The effect of posterior compression of the facet joints for initial stability and sagittal profile in the treatment of thoracolumbar fractures: a biomechanical study

Abstract Purpose Surgical treatment of thoracolumbar A3-fractures usually comprises posterior fixation—in neutral position or distraction—potentially followed by subsequent anterior support. We hypothesized that additional posterior compression in circumferential stabilization may increase stability by locking the facets, and better restore the sagittal profile. Methods Burst fractures Type A3 were created in six fresh frozen cadaver spine segments (T12–L2). Testing was performed in a custom-made spinal loading simulator. Loads were applied as pure bending moments of ± 3.75 Nm in all six movement axes. We checked range of motion, neutral zone and Cobb’s angle over the injured/treated segment within the following conditions: Intact, fractured, instrumented in neutral alignment, instrumented in distraction, with cage left in posterior distraction, with cage with posterior compression. Results We found that both types of instrumentation with cage stabilized the segment compared to the fractured state in all motion planes. For flexion/extension and lateral bending, flexibility was decreased even compared to the intact state, however, not in axial rotation, being the most critical movement axis. Additional posterior compression in the presence of a cage significantly decreased flexibility in axial rotation, thus achieving stability comparable to the intact state even in this movement axis. In addition, posterior compression with cage significantly increased lordosis compared to the distracted state. Conclusion Among different surgical modifications tested, circumferential fixation with final posterior compression as the last step resulted in superior stability and improved sagittal alignment. Thus, posterior compression as the last step is recommended in these pathologies.

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Endoscopic endonasal atlantoaxial transarticular screw fixation technique: an anatomical feasibility and biomechanical study

Journal of Neurosurgery Spine ◽

10.3171/2014.10.spine14374 ◽

2015 ◽

Vol 22 (5) ◽

pp. 470-477 ◽

Cited By ~ 5

Author(s):

George A. C. Mendes ◽

Curtis A. Dickman ◽

Nestor G. Rodriguez-Martinez ◽

Samuel Kalb ◽

Neil R. Crawford ◽

...

Keyword(s):

Odontoid Process ◽

Axial Rotation ◽

Biomechanical Study ◽

Entry Point ◽

Biomechanical Analysis ◽

Posterior Fixation ◽

Anatomical Landmarks ◽

Endoscopic Endonasal ◽

Second Stage ◽

Flexion Extension

OBJECT The primary disadvantage of the posterior cervical approach for atlantoaxial stabilization after odontoidectomy is that it is conducted as a second-stage procedure. The goal of the current study is to assess the surgical feasibility and biomechanical performance of an endoscopic endonasal surgical technique for C1–2 fixation that may eliminate the need for posterior fixation after odontoidectomy. METHODS The first step of the study was to perform endoscopic endonasal anatomical dissections of the craniovertebral junction in 10 silicone-injected fixed cadaveric heads to identify relevant anatomical landmarks. The second step was to perform a quantitative analysis using customized software in 10 reconstructed adult cervical spine CT scans to identify the optimal screw entry point and trajectory. The third step was biomechanical flexibility testing of the construct and comparison with the posterior C1–2 transarticular fixation in 14 human cadaveric specimens. RESULTS Adequate surgical exposure and identification of the key anatomical landmarks, such as C1–2 lateral masses, the C-1 anterior arch, and the odontoid process, were provided by the endonasal endoscopic approach in all specimens. Radiological analysis of anatomical detail suggested that the optimal screw entry point was on the anterior aspect of the C-1 lateral mass near the midpoint, and the screw trajectory was inferiorly and slightly laterally directed. The custommade angled instrumentation was crucial for screw placement. Biomechanical analysis suggested that anterior C1–2 fixation compared favorably to posterior fixation by limiting flexion-extension, axial rotation, and lateral bending (p > 0.3). CONCLUSIONS This is the first study that demonstrates the feasibility of an endoscopic endonasal technique for C1–2 fusion. This novel technique may have clinical utility by eliminating the need for a second-stage posterior fixation operation in certain patients undergoing odontoidectomy.

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Single-Level In Vitro Kinematic Comparison of Novel Inline Cervical Interbody Devices With Intervertebral Screw, Anchor, or Blade

Global Spine Journal ◽

10.1177/2192568219833055 ◽

2019 ◽

Vol 9 (7) ◽

pp. 697-707 ◽

Cited By ~ 1

Author(s):

Paul M. Arnold ◽

Ivan Cheng ◽

Jonathan A. Harris ◽

Mir M. Hussain ◽

Chengmin Zhang ◽

...

Keyword(s):

Axial Rotation ◽

Biomechanical Study ◽

Posterior Fixation ◽

Lateral Mass ◽

Flexion Extension ◽

Before And After ◽

Fixation Techniques ◽

Lateral Mass Screws ◽

Loading Modes

Study Design: In vitro cadaveric biomechanical study. Objective: To compare the biomechanics of integrated anchor and blade versus traditional screw fixation techniques for interbody fusion. Methods: Fifteen cadaveric cervical spines were divided into 3 equal groups (n = 5). Each spine was tested: intact, after discectomy (simulating an injury model), interbody spacer alone (S), integrated interbody spacer (iSA), and integrated spacer with lateral mass screw and rod fixation (LMS+iS). Each treatment group included integrated spacers with either screw, anchor, or blade integrated spacers. Constructs were tested in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) under pure moments (±1.5 N m). Results: Across all 3 planes, the following range of motion trend was observed: Injured > Intact > S > iSA > LMS+iS. In FE and LB, integrated anchor and blade significantly decreased motion compared with intact and injured conditions, before and after supplemental posterior fixation ( P < .05). Comparing tested devices revealed biomechanical equivalence between screw, anchor, and blade fixation methods in all loading modes ( P > .05). Conclusion: All integrated interbody devices reduced intact and injured motion; lateral mass screws and rods further stabilized the single motion segment. Comparing screw, anchor, or bladed integrated anterior cervical discectomy and fusion spacers revealed no significant differences.

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Biomechanical comparison of a C1 posterior arch clamp with C1 lateral mass screws in constructs for C1-C2 fusion

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine ◽

10.1177/09544119211032479 ◽

2021 ◽

pp. 095441192110324

Author(s):

Timothy L Lasswell ◽

John B Medley ◽

Jack P Callaghan ◽

Duane S Cronin ◽

Colin D McKinnon ◽

...

Keyword(s):

Axial Rotation ◽

Atlantoaxial Instability ◽

Posterior Arch ◽

Lateral Mass ◽

Lateral Bending ◽

Intact State ◽

Significant Difference ◽

Flexion Extension ◽

Translaminar Screw ◽

Fresh Frozen

The aim of this experimental study was to assess the biomechanical performance of a novel C1 posterior arch (C1PA) clamp compared with C1 lateral mass (C1LM) screws in constructs used to treat atlantoaxial instability. These constructs had either C2 pedicle (C2P) screws or C2 translaminar (C2TL) screws. Eight fresh-frozen human cadaveric ligamentous spine specimens (C0-C3) were tested under six conditions: the intact state, the destabilized state after a simulated odontoid fracture, and when instrumented with four constructs (C1LM-C2P, C1LM-C2TL, C1PA-C2P, C1PA-C2TL). Each specimen was tested in a spinal loading simulator that separately applied axial rotation, flexion-extension and lateral bending. In each test condition, displacement controlled angular motion was applied in both directions at a speed of 2 deg/s until a resulting moment of 1.5 Nm was achieved. The measured ranges of motion (ROM) of the C1-C2 segments were compared for each test condition using nonparametric Friedman tests. The destabilized state had significantly more C1-C2 motion ( p < 0.05) than the intact state in all cases, and all constructs greatly reduced this motion. C2 pedicle screw constructs that used the C1PA clamp had significantly less C1-C2 motion ( p < 0.05) than those with C1LM screws in flexion-extension as well as axial rotation and no statistically significant difference was detected in lateral bending. C2 translaminar screw constructs that used the C1PA clamp had significantly less C1-C2 motion ( p < 0.05) than those with C1LM screws in flexion-extension and no statistically significant difference was detected in axial rotation or in lateral bending. Data from the current study suggested that constructs using the novel C1PA clamp would provide as good, or improved, biomechanical stability to the C1-C2 segment compared with constructs using C1LM screws.

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

Journal of Neurosurgery Spine ◽

10.3171/2021.8.spine21879 ◽

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.

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Biomechanical Evaluation of Unilateral Versus Bilateral C1 Lateral Mass-C2 Intralaminar Fixation

Global Spine Journal ◽

10.1177/2192568217694152 ◽

2017 ◽

Vol 7 (3) ◽

pp. 239-245 ◽

Cited By ~ 3

Author(s):

Nitin Bhatia ◽

Asheen Rama ◽

Brandon Sievers ◽

Ryan Quigley ◽

Michelle H. McGarry ◽

...

Keyword(s):

Range Of Motion ◽

Axial Rotation ◽

Biomechanical Properties ◽

Lateral Mass ◽

Intact State ◽

Flexion Extension ◽

Fixation Techniques ◽

Rotation Stiffness ◽

Biomechanical Evaluation ◽

C2 Fixation

Study Design: Biomechanical, cadaveric study. Objectives: To compare the relative stiffness of unilateral C1 lateral mass-C2 intralaminar fixation to intact specimens and bilateral C1 lateral mass-C2 intralaminar constructs. Methods: The biomechanical integrity of a unilateral C1 lateral mass-C2 intralaminar screw construct was compared to intact specimens and bilateral C1 lateral mass-C2 intralaminar screw constructs. Five human cadaveric specimens were used. Range of motion and stiffness were tested to determine the stiffness of the constructs. Results: Unilateral fixation significantly decreased flexion/extension range of motion compared to intact ( P < .001) but did not significantly affect axial rotation ( P = .3) or bending range of motion ( P = .3). There was a significant decrease in stiffness in extension for both unilateral and bilateral fixation techniques compared to intact ( P = .04 and P = .03, respectively). There was also a significant decrease in stiffness for ipsilateral rotation for the unilateral construct compared to intact ( P = .007) whereas the bilateral construct significantly increased ipsilateral rotation stiffness compared to both intact and unilateral fixation ( P < .001). Conclusion: Bilateral constructs did show improved biomechanical properties compared to the unilateral constructs. However, unilateral C1-C2 fixation using a C1 lateral mass and C2 intralaminar screw-rod construct decreased range of motion and improved stiffness compared to the intact state with the exception of extension and ipsilateral rotation. Hence, a unilateral construct may be acceptable in clinical situations in which bilateral fixation is not possible, but an external orthosis may be necessary to achieve a fusion.

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Biomechanical Consequences of Cervical Spondylectomy Versus Corpectomy

Operative Neurosurgery ◽

10.1227/01.neu.0000327569.03654.96 ◽

2008 ◽

Vol 63 (suppl_4) ◽

pp. ONS303-ONS308 ◽

Cited By ~ 3

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.

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

Neurosurgery ◽

10.1097/00006123-200112000-00019 ◽

2001 ◽

Vol 49 (6) ◽

pp. 1399-1408 ◽

Cited By ~ 3

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.

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

Global Spine Journal ◽

10.1177/2192568219834252 ◽

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.

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Stability of the craniovertebral junction after unilateral occipital condyle resection: a biomechanical study

Journal of Neurosurgery Spine ◽

10.3171/spi.1999.90.1.0091 ◽

1999 ◽

Vol 90 (1) ◽

pp. 91-98 ◽

Cited By ~ 36

Author(s):

A. Giancarlo Vishteh ◽

Neil R. Crawford ◽

M. Stephen Melton ◽

Robert F. Spetzler ◽

Volker K. H. Sonntag ◽

...

Keyword(s):

Axial Rotation ◽

Craniovertebral Junction ◽

Biomechanical Study ◽

Occipital Condyle ◽

Upper Cervical Spine ◽

Lateral Bending ◽

Content Type ◽

Axial Translation ◽

Flexion Extension ◽

Fine Print

Object. The authors sought to determine the biomechanics of the occipitoatlantal (occiput [Oc]—C1) and atlantoaxial (C1–2) motion segments after unilateral gradient condylectomy. Methods. Six human cadaveric specimens (skull with attached upper cervical spine) underwent nondestructive biomechanical testing (physiological loads) during flexion—extension, lateral bending, and axial rotation. Axial translation from tension to compression was also studied across Oc—C2. Each specimen served as its own control and underwent baseline testing in the intact state. The specimens were then tested after progressive unilateral condylectomy (25% resection until completion), which was performed using frameless stereotactic guidance. At Oc—C1 for all motions that were tested, mobility increased significantly compared to baseline after a 50% condylectomy. Flexion—extension, lateral bending, and axial rotation increased 15.3%, 40.8%, and 28.1%, respectively. At C1–2, hypermobility during flexion—extension occurred after a 25% condylectomy, during axial rotation after 75% condylectomy, and during lateral bending after a 100% condylectomy. Conclusions. Resection of 50% or more of the occipital condyle produces statistically significant hypermobility at Oc—C1. After a 75% resection, the biomechanics of the Oc—C1 and C1–2 motion segments change considerably. Performing fusion of the craniovertebral junction should therefore be considered if half or more of one occipital condyle is resected.

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Finite element analysis of wedge and biconcave deformity in four different height restoration after augmentation of osteoporotic vertebral compression fracture

10.21203/rs.3.rs-38291/v1 ◽

2020 ◽

Author(s):

Xiao-Hua Zuo ◽

Ying-Bing Chen ◽

Peng Xie ◽

Wen-Dong Zhang ◽

Xiang-Yun Xue ◽

...

Keyword(s):

Finite Element ◽

Three Dimensional ◽

Axial Rotation ◽

Neutral Position ◽

Element Analysis ◽

Flexion Extension ◽

Dimensional Finite Element ◽

Von Mises ◽

Three Dimensional Finite Element ◽

Wedge Fracture

Abstract Purpose Biomechanical comparison of wedge and biconcave deformity of different height restoration after augmentation of osteoporotic vertebral compression fractures was analyzed by three-dimensional finite element analysis (FEA). Methods Three-dimensional finite element model (FEM) of T11-L2 segment was constructed from CT scan of elderly osteoporosis patient. The von Mises stresses of vertebrae, intervertebral disc, facet joints, displacement, and range of motion (ROM) of wedge and biconcave deformity were compared at four different heights (Genant 0–3 grade) after T12 vertebral augmentation. Results In wedge deformity, the stress of T12 decreased as the vertebral height in neutral position, flexion, extension and left axial rotation, whereas increased sharply in bending at Genant 0; L1 and L2 decreased in all positions excluding flexion of L2, and T11 increased in neutral position, flexion, extension, and right axial rotation at Genant 0. No significant changes in biconcave deformity. The stress of T11-T12, T12-L1, and L1-L2 intervertebral disc gradually increased or decreased under other positions in wedge fracture, whereas L1-L2 no significant change in biconcave fracture. The utmost overall facet joint stress is at Genant 3, whereas there is no significant change under the same position in biconcave fracture. The displacement and ROM of the wedge fracture had ups and downs, while a decline in all positions excluding extension in biconcave fracture. Conclusions The vertebral restoration height after augmentation to Genant 0 affects the von Mises stress, displacement, and ROM in wedge deformity, which may increase the risk of fracture; Whereas restored or not in biconcave deformity.

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