scholarly journals Biomechanical evaluation of an integrated fixation cage during fatigue loading: a human cadaver study

2017 ◽  
Vol 26 (4) ◽  
pp. 524-531 ◽  
Author(s):  
Vivek Palepu ◽  
Jonathan H. Peck ◽  
David D. Simon ◽  
Melvin D. Helgeson ◽  
Srinidhi Nagaraja
Keyword(s):  
Mechanical Stability ◽  
Fatigue Testing ◽  
Plate Fixation ◽  
Fatigue Loading ◽  
Axial Rotation ◽  
Cadaver Study ◽  
Anterior Plate ◽  
Stability Parameters ◽  
Loading Mode ◽  
Flexion Extension

OBJECTIVE Lumbar cages with integrated fixation screws offer a low-profile alternative to a standard cage with anterior supplemental fixation. However, the mechanical stability of integrated fixation cages (IFCs) compared with a cage with anterior plate fixation under fatigue loading has not been investigated. The purpose of this study was to compare the biomechanical stability of a screw-based IFC with a standard cage coupled with that of an anterior plate under fatigue loading. METHODS Eighteen functional spinal units were implanted with either a 4-screw IFC or an anterior plate and cage (AP+C) without integrated fixation. Flexibility testing was conducted in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) on intact spines, immediately after device implantation, and post-fatigue up to 20,000 cycles of FE loading. Stability parameters such as range of motion (ROM) and lax zone (LZ) for each loading mode were compared between the 2 constructs at multiple stages of testing. In addition, construct loosening was quantified by subtracting post-instrumentation ROM from post-fatigue ROM. RESULTS IFC and AP+C configurations exhibited similar stability (ROM and LZ) at every stage of testing in FE (p ≥ 0.33) and LB (p ≥ 0.23) motions. In AR, however, IFCs had decreased ROM compared with AP+C constructs at pre-fatigue (p = 0.07) and at all post-fatigue time points (p ≤ 0.05). LZ followed a trend similar to that of ROM in AR. ROM increased toward intact motion during fatigue cycling for AP+C and IFC implants. IFC specimens remained significantly (p < 0.01) more rigid than specimens in the intact condition during fatigue for each loading mode, whereas AP+C construct motion did not differ significantly (p ≥ 0.37) in FE and LB and was significantly greater (p < 0.01) in AR motion compared with intact specimens after fatigue. Weak to moderate correlations (R2 ≤ 56%) were observed between T-scores and construct loosening, with lower T-scores leading to decreased stability after fatigue testing. CONCLUSIONS These data indicate that a 4-screw IFC design provides fixation similar to that provided by an AP+C construct in FE and LB during fatigue testing and better stability in AR motion.

Biomechanical Assessment of Anchored Cervical Interbody Cages: Comparison of 2-Screw and 4-Screw Designs

2014 ◽  
Vol 10 (3) ◽  
pp. 412-417 ◽  
Author(s):  
Marco T. Reis ◽  
Phillip M. Reyes ◽  
Neil R. Crawford
Keyword(s):  
Axial Rotation ◽  
Anterior Plate ◽  
Biomechanical Assessment ◽  
Loading Mode ◽  
Variable Angle ◽  
Flexion Extension ◽  
Standard Plate ◽  
Vertebral Bodies ◽  
The Stability

Abstract BACKGROUND: A new anchored cervical interbody polyetheretherketone spacer was devised that uses only 2 integrated variable-angle screws diagonally into the adjacent vertebral bodies instead of the established device that uses 4 diagonal fixed-angle screws. OBJECTIVE: To compare in vitro the stability provided by the new 2-screw interbody spacer with that of the 4-screw spacer and a 4-screw anterior plate plus independent polyetheretherketone spacer. METHODS: Three groups of cadaveric specimens were tested with 2-screw anchored cage (n = 8), 4-screw anchored cage (n = 8), and standard plate/cage (n = 16). Pure moments (1.5 Nm) were applied to induce flexion, extension, lateral bending, and axial rotation while measuring 3-D motion optoelectronically. RESULTS: In all 3 groups, the mean range of motion (ROM) and lax zone were significantly reduced relative to the intact spine after discectomy and fixation. The 2-screw anchored cage allowed significantly greater ROM (P &lt; .05) than the standard plate during flexion, extension, and axial rotation and allowed significantly greater ROM than the 4-screw cage during extension and axial rotation. The 4-screw anchored cage did not allow significantly different ROM or lax zone than the standard plate during any loading mode. CONCLUSION: The 2-screw variable-angle anchored cage significantly reduces ROM relative to the intact spine. Greater stability can be achieved, especially during extension and axial rotation, by using the 4-screw cage or standard plate plus cage.

scholarly journals Biomechanical analysis of occipitocervical stabilization techniques: emphasis on integrity of osseous structures at the occipital implantation sites

2020 ◽  
Vol 33 (2) ◽  
pp. 138-147
Author(s):  
Bryan W. Cunningham ◽  
Kyle B. Mueller ◽  
Kenneth P. Mullinix ◽  
Xiaolei Sun ◽  
Faheem A. Sandhu
Keyword(s):  
Fatigue Testing ◽  
Plate Fixation ◽  
Axial Rotation ◽  
Biomechanical Analysis ◽  
Lateral Bending ◽  
Mineral Density ◽  
Plate Group ◽  
Significant Difference ◽  
Flexion Extension ◽  
Implantation Sites

OBJECTIVEThe objective of the current study was to quantify and compare the multidirectional flexibility properties of occipital anchor fixation with conventional methods of occipitocervical screw fixation using nondestructive and destructive investigative methods.METHODSFourteen cadaveric occipitocervical specimens (Oc–T2) were randomized to reconstruction with occipital anchors or an occipital plate and screws. Using a 6-degree-of-freedom spine simulator with moments of ± 2.0 Nm, initial multidirectional flexibility analysis of the intact and reconstructed conditions was performed followed by fatigue loading of 25,000 cycles of flexion-extension (x-axis, ± 2.0 Nm), 15,000 cycles of lateral bending (z-axis, ± 2.0 Nm), and 10,000 cycles of axial rotation (y-axis, ± 2.0 Nm). Fluoroscopic images of the implantation sites were obtained before and after fatigue testing and placed on an x-y coordinate system to quantify positional stability of the anchors and screws used for reconstruction and effect, if any, of the fatigue component. Destructive testing included an anterior flexural load to construct failure. Quantification of implant, occipitocervical, and atlantoaxial junction range of motion is reported as absolute values, and peak flexural failure moment in Newton-meters (Nm).RESULTSAbsolute value comparisons between the intact condition and 2 reconstruction groups demonstrated significant reductions in segmental flexion-extension, lateral bending, and axial rotation motion at the Oc–C1 and C1–2 junctions (p < 0.05). The average bone mineral density at the midline keel (1.422 g/cm3) was significantly higher compared with the lateral occipital region at 0.671 g/cm3 (p < 0.05). There were no significant differences between the occipital anchor and plate treatments in terms of angular rotation (degrees; p = 0.150) or x-axis displacement (mm; p = 0.572), but there was a statistically significant difference in y-axis displacement (p = 0.031) based on quantitative analysis of the pre- and postfatigue fluoroscopic images (p > 0.05). Under destructive anterior flexural loading, the occipital anchor group failed at 90 ± 31 Nm, and the occipital plate group failed at 79 ± 25 Nm (p > 0.05).CONCLUSIONSBoth reconstructions reduced flexion-extension, lateral bending, and axial rotation at the occipitocervical and atlantoaxial junctions, as expected. Flexural load to failure did not differ significantly between the 2 treatment groups despite occipital anchors using a compression-fit mechanism to provide fixation in less dense bone. These data suggest that an occipital anchor technique serves as a biomechanically viable clinical alternative to occipital plate fixation.

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.

Gait-simulating fatigue loading analysis and sagittal alignment failure of spinal pelvic reconstruction after total sacrectomy: comparison of 3 techniques

2014 ◽  
Vol 20 (4) ◽  
pp. 364-370 ◽  
Author(s):  
Aaron J. Clark ◽  
Jessica A. Tang ◽  
Jeremi M. Leasure ◽  
Michael E. Ivan ◽  
Dimitriy Kondrashov ◽  
...  
Keyword(s):  
Load Transfer ◽  
Fatigue Testing ◽  
Tumor Resection ◽  
Early Mobilization ◽  
Fatigue Loading ◽  
Axial Rotation ◽  
Intact Specimen ◽  
Flexion Extension ◽  
Sacral Tumor ◽  
Total Sacrectomy

Object Reconstruction after total sacrectomy is a critical component of malignant sacral tumor resection, permitting early mobilization and maintenance of spinal pelvic alignment. However, implant loosening, graft migration, and instrumentation breakage remain major problems. Traditional techniques have used interiliac femoral allograft, but more modern methods have used fibular or cage struts from the ilium to the L-5 endplate or sacral body replacement with transiliac bars anchored to cages to the L-5 endplate. This study compares the biomechanical stability under gait-simulating fatigue loading of the 3 current methods. Methods Total sacrectomy was performed and reconstruction was completed using 3 different constructs in conjunction with posterior spinal screw rod instrumentation from L-3 to pelvis: interiliac femur strut allograft (FSA); L5–iliac cage struts (CSs); and S-1 body replacement expandable cage (EC). Intact lumbar specimens (L3–sacrum) were tested for flexion-extension range of motion (FE-ROM), axial rotation ROM (AX-ROM), and lateral bending ROM (LB-ROM). Each instrumented specimen was compared with its matched intact specimen to generate an ROM ratio. Fatigue testing in compression and flexion was performed using a custom-designed long fusion gait model. Results Compared with intact specimen, the FSA FE-ROM ratio was 1.22 ± 0.60, the CS FE-ROM ratio was significantly lower (0.37 ± 0.12, p < 0.001), and EC was lower still (0.29 ± 0.14, p < 0.001; values are expressed as the mean ± SD). The difference between CS and EC in FE-ROM ratio was not significant (p = 0.83). There were no differences in AX-ROM or LB-ROM ratios (p = 0.77 and 0.44, respectively). No failures were noted on fatigue testing of any EC construct (250,000 cycles). This was significantly improved compared with FSA (856 cycles, p < 0.001) and CS (794 cycles, p < 0.001). Conclusions The CS and EC appear to be significantly more stable constructs compared with FSA with FE-ROM. The 3 constructs appear to be equal with AX-ROM and LB-ROM. Most importantly, EC appears to be significantly more resistant to fatigue compared with FSA and CS. Reconstruction of the load transfer mechanism to the pelvis via the L-5 endplate appears to be important in maintenance of alignment after total sacrectomy reconstruction.

New anterior controllable antedisplacement and fusion surgery for cervical ossification of the posterior longitudinal ligament: a biomechanical study

2022 ◽  
pp. 1-9
Keyword(s):  
Fatigue Loading ◽  
Axial Rotation ◽  
Posterior Longitudinal Ligament ◽  
Cyclic Fatigue ◽  
Biomechanical Study ◽  
Biomechanical Stability ◽  
Loading Test ◽  
Crossover Effect ◽  
Flexion Extension

OBJECTIVE The traditional anterior approach for multilevel severe cervical ossification of the posterior longitudinal ligament (OPLL) is demanding and risky. Recently, a novel surgical procedure—anterior controllable antedisplacement and fusion (ACAF)—was introduced by the authors to deal with these problems and achieve better clinical outcomes. However, to the authors’ knowledge, the immediate and long-term biomechanical stability obtained after this procedure has never been evaluated. Therefore, the authors compared the postoperative biomechanical stability of ACAF with those of more traditional approaches: anterior cervical discectomy and fusion (ACDF) and anterior cervical corpectomy and fusion (ACCF). METHODS To determine and assess pre- and postsurgical range of motion (ROM) (2 Nm torque) in flexion-extension, lateral bending, and axial rotation in the cervical spine, the authors collected cervical areas (C1–T1) from 18 cadaveric spines. The cyclic fatigue loading test was set up with a 3-Nm cycled load (2 Hz, 3000 cycles). All samples used in this study were randomly divided into three groups according to surgical procedures: ACDF, ACAF, and ACCF. The spines were tested under the following conditions: 1) intact state flexibility test; 2) postoperative model (ACDF, ACAF, ACCF) flexibility test; 3) cyclic loading (n = 3000); and 4) fatigue model flexibility test. RESULTS After operations were performed on the cadaveric spines, the segmental and total postoperative ROM values in all directions showed significant reductions for all groups. Then, the ROMs tended to increase during the fatigue test. No significant crossover effect was detected between evaluation time and operation method. Therefore, segmental and total ROM change trends were parallel among the three groups. However, the postoperative and fatigue ROMs in the ACCF group tended to be larger in all directions. No significant differences between these ROMs were detected in the ACDF and ACAF groups. CONCLUSIONS This in vitro biomechanical study demonstrated that the biomechanical stability levels for ACAF and ACDF were similar and were both significantly greater than that of ACCF. The clinical superiority of ACAF combined with our current results showed that this procedure is likely to be an acceptable alternative method for multilevel cervical OPLL treatment.

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.

scholarly journals A Biomechanical Evaluation of a Next-Generation Integrated and Modular ACDF Device Possessing Full-Plate, Half-Plate, and No-Profile Fixation Iterations

2019 ◽  
Vol 9 (8) ◽  
pp. 826-833
Author(s):  
Ripul Panchal ◽  
Anup Gandhi ◽  
Chris Ferry ◽  
Sam Farmer ◽  
Jeremy Hansmann ◽  
...  
Keyword(s):  
Plate Fixation ◽  
Testing Machine ◽  
Axial Rotation ◽  
Biomechanical Study ◽  
The Novel ◽  
Novel Device ◽  
Plate Group ◽  
Flexion Extension ◽  
Group 2

Study Design: In vitro biomechanical study. Objectives: The objective of this in vitro biomechanical range-of-motion (ROM) study was to evaluate spinal segmental stability following fixation with a novel anterior cervical discectomy and fusion (ACDF) device (“novel device”) that possesses integrated and modular no-profile, half-plate, and full-plate fixation capabilities. Methods: Human cadaveric (n = 18, C3-T1) specimens were divided into 3 groups (n = 6/group). Each group would receive one novel device iteration. Specimen terminal ends were potted. Each specimen was first tested in an intact state, followed by anterior discectomy (C5/C6) and iterative instrumentation. Testing order: (1) novel device (group 1, no-profile; group 2, half-plate; group 3, full-plate); (2) novel device (all groups) with lateral mass screws (LMS); (3) traditional ACDF plate + cage; (4) traditional ACDF plate + cage + LMS. A 2 N·m moment was applied in flexion/extension (FE), lateral bending (LB), and axial rotation (AR) via a kinematic testing machine. Segmental ROM was tracked and normalized to intact conditions. Comparative statistical analyses were performed. Results: Key findings: (1) the novel half- and full-plate constructs provided comparable reduction in FE and LB ROM to that of traditional plated ACDF ( P ≥ .05); (2) the novel full-plate construct significantly exceeded all other anterior-only constructs ( P ≤ .05) in AR ROM reduction; and (3) the novel half-plate construct significantly exceeded the no-profile construct in FE ( P < .05). Conclusions: The novel ACDF device may be a versatile alternative to traditional no-profile and independent plating techniques, as it provides comparable ROM reduction in all principle motion directions, across all device iterations.

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.

Biomechanical evaluation of the impact of various facet joint lesions on the primary stability of anterior plate fixation in cervical dislocation injuries: a cadaver study

2014 ◽  
Vol 21 (4) ◽  
pp. 634-639 ◽  
Author(s):  
Ludwig Oberkircher ◽  
Sebastian Born ◽  
Johannes Struewer ◽  
Christopher Bliemel ◽  
Benjamin Buecking ◽  
...  
Keyword(s):  
Facet Joint ◽  
Plate Fixation ◽  
Primary Stability ◽  
Cadaver Study ◽  
Facet Joints ◽  
Anterior Plate ◽  
The Third ◽  
Subaxial Cervical Spine ◽  
The Mean ◽  
Anterior Posterior

Object Injuries of the subaxial cervical spine including facet joints and posterior ligaments are common. Potential surgical treatments consist of anterior, posterior, or anterior-posterior fixation. Because each approach has its advantages and disadvantages, the best treatment is debated. This biomechanical cadaver study compared the effect of different facet joint injuries on primary stability following anterior plate fixation. Methods Fractures and plate fixation were performed on 15 fresh-frozen intact cervical spines (C3–T1). To simulate a translation-rotation injury in all groups, complete ligament rupture and facet dislocation were simulated by dissecting the entire posterior and anterior ligament complex between C-4 and C-5. In the first group, the facet joints were left intact. In the second group, one facet joint between C-4 and C-5 was removed and the other side was left intact. In the third group, both facet joints between C-4 and C-5 were removed. The authors next performed single-level anterior discectomy and interbody grafting using bone material from the respective thoracic vertebral bodies. An anterior cervical locking plate was used for fixation. Continuous loading was performed using a servohydraulic test bench at 2 N/sec. The mean load failure was measured when the implant failed. Results In the group in which both facet joints were intact, the mean load failure was 174.6 ± 46.93 N. The mean load failure in the second group where only one facet joint was removed was 127.8 ± 22.83 N. In the group in which both facet joints were removed, the mean load failure was 73.42 ± 32.51 N. There was a significant difference between the first group (both facet joints intact) and the third group (both facet joints removed) (p < 0.05, Kruskal-Wallis test). Conclusions In this cadaver study, primary stability of anterior plate fixation for dislocation injuries of the subaxial cervical spine was dependent on the presence of the facet joints. If the bone in one or both facet joints is damaged in the clinical setting, anterior plate fixation in combination with bone grafting might not provide sufficient stabilization; additional posterior stabilization may be needed.

Sign in / Sign up

Export Citation Format

Share Document