scholarly journals Biomechanical Effects of Lateral Inclination C 1 and C 2 Pedicle Screws on Atlantoaxial Fixation

2021 ◽  
Author(s):  
Lei Zhang ◽  
Huan Wang
Keyword(s):  
Pedicle Screws ◽  
Atlantoaxial Fixation

scholarly journals Unilateral C-1 posterior arch screws and C-2 laminar screws combined with a 1-side C1–2 pedicle screw system as salvage fixation for atlantoaxial instability

2016 ◽  
Vol 24 (2) ◽  
pp. 315-320 ◽  
Author(s):  
Jin Guo-Xin ◽  
Wang Huan
Keyword(s):  
Biomechanical Testing ◽  
Pedicle Screws ◽  
Atlantoaxial Instability ◽  
Posterior Arch ◽  
Lateral Bending ◽  
Significant Difference ◽  
Flexion Extension ◽  
Intact Condition ◽  
Atlantoaxial Fixation ◽  
Group B

OBJECT Atlantoaxial instability often requires surgery, and the current methods for fixation pose some risk to vascular and neurological tissues. Thus, new effective and safer methods are needed for salvage operations. This study sought to assess unilateral C-1 posterior arch screws (PASs) and C-2 laminar screws (LSs) combined with 1-side C1–2 pedicle screws (PSs) for posterior C1–2 fixation using biomechanical testing with bilateral C1–2 PSs in a cadaveric model. METHODS Six fresh ligamentous human cervical spines were evaluated for their biomechanics. The cadaveric specimens were tested in their intact condition, stabilization after injury, and after injury at 1.5 Nm of pure moment in 6 directions. The 3 groups tested were bilateral C1–2 PSs (Group A); left side C1–2 PSs with an ipsilateral C-1 PAS + C-2 laminar screw (Group B); and left side C1–2 PSs with a contralateral C-1 PAS + C-2 LS (Group C). During the testing, angular motion was measured using a motion capture platform. Data were recorded, and statistical analyses were performed. RESULTS Biomechanical testing showed that there was no significant difference among the stabilities of these fixation systems in flexion-extension and rotation control. In left lateral bending, the bilateral C1–2 PS group decreased flexibility by 71.9% compared with the intact condition, the unilateral C1–2 PS and ipsilateral PAS+LS group decreased flexibility by 77.6%, and the unilateral C1–2 PS and contralateral PAS+LS group by 70.0%. Each method significantly decreased C1–2 movements in right lateral bending compared with the intact condition, and the bilateral C1–2 PS system was more stable than the C1–2 PS and contralateral PAS+LS system (p = 0.036). CONCLUSIONS A unilateral C-1 PAS + C-2 LS combined with 1-side C-1 PSs provided the same acute stability as the PS, and no statistically significant difference in acute stability was found between the 2 screw techniques. These methods may constitute an alternative method for posterior atlantoaxial fixation.

scholarly journals Differences in fixation strength among constructs of atlantoaxial fixation

2019 ◽  
Vol 30 (1) ◽  
pp. 52-59 ◽  
Author(s):  
Chih-Chang Chang ◽  
Wen-Cheng Huang ◽  
Tsung-Hsi Tu ◽  
Peng-Yuan Chang ◽  
Li-Yu Fay ◽  
...  
Keyword(s):  
Pedicle Screws ◽  
Fixation Strength ◽  
Success Rates ◽  
Translaminar Screw ◽  
Atlantoaxial Fixation ◽  
Lateral Mass Screws ◽  
Translaminar Screws ◽  
Rate Of Success

OBJECTIVETo avoid jeopardizing an aberrant vertebral artery, there are three common options in placing a C2 screw, including pedicle, pars, and translaminar screws. Although biomechanical studies have demonstrated similar strength among these C2 screws in vitro, there are limited clinical data to address their differences in vivo. When different screws were placed in each side, few reports have compared the outcomes. The present study aimed to evaluate these multiple combinations of C2 screws.METHODSConsecutive adult patients who underwent posterior atlantoaxial (AA) fixation were retrospectively reviewed. Every patient uniformly had bilateral C1 lateral mass screws in conjunction with 2 C2 screws (1 C2 screw on each side chosen among the three options: pedicle, pars, or translaminar screws, based on individualized anatomical consideration). These patients were then grouped according to the different combinations of C2 screws for comparison of the outcomes.RESULTSA total of 63 patients were analyzed, with a mean follow-up of 34.3 months. There were five kinds of construct combinations of the C2 screws: 2 pedicle screws (the Ped-Ped group, n = 24), 2 translaminar screws (the La-La group, n = 7), 2 pars screws (the Pars-Pars group, n = 6), 1 pedicle and 1 pars screw (the Ped-Pars group, n = 7), and 1 pedicle and 1 translaminar screw (the Ped-La group, n = 19). The rate of successful fixation in each of the groups was 100%, 57.1%, 100%, 100%, and 78.9% (Ped-Ped, La-La, Par-Par, Ped-Par, and Ped-La, respectively). The patients who had no translaminar screw had a higher rate of success than those who had 1 or 2 translaminar screws (100% vs 73.1%, p = 0.0009). Among the 5 kinds of construct combinations, 2 C2 pedicle screws (the Ped-Ped group) had higher rates of success than 1 C2 pedicle and 1 C2 translaminar screw (the Ped-La group, p = 0.018). Overall, the rate of successful fixation was 87.3% (55/63). There were 7 patients (4 in the Ped-La group and 3 in the La-La group) who lost fixation/reduction, and they all had at least 1 translaminar screw.CONCLUSIONSIn AA fixation, C2 pedicle or pars screws or a combination of both provided very high success rates. Involvement of 1 or 2 C2 translaminar screws in the construct significantly lowered success rates. Therefore, a C2 pars screw is recommended over a translaminar screw.

Image-Guided Spinal Surgery and Robotics in MIS: Where Are We Now?

2018 ◽  
Vol 1 (2) ◽  
pp. 2
Author(s):  
Chiung Chyi Shen
Keyword(s):  
Pedicle Screw ◽  
Spinal Surgery ◽  
Surgical Navigation ◽  
Improve Patient Safety ◽  
Intraoperative Imaging ◽  
Spinal Instrumentation ◽  
Pedicle Screws ◽  
Computer Assisted ◽  
Navigation Systems ◽  
Image Guided

Use of pedicle screws is widespread in spinal surgery for degenerative, traumatic, and oncological diseases. The conventional technique is based on the recognition of anatomic landmarks, preparation and palpation of cortices of the pedicle under control of an intraoperative C-arm (iC-arm) fluoroscopy. With these conventional methods, the median pedicle screw accuracy ranges from 86.7% to 93.8%, even if perforation rates range from 21.1% to 39.8%.The development of novel intraoperative navigational techniques, commonly referred to as image-guided surgery (IGS), provide simultaneous and multiplanar views of spinal anatomy. IGS technology can increase the accuracy of spinal instrumentation procedures and improve patient safety. These systems, such as fluoroscopy-based image guidance ("virtual fluoroscopy") and computed tomography (CT)-based computer-guidance systems, have sensibly minimized risk of pedicle screw misplacement, with overall perforation rates ranging from between 14.3% and 9.3%, respectively."Virtual fluoroscopy" allows simultaneous two-dimensional (2D) guidance in multiple planes, but does not provide any axial images; quality of images is directly dependent on the resolution of the acquired fluoroscopic projections. Furthermore, computer-assisted surgical navigation systems decrease the reliance on intraoperative imaging, thus reducing the use of intraprocedure ionizing radiation. The major limitation of this technique is related to the variation of the position of the patient from the preoperative CT scan, usually obtained before surgery in a supine position, and the operative position (prone). The next technological evolution is the use of an intraoperative CT (iCT) scan, which would allow us to solve the position-dependent changes, granting a higher accuracy in the navigation system. 

Augmented reality–assisted pedicle screw insertion: a cadaveric proof-of-concept study

2019 ◽  
Vol 31 (1) ◽  
pp. 139-146 ◽  
Author(s):  
Camilo A. Molina ◽  
Nicholas Theodore ◽  
A. Karim Ahmed ◽  
Erick M. Westbroek ◽  
Yigal Mirovsky ◽  
...  
Keyword(s):  
Augmented Reality ◽  
Pedicle Screw ◽  
User Experience ◽  
Pedicle Screws ◽  
Screw Insertion ◽  
Pedicle Screw Insertion ◽  
Insertion Method ◽  
Comparative Accuracy ◽  
Placement Accuracy ◽  
Surgical Field

OBJECTIVEAugmented reality (AR) is a novel technology that has the potential to increase the technical feasibility, accuracy, and safety of conventional manual and robotic computer-navigated pedicle insertion methods. Visual data are directly projected to the operator’s retina and overlaid onto the surgical field, thereby removing the requirement to shift attention to a remote display. The objective of this study was to assess the comparative accuracy of AR-assisted pedicle screw insertion in comparison to conventional pedicle screw insertion methods.METHODSFive cadaveric male torsos were instrumented bilaterally from T6 to L5 for a total of 120 inserted pedicle screws. Postprocedural CT scans were obtained, and screw insertion accuracy was graded by 2 independent neuroradiologists using both the Gertzbein scale (GS) and a combination of that scale and the Heary classification, referred to in this paper as the Heary-Gertzbein scale (HGS). Non-inferiority analysis was performed, comparing the accuracy to freehand, manual computer-navigated, and robotics-assisted computer-navigated insertion accuracy rates reported in the literature. User experience analysis was conducted via a user experience questionnaire filled out by operators after the procedures.RESULTSThe overall screw placement accuracy achieved with the AR system was 96.7% based on the HGS and 94.6% based on the GS. Insertion accuracy was non-inferior to accuracy reported for manual computer-navigated pedicle insertion based on both the GS and the HGS scores. When compared to accuracy reported for robotics-assisted computer-navigated insertion, accuracy achieved with the AR system was found to be non-inferior when assessed with the GS, but superior when assessed with the HGS. Last, accuracy results achieved with the AR system were found to be superior to results obtained with freehand insertion based on both the HGS and the GS scores. Accuracy results were not found to be inferior in any comparison. User experience analysis yielded “excellent” usability classification.CONCLUSIONSAR-assisted pedicle screw insertion is a technically feasible and accurate insertion method.

Comparison of metal artifact reduction techniques in magnetic resonance imaging of carbon-reinforced PEEK and titanium spinal implants

2021 ◽  
pp. 028418512110290
Author(s):  
Georg Osterhoff ◽  
Florian A Huber ◽  
Laura C Graf ◽  
Ferdinand Erdlen ◽  
Hans-Christoph Pape ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Pedicle Screws ◽  
Artifact Reduction ◽  
Metal Artifact ◽  
Metal Artifact Reduction ◽  
Signal Loss ◽  
Resonance Imaging ◽  
Spinal Implants ◽  
Titanium Screws

Background Carbon-reinforced PEEK (C-FRP) implants are non-magnetic and have increasingly been used for the fixation of spinal instabilities. Purpose To compare the effect of different metal artifact reduction (MAR) techniques in magnetic resonance imaging (MRI) on titanium and C-FRP spinal implants. Material and Methods Rod-pedicle screw constructs were mounted on ovine cadaver spine specimens and instrumented with either eight titanium pedicle screws or pedicle screws made of C-FRP and marked with an ultrathin titanium shell. MR scans were performed of each configuration on a 3-T scanner. MR sequences included transaxial conventional T1-weighted turbo spin echo (TSE) sequences, T2-weighted TSE, and short-tau inversion recovery (STIR) sequences and two different MAR-techniques: high-bandwidth (HB) and view-angle-tilting (VAT) with slice encoding for metal artifact correction (SEMAC). Metal artifact degree was assessed by qualitative and quantitative measures. Results There was a much stronger effect on artifact reduction with using C-FRP implants compared to using specific MRI MAR-techniques (screw shank: P < 0.001; screw tulip: P < 0.001; rod: P < 0.001). VAT-SEMAC sequences were able to reduce screw-related signal loss artifacts in constructs with titanium screws to a certain degree. Constructs with C-FRP screws showed less artifact-related implant diameter amplification when compared to constructs with titanium screws ( P < 0.001). Conclusion Constructs with C-FRP screws are associated with significantly less artifacts compared to constructs with titanium screws including dedicated MAR techniques. Artifact-reducing sequences are able to reduce implant-related artifacts. This effect is stronger in constructs with titanium screws than in constructs with C-FRP screws.

scholarly journals Minimally Invasive Techniques for Iliac Bolt Placement: 2-Dimensional Operative Video

2021 ◽  
Vol 20 (4) ◽  
pp. E292-E292
Author(s):  
Travis Hamilton ◽  
Mohamed Macki ◽  
Thomas M Zervos ◽  
Victor Chang
Keyword(s):  
Minimally Invasive ◽  
Imaging System ◽  
Pedicle Screws ◽  
Vertical Axis ◽  
Spinal Diseases ◽  
Open Approach ◽  
Sagittal Vertical Axis ◽  
Pelvic Fixation ◽  
Iliac Screws ◽  
Invasive Techniques

Abstract As the popularity of minimally invasive surgery (MIS) continues to grow, novel techniques are needed to meet the demands of multisegment fixation for advanced spinal diseases. In one such example, iliac bolts are often required to anchor large fusion constructs, but MIS technical notes are missing from the literature.  A 67-yr-old female presented with a symptomatic coronal deformity: preoperative pelvic incidence = 47°, pelvic tilt = 19°, and lumbar lordosis = 29°, sagittal vertical axis = +5.4 cm with 30° of scoliosis. The operative plan included T10-ilium fusion with transforaminal interbody grafts at L2-3, L3-4, L4-5, and L5-S1. The intraoperative video is of minimally invasive placement of iliac bolts using the O-Arm Surgical Imaging System (Medtronic®). The patient consented to the procedure.  A mini-open exposure that remains above the fascial planes allows for multilevel instrumentation with appropriate decompression at the interbody segments. After the placement of the pedicle screws under image-guidance, the direction is turned to the minimally invasive iliac bolts. Following the trajectory described in the standard open approach,1 the posterior superior iliac spine (PSIS) is identified with the navigation probe, which will guide the Bovie cautery through the fascia. This opening assists in the trajectory of the navigated-awl tap toward the anterior superior iliac spine (ASIS). Next, 8.5 mm x 90 mm iliac screws were placed in the cannulated bone under navigation. After intraoperative image confirmation of screw placement, the contoured rods are threaded under the fascia. The setscrews lock the rod in position. MIS approaches obviate cross-linking the rods, rendering pelvic fixation more facile.  This technique allows for minimal dissection of the posterior pelvic soft tissue while maintaining adequate fixation.

scholarly journals Early loss of angular kyphosis correction in patients with thoracolumbar vertebral burst (A3-A4) fractures who underwent percutaneous pedicle screws fixation

2021 ◽  
Vol 24 ◽  
pp. 77-81
Author(s):  
Andrea Perna ◽  
Domenico Alessandro Santagada ◽  
Maria Beatrice Bocchi ◽  
Gianfranco Zirio ◽  
Luca Proietti ◽  
...  
Keyword(s):  
Pedicle Screws ◽  
Early Loss ◽  
Kyphosis Correction ◽  
Angular Kyphosis

scholarly journals Hi-PoAD technique for Adolescent Idiopathic Scoliosis in Adult: Personal case series

2021 ◽  
Author(s):  
Cesare Faldini ◽  
Francesca Barile ◽  
Fabrizio Perna ◽  
Stefano Pasini ◽  
Michele Fiore ◽  
...  
Keyword(s):  
Surgical Technique ◽  
Idiopathic Scoliosis ◽  
Case Series ◽  
Deformity Correction ◽  
Pedicle Screws ◽  
Mechanical Complication ◽  
Non Union ◽  
Implant Retention ◽  
Surgical Data

Abstract Purpose The aim of this article is to present an original surgical technique for the treatment of rigid Adult Idiopathic Scoliosis (AdIS) and the results at minimum 2 years follow-up in a cohort of 40 patients. Methods We retrospectively reviewed 40 patients affected by rigid AdIS, older than 40 years and operated with a posterior one stage surgical technique summarized with the acronym Hi-PoAD, (high-density pedicle screws, Ponte osteotomies, asymmetric rods contouring, direct vertebral rotation). The demographic and surgical data were collected, and the improvement of clinical scores and radiologic parameters was obtained after surgery, at 1 and 2 years and at final follow-up, to assess deformity correction, coronal and sagittal balance and clinical outcome. Results The average follow-up was 2.9 years (range 2–3.5). Average coronal Cobb angle decreased from 65.0° ± 8.4 to 18.9° ± 3.9 (p < 0.01). Rotation sagittal angle decreased from 26.2° ± 4.4° to 12.4° ± 2.8° (p < 0.01). Mean thoracic kyphosis improved from 23.1° ± 3.6° to 36.0° ± 3.9°. SRS-22 improved form 2.9 ± 0.4 to 3.7 ± 0.6 (p < 0.01). Four early post-operative deep wound infections were observed, all healed after debridement and implant retention. No mechanical complication, junctional kyphosis, deformity progression or non-union were recorded at the last follow-up. Conclusions Hi-PoAD technique proved to be safe and effective in the treatment of rigid Adult Idiopathic Scoliosis. The reason for the success is related to the combined strategies adopted, that dissipates corrective forces over several levels, reducing mechanical stress at the screw–bone interface and optimizing corrective potential.

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