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>

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 Annular Defects Impair the Mechanical Stability of the Intervertebral Disc

2021 ◽  
pp. 219256822110060
Author(s):  
Jun-Xin Chen ◽  
Yun-He Li ◽  
Jian Wen ◽  
Zhen Li ◽  
Bin-Sheng Yu ◽  
...  
Keyword(s):  
Intervertebral Disc ◽  
Degrees Of Freedom ◽  
Mechanical Stability ◽  
Biomechanical Testing ◽  
Bending Stiffness ◽  
Biomechanical Study ◽  
Torsional Stiffness ◽  
P Value ◽  
Lateral Bending ◽  
Flexion Extension

Study Design: A biomechanical study. Objectives: The purpose of this study was to investigate the effects of cruciform and square incisions of annulus fibrosus (AF) on the mechanical stability of bovine intervertebral disc (IVD) in multiple degrees of freedom. Methods: Eight bovine caudal IVD motion segments (bone-disc-bone) were obtained from the local abattoir. Cruciform and square incisions were made at the right side of the specimen’s annulus using a surgical scalpel. Biomechanical testing of three-dimensional 6 degrees of freedom was then performed on the bovine caudal motion segments using the mechanical testing and simulation (MTS) machine. Force, displacement, torque and angle were recorded synchronously by the MTS system. P value <.05 was considered statistically significant. Results: Cruciform and square incisions of the AF reduced both axial compressive and torsional stiffness of the IVD and were significantly lower than those of the intact specimens ( P < .01). Left-side axial torsional stiffness of the cruciform incision was significantly higher than a square incision ( P < .01). Neither incision methods impacted flexional-extensional stiffness or lateral-bending stiffness. Conclusions: The cruciform and square incisions of the AF obviously reduced axial compression and axial rotation, but they did not change the flexion-extension and lateral-bending stiffness of the bovine caudal IVD. This mechanical study will be meaningful for the development of new approaches to AF repair and the rehabilitation of the patients after receiving discectomy.

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.

A biomechanical study of a cervical spine stabilization device

2002 ◽  
Author(s):  
M.E. Smith ◽  
J.R. Parsons ◽  
N.A. Langrana ◽  
M. Cibischino ◽  
C.K. Lee ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Biomechanical Study ◽  
Spine Stabilization

Experiments on Linear and Nonlinear Control of a Multi-DOF Parallel Mechanism

2003 ◽  
Author(s):  
Sandor Riebe ◽  
Heinz Ulbrich
Keyword(s):  
Degrees Of Freedom ◽  
Motion Tracking ◽  
Parallel Robot ◽  
Parallel Kinematics ◽  
Control Laws ◽  
Six Degrees Of Freedom ◽  
Position Accuracy ◽  
Nonlinear Approach ◽  
Linear Approach ◽  
Measurement Results

Parallel kinematics with multi degrees-of-freedom (DOF), like hexapod-systems, are mostly used in applications where high demands on position accuracy are required and/or high accelerations are needed. Adequate control concepts are essential in order to achieve the desired dynamic response. This paper deals with a comparative study of two structural different control concepts applied on a parallel robot with six degrees-of-freedom. The first one is a decentral linear approach and the second one is a multivariable nonlinear approach. The two concepts are presented and implemented on an experimental hexapod-system. In order to verify the used dynamic model comparisons between simulation and measurement results are shown. Finally, experiments have been carried out to compare the control laws with respect to their motion tracking performance.

scholarly journals Studies Evaluating Measurement Accuracy of CMS-JAW, a Jaw Motion Tracking Device with Six Degrees of Freedom Using an Ultrasonic Recording System

2008 ◽  
Vol 52 (3) ◽  
pp. 350-359 ◽  
Author(s):  
Takashi Uchida ◽  
Jun Sakai ◽  
Yasuhiro Okamoto ◽  
Tsukasa Watanabe ◽  
Tsuyoshi Kitagawa ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Motion Tracking ◽  
Measurement Accuracy ◽  
Recording System ◽  
Six Degrees Of Freedom ◽  
Tracking Device

Tendon Transfer Fixation in the Foot and Ankle: A Biomechanical Study Evaluating Two Sizes of Pilot Holes for Bioabsorbable Screws

2003 ◽  
Vol 24 (1) ◽  
pp. 67-72 ◽  
Author(s):  
Keith W. Louden ◽  
Catherine G. Ambrose ◽  
Stacy G. Beaty ◽  
William C. McGarvey ◽  
Thomas O. Clanton
Keyword(s):  
Tendon Transfer ◽  
Biomechanical Testing ◽  
Biomechanical Study ◽  
Hole Size ◽  
Foot And Ankle ◽  
Pilot Hole ◽  
Initial Fixation ◽  
Significant Difference ◽  
Bioabsorbable Screws ◽  
Drill Holes

The purpose of this study was to compare the initial fixation strengths of bioabsorbable screws for tendon transfers in the foot and ankle when the pilot hole size varied. A 7times20 mm screw was used with 5.5 mm and 6.5 mm drill holes, and a 5times20 mm screw was used with 3.9 mm and 4.5 mm drill holes. Biomechanical testing was performed on each tendon transfer in cadaver specimens. A paired t-test showed no significant difference in pullout strength when pilot hole size varied between 79 to 93% of the screw size for the 7 mm screw and 78 to 90% of the screw size for the 5 mm screw. Previous studies have found a critical value of tendon tension equaling 50 N with passive dorsiflexion of the foot. With an average value of approximately 170 N, the 7 mm screw provided three times the requisite strength. The 5 mm screw provided 1.5 times the requisite strength, but the transfer was technically more difficult.

scholarly journals Application of a Jaw Motion Tracking Device That Measures Six Degrees of Freedom Using Optoelectronics

2006 ◽  
Vol 50 (2) ◽  
pp. 210-218 ◽  
Author(s):  
Takumi Ogawa ◽  
Yuko Shigeta ◽  
Eriko Ando ◽  
Shinya Hirai ◽  
Mayumi Suma ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Motion Tracking ◽  
Six Degrees Of Freedom ◽  
Tracking Device

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.

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