Cortex of the pedicle of the vertebral arch. Part I: deformation characteristics during screw insertion

2007 ◽  
Vol 7 (3) ◽  
pp. 341-346 ◽  
Author(s):  
İnceoğlu Serkan ◽  
Cumhur Kılınçer ◽  
Andrea Tami ◽  
Robert F. McLain
Keyword(s):  
Plastic Deformation ◽  
Pedicle Screws ◽  
Lateral Wall ◽  
Optimal Placement ◽  
Screw Placement ◽  
Deformation Characteristics ◽  
Pullout Strength ◽  
Screw Insertion ◽  
Medial Cortex ◽  
Vertebral Arch

Object Elastic deformation has been proposed as a mechanism by which vertebral pedicles can maintain pullout strength when conical screws are backed out from full insertion. The response to the insertion technique may influence both the extent of deformation and the risk of acute fracture during screw placement. The aim of this study was to determine the deformation characteristics of the lumbar pedicle cortex during screw placement. Methods Lumbar pedicles with linear strain gauges attached at the lateral and medial cortices were instrumented using 7.5-mm pedicle screws with or without preconditioning by insertion and removal of 6.5-mm screws. The strains and elastic recoveries of the medial and lateral cortices were determined. Results Mean medial wall strains tended to be lower than mean lateral wall strains when the 6.5-mm and 7.5-mm screw data were pooled (p = 0.07). After the screws had been removed, 71 to 79% of the deformation at the lateral cortex and 70 to 96% of the deformation at the medial cortex recovered. When inserted first, the 7.5-mm screw caused more plastic deformation at the cortex than it did when inserted after the 6.5-mm screw. Occasional idiosyncratic strain patterns were observed. No gross fracture was observed during screw placement. Conclusions Screw insertion generated plastic deformation at the pedicle cortex even though the screw did not directly contact the cortex. The lateral and medial cortices responded differently to screw insertion. The technique of screw insertion affected the deformation behavior of the lumbar pedicles. With myriad options for screw selection and placement available, further study is needed before optimal placement parameters can be verified.

Transfacet screw placement for posterior fixation of C-7

2008 ◽  
Vol 9 (2) ◽  
pp. 200-206 ◽  
Author(s):  
Eric M. Horn ◽  
Nicholas Theodore ◽  
Neil R. Crawford ◽  
Nicholas C. Bambakidis ◽  
Volker K. H. Sonntag
Keyword(s):  
Intraoperative Complications ◽  
Pedicle Screws ◽  
Retrospective Chart Review ◽  
Screw Placement ◽  
Posterior Fixation ◽  
Lateral Mass ◽  
Screw Insertion ◽  
Novel Technique ◽  
Hardware Failures

Object Lateral mass screws are traditionally used to fixate the subaxial cervical spine, while pedicle screws are used in the thoracic spine. Lateral mass fixation at C-7 is challenging due to thin facets, and placing pedicle screws is difficult due to the narrow pedicles. The authors describe their clinical experience with a novel technique for transfacet screw placement for fixation at C-7. Methods A retrospective chart review was undertaken in all patients who underwent transfacet screw placement at C-7. The technique of screw insertion was the same for each patient. Polyaxial screws between 8- and 10-mm-long were used in each case and placed through the facet from a perpendicular orientation. Postoperative radiography and clinical follow-up were analyzed for aberrant screw placement or construct failure. Results Ten patients underwent C-7 transfacet screw placement between June 2006 and March 2007. In all but 1 patient screws were placed bilaterally, and the construct lengths ranged from C-3 to T-5. One patient with a unilateral screw had a prior facet fracture that precluded bilateral screw placement. There were no intraoperative complications or screw failures in these patients. After an average of 6 months of follow-up there were no hardware failures, and all patients showed excellent alignment. Conclusions The authors present the first clinical demonstration of a novel technique of posterior transfacet screw placement at C-7. These results provide evidence that this technique is safe to perform and adds stability to cervicothoracic fixation.

scholarly journals Does the application of Robotics improve outcomes of pedicle screw insertion in spine surgery compared to conventional fluoroscopy guidance? A protocol for Systematic Review and Meta-Analysis

2021 ◽  
Author(s):  
Vishal Kumar ◽  
Vishnu Baburaj ◽  
Prasoon Kumar ◽  
Sarvdeep Singh Dhatt
Keyword(s):  
Systematic Review ◽  
Pedicle Screw ◽  
Clinical Outcomes ◽  
Spine Surgery ◽  
Meta Analysis ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Screw Insertion ◽  
Pedicle Screw Insertion ◽  
Fluoroscopy Guidance

AbstractBackgroundPedicle screw insertion is routinely carried out in spine surgery that has traditionally been performed under fluoroscopy guidance. Robotic guidance has recently gained popularity in order to improve the accuracy of screw placement. However, it is unclear whether the use of robotics alters the accuracy of screw placement or clinical outcomes.ObjectivesThis systematic review aims to compare the results of pedicle screws inserted under fluoroscopy guidance, with those inserted under robotic guidance, in terms of both short-term radiographic outcomes, as well as long-term clinical outcomes.MethodsThis systematic review will be conducted according to the PRISMA guidelines. A literature search will be conducted on the electronic databases of PubMed, Embase, Scopus, and Ovid with a pre-determined search strategy. A manual bibliography search of included studies will also be done. Original articles in English that directly compare pedicle screw insertion under robotic guidance to those inserted under fluoroscopy guidance will be included. Data on outcomes will be extracted from included studies and analysis carried out with the help of appropriate software.

scholarly journals Placement of Guide-Wireless Sharp Percutaneous Pedicle Screws Utilizing Computed Tomography-Navigation and Sentinel Fluoroscopy: 2-Dimensional Operative Video

2019 ◽  
Vol 19 (2) ◽  
pp. E149-E150 ◽  
Author(s):  
Nikolay L Martirosyan ◽  
Joshua T Wewel ◽  
Juan S Uribe
Keyword(s):  
Computed Tomography ◽  
Pedicle Screw ◽  
Pedicle Screws ◽  
Transverse Process ◽  
Screw Placement ◽  
Osteoporotic Bone ◽  
Screw Insertion ◽  
Institutional Review ◽  
Stab Incision ◽  
Anterior Posterior

Abstract Many established techniques exist for minimally invasive pedicle screw placement. Nearly all techniques incorporate the use of a Kershner wire (K-wire) at various points in the work-flow. The use of a K-wire adds an additional step. If its position is lost, it requires repeating all previous steps, and placement is not without complication. The use of a guide-wireless sharp screws allows the surgeon to place a pedicle screw in 1 step with several fluid maneuvers.1 The patient underwent Institutional Review Board-approved consent for this study. Following traditional computed tomography-based navigation, a stab incision is made, followed by fascial dissection with monopolar cautery. The sharp screw is placed percutaneously at the facet-transverse process junction. The precise entry point is confirmed with navigation, followed by a sentinel anterior-posterior fluoroscopic image, verifying the accuracy of the navigation. The cortical bone is traversed by malleting the sharp tip through the cortex. When the cancellous bone is engaged, the screw is then advanced through the pedicle. This set of steps allows for safe, efficient placement of percutaneous pedicle screws without the need for a guidewire. Mal-placement regarding sharp pedicle screw insertion is similar to K-wire-dependent screw placement. Surgeons must be cognoscente of exceptionally sclerotic bone, which can prove difficult to cannulate. Conversely, osteoporotic bone that is liable to a cortical pedicle breach, transverse process fracture, and/or maltrajectory are all considerations when placing a K-wireless, sharp pedicle screw. Anterior-posterior fluoroscopy is utilized to confirm accuracy of image-guided navigation and mitigate malplacement of pedicle screws.

Accuracy of percutaneous lumbar pedicle screw placement using the oblique or “owl's-eye” view and novel guidance technology

2010 ◽  
Vol 13 (4) ◽  
pp. 509-515 ◽  
Author(s):  
Cary Idler ◽  
Kevin W. Rolfe ◽  
Josef E. Gorek
Keyword(s):  
Pedicle Screw ◽  
Facet Joint ◽  
Pedicle Screws ◽  
Guidance System ◽  
Screw Placement ◽  
Pedicle Screw Placement ◽  
Screw Insertion ◽  
Percutaneous Pedicle Screw ◽  
Clinical Series ◽  
Lumbar Pedicle

Object This study was conducted to assess the in vivo safety and accuracy of percutaneous lumbar pedicle screw placement using the owl's-eye view of the pedicle axis and a new guidance technology system that facilitates orientation of the C-arm into the appropriate fluoroscopic view and the pedicle cannulation tool in the corresponding trajectory. Methods A total of 326 percutaneous pedicle screws were placed from L-3 to S-1 in 85 consecutive adult patients. Placement was performed using simple coaxial imaging of the pedicle with the owl's-eye fluoroscopic view. NeuroVision, a new guidance system using accelerometer technology, helped align the C-arm trajectory into the owl's-eye view and the cannulation tool in the same trajectory. Postoperative fine-cut CT scans were acquired to assess screw position. Medical records were reviewed for complications. Results Five of 326 screws breached a pedicle cortex—all breaches were less than 2 mm—for an accuracy rate of 98.47%. Five screws violated an adjacent facet joint. All were at the S-1 superior facet and included in a fusion. No screw violated an adjacent mobile facet or disc space. There were no cases of new or worsening neurological symptoms or deficits for an overall clinical accuracy of 100%. Conclusions The owl's-eye technique of coaxial pedicle imaging with the C-arm fluoroscopy, facilitated by NeuroVision, is a safe and accurate means by which to place percutaneous pedicle screws for degenerative conditions of the lumbar spine. This is the largest series reported to use the oblique or owl's-eye projection for percutaneous pedicle screw insertion. The accuracy of percutaneous screw insertion with this technique meets or exceeds that of other reported clinical series or techniques.

scholarly journals Minimally invasive guidewireless, navigated pedicle screw placement: a technical report and case series

2017 ◽  
Vol 43 (2) ◽  
pp. E9 ◽  
Author(s):  
Brandon W. Smith ◽  
Jacob R. Joseph ◽  
Michael Kirsch ◽  
Mary Oakley Strasser ◽  
Jacob Smith ◽  
...  
Keyword(s):  
Minimally Invasive ◽  
Pedicle Screw ◽  
Kirschner Wire ◽  
Case Series ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Pedicle Screw Placement ◽  
Minimally Invasive Spinal Surgery ◽  
Screw Insertion ◽  
Percutaneous Pedicle Screw

OBJECTIVEPercutaneous pedicle screw insertion (PPSI) is a mainstay of minimally invasive spinal surgery. Traditionally, PPSI is a fluoroscopy-guided, multistep process involving traversing the pedicle with a Jamshidi needle, placement of a Kirschner wire (K-wire), placement of a soft-tissue dilator, pedicle tract tapping, and screw insertion over the K-wire. This study evaluates the accuracy and safety of PPSI with a simplified 2-step process using a navigated awl-tap followed by navigated screw insertion without use of a K-wire or fluoroscopy.METHODSPatients undergoing PPSI utilizing the K-wire–less technique were identified. Data were extracted from the electronic medical record. Complications associated with screw placement were recorded. Postoperative radiographs as well as CT were evaluated for accuracy of pedicle screw placement.RESULTSThirty-six patients (18 male and 18 female) were included. The patients’ mean age was 60.4 years (range 23.8–78.4 years), and their mean body mass index was 28.5 kg/m2 (range 20.8–40.1 kg/m2). A total of 238 pedicle screws were placed. A mean of 6.6 pedicle screws (range 4–14) were placed over a mean of 2.61 levels (range 1–7). No pedicle breaches were identified on review of postoperative radiographs. In a subgroup analysis of the 25 cases (69%) in which CT scans were performed, 173 screws were assessed; 170 (98.3%) were found to be completely within the pedicle, and 3 (1.7%) demonstrated medial breaches of less than 2 mm (Grade B). There were no complications related to PPSI in this cohort.CONCLUSIONSThis streamlined 2-step K-wire–less, navigated PPSI appears safe and accurate and avoids the need for radiation exposure to surgeon and staff.

Biomechanical Effects of Lumbar Pedicle Screw Insertion Depth on Screw Loosening and Fulcrum Location

2013 ◽  
Author(s):  
Laura E. Buckenmeyer ◽  
Kristophe J. Karami ◽  
Ata M. Kiapour ◽  
Vijay K. Goel ◽  
Constantine K. Demetropoulos ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Pedicle Screws ◽  
Screw Loosening ◽  
Pullout Strength ◽  
Insertion Depth ◽  
Bone Implant ◽  
Screw Insertion ◽  
Pedicle Screw Insertion ◽  
Increased Risk ◽  
Screw Length

Osteoporosis is a critical challenge in orthopedic surgery. Osteoporotic patients have an increased risk of loosening and failure of implant constructs due to a weaker bone-implant interface than with healthy bone. Pullout strength of pedicle screws is enhanced by increased screw insertion depth. However, more knowledge is needed to define optimal pedicle screw insertion depth in relation to screw-bone interface biomechanics and the resulting loosening risk. This study evaluates the effects of screw length on loosening risk in the osteoporotic lumbar spine.

scholarly journals Accuracy of robot-guided versus freehand fluoroscopy-assisted pedicle screw insertion in thoracolumbar spinal surgery

2017 ◽  
Vol 42 (5) ◽  
pp. E14 ◽  
Author(s):  
Granit Molliqaj ◽  
Bawarjan Schatlo ◽  
Awad Alaid ◽  
Volodymyr Solomiichuk ◽  
Veit Rohde ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Spinal Instrumentation ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Robotic Assistance ◽  
Anatomical Landmarks ◽  
Pedicle Screw Placement ◽  
Robot Assisted ◽  
Screw Insertion ◽  
Freehand Technique

OBJECTIVEThe quest to improve the safety and accuracy and decrease the invasiveness of pedicle screw placement in spine surgery has led to a markedly increased interest in robotic technology. The SpineAssist from Mazor is one of the most widely distributed robotic systems. The aim of this study was to compare the accuracy of robot-guided and conventional freehand fluoroscopy-guided pedicle screw placement in thoracolumbar surgery.METHODSThis study is a retrospective series of 169 patients (83 women [49%]) who underwent placement of pedicle screw instrumentation from 2007 to 2015 in 2 reference centers. Pathological entities included degenerative disorders, tumors, and traumatic cases. In the robot-assisted cohort (98 patients, 439 screws), pedicle screws were inserted with robotic assistance. In the freehand fluoroscopy-guided cohort (71 patients, 441 screws), screws were inserted using anatomical landmarks and lateral fluoroscopic guidance. Patients treated before 2009 were included in the fluoroscopy cohort, whereas those treated since mid-2009 (when the robot was acquired) were included in the robot cohort. Since then, the decision to operate using robotic assistance or conventional freehand technique has been based on surgeon preference and logistics. The accuracy of screw placement was assessed based on the Gertzbein-Robbins scale by a neuroradiologist blinded to treatment group. The radiological slice with the largest visible deviation from the pedicle was chosen for grading. A pedicle breach of 2 mm or less was deemed acceptable (Grades A and B) while deviations greater than 2 mm (Grades C, D, and E) were classified as misplacements.RESULTSIn the robot-assisted cohort, a perfect trajectory (Grade A) was observed for 366 screws (83.4%). The remaining screws were Grades B (n = 44 [10%]), C (n = 15 [3.4%]), D (n = 8 [1.8%]), and E (n = 6 [1.4%]). In the fluoroscopy-guided group, a completely intrapedicular course graded as A was found in 76% (n = 335). The remaining screws were Grades B (n = 57 [12.9%]), C (n = 29 [6.6%]), D (n = 12 [2.7%]), and E (n = 8 [1.8%]). The proportion of non-misplaced screws (corresponding to Gertzbein-Robbins Grades A and B) was higher in the robot-assisted group (93.4%) than the freehand fluoroscopy group (88.9%) (p = 0.005).CONCLUSIONSThe authors’ retrospective case review found that robot-guided pedicle screw placement is a safe, useful, and potentially more accurate alternative to the conventional freehand technique for the placement of thoracolumbar spinal instrumentation.

Fixation Strength of Pedicle and Cortical Lumbar Vertebral Screws after Laminectomy: A Cadaver Study

2018 ◽  
Vol 79 (04) ◽  
pp. 273-278
Author(s):  
Dai-Soon Kwak ◽  
Ho-Jung Cho ◽  
Ho Chang ◽  
Moon Park ◽  
In-Sung Kim ◽  
...  
Keyword(s):  
Lumbar Vertebrae ◽  
Pedicle Screws ◽  
Cadaver Study ◽  
Fixation Strength ◽  
Pullout Strength ◽  
Screw Insertion ◽  
Cortical Screw ◽  
Significant Difference ◽  
Midline Approach ◽  
Biomechanical Strength

Background and Study Aim Cortical screws were proposed as an alternative to the traditional pedicle screws. Diverse experimental results support the biomechanical superiority of cortical screws compared to pedicle screws. Laminectomy is often part of multilevel lumbar surgeries. Laminectomy might weaken the medial bony edge at the entry of the divergently oriented screw and, thereby, the screw purchase. This study investigated the biomechanical strength of lumbar cortical screw after laminectomy. Objective To compare the fixation strength of cortical screws and traditional pedicle screws after lumbar laminectomy. Material and Methods A total of 120 pedicles from 60 lumbar vertebrae of 12 cadavers (8 men, 4 women) were assessed. The mean age of the cadavers was 73.4 ± 6.2 years (range: 62–82 years). Using a posterior midline approach, we inserted the traditional pedicle screws into one and the cortical screws into the other side of each vertebra. Laminectomy was performed after screw insertion. Vertical pullout strength and toggle strength testing were performed to compare the fixation strength between the two sides. Results After laminectomy, the pullout strength of the cortical screws was 718.92 ± 340.76 N, and that of the pedicle screws was 625.78 ± 287.10 N (p = 0.183). The toggle strength of the cortical screws was 544.83 ± 329.97 N; that of the pedicle screws was 613.17 ± 311.70 N (p = 0.145). No significant difference was found in biomechanical strength between the two types of screws. Conclusion Despite laminectomy, lumbar cortical screws offers comparable pullout and toggle biomechanical strength as traditional pedicle screws.

scholarly journals Comparison of intraoperative O-arm- and conventional fluoroscopy (C-arm)-assisted insertion of pedicle screws in the treatment of fracture of thoracic vertebrae

2017 ◽  
Vol 25 (1) ◽  
pp. 230949901668409 ◽  
Author(s):  
Hao Liu ◽  
Yimeng Wang ◽  
Bin Pi ◽  
Zhonglai Qian ◽  
Xiaoyu Zhu ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Thoracic Vertebrae ◽  
Pedicle Screw Placement ◽  
Screw Insertion ◽  
Pedicle Screw Insertion ◽  
Computed Tomography Images ◽  
Hospitalization Time ◽  
Time Required

Purpose: To introduce the intraoperative O-arm-assisted pedicle screw insertion without any navigation system in the treatment of thoracic vertebrae fracture and compare it to conventional fluoroscopy (C-arm)-assisted pedicle screw insertion technique. Methods: About 156 pedicle screws were inserted in 23 patients (C-arm group), and 208 pedicle screws were inserted in 30 patients (O-arm group). The postoperative computed tomography images were analyzed for pedicle violation based on Gertzbein classification. The total surgery time, the average time required for inserting a screw, the mean action times of adjusting guide probe and pedicle screw, and the hospitalization time were compared in both groups, respectively. The American Spinal Injury Association (ASIA) was used for evaluating the health outcomes pre- and postoperatively. Results: There are the higher accuracy rate of satisfactory pedicle screw placement (grades 0 and 1) and the less incidence of medial perforation in the O-arm group compared to the C-arm group ( p < 0.05). The average time required for inserting a screw, the action times of adjusting the guide probe and pedicle screw, and the hospitalization time in the O-arm group are less than the respective ones in the C-arm group ( p < 0.05). There was no significant difference for the total surgery time between both groups. No further damage of the nerve function postoperatively is found according to the ASIA grade. Conclusion: The O-arm-assisted pedicle screw insertion without navigation we described provides higher accuracy of pedicle screw placement and better clinical efficacy compared to conventional fluoroscopy (C-arm) technique.

BIOMECHANICAL STUDY OF PEDICLE SCREW FIXATION STRENGTH: ASSOCIATION OF SCREW MALPOSITION AND SCREW INSERTION TORQUE

2019 ◽  
Vol 19 (02) ◽  
pp. 1940012
Author(s):  
TSUNG-TING TSAI ◽  
YU-HUNG CHEN ◽  
CHAO-YAUG LIAO ◽  
HSIN-TZU LIN ◽  
MU-YI LIU ◽  
...  
Keyword(s):  
Real Time ◽  
Pedicle Screw ◽  
Screw Fixation ◽  
Fixation Strength ◽  
Control Group ◽  
Insertion Torque ◽  
Pullout Strength ◽  
Screw Insertion ◽  
Medial Cortex ◽  
Screw Penetration

Pedicle screws have been widely used for the treatment of spinal diseases, but improper screw placement is not uncommon and may lead to neurovascular injuries and reduced screw fixation strength. This study aimed to investigate the feasibility of using real-time screw insertion torque monitoring to prevent screw penetration. Commercially available synthetic L4 vertebrae were divided in to seven test groups based on different screw placements. Screw insertion torque and maximal pullout strength were compared among groups. The results indicated that the insertion torque gradually increased when the screw tip was within vertebral cancellous bone without penetration. However, an instantaneous decrease of torque value was observed once the screw tip penetrated the cortex wall. When compared to the control group, higher pullout strength was found for the groups with medial cortex penetration. However, vertebrae with medial cortex penetration may lead to the concern of neurovascular damage. Meanwhile, lower pullout strength was found for the groups with lateral cortex penetration and end-plate penetration, which may lead to the concern of screw loosening. We concluded that pedicle screw penetration can be judged using real-time screw insertion torque monitoring during surgery, which may aid surgeons in avoiding neurovascular injury and reduction of screw fixation strength.

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