Biomechanical rigidity of cadaveric cervical spine with posterior versus combined posterior and anterior instrumentation

2009 ◽  
Vol 10 (2) ◽  
pp. 133-138 ◽  
Author(s):  
Nader S. Dahdaleh ◽  
Satoshi Nakamura ◽  
James C. Torner ◽  
Tae-Hong Lim ◽  
Patrick W. Hitchon
Keyword(s):  
Cervical Spine ◽  
Posterior Instrumentation ◽  
Biomechanical Testing ◽  
Neutral Position ◽  
Lateral Mass ◽  
Anterior Instrumentation ◽  
Intact State ◽  
Significant Difference ◽  
Fresh Frozen ◽  
Postoperative Instability

Object In patients with cervical stenosis with myelopathy, posterior instrumentation following cervical laminectomy has been shown to reduce the incidence of postoperative instability and kyphosis. However, the indications for posterior plus anterior instrumentation are not always obvious, and using both posterior and anterior instrumentation routinely is unnecessary and excessive. This study examines the rigidity of the intact isolated cadaveric cervical spine, after C4–6 laminectomy, with posterior lateral mass instrumentation, and following posterior plus anterior instrumentation. Methods Ten fresh-frozen human cadaveric cervical spines from C-1 to T-2 were potted in the neutral position, and retroreflective markers were placed on C-3 and C-7. Specimens were mounted on a biomechanical testing frame, and angular rotations of C-3 relative to C-7 were measured. Pure moments of 0, 0.3, 0.6, 0.9, and 1.2 Nm were applied at C-2 in all 3 planes. Each specimen was load tested as follows: 1) in the intact state; 2) after C4–6 laminectomy; 3) with C3–7 lateral mass instrumentation; and 4) with C3–7 posterior plus anterior instrumentation. Results Laminectomy was not associated with a significant increase in motion compared with the intact state with any load or in any direction. Instrumentation was associated with reduction in motion in all directions, and there was no significant difference in posterior versus combined posterior and anterior instrumentation. Conclusions Rigidity imparted to the cervical spine by a 5-level posterior lateral mass fixation is not augmented by anterior instrumentation.

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

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.

scholarly journals The “Skipped Segment Screw” Construct: An Alternative to Conventional Lateral Mass Fixation–Biomechanical Analysis in a Porcine Cervical Spine Model

2017 ◽  
Vol 11 (5) ◽  
pp. 733-738
Author(s):  
Kedar Prashant Padhye ◽  
Yuvaraja Murugan ◽  
Raunak Milton ◽  
N. Arunai Nambi Raj ◽  
Kenny Samuel David
Keyword(s):  
Cervical Spine ◽  
Degrees Of Freedom ◽  
Motion Tracking ◽  
Biomechanical Testing ◽  
Biomechanical Study ◽  
Biomechanical Analysis ◽  
Lateral Mass ◽  
Six Degrees Of Freedom ◽  
Spine Stabilization ◽  
Significant Difference

<sec><title>Study Design</title><p>Cadaveric biomechanical study.</p></sec><sec><title>Purpose</title><p>We compared the “skipped segment screw” (SSS) construct with the conventional “all segment screw” (ASS) construct for cervical spine fixation in six degrees of freedom in terms of the range of motion (ROM).</p></sec><sec><title>Overview of Literature</title><p>Currently, no clear guidelines are available in the literature for the configuration of lateral mass (LM) screwrod fixation for cervical spine stabilization. Most surgeons tend to insert screws bilaterally at all segments from C3 to C6 with the assumption that implants at every level will provide maximum stability.</p></sec><sec><title>Methods</title><p>Six porcine cervical spine specimens were harvested from fresh 6–9-month-old pigs. Each specimen was sequentially tested in the following order: intact uninstrumented (UIS), SSS (LM screws in C3, C5, and C7 bilaterally), and ASS (LM screws in C3–C7 bilaterally). Biomechanical testing was performed with a force of 2 Nm in six degrees of freedom and 3D motion tracking was performed.</p></sec><sec><title>Results</title><p>The two-tailed paired <italic>t</italic>-test was used for statistical analysis. There was a significant decrease in ROM in instrumented specimens compared with that in UIS specimens in all six degrees of motion (<italic>p</italic>&lt;0.05), whereas there was no significant difference in ROM between the different types of constructs (SSS and ASS).</p></sec><sec><title>Conclusions</title><p>Because both configurations provide comparable stability under physiological loading, we provide a biomechanical basis for the use of SSS configuration owing to its potential clinical advantages, such as relatively less bulk of implants within a small operative field, relative ease of manipulating the rod into position, shorter surgical time, less blood loss, lower risk of screw-related complications, less implant-related costs, and most importantly, no compromise in the required stability needed until fusion.</p></sec>

scholarly journals Use of 3D Navigation in Subaxial Cervical Spine Lateral Mass Screw Insertion

2018 ◽  
Vol 79 (01) ◽  
pp. e1-e8 ◽  
Author(s):  
Abdullah Arab ◽  
Fahad Alkherayf ◽  
Adam Sachs ◽  
Eugene Wai
Keyword(s):  
Cervical Spine ◽  
Navigation System ◽  
Lateral Mass ◽  
3D Navigation ◽  
Subaxial Cervical Spine ◽  
Navigation Group ◽  
Freehand Technique ◽  
Significant Difference ◽  
Cord Injury ◽  
Screw Malposition

Objective Cervical spine can be stabilized by different techniques. One of the common techniques used is the lateral mass screws (LMSs), which can be inserted either by freehand techniques or three-dimensional (3D) navigation system. The purpose of this study is to evaluate the difference between the 3D navigation system and the freehand technique for cervical spine LMS placement in terms of complications. Including intraoperative complications (vertebral artery injury [VAI], nerve root injury [NRI], spinal cord injury [SCI], lateral mass fracture [LMF]) and postoperative complications (screw malposition, screw complications). Methods Patients who had LMS fixation for their subaxial cervical spine from January 2014 to April 2015 at the Ottawa Hospital were included. A total of 284 subaxial cervical LMS were inserted in 40 consecutive patients. Surgical indications were cervical myelopathy and fractures. The screws' size was 3.5 mm in diameter and 8 to 16 mm in length. During the insertion of the subaxial cervical LMS, the 3D navigation system was used for 20 patients, and the freehand technique was used for the remaining 20 patients. We reviewed the charts, X-rays, computed tomography (CT) scans, and follow-up notes for all the patients pre- and postoperatively. Results Postoperative assessment showed that the incidence of VAI, SCI, and NRI were the same between the two groups. The CT scan analysis showed that the screw breakage, screw pull-outs, and screw loosening were the same between the two groups. LMF was less in the 3D navigation group but statistically insignificant. Screw malposition was less in the 3D navigation group compared with the freehand group and was statistically significant. The hospital stay, operative time, and blood loss were statistically insignificant between the two groups. Conclusions The use of CT-based navigation in LMS insertion decreased the rate of screw malpositions as compared with the freehand technique. Further investigations and trials will determine the effect of malpositions on the c-spine biomechanics. The use of navigation in LMS insertion did not show a significant difference in VAI, LMF, SCI, or NRI as compared with the freehand technique.

Dynamic somatosensory evoked potentials to determine electrophysiological effects on the spinal cord during cervical spine extension

2013 ◽  
Vol 19 (3) ◽  
pp. 288-292 ◽  
Author(s):  
Yuichiro Morishita ◽  
Takeshi Maeda ◽  
Takayoshi Ueta ◽  
Masatoshi Naito ◽  
Keiichiro Shiba
Keyword(s):  
Spinal Cord ◽  
Cervical Spine ◽  
Evoked Potentials ◽  
Somatosensory Evoked Potentials ◽  
Cervical Cord ◽  
Control Group ◽  
Neutral Position ◽  
Healthy Controls ◽  
Median Nerve Stimulation ◽  
Significant Difference

Object The goal of this prospective study was to investigate somatosensory evoked potentials (SSEPs) during dynamic motion of the cervical spine and to evaluate the efficacy of analyzing dynamic SSEPs for predicting dynamic effects on the spinal cord in patients with cervical spondylotic myelopathy (CSM). Methods In total, 40 human subjects (20 CSM patients and 20 healthy volunteers as a control group) were examined prospectively using dynamic SSEPs with median nerve stimulation. The CSM patients showed cervical myelopathy due to cervical cord compression at the C4–5 segment. The SSEPs were examined with the cervical spine in a neutral position and at a 20° extension for 10 and 20 minutes. Changes in the N20 latency and amplitude were determined and analyzed. The authors defined the changes in the N20 latency and N20 amplitude between the neutral and extension positions of the cervical spine as percent latency and amplitude, respectively. Results In the CSM patients, SSEPs tended to deteriorate after cervical spine extension, and a statistically significant deterioration of the N20 amplitude after the extension was observed. Moreover, the percent latency and amplitude progressively increased during cervical spine extension in these patients. In the healthy controls, SSEPs tended to deteriorate with cervical spine extension, but these changes did not result in statistically significant differences. Moreover, in this group the percent latency and amplitude were almost identical during the extension. When the CSM patients and the healthy controls were compared, a significant difference in the percent amplitude was observed between the 2 groups during the cervical spine extension. Conclusions This study suggests the potential of dynamic SSEPs as a useful neurophysiological technique to detect the effect of dynamic factors on the pathogenesis of CSM.

scholarly journals Posterior cervical foraminotomy: anatomic study in cadavers

2014 ◽  
Vol 13 (1) ◽  
pp. 49-52
Author(s):  
Luizio Augusto Arantes Júnior ◽  
Francisco Alves de Araújo Júnior ◽  
José Augusto Malheiros ◽  
Sebastião Nataniel Silva Gusmão ◽  
Arthur Adolfo Nicolato ◽  
...  
Keyword(s):  
Cervical Spine ◽  
High Speed ◽  
Facet Joint ◽  
Lateral Mass ◽  
Average Percentage ◽  
Dural Sac ◽  
Significant Difference ◽  
Posterior Cervical Foraminotomy ◽  
Cervical Foraminotomy ◽  
Cervical Root

OBJECTIVE: This study was designed to use different segments of the cervical spine in cadavers to determine how much lateral mass should be resected for adequate foraminal decompression. METHODS: Six cadavers were used. The region of the cervical spine from C1 to the C7-T1 transition was dissected and exposed. The lateral mass of each vertebra was measured bilaterally before the foraminotomy in the following segments: C2-C3, C3-C4, C4-C5, C5-C6 and C6-C7. The procedure was performed with a high-speed drill and through surgical microscopy. Three foraminotomies were performed (F1, F2, F3) in each level. Lateral masses were measured after foraminotomy procedures and compared to the initial measurement, creating a percentage of lateral mass needed for decompression.. The value of the entire surface was defined as 100%. RESULTS: There was a statistical difference between the amounts of the resected lateral mass through each foraminotomy (F1, F2, F3) at the same level. However, there was no statistical significant difference among the different levels. The average percentage of resection of the lateral masses in F2 were 27.7% at C2-C3, 24.8% at C3-C4, 24.4% at C4-C5 and 23.8% and 31.2% at C5-C6 and C6-C7, respectively. In F3, the level that needed greater resection of the lateral masses was C6-C7 level, where the average resection ranged between 41.2% and 47.9%. CONCLUSION: In all segments studied, the removal of approximately 24 to 32% of the facet joint allowed adequate exposure of the foraminal segment, with visualization of the dural sac and the exit of the cervical root.

Risk factors for intraoperative lateral mass fracture of lateral mass screw fixation in the subaxial cervical spine

2014 ◽  
Vol 20 (1) ◽  
pp. 11-17 ◽  
Author(s):  
Shinichi Inoue ◽  
Tokuhide Moriyama ◽  
Toshiya Tachibana ◽  
Fumiaki Okada ◽  
Keishi Maruo ◽  
...  
Keyword(s):  
Risk Factors ◽  
Cervical Spine ◽  
Screw Fixation ◽  
Lateral Mass ◽  
Lateral Mass Screw ◽  
Screw Insertion ◽  
Significant Difference ◽  
Independent Risk Factors ◽  
Lateral Mass Fracture ◽  
Destructive Spondyloarthropathy

ObjectAlthough lateral mass screw fixation for the cervical spine is a safe technique, lateral mass fracture during screw fixation is occasionally encountered intraoperatively. This event is regarded as a minor complication; however, it poses difficulties in management that may affect fixation stability and clinical outcome. The purpose of this study is to determine the incidence and etiology of lateral mass fractures during cervical lateral mass screw fixation.MethodsA retrospective clinical review of patient records was performed in 117 consecutive patients (mean age 57 years, range 15–86 years) who underwent lateral mass screw fixation using a modified Magerl method from 1997 to 2010 at a single institution. A total of 555 lateral masses were included in this study. The outer diameters of the screws were 3.5 or 4.0 mm. In the retrospective clinical analysis, the incidence of intraoperative lateral mass fractures was reviewed. Potential risk factors for this complication were assessed using multivariate analysis.ResultsThe incidence of lateral mass fractures during cervical lateral mass screw fixation was 4.7% (26 lateral masses) among all cases. Among the disorders, the incidence was highest in patients with destructive spondyloarthropathy (DSA) (18.8%, 12 lateral masses). There was no significant difference with respect to lateral mass fracture between the use of 4.0-mm screws (5.6%) and 3.5-mm screws (3.6%). Independent risk factors identified by logistic regression were DSA (OR 7.89, p < 0.001) and screw insertion in the C-6 lateral masses (OR 2.80, p = 0.018).ConclusionsThe overall incidence of lateral mass fracture during cervical lateral mass screw fixation was 4.7%. Destructive spondyloarthropathy as an underlying cause of morbidity and screw placement in the C-6 lateral mass were identified as independent risk factors. Use of a 4.0-mm screw in patients with DSA may be a principal risk factor for this complication.

Biomechanical testing of anterior and posterior thoracolumbar instrumentation in the cadaveric spine

2004 ◽  
Vol 1 (1) ◽  
pp. 116-121 ◽  
Author(s):  
Kurt M. Eichholz ◽  
Patrick W. Hitchon ◽  
Aaron From ◽  
Paige Rubenbauer ◽  
Satoshi Nakamura ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Degrees Of Freedom ◽  
Posterior Instrumentation ◽  
Axial Rotation ◽  
Anterior Instrumentation ◽  
Content Type ◽  
Advantages And Disadvantages ◽  
Intact State ◽  
Flexion Extension ◽  
Fine Print

Object. Thoracolumbar burst fractures frequently require surgical intervention. Although the use of either anterior or posterior instrumentation has advantages and disadvantages, there have been few studies in which these two approaches have been compared biomechanically. Methods. Ten human cadaveric spines were subjected to subtotal L-3 corpectomy. In five spines placement of L-3 wooden strut grafts with lateral L2–4 dual rod and screw instrumentation was performed. Five other spines underwent L1–5 pedicle screw fixation. The spines were fatigued between steps of the experiment. The spines were load tested with pure moments of 1.5, 3, 4.5, and 6 Nm in the intact state and after placement of instrumentation in six degrees of freedom (flexion, extension, right and left lateral bending, and right and left axial rotation). In axial rotation posterior instrumentation significantly increased spinal rigidity compared with that of the intact state, whereas anterior instrumentation did not. Combined anterior—posterior instrumentation did not significantly increase the rigidity of the spine when compared with anterior or posterior instrumentation alone. Posterior instrumentation alone provided a greater reduction in angular rotation compared with anterior instrumentation alone in all degrees of freedom; however, statistical significance was achieved only in extension at 6 Nm. Conclusions. The increased rigidity provided by pedicle screw instrumentation compared with the intact state or with anterior instrumentation is due to the longer construct spanning five levels and the three-column engagement of the pedicle screws. The decision to use anterior or posterior instrumentation should be based on the clinical necessity of canal decompression and correction of angulation.

scholarly journals The influence of different sample preparation on mechanical properties of human iliotibial tract

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Benjamin Fischer ◽  
Sascha Kurz ◽  
Andreas Höch ◽  
Stefan Schleifenbaum
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Biomechanical Testing ◽  
Collagen Fibre ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Tissue Samples ◽  
Iliotibial Tract ◽  
Significant Difference ◽  
Fresh Frozen

Abstract In the run-up to biomechanical testing, fresh human tissue samples are often frozen in order to inhibit initial decomposition processes and to achieve a temporal independence of tissue acquisition from biomechanical testing. The aim of this study was to compare the mechanical properties of fresh tissue samples of the human iliotibial tract (IT) to fresh-frozen samples taken from the same IT and those modified with different concentrations of Dimethylsulfoxide (DMSO) prior to freezing. All samples were partial plastinated and destructive tensile tests were conducted with a uniaxial tensile test setup. A plastination technique already established in the laboratory was modified to improve the clamping behaviour of the samples. Material failure was caused by a gradual rupture of the load-bearing collagen fibre bundles. Contrary to our expectations, no significant difference was found between the tensile strength of fresh and fresh frozen specimens. The addition of 1 wt% DMSO did not increase the tensile strength compared to fresh-frozen samples; an addition of 10 wt% DMSO even resulted in a decrease. Based on our findings, the use of simple fresh-frozen specimens to determine the tensile strength is viable; however fresh specimens should be used to generate a complete property profile.

scholarly journals Transfixing Screw Placement for Syndesmotic Injury

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0031
Author(s):  
Si Wook Lee
Keyword(s):  
Ct Scan ◽  
Screw Fixation ◽  
Screw Placement ◽  
Neutral Position ◽  
Syndesmotic Injury ◽  
Interosseous Ligament ◽  
Screw Insertion ◽  
Insertion Angle ◽  
Significant Difference ◽  
Fresh Frozen

Category: Trauma Introduction/Purpose: The strategy of transfixing screw fixation including screw number, size, material, the number of cortex involved, and penetrating angle is controversial. The purpose of this fresh frozen cadaveric study is to demonstrate the optimal degree of transfixing screw insertion after syndesmotic reduction in the Pronation External Rotation (PER) type ankle fractures, and to study reliable parameters to evaluate the syndesmotic reduction. Methods: Twenty paired fresh frozen anatomic specimens of the ankles were obtained. Before dissection, CT scans were taken preoperatively. Then, preparation was performed by cutting and dissection of anterior interior tibiofibular ligament (AITFL), interosseous ligament and membrane. Two types of screw placement were set. Ten screws were inserted into right ankle at an angle of 25 to 30 degrees from neutral position. The other 10 screws were inserted into the left ankle at a 0 degree angle from neutral position. Postoperative CT scan was performed after screw insertion. Anterior fibular distance(AFD), posterior fibular distance(PFD), anterior translation distance(AT), diastasis, anterior-posterior translation(APT) were measured in 2D axial section and volume of the syndesmotic space were measured in 3D reconstruction data of preoperative and postoperative CT scan. Results: The transfixing screw fixation induce the significant difference in syndesmotic space regardless of insertion angle. There was significant difference only in fibular diastasis between both ankle model. There was no statistically significant difference in AFD, PFD, AT, APT and 3D reconstructed volume according to transfixing screw insertion angle when each measured value was compared through left and right ratio and absolute volume value. Conclusion: In ankle syndesmotic injury, transfixing screw insertion should be considered for the ankle stability. But, regardless of the insertion angle, transfixing screw insertion would have a significant therapeutic effect on ankle syndesmotic injury. Fibular diastasis would be the reliable parameters to evaluate syndesmotic reduction.

scholarly journals DYNAMIC MAGNETIC RESONANCE IMAGING: PRELIMINARY PRESENTATION OF A TECHNIQUE

2016 ◽  
Vol 15 (3) ◽  
pp. 209-212
Author(s):  
BRUNO DA COSTA ANCHESCHI ◽  
ANIELLO SAVARESE ◽  
RAPHAEL DE REZENDE PRATALI ◽  
DANIEL AUGUSTO CARVALHO MARANHO ◽  
MARCELLO TEIXEIRA CASTILHA ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Spinal Cord ◽  
Cervical Spine ◽  
Magnetic Resonance ◽  
Cervical Spondylotic Myelopathy ◽  
Dynamic Magnetic Resonance Imaging ◽  
Neutral Position ◽  
Resonance Imaging ◽  
Significant Difference ◽  
Flexion And Extension

ABSTRACT Objective: To evaluate morphometric variations of the cervical spine in patients with cervical spondylotic myelopathy (CSM) using dynamic magnetic resonance imaging (MRI) in neutral, flexion and extension positions. Methods: This is a prospective study of patients with CSM secondary to degenerative disease of the cervical spine. The morphometric parameters were evaluated using T2-weighted MRI sequences in the sagittal plane in neutral, flexion and extension position of the neck. The parameters studied were the anterior length of the spinal cord (ALSC), the posterior length of the spinal cord (PLSC), the diameter of the vertebral canal (DVC) and the diameter of the spinal cord (DSC). Results: The ALSC and PLSC were longer in flexion than in extension and neutral position, with statistically significant difference between the flexion and extension position. The DVC and the DSC were greater in flexion than in extension and neutral position, however, there was no statistically significant difference when they were compared in the neutral, flexion and extension positions. Conclusion: Dynamic MRI allows to evaluate morphometric variations in the cervical spinal canal in patients with cervical spondylotic myelopathy.

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