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 Effect of Screw Length and Geometry on Interfragmentary Compression in a Simulated Proximal Pole Scaphoid Fracture Model

Hand ◽  
2018 ◽  
Vol 15 (3) ◽  
pp. 378-383
Author(s):  
Samik Patel ◽  
Juan M. Giugale ◽  
Richard E. Debski ◽  
John R. Fowler
Keyword(s):  
Analysis Of Variance ◽  
Scaphoid Fracture ◽  
Fracture Site ◽  
Proximal Pole ◽  
Scaphoid Fractures ◽  
Screw Length ◽  
Significant Difference ◽  
Headless Compression Screws ◽  
With Screws ◽  
Interfragmentary Compression

Background: The objective of this study was to determine interfragmentary compression forces based on screw length and geometry for simulated proximal scaphoid fractures. Methods: Sixty-four foam model simulated fractures were stabilized with screws of various length (10 mm, 18 mm, 20 mm, or 24 mm) and geometry (central threadless or fully threaded) across a proximal fracture. Interfragmentary compression was measured at the simulated fracture site upon fixation. An independent sample t test and 1-way analysis of variance were performed to assess differences in interfragmentary compression. Results: Fixation utilizing a 10-mm screw generated significantly less interfragmentary compression than fixation utilizing a 20-mm or 24-mm screw. When accounting for both screw length and geometry, an 18-mm central threadless screw generated greater interfragmentary compression than a 20-mm and 24-mm fully threaded screw; there was no significant difference in compression between an 18-mm and 24-mm central threadless screw. Conclusions: The design of headless compression screws allows for maximal interfragmentary compression at the screw midpoint; we questioned whether a short screw centered on the fracture site resulted in superior compression to a longer, noncentered screw. Our data suggest that centering a small screw (10 mm) along a proximal fracture generates significantly less interfragmentary compression than a longer, noncentered screw. Our results demonstrate that balance between maximizing screw length and centering the screw on the fracture is vital toward maximizing interfragmentary compression for the fixation of proximal third scaphoid fractures.

Anatomical considerations for the placement of cervical transarticular screws

2011 ◽  
Vol 14 (1) ◽  
pp. 114-121 ◽  
Author(s):  
Guanyi Liu ◽  
Rongming Xu ◽  
Weihu Ma ◽  
Shaohua Sun ◽  
Jianxiang Feng
Keyword(s):  
Ct Scan ◽  
Soft Tissues ◽  
Sagittal Plane ◽  
Axial Plane ◽  
Screw Placement ◽  
Lateral Mass ◽  
Transarticular Screw ◽  
Spinal Nerves ◽  
Starting Point ◽  
The Ideal

Object The object of this study was to determine the safe screw placement technique for cervical transarticular screw fixation. Methods Twenty cadaveric adult cervical spines were studied. All soft tissues surrounding the cervical spinal nerves from C-2 to T-1 were dissected carefully to expose the lateral mass, facet joint, transverse process, vertebral artery (VA), and spinal nerves (ventral and dorsal rami). After the proper entrance and exit points for the transarticular screws were determined, posterior transarticular screw implantation was performed under direct visualization from C2–3 to C5–6. A CT scan was performed to check the screw placement. The angle and length of the transarticular screw trajectory, the distance between the tip of the screw and the VA, and the sagittal safety angle were measured on the CT scan. Statistical analysis was performed using ANOVA (p < 0.05). Sagittal and axial orientations of transarticular screws were carefully analyzed. Results There was no nerve or artery impingement or penetration. The average caudal angle of the screws in the sagittal plane was 37.3° ± 5.0° and the lateral angle in the axial plane was 16.6° ± 4.6°. The average distance between the tip of the screw and the VA (the posterior border of the VA foramen) was 5.8 ± 1.5 mm. The average sagittal safety angle was 41.9° ± 5.6°. No difference was observed according to the vertebral level. The average bone purchase was 18.7 ± 1.4 mm. Bone purchase was significantly greater at C2–3 (23.2 ± 1.6 mm) than at C3–4 through C5–6 (17.2 ± 1.3 mm, p < 0.05). Conclusions This study establishes anatomical guidelines to allow for safe cervical transarticular screw insertion. The starting point of transarticular screws should be 1 mm medial to the midpoint of the lateral mass. The “ideal” drilling angle is approximately 37° in the inferior direction and 16° in the lateral direction for the C2–3 through the C5–6 levels. The screw should be directed as laterally as possible in the axial plane without causing the lateral mass to fracture and as caudally as the occipital bone permits in the sagittal plane. The ideal screw size would be 3.5 mm in diameter and 18 mm in length.

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.

Pedicle screw insertion angle and pullout strength: comparison of 2 proposed strategies

2011 ◽  
Vol 14 (5) ◽  
pp. 670-676 ◽  
Author(s):  
Serkan İnceoğlu ◽  
William H. Montgomery ◽  
Selvon St. Clair ◽  
Robert F. McLain
Keyword(s):  
Pedicle Screw ◽  
Vertebral Body ◽  
Screw Thread ◽  
Pullout Strength ◽  
Screw Insertion ◽  
Starting Point ◽  
Entry Points ◽  
Group A ◽  
Group B ◽  
Screw Group

Object Minimally invasive pedicle screws inserted vertically (that is, dorsoventrally) through the pedicle, as opposed to the more common coaxial technique, offer potential advantages by minimizing soft-tissue stripping during screw placement. The screws are designed for insertion through a medial starting point with vertical trajectory through the pedicle and into the vertebral body. As such, no lateral dissection beyond the insertion point is necessary. However, the effects of this insertion technique on the screw biomechanical performance over a short- and long-term are unknown. The authors investigated the pullout strength and stiffness of these screws, with or without fatigue cycling, compared with comparably sized, traditional screws placed by coaxial technique. Methods Twenty-one lumbar vertebrae (L-3, L-4, and L-5) were tested. Each pedicle of each vertebra was instrumented with either a traditional, coaxial pedicle screw (Group A), placed through a standard starting point, or a vertically oriented, alternative-design screw (Group B), with a medial starting point and vertical trajectory. The specimens were divided into 2 groups for testing. One group was tested for direct pullout (10 specimens) while the other was subject to pullout after tangential (toggle) cyclic loading (11 specimens). The screws were cycled in displacement control (± 5 mm producing ~ 4-Nm moment) at a rate of 3 Hz for 5000 cycles. Pullout tests were performed at a rate of 1 mm/minute. Results Two-way ANOVA showed that Group B screws with a medial starting point (2541 ± 1090 N for cycled vs 2135 ± 1323 N for noncycled) had significantly higher pullout loads than Group A screws with a standard entry point (1585 ± 766 N for cycled vs 1417 ± 812 N noncycled) (p = 0.001). There was no significant effect of cycling or screw insertion type on pullout stiffness. Tangential stiffness of the Group B screws was significantly less than that of the Group A screws (p = 0.001). The stiffness of both screws in the toe region was significantly affected by cycling (p = 0.001). Conclusions The use of Group B screws inserted through a medial starting point showed greater pullout load than a Group A screw inserted through a standard starting point. The greater pullout strength in Group B screws may be due to screw thread design and increased cortical bone purchase at the medial starting point. Nevertheless, anatomical considerations of the medial starting point, that is, pedicle or lateral vertebral body cortex breach, may limit its application. The medial starting point of the Group B screw was frequently in the facet at the L-3 and L-4 pedicle entry points, which may have clinical importance.

iPod Touch-Assisted Instrumentation of the Spine A Technical Report

2013 ◽  
Vol 73 (2) ◽  
pp. ons233-ons237 ◽  
Author(s):  
Gregory F. Jost ◽  
Erica F. Bisson ◽  
Meic H. Schmidt
Keyword(s):  
Lumbar Spine ◽  
Image Guidance ◽  
Simple Technique ◽  
Sagittal Plane ◽  
Pedicle Screws ◽  
Ipod Touch ◽  
Screw Insertion ◽  
Technical Report ◽  
Modern Image ◽  
The Ideal

Abstract BACKGROUND: Instrumentation of the spine depends on choosing the correct insertion angles to implant screws. Although modern image guidance facilitates precise instrumentation of the spine, the equipment is costly and availability is limited. Although most surgeons use lateral fluoroscopy to guide instrumentation in the sagittal plane, the lateromedial angulation is often chosen by estimation. To overcome the associated uncertainty, iPod touch–based applications for measuring angles can be used to assist with screw implantation. OBJECTIVE: To evaluate the use of the iPod touch to adjust instruments to the optimal axial insertion angle for placement of pedicle screws in the lumbar spine. METHODS: Twenty lumbar pedicle screws in 5 consecutive patients were implanted using the iPod touch. The lateromedial angulation was measured on preoperative images and reproduced in the operative field with the iPod touch. The instruments to implant the screws were aligned with the side of the iPod for screw insertion. Actual screw angles were remeasured on postoperative imaging. We collected demographic, clinical, and operative data for each patient. RESULTS: In 16 of 20 screws, the accuracy of implantation was within 3 degrees of the ideal trajectory. The 4 screws with an angle mismatch of 7 to 13 degrees were all implanted at the caudal end of the exposure, where maintaining the planned angulation was impeded by strong muscles pushing medially. CONCLUSION: iPod touch–assisted instrumentation of the spine is a very simple technique, which, in combination with a lateral fluoroscopy, may guide placement of pedicle screws in the lumbar spine.

ANATOMICAL STUDY OF THE IDEAL POSITIONING OF THE S2 ILIAC SCREW

2021 ◽  
Vol 20 (4) ◽  
pp. 282-286
Author(s):  
Italo Cordeiro de Barros Izaías ◽  
Lucilo S. de A. Maranhão Neto ◽  
André Flávio Freire Pereira ◽  
Marcus André Costa Ferreira ◽  
Rodrigo Castro de Medeiros ◽  
...  
Keyword(s):  
Sagittal Plane ◽  
Pelvic Ring ◽  
Anatomical Study ◽  
Level Of Evidence ◽  
Cross Sectional ◽  
Sacroiliac Screw ◽  
Screw Length ◽  
Significant Difference ◽  
Iliac Screw ◽  
The Ideal

ABSTRACT Objective: To evaluate the morphometry of the pelvis to determine the safe trajectory for the insertion of the S2-iliac screw, and to correlate it with studies reported in the literature for other populations. Method: The computed tomography (CT) pelvic exams of 36 Brazilian patients without congenital malformations, tumors, pelvic ring fractures or dysplasias were selected from the database of a radiological clinic. To define the ideal trajectory of the S2-iliac screw, the following variables were measured: 1- maximum sacroiliac screw length; 2- thickness of the iliac dipole for planning the choice of screw dimensions (length and diameter); 3 - distance between the insertion point of the iliac S2 screw and the posterior sacral cortex; 4 - angulation for insertion of the screw in the mediolateral direction, representing the angle formed between the “iliac line” and the anatomical sagittal plane; 5- Angulation for insertion of the screw in the craniocaudal direction. The Pearson's chi squared and student's t tests were used for statistical analysis. Results: The sample consisted of 36 patients, 50% (18/36) of whom were women. The mean age was 63.7 years, ranging from 23 to 96 years. All the pelvic morphometric variables analyzed presented values similar to those described in the literature for other populations. Conclusion: Prior evaluation of the tomography exams was important for preoperative planning, and there was a statistically significant difference between the sexes only in relation to the variables left craniocaudal and length of the left internal table. Level of evidence III; Observational cross-sectional study.

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.

scholarly journals Biomechanical Strength of Retrograde Fixation in Proximal Third Scaphoid Fractures

Hand ◽  
2018 ◽  
Vol 14 (6) ◽  
pp. 760-764 ◽  
Author(s):  
Charles A. Daly ◽  
Allison L. Boden ◽  
William C. Hutton ◽  
Michael B. Gottschalk
Keyword(s):  
Cyclic Loading ◽  
Scaphoid Fracture ◽  
Maximum Load ◽  
Vascular Supply ◽  
Proximal Pole ◽  
Wrist Fractures ◽  
Scaphoid Fractures ◽  
Screw Length ◽  
Load To Failure ◽  
Biomechanical Strength

Background: Current techniques for fixation of proximal pole scaphoid fractures utilize antegrade fixation via a dorsal approach endangering the delicate vascular supply of the dorsal scaphoid. Volar and dorsal approaches demonstrate equivalent clinical outcomes in scaphoid wrist fractures, but no study has evaluated the biomechanical strength for fractures of the proximal pole. This study compares biomechanical strength of antegrade and retrograde fixation for fractures of the proximal pole of the scaphoid. Methods: A simulated proximal pole scaphoid fracture was produced in 22 matched cadaveric scaphoids, which were then assigned randomly to either antegrade or retrograde fixation with a cannulated headless compression screw. Cyclic loading and load to failure testing were performed and screw length, number of cycles, and maximum load sustained were recorded. Results: There were no significant differences in average screw length (25.5 mm vs 25.6 mm, P = .934), average number of cyclic loading cycles (3738 vs 3847, P = .552), average load to failure (348 N vs 371 N, P = .357), and number of catastrophic failures observed between the antegrade and retrograde fixation groups (3 in each). Practical equivalence between the 2 groups was calculated and the 2 groups were demonstrated to be practically equivalent (upper threshold P = .010). Conclusions: For this model of proximal pole scaphoid wrist fractures, antegrade and retrograde screw configuration have been proven to be equivalent in terms of biomechanical strength. With further clinical study, we hope surgeons will be able to make their decision for fixation technique based on approaches to bone grafting, concern for tenuous blood supply, and surgeon preference without fear of poor biomechanical properties.

Secondary Fractures Following Internal Fixation in Two Horses

1989 ◽  
Vol 02 (03) ◽  
pp. 125-128
Author(s):  
E. M. Gaughan ◽  
N. G. Duchar
Keyword(s):  
Internal Fixation ◽  
Sagittal Plane ◽  
Proximal Phalanx ◽  
Fracture Repair ◽  
Fracture Line ◽  
Carpal Bone ◽  
Fracture Plane ◽  
The Third ◽  
Lag Screw ◽  
Secondary Fractures

SummaryImplant associated fractures have not been reported in horses. Two horses were evaluated for fractures in the fore limbs, occurring subsequent to previous fracture repair. Previously, the horses had sustained fractures of unusual configurations which were repaired using internal fixation. Following repair and healing of the fractures, secondary fractures occurred in the same bone, but in a different (more common) configuration. The first horse was evaluated ten months following lag screw fixation of a longitudinal fracture of the proximal phalanx in a frontal plane. This horse presented with a more typical comminuted fracture in the sagittal plane with the screws from the first fixation lying in the fracture line. This fracture was successfully treated with a cast. The second horse was examined eightteen months after repair of a medial sagittal slab fracture of the third carpal bone. The horse presented with a more typical dorsal slab fracture of the third carpal bone with the previously placed lag screw lying in the fracture line. The screw was removed and a lag screw was placed perpendicular to the new fracture plane through the dorsal surface of the third carpal bone to repair the fracture.

Sign in / Sign up

Export Citation Format

Share Document