—the posterior C-1 lateral mass combined with C-2 pedicle screw/rod (PLM/APSR) fixation and the posterior C1–2 transarticular screw (PTS) fixation after destabilization. Methods. Sixteen human cervical spine specimens (Oc—C3) were tested in three-dimensional flexion—extension, axial rotation, and lateral bending motions after destabilization by using an atlantoaxial C1–2 instability model. In each loading mode, moments were applied to a maximum of 1.5 Nm, and the range of motion (ROM), neutral zone (NZ), and elastic zone (EZ) were determined and values compared using the intact spine, the destabilized spine, and the postfixation spine. The AHPS method produced inferior biomechanical results in flexion—extension and lateral bending modes compared with the intact spine. The lateral bending NZ and ROM for this method differed significantly from the other three fixation techniques (p < 0.05), although statistically significant differences were not obtained for all other values of ROM and NZ for the other three procedures. The remaining three methods restored biomechanical stability and improved it over that of the intact spine. Conclusions. The PLM/APSR fixation method was found to have the highest biomechanical stiffness followed by PTS, ATS, and AHPS fixation. The PLM/APSR fixation and AATS methods can be considered good procedures for stabilizing the atlantoaxial joints, although specific fixation methods are determined by the proper clinical and radiological characteristics in each patient.

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