Effects of hole preparation on screw pullout resistance and insertional torque: a biomechanical study

2001 ◽  
Vol 94 (1) ◽  
pp. 91-96 ◽  
Author(s):  
B. Tunç Öktenoǧlu ◽  
Lisa A. Ferrara ◽  
Niteen Andalkar ◽  
A. Fahir Özer ◽  
Ali Çetin Sarioǧlu ◽  
...  
Keyword(s):  
Pedicle Screws ◽  
Test Material ◽  
Lateral Mass ◽  
Core Diameter ◽  
Content Type ◽  
Pilot Hole ◽  
Pullout Resistance ◽  
Insertional Torque ◽  
Lateral Mass Screws ◽  
Fine Print

Object. The authors conducted a study to assess the effect of a pilot hole preparation on screw pullout resistance and screw insertional torque. Methods. Three different screws were tested: cancellous lateral mass screws, cortical lateral mass screws, and pedicle screws. Synthetic bone blocks were used as the host material. Each screw group was separated into two subgroups. The first subgroup of screws was inserted into the test material following pilot hole preparation. Pilot holes were prepared; a drill bit diameter size smaller than the core diameter of the screws was used. The second group of screws was inserted into the test material without pilot hole preparation (a 3- or 4-mm hole drilled for entrance site preparation only). The insertional torque was measured as the screw was advanced into the material. The screws were axially extracted from the host material at a constant speed of 2.5 mm/minute. The pullout resistances and insertional torques for the pilot hole and the nonpilot hole groups were then statistically compared. The authors found that preparation of a pilot hole caused a significant decrease in the insertional torque. The screws inserted without a pilot hole showed greater pullout resistances compared with those inserted following a pilot hole preparation; however, there was no statistically significant difference. Conclusions. The optimum screw insertion technique may involve drilling a short pilot hole and using a drill bit with a smaller diameter than the screw core diameter to increase bone—screw purchase. This applies to cancellous and cortical lateral mass screws as well as pedicle screws.

Effects of pilot hole preparation technique on pedicle screw fixation in different regions of the osteoporotic thoracic and lumbar spine

2005 ◽  
Vol 3 (5) ◽  
pp. 364-370 ◽  
Author(s):  
Jonathan J. Carmouche ◽  
Robert W. Molinari ◽  
Tad Gerlinger ◽  
John Devine ◽  
Troy Patience
Keyword(s):  
Lumbar Spine ◽  
Thoracic Spine ◽  
Pedicle Screws ◽  
Preparation Technique ◽  
Content Type ◽  
Pilot Hole ◽  
Pullout Resistance ◽  
Insertional Torque ◽  
Upper Thoracic ◽  
Fine Print

Object. The authors evaluated the effects of pilot hole preparation technique on insertional torque and axial pullout resistance in osteoporotic thoracic and lumbar vertebrae. Methods. Using a probe technique and fluoroscopy, 102 pedicle screws were placed in 51 dual-energy x-ray absorptiometry—proven osteoporotic thoracic and lumbar levels. Screws were inserted using the same-size tapping, one-size-under tapping, or no-tapping technique. Insertional torque and axial pullout resistance were measured. Analysis of variance, Fisher exact test, and regression analysis were performed. Same-size tapping decreased pullout resistance in the lumbar spine. There was no effect on pullout resistance in the thoracic spine. Pullout resistance values were lower for all insertion techniques in the upper thoracic spine. Insertional torque and bone mineral density correlated with pullout resistance in the thoracic and lumbar spine. Conclusions. Tapping decreased pedicle screw pullout resistance in the osteoporotic human lumbar spine, although it did not affect pullout strength in the thoracic spine. Tapping decreased insertional torque in upper thoracic levels. Surgeons should optimize overall construct rigidity when placing thoracic pedicle screws in patients with spinal segment osteoporosis.

Pedicle Screws Can be 4 Times Stronger Than Lateral Mass Screws for Insertion in the Midcervical Spine

2014 ◽  
Vol 27 (2) ◽  
pp. 80-85 ◽  
Author(s):  
Zenya Ito ◽  
Kosaku Higashino ◽  
Satoshi Kato ◽  
Sung Soo Kim ◽  
Eugene Wong ◽  
...  
Keyword(s):  
Pedicle Screws ◽  
Lateral Mass ◽  
Lateral Mass Screws

Vertical translocation: the enigma of the disappearing atlantodens interval in patients with myelopathy and rheumatoid arthritis. Part I. Clinical, radiological, and neuropathological features

1997 ◽  
Vol 87 (6) ◽  
pp. 856-862 ◽  
Author(s):  
Adrian T. H. Casey ◽  
H. Alan Crockard ◽  
Jennian F. Geddes ◽  
John Stevens
Keyword(s):  
Cervical Myelopathy ◽  
Survival Rates ◽  
Cord Compression ◽  
Atlantoaxial Subluxation ◽  
Lateral Mass ◽  
Progressive Decrease ◽  
Content Type ◽  
Statistical Comparison ◽  
High Cervical ◽  
Fine Print

✓ This statistical comparison between patients with cervical myelopathy secondary to horizontal atlantoaxial subluxation and those with vertical translocation is designed to elucidate the mechanisms responsible for cranial settling and the effect of translocation on the development of spinal cord compression. In a 10-year study of a cohort of 256 patients, 186 suffered from myelopathy and 116 (62%) of these exhibited vertical translocation according to the Redlund-Johnell criteria. Vertical translocation occurred after a significantly longer period of disease than atlantoaxial subluxation (p < 0.001). Translocation was characterized clinically by a high cervical myelopathy with features of a cruciate paralysis present in 35% of individuals compared with 26% who exhibited horizontal atlantoaxial subluxation (p = 0.29), but there was a surprising paucity of cranial nerve problems. The patients with vertical translocation had a greater degree of neurological disability (p = 0.002) and poorer survival rates (p = 0.04). Radiologically, vertical translocation was secondary to lateral mass collapse and associated with a progressive decrease in the atlantodens interval ([ADI], r = 0.4; p < 0.001) and pannus (p = 0.003). Thirty percent of patients exhibited an ADI of less than 5 mm. This phenomenon has been termed pseudostabilization. The authors' studies emphasize that the ADI (frequently featured in the literature) is totally unreliable as an indicator of neuraxial compromise in the presence of vertical translocation.

scholarly journals The use of intraoperative navigation for complex upper cervical spine surgery

2014 ◽  
Vol 36 (3) ◽  
pp. E5 ◽  
Author(s):  
Kern H. Guppy ◽  
Indro Chakrabarti ◽  
Amit Banerjee
Keyword(s):  
Cervical Spine ◽  
Navigation System ◽  
Surgical Navigation ◽  
Spinal Instrumentation ◽  
Pedicle Screws ◽  
Upper Cervical Spine ◽  
Cervical Canal ◽  
Lateral Mass ◽  
Upper Cervical ◽  
Lateral Mass Screws

Imaging guidance using intraoperative CT (O-arm surgical imaging system) combined with a navigation system has been shown to increase accuracy in the placement of spinal instrumentation. The authors describe 4 complex upper cervical spine cases in which the O-arm combined with the StealthStation surgical navigation system was used to accurately place occipital screws, C-1 screws anteriorly and posteriorly, C-2 lateral mass screws, and pedicle screws in C-6. This combination was also used to navigate through complex bony anatomy altered by tumor growth and bony overgrowth. The 4 cases presented are: 1) a developmental deformity case in which the C-1 lateral mass was in the center of the cervical canal causing cord compression; 2) a case of odontoid compression of the spinal cord requiring an odontoidectomy in a patient with cerebral palsy; 3) a case of an en bloc resection of a C2–3 chordoma with instrumentation from the occiput to C-6 and placement of C-1 lateral mass screws anteriorly and posteriorly; and 4) a case of repeat surgery for a non-union at C1–2 with distortion of the anatomy and overgrowth of the bony structure at C-2.

scholarly journals Posterior spinal fusion using a unilateral C1 posterior arch screw and a C2 laminar screw for atlantoaxial fracture dislocation

2019 ◽  
Vol 7 ◽  
pp. 2050313X1984927 ◽  
Author(s):  
Yuichi Ono ◽  
Naohisa Miyakoshi ◽  
Michio Hongo ◽  
Yuji Kasukawa ◽  
Yoshinori Ishikawa ◽  
...  
Keyword(s):  
Pedicle Screws ◽  
Fracture Site ◽  
Fracture Dislocation ◽  
Posterior Arch ◽  
Lateral Mass ◽  
Laminar Screw ◽  
Upper Cervical ◽  
Lateral Mass Screws ◽  
The Right ◽  
C2 Laminar Screw

Introduction: C1 lateral mass screws and C2 pedicle screws are usually chosen to fix atlantoaxial (C1–C2) instability. However, there are a few situations in which these screws are difficult to use, such as in a case with a fracture line at the screw insertion point and bleeding from the fracture site. A new technique using a unilateral C1 posterior arch screw and a C2 laminar screw combined with a contralateral C1 lateral mass screws–C2 pedicle screws procedure for upper cervical fixation is reported. Case Report: A 24-year-old woman had an irreducible C1–C2 anterior dislocation with a type III odontoid fracture on the right side due to a traffic accident. The patient underwent open reduction and posterior C1–C2 fixation. On the left side, a C1 lateral mass screws and a C2 pedicle screws were placed. Because there was bleeding from the fracture site and a high-riding vertebral artery was seen on the right side, a C1 posterior arch screw and a C2 laminar screw were chosen. Eight months after the surgery, computed tomography scans showed healing of the odontoid fracture with anatomically correct alignment. Conclusions: Although there have been few comparable studies, fixation with unilateral C1 posterior arch screw–C2 laminar screw could be a beneficial choice for surgeries involving the upper cervical region in patients with fracture dislocation or arterial abnormalities.

Vertical atlantoaxial distraction injuries: radiological criteria and clinical implications

2004 ◽  
Vol 1 (3) ◽  
pp. 273-280 ◽  
Author(s):  
L. Fernando Gonzalez ◽  
David Fiorella ◽  
Neil R. Crawford ◽  
Robert C. Wallace ◽  
Iman Feiz-Erfan ◽  
...  
Keyword(s):  
Mr Imaging ◽  
Control Group ◽  
Lateral Mass ◽  
Healthy Individuals ◽  
Mr Images ◽  
Content Type ◽  
Radiological Criteria ◽  
Surgical Fusion ◽  
Imaging Results ◽  
Fine Print

Object. The authors sought to establish radiological criteria for the diagnosis of C1–2 vertical distraction injuries. Methods. Conventional radiography, computerized tomography (CT), and magnetic resonance (MR) imaging findings in five patients with a C1–2 vertical distraction injury were correlated with their clinical history, operative findings, and autopsy findings. The basion—dens interval (BDI) and the C-1 and C-2 lateral mass interval (LMI) were measured in 93 control patients who underwent CT angiography; these measurements were used to define the normal BDI and LMI. The MR imaging results obtained in 30 healthy individuals were used to characterize the normal signal intensity of the C1–2 joint. The MR imaging results were compared with MR images obtained in five patients with distraction injuries. In the 93 patients, the BDI averaged 4.7 mm (standard deviation [SD] 1.7 mm, range 0.6–9 mm) and the LMI averaged 1.7 mm (SD 0.48 mm, range 0.7–3.3 mm). Based on CT scanning in the five patients with distraction injuries, the BDIs (mean 11.9 mm, SD 3.2 mm; p < 0.001) and LMIs (mean 5.5 mm, SD 2 mm; p < 0.0001) were significantly greater than in the control group. Fast—spin echo inversion-recovery MR images obtained in these five patients revealed markedly increased signal distributed throughout the C1–2 lateral mass articulations bilaterally. Conclusions. In 95% of healthy individuals, the LMI ranged between 0.7 and 2.6 mm. An LMI greater than 2.6 mm indicates the possibility of a distraction injury, which can be confirmed using MR imaging. Patients with a suspected C1–2 distraction injury may be candidates for surgical fusion of C1–2.

Three-dimensional fluoroscopy-guided percutaneous thoracolumbar pedicle screw placement

2003 ◽  
Vol 99 (3) ◽  
pp. 324-329 ◽  
Author(s):  
Langston T. Holly ◽  
Kevin T. Foley
Keyword(s):  
Pedicle Screw ◽  
Three Dimensional ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Content Type ◽  
Image Guided ◽  
Spinal Navigation ◽  
Mean Diameter ◽  
The Mean ◽  
Fine Print

✓ The authors sought to evaluate the feasibility and accuracy of three-dimensional (3D) fluoroscopic guidance for percutaneous placement of thoracic and lumbar pedicle screws in three cadaveric specimens. After attaching a percutaneous dynamic reference array to the surgical anatomy, an isocentric C-arm fluoroscope was used to obtain images of the region of interest. Light-emitting diodes attached to the C-arm unit were tracked using an electrooptical camera. The image data set was transferred to the image-guided workstation, which performed an automated registration. Using the workstation display, pedicle screw trajectories were planned. An image-guided drill guide was passed through a stab incision, and this was followed by sequential image-guided pedicle drilling, tapping, and screw placement. Pedicle screws of various diameters (range 4–6.5 mm) were placed in all pedicles greater than 4 mm in diameter. Postoperatively, thin-cut computerized tomography scans were obtained to determine the accuracy of screw placement. Eighty-nine (94.7%) of 94 percutaneous screws were placed completely within the cortical pedicle margins, including all 30 lumbar screws (100%) and 59 (92%) of 64 thoracic screws. The mean diameter of all thoracic pedicles was 6 mm (range 2.9–11 mm); the mean diameter of the five pedicles in which wall violations occurred was 4.6 mm (range 4.1–6.3 mm). Two of the violations were less than 2 mm beyond the cortex; the others were between 2 and 3 mm. Coupled with an image guidance system, 3D fluoroscopy allows highly accurate spinal navigation. Results of this study suggest that this technology will facilitate the application of minimally invasive techniques to the field of spine surgery.

Translaminar rigid screw fixation of the axis

2005 ◽  
Vol 3 (5) ◽  
pp. 409-414 ◽  
Author(s):  
Neill M. Wright
Keyword(s):  
At Risk ◽  
Vertebral Artery ◽  
Screw Fixation ◽  
Vascular Complications ◽  
Pedicle Screws ◽  
Rigid Fixation ◽  
Content Type ◽  
Risk Of Injury ◽  
Translaminar Screws ◽  
Fine Print

✓ Rigid fixation of the axis with C1–2 transarticular screws or C-2 pedicle screws results in high fusion rates but remains technically demanding because of the risk of injury to the vertebral artery (VA) and the limitations imposed by anatomical variability. Translaminar fixation of the axis with crossing bilateral screws provides rigid fixation and is technically simple, is not affected by variations in individual anatomy, and does not place the VA at risk. The longterm results in 20 patients treated with translaminar fixation for craniocervical, atlantoaxial, and axial—subaxial instability are presented, with 100% fusion rates and no neurological or vascular complications. Translaminar screws may be a good option for rigid fixation of the axis for surgeons not proficient in the more technically demanding methods of stabilization.

Quadrant anatomy of the articular pillars (lateral cervical mass) of the cervical spine

1995 ◽  
Vol 82 (6) ◽  
pp. 1011-1014 ◽  
Author(s):  
T. Glenn Pait ◽  
Phillip V. McAllister ◽  
Howard H. Kaufman
Keyword(s):  
Anatomical Landmarks ◽  
Cervical Mass ◽  
Content Type ◽  
Bony Landmarks ◽  
Fixation Devices ◽  
Human Cadavers ◽  
Lateral Mass Screws ◽  
Neurovascular Structures ◽  
Lateral Facet ◽  
Fine Print

✓ Knowledge of the relevant anatomy is important when developing a strategy for introducing screws into the lateral masses to secure internal fixation devices. This paper defines key bony landmarks and their relationship to critical neurovascular structures and identifies a location for safe placement of cervical articular pillar (lateral mass) screws. Measurements of anatomical landmarks in 10 spines from human cadavers aged 61 to 85 years were made by caliper and a metric ruler. Landmarks were the lateral facet line, rostrocaudal line, medial facet line, intrafacet line, and medial facet line—vertebral artery line. The average distances and ranges were recorded. Such great variance existed in measurements from spine to spine and within the same spine as to render averages clinically unreliable. Dissection revealed that division of the articular pillar into four quadrants leaves one, the superior lateral quadrant, under which there are no neurovascular structures; this may be considered the “safe quadrant” for placement of posterior screws and plates.

Crossed-screw fixation of the unstable thoracic and lumbar spine

1995 ◽  
Vol 82 (1) ◽  
pp. 11-16 ◽  
Author(s):  
Edward C. Benzel ◽  
Nevan G. Baldwin
Keyword(s):  
Vertebral Body ◽  
Screw Fixation ◽  
Three Dimensional ◽  
Deformity Correction ◽  
Pedicle Screws ◽  
Short Segment ◽  
Content Type ◽  
Thoracic And Lumbar Spine ◽  
Spinal Segments ◽  
Fine Print

✓ An ideal spinal construct should immobilize only the unstable spinal segments, and thus only the segments fused. Pedicle fixation techniques have provided operative stabilization with the instrumentation of a minimal number of spinal segments; however, some failures have been observed with pedicle instrumentation. These failures are primarily related to excessive preload forces and limitations caused by the size and orientation of the pedicles. To circumvent these problems, a new technique, the crossed-screw fixation method, was developed and is described in this report. This technique facilitates short-segment spinal fixation and uses a lateral extracavitary approach, which provides generous exposure for spinal decompression and interbody fusion. The technique employs two large transverse vertebral body screws (6.5 to 8.5 mm in diameter) to bear axial loads, and two unilateral pedicle screws (placed on the side of the exposure) to restrict flexion and extension deformation around the transverse screws and to provide three-dimensional deformity correction. The horizontal vertebral body and the pedicle screws are connected to rods and then to each other via rigid crosslinking. The transverse vertebral body screws are unloaded during insertion by placing the construct in a compression mode after the interbody bone graft is placed, thus optimizing the advantage gained by the significant “toe-in” configuration provided and further decreasing the chance for instrumentation failure. The initial results of this technique are reported in a series of 10 consecutively treated patients, in whom correction of the deformity was facilitated. Follow-up examination (average 10.1 months after surgery) demonstrated negligible angulation. Chronic pain was minimal. The crossed-screw fixation technique is biomechanically sound and offers a rapid and safe form of short-segment three-dimensional deformity correction and solid fixation when utilized in conjunction with the lateral extracavitary approach to the unstable thoracic and lumbar spine. This approach also facilitates the secure placement of an interbody bone graft.

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