scholarly journals Morphometric Evaluation of Occipital Condyles: Defining Optimal Trajectories and Safe Screw Lengths for Occipital Condyle-Based Occipitocervical Fixation in Indian Population

2018 ◽  
Vol 12 (2) ◽  
pp. 214-223 ◽  
Author(s):  
Aju Bosco ◽  
Prakash Venugopal ◽  
Ajoy Prasad Shetty ◽  
Rajasekaran Shanmuganathan ◽  
Rishi Mugesh Kanna
Keyword(s):  
Vertebral Artery ◽  
Morphometric Analysis ◽  
Three Dimensional ◽  
Vascular Anatomy ◽  
Application Rate ◽  
Screw Placement ◽  
Occipital Condyle ◽  
Screw Insertion ◽  
Occipitocervical Fixation ◽  
Screw Length

<sec><title>Study Design</title><p>Computed tomographic (CT) morphometric analysis.</p></sec><sec><title>Purpose</title><p>To assess the feasibility and safety of occipital condyle (OC)-based occipitocervical fixation (OCF) in Indians and to define anatomical zones and screw lengths for safe screw placement.</p></sec><sec><title>Overview of Literature</title><p>Limitations of occipital squama-based OCF has led to development of two novel OC-based OCF techniques.</p></sec><sec><title>Methods</title><p>Morphometric analysis was performed on the OCs of 70 Indian adults. The feasibility of placing a 3.5-mm-diameter screw into OCs was investigated. Safe trajectories and screw lengths for OC screws and C0–C1 transarticular screws without hypoglossal canal or atlantooccipital joint compromise were estimated.</p></sec><sec><title>Results</title><p>The average screw length and safe sagittal and medial angulations for OC screws were 19.9±2.3 mm, ≤6.4°±2.4° cranially, and 31.1°±3° medially, respectively. An OC screw could not be accommodated by 27% of the population. The safe sagittal angles and screw lengths for C0–C1 transarticular screw insertion (48.9°±5.7° cranial, 26.7±2.9 mm for junctional entry technique; 36.7°±4.6° cranial, 31.6±2.7 mm for caudal C1 arch entry technique, respectively) were significantly different than those in other populations. The risk of vertebral artery injury was high for the caudal C1 arch entry technique. Screw placement was uncertain in 48% of Indians due to the presence of aberrant anatomy.</p></sec><sec><title>Conclusions</title><p>There were significant differences in the metrics of OC-based OCF between Indian and other populations. Because of the smaller occipital squama dimensions in Indians, OC-based OCF techniques may have a higher application rate and could be a viable alternative/salvage option in selected cases. Preoperative CT, including three-dimensional-CT-angiography (to delineate vertebral artery course), is imperative to avoid complications resulting from aberrant bony and vascular anatomy. Our data can serve as a valuable reference guide in placing these screws safely under fluoroscopic guidance.</p></sec>

scholarly journals CT-based morphometric analysis of the occipital condyle: focus on occipital condyle screw insertion

2016 ◽  
Vol 25 (5) ◽  
pp. 572-579 ◽  
Author(s):  
Jinsong Zhou ◽  
Alejandro A. Espinoza Orías ◽  
Xia Kang ◽  
Jade He ◽  
Zhihai Zhang ◽  
...  
Keyword(s):  
Morphometric Analysis ◽  
Sagittal Plane ◽  
Simulation Method ◽  
Entry Point ◽  
Screw Placement ◽  
Occipital Condyle ◽  
Hypoglossal Canal ◽  
Screw Length ◽  
Preoperative Simulation ◽  
The Mean

OBJECTIVE The segmental occipital condyle screw (OCS) is an alternative fixation technique in occipitocervical fusion. A thorough morphological study of the occipital condyle (OC) is critical for OCS placement. The authors set out to introduce a more precise CT-based method for morphometric analysis of the OC as it pertains to the placement of the segmental OCS, and they describe a novel preoperative simulation method for screw placement. Two new clinically relevant parameters, the height available for the OCS and the warning depth, are proposed. METHODS CT data sets from 27 fresh-frozen human cadaveric occipitocervical spines were used. All measurements were performed using a commercially available 3D reconstruction software package. The length, width, and sagittal angle of the condyle were measured in the axial plane at the base of the OC. The height of the OC and the height available for the segmental OCS were measured in the reconstructed oblique sagittal plane, fitting the ideal trajectory of the OCS recommended in the literature. The placement of a 3.5-mm-diameter screw that had the longest length of bicortical purchase was simulated into the OC in the oblique sagittal plane, with the screw path not being blocked by the occiput and not violating the hypoglossal canal cranially or the atlantooccipital joint caudally. The length of the simulated screw was recorded. The warning depth was measured as the shortest distance from the entry point of the screw to the posterior border of the hypoglossal canal. RESULTS The mean length and width of the OC were found to be larger in males: 22.2 ± 1.7 mm and 12.1 ± 1.0 mm, respectively, overall (p < 0.0001 for both). The mean sagittal angle was 28.0° ± 4.9°. The height available for the OCS was significantly less than the height of the OC (6.2 ± 1.3 mm vs 9.4 ± 1.5 mm, p < 0.0001). The mean screw length (19.3 ± 1.9 mm) also presented significant sex-related differences: male greater than female (p = 0.0002). The mean warning depth was 7.5 ± 1.7 mm. In 7.4% of the samples, although the height of the OC was viable, the height available for the OCS was less than 4.5 mm, thus making screw placement impractical. For these cases, a new preoperative simulation method of the OCS placement was proposed. In 92.6% of the samples that could accommodate a 3.5-mm-diameter screw, 24.0% showed that the entry point of the simulated screw was covered by a small part of the C-1 posterosuperior joint rim. CONCLUSIONS The placement of the segmental OCS is feasible in most cases, but a thorough preoperative radiological analysis is essential and cannot be understated. The height available for the OCS is a more clinically relevant and precise parameter than the height of the OC to enable proper screw placement. The warning depth may be helpful for the placement of the OCS.

scholarly journals P.141 Is occipito-condylar screw a better alternative fixation point for occipitocervical stabilization? 1. Review of the literature

2018 ◽  
Vol 45 (s2) ◽  
pp. S53-S54
Author(s):  
Ns Alshafai ◽  
M Dibenedetto
Keyword(s):  
Surgical Techniques ◽  
Biomechanical Properties ◽  
Occipital Condyle ◽  
Occipitocervical Fusion ◽  
Anatomical Structures ◽  
Screw Insertion ◽  
Screw Length ◽  
Entry Points ◽  
Alternative Fixation ◽  
Fixation Points

Background: Occipitocervical fusion (OCF) using screws and rods offers immediate stability and an high fusion rates. However, multiple cranial fixation points are required in order to compensate for the poor bony purchase. Methods: The aim of this study was to compare the occipital condyle screw with the standard OCF techniques as well as to compare available techniques of the occipital condyle screw insertion. Materials and Methods: A comprehensive “Medline” and “Web of science” database search was performed. Cadaveric, radiographic and case studies were included. Results: The occipital condyle screw in comparison to the occipital plate enables an increased screw length, greater screw pullout strength, lower profile of the hardware and extended grafting surface. Both constructs have similar biomechanical properties (range of motion restriction, stiffness). Proximity of the vertebral artery and hypoglossal canal presents the greatest technical challenge of occipital condyle screw. Four surgical techniques with different entry points, cranial-caudal and medial angulations were described. None of these techniques is superior to the other. Conclusions: Occipital condyle screw is a viable alternative to standard OCF techniques. Challenges exist due to the proximity of the vital anatomical structures. Choice between four available techniques depends on unique patient’s anatomy

scholarly journals Radiographic parameters and a novel fluoroscopic control view for posterior screw fixation of coracoid base fractures

SICOT-J ◽  
2020 ◽  
Vol 6 ◽  
pp. 9
Author(s):  
Hatem Galal Said ◽  
Tarek Nabil Fetih ◽  
Hosam Elsayed Abd-Elzaher ◽  
Simon Martin Lambert
Keyword(s):  
Sagittal Plane ◽  
Coracoid Process ◽  
Entry Point ◽  
Coronal Plane ◽  
Screw Placement ◽  
Posterior Fixation ◽  
Screw Insertion ◽  
Screw Length ◽  
Scapular Spine ◽  
The Mean

Introduction: Coracoid fractures have the potential to lead to inadequate shoulder function. Most coracoid base fractures occur with scapular fractures and the posterior approaches would be utilized for surgical treatment. We investigated the possibility of fixing the coracoid through the same approach without an additional anterior approach. Materials and methods: Multi-slice CT scans of 30 shoulders were examined and the following measurements were performed by an independent specialized radiologist: posterior coracoid screw entry point measured form infraglenoid tubercle, screw trajectory in coronal plane in relation to scapular spine and lateral scapular border, screw trajectory in sagittal plane in relation to glenoid face bisector line and screw length. We used the results from the CT study to guide postero-anterior coracoid screw insertion under fluoroscopic guidance on two fresh frozen cadaveric specimens to assess the reproducibility of accurate screw placement based on these parameters. We also developed a novel fluoroscopic projection, the anteroposterior (AP) coracoid view, to guide screw placement in the para-coronal plane. Results: The mean distance between entry point and the infraglenoid tubercle was 10.8 mm (range: 9.2–13.9, SD 1.36). The mean screw length was 52 mm (range: 46.7–58.5, SD 3.3). The mean sagittal inclination angle between was 44.7 degrees (range: 25–59, SD 5.8). The mean angle between screw line and lateral scapular border was 47.9 degrees (range: 34–58, SD 4.3). The mean angle between screw line and scapular spine was 86.2 degrees (range: 75–95, SD 4.9). It was easy to reproduce the screw trajectory in the para-coronal plane; however, multiple attempts were needed to reach the correct angle in the parasagittal plane, requiring several C-arm corrections. Conclusion: This study facilitates posterior fixation of coracoid process fractures and will inform the “virtual visualization” of coracoid process orientation.

scholarly journals Safe trajectory for an occipital condyle screw: A computer simulation study

2019 ◽  
Vol 27 (3) ◽  
pp. 230949901987954
Author(s):  
Zhen-Qi Lou ◽  
Yang Wang ◽  
Ding-Li Xu ◽  
Guo-Qing Li ◽  
Wei-Hu Ma ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Computed Tomographic Angiography ◽  
Screw Placement ◽  
Occipital Condyle ◽  
Anatomical Structures ◽  
Screw Insertion ◽  
Computed Tomographic ◽  
Left And Right ◽  
Tomographic Angiography ◽  
Occipital Condyles

Objective: The purpose of this study was to evaluate the feasibility of posterior occipital condyle screw (OCS) placement analysis of the safe trajectory area for screw insertion. Methods: Computed tomographic angiography scans of patients (46 males and 27 females) with normal occipitocervical structures were obtained consecutively. Vertebral artery (VA)-occiput distance <4.0 mm was defined as “unfeasible” for OCS fixation, and occipital-atlas angulation was measured to assess the feasibility of screw placement. Next, the placement of 3.5 mm diameter OCS was simulated, the probability of breach of structures surrounding occipital condyles was calculated, and placement parameters were analyzed. Results: OCS placement was feasible in 91.1% (133/146) of occipital condyles, and the feasible probability also presented a significant sex-related difference: The probability was higher for males than for females (95.7% vs. 83.3%, p < 0.05). The incidence of anatomical structures injured under screw placement limitation was 18.8% (VA), 81.2% (hypoglossal canal), 59.4% (occipital-atlas joint), and 40.6% (occiput bone surface). There were no significant differences between the left and right condyles in relation to the measured parameters ( p > 0.05). The screw range of motion was significantly smaller in females than in males ( p < 0.05). The feasibility of OCS placement and OCS range of motion were significantly greater in the kyphosis group (>5°) than in the other two groups ( p < 0.05). Conclusion: OCS placement is a feasible technique for occipital-cervical fusion. The male group and occipitocervical region kyphosis group had a wider available space for OCS placement. Tangent angulation may be useful for the accurate and safe placement of an OCS.

Feasible and Accurate Occipitoatlantal Transarticular Fixation: An Anatomic Study

2010 ◽  
Vol 66 (suppl_1) ◽  
pp. ons-173-ons-177 ◽  
Author(s):  
Mehmet Senoglu ◽  
Sam Safavi-Abbasi ◽  
Nicholas Theodore ◽  
Neil R. Crawford ◽  
Volker K.H. Sonntag
Keyword(s):  
Anatomical Study ◽  
Craniovertebral Junction ◽  
Screw Placement ◽  
Occipital Condyle ◽  
X Rays ◽  
Anatomic Study ◽  
Screw Insertion ◽  
Computed Tomographic ◽  
Entry Points ◽  
Transarticular Fixation

Abstract Background: Defining the anatomic zones for the placement of occiput-C1 transarticular screws is essential for patient safety. Objective: The feasibility and accuracy of occiput-C1 transarticular screw placement were evaluated in this anatomical study of normal cadaveric specimens. Material and Methods: Sixteen measurements were determined for screw entry points, trajectories, and lengths for placement of transarticular screws, as applied in the technique described by Grob, on the craniovertebral junction segments (occiput-C2) of 16 fresh human cadaveric cervical spines and 41 computed tomographic reconstructions of the craniovertebral junction. Acceptable angles for screw positioning were measured on digital x-rays. Results: All 32 screws were placed accurately. As determined by dissection of the specimens, none of the screws penetrated the spinal canal. Screw insertion caused no fractures, and the integrity of the hypoglossal canal was maintained in all the disarticulated specimens. Conclusion: Viable transarticular occiput-C1 screw placement is possible, despite variability of the anatomy of the occipital condyle.

scholarly journals 205 Pediatric Occipital Condyle Morphometric Analysis Using Computed Tomography With Evaluation for Occipital Condyle Screw Placement

Neurosurgery ◽  
2018 ◽  
Vol 65 (CN_suppl_1) ◽  
pp. 117-117
Author(s):  
Khoi D Nguyen ◽  
Angela Viers ◽  
Jonathan A Tuttle ◽  
Ian M Heger
Keyword(s):  
Computed Tomography ◽  
Morphometric Analysis ◽  
Screw Placement ◽  
Occipital Condyle

scholarly journals Postoperative 320 multi-slice computed tomography in assessment of pedicle screw insertion in thoraco-lumbar fixation

2019 ◽  
Vol 50 (1) ◽  
Author(s):  
Alsiagy A. Salama ◽  
Mohamed A. Amin ◽  
Ahmed Y. Soliman ◽  
Ahmed El-Tantaway
Keyword(s):  
Computed Tomography ◽  
Pedicle Screw ◽  
Assessment Tool ◽  
Three Dimensional ◽  
Screw Placement ◽  
Spinal Fixation ◽  
Pedicle Screw Placement ◽  
Screw Insertion ◽  
Postoperative Assessment ◽  
Reformatted Ct

Abstract Background Pedicle screw instrumentation is used widely in lumbar spine for stabilization to enhance arthrodesis and has been accepted in the thoracic spine in recent years. The purpose of this study was to assess the value of postoperative 320 multi-slice computed tomography (MSCT) in assessment of pedicle screw placement in patients with spinal fixation with clinical and surgical correlation. Results A total of 340 pedicular screws were inserted to 70 cases. 286 (84.12%) were in, 54 screws (15.88%) were violated, and revision surgeries were required for 5 displaced screws. On axial, coronal reconstruction and three-dimensional (3D) reformatted CT images 36, 47, and 54 displaced screws were detected, respectively. Both sensitivity and specificity for 3D reformatted images were 100%. For axial image, they were 97.6% and 89.4%, respectively, compared with surgical findings in 5 revised screws. Conclusion Multi-slice CT scan is a valuable and valid postoperative assessment tool of accuracy of spinal pedicle screw placement.

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