scholarly journals Optimal ilio-sacral screw trajectory in paediatric patients : a computed tomography study

2021 ◽  
Vol 87 (2) ◽  
pp. 285-291
Author(s):  
Mathilde Gaume ◽  
Mohamed Amine Triki ◽  
Christophe Glorion ◽  
Sylvain Breton ◽  
Lofti Miladi
Keyword(s):  
Computed Tomography ◽  
Spinal Canal ◽  
Sagittal Plane ◽  
Optimal Angle ◽  
Pelvic Fixation ◽  
Screw Insertion ◽  
Insertion Angle ◽  
Paediatric Patients ◽  
Screw Length ◽  
Screw Insertion Angle

Pelvic fixation during procedures performed to treat spinal deformities in paediatric patients remains challenging. No computed tomography studies in paediatric have assessed the optimal trajectory of ilio- sacral screws to prevent screw malposition. We used pelvic computed tomography from 80 children divided into four groups : females <10 and ≥10 years and males <10 and ≥10 years. A secure triangular corridor parallel to the upper S1 endplate was delineated based on three fixed landmarks. The optimal screw insertion angle was subtended by the horizontal and the line bisecting the secure corridor. Student’s t test was applied to determine whether the optimal screw insertion angle and/or anatomical parameters were associated with age and/or sex. Mean optimal angle was 32.3°±3.6°, 33.8°±4.7°, 30.2°±5.0°, and 30.4°±4.7° in the younger females, younger males, older females, and older males, respectively. The mean optimal angle differed between the two age groups (p=0.004) but not between females and males (p=0.55). Optimal mean screw length was 73.4±9.9 mm. Anatomical spinal canal parameters in the transverse plane varied with age (p=0.02) and with sex in the older children (p=0.008), and those in the sagittal plane varied with sex (p=0.04). Age affected ilio-sacral screw positioning, whereas sex did not. Several anatomical spinal canal parameters varied with age and sex. These results should help to ensure safe and easy ilio-sacral screw placement within a secure corridor.

Optimal cervical screw insertion angle determined by means of computed tomography scans pre- and postoperatively

2017 ◽  
Vol 17 (2) ◽  
pp. 190-195 ◽  
Author(s):  
Masashi Uehara ◽  
Jun Takahashi ◽  
Shota Ikegami ◽  
Hiroyuki Hashidate ◽  
Shugo Kuraishi ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Screw Insertion ◽  
Insertion Angle ◽  
Computed Tomography Scans ◽  
Screw Insertion Angle

The morphology of proximal pole scaphoid fractures: implications for optimal screw placement

2017 ◽  
Vol 43 (1) ◽  
pp. 73-79 ◽  
Author(s):  
Timothy J. Luchetti ◽  
Youssef Hedroug ◽  
John J. Fernandez ◽  
Mark S. Cohen ◽  
Robert W. Wysocki
Keyword(s):  
Sagittal Plane ◽  
Fracture Line ◽  
Screw Thread ◽  
Proximal Pole ◽  
Screw Insertion ◽  
Scaphoid Fractures ◽  
Starting Point ◽  
Screw Length ◽  
Sagittal Image ◽  
The Ideal

The purpose of this study was to measure the radiographic parameters of proximal pole scaphoid fractures, and calculate the ideal starting points and trajectories for antegrade screw insertion. Computed tomography scans of 19 consecutive patients with proximal pole fractures were studied using open source digital imaging and communications in medicine (DICOM) imaging measurement software. For scaphoid sagittal measurements, fracture inclination was measured with respect to the scaphoid axis. The ideal starting point for a screw in the proximal pole fragment was then identified on the scaphoid sagittal image that demonstrated the largest dimensions of the proximal pole, and hence the greatest screw thread purchase. Measurements were then taken for a standard screw trajectory in the axis of the scaphoid, and a trajectory that was perpendicular to the fracture line. The fracture inclination in the scaphoid sagittal plane was 25 (SD10) °, lying from proximal palmar to dorsal distal. The fracture inclination in the coronal plane was 9 (SD16) °, angling distal radial to proximal ulnar with reference to the coronal axis of the scaphoid. Using an ideal starting point that maximized the thread purchase in the proximal pole, we measured a maximum screw length of 20 (SD 2) mm when using a screw trajectory that was perpendicular to the fracture line. This was quite different from the same measurements taken in a trajectory in the axis of the scaphoid. We also identified a mean distance of approximately 10 mm from the dorsal fracture line to the ideal starting point. A precise understanding of this anatomy is critical when treating proximal pole scaphoid fractures surgically.

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 CORRELATION BETWEEN THE SCHANZ SCREW INSERTION ANGLE AND THE LOSS OF KYPHOSIS CORRECTION IN THORACOLUMBAR FRACTURES

2020 ◽  
Vol 19 (3) ◽  
pp. 209-212
Author(s):  
FABIO ANTONIO VIEIRA ◽  
ANDRÉ SOUSA GARCIA ◽  
FERNANDO TADASHI SALVIONI UETA ◽  
DAVID DEL CURTO ◽  
RENATO HIROSHI SALVIONI UETA ◽  
...  
Keyword(s):  
Statistical Difference ◽  
Burst Fracture ◽  
Level Of Evidence ◽  
Thoracolumbar Burst Fractures ◽  
Screw Insertion ◽  
Insertion Angle ◽  
Kyphosis Correction ◽  
Screw Insertion Angle ◽  
Parallel Assembly

ABSTRACT Objective To compare the Schanz screw insertion angle and the loss of the regional kyphosis correction in thoracolumbar burst fractures following posterior short instrumentation surgery. Methods Patients with a thoracolumbar burst fracture between levels T11-L2 were divided into two groups (parallel and divergent) according to the angle formed between the Schanz screw and the vertebral plateau. Regional kyphosis was evaluated in preoperative, immediate postoperative and last follow-up radiographs. Results Of the 58 patients evaluated, 31 had a parallel assembly and 27 had a divergent assembly. When we analyzed the angle of kyphosis, no statistical difference was observed between the pre- and postoperative radiographs. However, a statistical difference in the last follow-up radiographs and in the final loss of the kyphosis correction was confirmed. Conclusion The insertion of Schanz screws with a divergent assembly presents better radiographic results with less loss of kyphosis correction angle when compared with the parallel assembly technique. Level of Evidence III; Retrospective cohort study.

scholarly journals Surgical Morphometry of C1 and C2 Vertebrae: A Three-Dimensional Computed Tomography Analysis of 180 Chinese, Indian, and Malay Patients

2017 ◽  
Vol 11 (2) ◽  
pp. 181-189 ◽  
Author(s):  
Chee Kean Lee ◽  
Tiam Siong Tan ◽  
Chris Yin Wei Chan ◽  
Mun Keong Kwan
Keyword(s):  
Computed Tomography ◽  
Sagittal Plane ◽  
Imaging Study ◽  
Asian Population ◽  
Safe Zone ◽  
Simulation Software ◽  
Axial Plane ◽  
Lateral Mass ◽  
Screw Length ◽  
Tomography Analysis

<sec><title>Study Design</title><p>Clinical imaging study.</p></sec><sec><title>Purpose</title><p>To study the surgical morphometry of C1 and C2 vertebrae in Chinese, Indian, and Malay patients.</p></sec><sec><title>Overview of Literature</title><p>C1 lateral mass and C2 pedicle screw fixation is gaining popularity. However, there is a lack of C1–C2 morphometric data for the Asian population.</p></sec><sec><title>Methods</title><p>Computed tomography analysis of 180 subjects (60 subjects each belonging to Chinese, Indian, and Malay populations) using simulation software was performed. Length and angulations of C1 lateral mass (C1LM) and C2 pedicle (C2P) screws were assessed.</p></sec><sec><title>Results</title><p>The predicted C1LM screw length was between 23.2 and 30.2 mm. The safe zone of trajectories was within 11.0°±7.7° laterally to 29.1°±6.2° medially in the axial plane and 37.0°±10.2° caudally to 20.9°±7.8° cephalically in the sagittal plane. The shortest and longest predicted C2P screw lengths were 22.1±2.8 mm and 28.5±3.2 mm, respectively. The safe trajectories were from 25.1° to 39.3° medially in the axial plane and 32.3° to 45.9° cephalically in the sagittal plane.</p></sec><sec><title>Conclusions</title><p>C1LM screw length was 23–30 mm with the axial safe zone from 11° laterally to 29° medially and sagittal safe zone at 21° cephalically. C2P screw length was 22–28 mm with axial safe zone from 26° to 40° medially and sagittal safe zone from 32° to 46° cephalically. These data serve as an important reference for Chinese, Indian, and Malay populations during C1–C2 instrumentation.</p></sec>

scholarly journals Biomechanical Analysis of Plate Fixation Compared With Various Screw Configurations for Use in the Latarjet Procedure

2020 ◽  
Vol 8 (7) ◽  
pp. 232596712093139
Author(s):  
Rachel M. Frank ◽  
Martina Roth ◽  
Coen Abel Wijdicks ◽  
Nicole Fischer ◽  
Alberto Costantini ◽  
...  
Keyword(s):  
Screw Fixation ◽  
Biomechanical Properties ◽  
Latarjet Procedure ◽  
Screw Insertion ◽  
Single Screw ◽  
Insertion Angle ◽  
Failure Loads ◽  
Cyclical Loading ◽  
Screw Insertion Angle ◽  
With Screws

Background: The biomechanical properties of coracoid fixation with a miniplate during the Latarjet procedure have not been described. Purpose: To determine the biomechanical properties of miniplate fixation for the Latarjet procedure compared with various screw fixation configurations. Study Design: Controlled laboratory study. Methods: A total of 8 groups (n = 5 specimens per group) were tested at a screw insertion angle of 0°: (1) 3.75-mm single screw, (2) 3.75-mm double screw, (3) 3.75-mm double screw with washers, (4) 3.75-mm double screw with a miniplate, (5) 4.00-mm single screw, (6) 4.00-mm double screw, (7) 4.00-mm double screw with washers, and (8) 4.00-mm double screw with a miniplate. In addition, similar to groups 1 to 3 and 5 to 7, there were 30 additional specimens (n = 5 per group) tested at a screw insertion angle of 15° (groups 9-14). To maintain specimen uniformity, rigid polyurethane foam blocks were used. Testing parameters included a preload of 214 N for 10 seconds, cyclical loading from 184 to 736 N at 1 Hz for 100 cycles, and failure loading at a rate of 15 mm/min until 10 mm of displacement or specimen failure occurred. Results: All single-screw constructs and 77% of 15° screw constructs failed before the completion of cyclical loading. Across all groups, group 8 (4.00-mm double screw with miniplate) demonstrated the highest maximum failure load ( P < .001). There were no differences in failure loads among specimens with single-screw fixation (groups 1, 5, 9, and 12; P > .05). All specimens in groups 9, 10, 11, 12, 13, and 14 (insertion angle of 15°) had significantly lower maximum failure loads compared with specimens in groups 2, 3, 4, 6, 7, and 8 (insertion angle of 0°) ( P < .001 for all). Conclusion: These results indicate significantly superior failure loads with the miniplate compared with all other constructs. Across all fixation techniques and screw sizes, constructs with screws inserted at 0° performed better than constructs with screws inserted at 15°. Clinical Relevance: The use of a miniplate for coracoid fixation during the Latarjet procedure may provide a more durable construct for the high-demand contact athlete.

scholarly journals Establishing a New Bony Landmark for Safe Screw Insertion in Medial Displacement Calcaneal Osteotomy: A Simulation-Based Approach

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0029
Author(s):  
Jaeyoung Kim ◽  
Jonathan Day
Keyword(s):  
Sagittal Plane ◽  
Axial Plane ◽  
Osteotomy Site ◽  
Bony Landmark ◽  
Screw Insertion ◽  
Sinus Tarsi ◽  
Calcaneal Osteotomy ◽  
Bony Landmarks ◽  
Screw Length ◽  
Trajectory Angle

Category: Hindfoot; Other Introduction/Purpose: Medial displacement calcaneal osteotomy (MDCO) is a commonly performed procedure in flatfoot reconstruction. Fixation is often achieved with screws due to its ability to compress across the osteotomy site. Screws are placed via a free-handed technique without direct fluoroscopic visualization, due to difficulty attaining a simultaneous axial calcaneal view. In addition, the posterior calcaneal tuber translates medially after displacement, resulting in altered anatomical geometry. It is therefore important to establish a reliable external bony landmark when performing free-handed interfragmentary fixation in order to avoid potential screw-related complications and to provide better surgical technique and fixation. The purposes of this study are to validate a new external bony landmark and to establish the appropriate trajectory and screw length for free-hand screw fixation in MDCO. Methods: A total of 84 postoperative computed tomography (CT) scans of MDCO in 70 patients were analyzed. The images were reconstructed using a 3-dimensional simulation program (Vworks 4.0, Cybermed). Virtual screw insertion was simulated by aiming towards two bony landmarks: the base of the 5th metatarsal in the axial plane, and the sinus tarsi in the sagittal plane (Figure 1). A grading system was also utilized to classify scenarios in which the screw breached the distal cortical wall: Grade 1 was defined as contact between the virtual screw and the cortex, Grade 2 as the screw approaching the outer margin of the cortex, and Grade 3 as the screw penetrating the outer cortex. The trajectory angle between the screw and the osteotomy, as well as the screw size, were also measured. Results: The average age of patients was 24.5 (range, 19 to 53), and 100% were males. The average displacement of the posterior calcaneal fragment was 7.3+-1.5 mm (range, 3.9 to 13.8). Among the 84 virtual screws, only five (6.0%) breached the medial cortical wall of the osteotomized calcaneus. All medial breaches were Grade 1. None of the virtual screws breached the lateral cortical wall. Mean trajectory angle between the virtual screw and the osteotomy site was 74.9+-6.7˚ (range, 60.0 to 89.8˚). In the perioperative data, estimated maximum screw length by simulation was 55.6+-4.4 mm (range, 50 to 65). Conclusion: Our results suggest that the optimal trajectory of free-handed screw placement can be determined through simulation of calcaneal interfragmentary screw insertion using postoperative CT imaging. Using this simulation technology, we determined a trajectory towards the sinus tarsi on the sagittal plane and the base of the 5th metatarsal on the axial plane to be a reliable external bony landmark for placement of screws in MDCO. These promising results have potential implications in achieving better fixation as well as improving union rates and operative outcomes.

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