A radiological evaluation of the morphometry and safety of S1, S2 and S2-ilium screws in the Asian population using three dimensional computed tomography scan: an analysis of 180 pelvis

Kwan, Mun Keong; Amit, Jeffry; Chan, Chris Yin Wei; Saw, Lim Beng

doi:10.1007/s00276-011-0919-2

Cited by 38 publications

(46 citation statements)

References 22 publications

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“…The ossification progress within neural processes is relevant in the ultrasound diagnosis and monitoring of neural tube defects [4, 8, 10, 13–16]. Hence, many spinal abnormalities including achondrogenesis, caudal regression syndrome, diastematomyelia, and skeletodysplasias may ultrasonografically be diagnosed and monitored in the fetus [26, 28, 30].…”

Section: Discussionmentioning

confidence: 99%

Cross-sectional study of the neural ossification centers of vertebrae C1–S5 in the human fetus

et al. 2013

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PurposeAn understanding of the normal evolution of the spine is of great relevance in the prenatal detection of spinal abnormalities. This study was carried out to estimate the length, width, cross-sectional area and volume of the neural ossification centers of vertebrae C1–S5 in the human fetus.Materials and methodsUsing the methods of CT (Biograph mCT), digital-image analysis (Osirix 3.9) and statistics (the one-way ANOVA test for paired data, the Kolmogorov–Smirnov test, Levene’s test, Student’s t test, the one-way ANOVA test for unpaired data with post hoc RIR Tukey comparisons) the size for the neural ossification centers throughout the spine in 55 spontaneously aborted human fetuses (27 males, 28 females) at ages of 17–30 weeks was studied.ResultsThe neural ossification centers were visualized in the whole pre-sacral spine, in 74.5 % for S1, in 61.8 % for S2, in 52.7 % for S3, and in 12.7 % for S4. Neither male–female nor right–left significant differences in the size of neural ossification centers were found. The neural ossification centers were the longest within the cervical spine. The maximum values referred to the axis on the right, and to C5 vertebra on the left. There was a gradual decrease in length for the neural ossification centers of T1–S4 vertebrae. The neural ossification centers were the widest within the proximal thoracic spine and narrowed bi-directionally. The growth dynamics for CSA of neural ossification centers were found to parallel that of volume. The largest CSAs and volumes of neural ossification centers were found in the C3 vertebra, and decreased in the distal direction.ConclusionsThe neural ossification centers show neither male–female nor right–left differences. The neural ossification centers are characterized by the maximum length for C2–C6 vertebrae, the maximum width for the proximal thoracic spine, and both the maximum cross-sectional area and volume for C3 vertebra. There is a sharp decrease in size of the neural ossification centers along the sacral spine. A decreasing sequence of values for neural ossification centers along the spine from cervical to sacral appears to parallel the same direction of the timing of ossification. The quantitative growth of the neural ossification centers is of potential relevance in the prenatal diagnosis and monitoring of achondrogenesis, caudal regression syndrome, diastematomyelia and spina bifida.

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Section: Discussionmentioning

confidence: 99%

Cross-sectional study of the neural ossification centers of vertebrae C1–S5 in the human fetus

et al. 2013

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“…Specifically, S2AI screws of females should be placed 5°more caudally than males. Recently, Kwan et al [27] conducted a study of sacral screws insertion in which S2AI screw was included, and Tsv angle and maxlength of S2AI screws were measured. Max-length was similar to our result (male 122.60 vs. 121.25 mm; female 122.2 vs. 120.63 mm), but Tsv angle was a little larger (male 39.3°vs.…”

Section: Discussionmentioning

confidence: 99%

Posterior second sacral alar iliac screw insertion: anatomic study in a Chinese population

Zhu

Bao

et al. 2013

Eur Spine J

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Objective To provide radiographic parameters for optimal placement of posterior second sacral alar iliac (S2AI) screw for instrumentation and fusion of scoliosis to the second sacral level in a Chinese population. Methods S2AI screw trajectories were mapped on threedimensional computed tomography (3DCT) reconstructions of 60 normal adult pelvises. 1 mm inferior and 1 mm lateral to the S1 dorsal foramen were chosen as the entry point, and ideal S2AI screw trajectories were explored by rotating and cutting the 3D pelvis, ensuring that the trajectories were of maximum length and width. The directions and depth of these determined trajectories were then measured. Results The ideal S2AI screw trajectories could be found in each pelvis. The left and right screw trajectory parameters for males were shown as follows: angulation was L 29.15 ± 8.60°vs. R 29.96 ± 8.28°(p = 0.286) caudally in the sagittal plane and L 36.49 ± 3.14°vs. R 37.16 ± 3.14°(p = 0.165) laterally in the transverse plane. The maximal and intrasacral lengths of trajectory were L 121.25 ± 8.33 vs. R 120.63 ± 7.54 mm (p = 0.460) and L 26.20 ± 3.31 vs. R 26.92 ± 4.76 mm (p = 0.268). The entry point was L 28.87 ± 3.33 vs. R 29.79 ± 3.55 mm (p = 0.186) lateral to the second sacral midline, and L 44.14 ± 11.87 vs. R 43.89 ± 12.53 mm (p = 0.687) underneath the skin. The trajectories for females were more caudal (L: 34.50 ± 6.56°vs. 29.15 ± 8.60°, p = 0.009; R: 35.72 ± 7.53°vs. 29.96 ± 8.28°, p = 0.007) in the sagittal plane, but the lateral angulation in the transverse plane showed no difference between genders (p [ 0.05). The female iliac medullar cavities were obviously narrower than those of males (L: 14.76 ± 2.46 vs. 16.98 ± 3.52, p = 0.006; R: 14.94 ± 2.60 vs. 17.00 ± 2.81, p = 0.005). Although the average maximal length of trajectories for females were about 5 mm shorter than those of males, intrasacral length were equal to those of males. Furthermore, both the distance from entry point to the S2 midline and skin in the transverse plane showed no difference between genders. Conclusion The feasibility to insert S2AI screws to the sacrum and ilium in an Asian population along with the ideal entry angle and length of trajectory were identified for clinical practice.

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“…Cortical fracture of the sacrum usually observed shortly after the initial surgery (on average after 42 days) and in presented series involved only women [4]. In order to avoid complications of this type, primary stabilization to the S2 vertebra or iliac bones can be performed [5,6], with optional interbody fusion from variable approaches [7,8], as well as using less common techniques with facet screws [9]. …”

Section: Introductionmentioning

confidence: 99%

Evidence-based support for S1 transpedicular screw entry point modification

Kubaszewski

Nowakowski

Kaczmarczyk

2014

Journal of Orthopaedic Surgery and Research

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BackgroundIn the literature, ‘below and lateral to the superior S1 facet’ is defined as the basic technique for screw introduction. Until a recently published modification, no analysis for alternative starting point has been proposed nor evaluated, although some surgeons claim to use some modifications. In this study, we analyse the data from anatomical and radiological studies for optimal starting point in transpedicular S1 screw placement.MethodsA Medline search for key word combination: sacrum, anatomy, pedicle, screws and bone density resulted in 26 publications relevant to the topic. After a review of literature, two articles were chosen, as those including the appropriate set of data. The data retrieved from the articles is used for the analysis. The spatial relation of S1 facet, pedicles and vertebral body with cortical thickness and bone density in normal, osteopenic and osteoporotic sacrum is analysed.ResultsPresented data advocates for more medial placement of the screws due to higher bone density and lower bone loss in osteoporosis. Medial shift of the starting point does not increase the risk of spinal canal perforation. Osteoarthritic changes within the facet can augment the posterior supporting point for screw. The facet angular orientation is similar to convergent screw trajectory.ConclusionsModified technique for S1 screw placement takes advantage of latest anatomical and clinical data. In our opinion, technique modification improves the reproducibility and may increase stability and the screws within the posterior cortex of the S1 vertebra. Further biomechanical and clinical study should be performed to prove its superiority to classical technique.

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A radiological evaluation of the morphometry and safety of S1, S2 and S2-ilium screws in the Asian population using three dimensional computed tomography scan: an analysis of 180 pelvis

Cited by 38 publications

References 22 publications

Cross-sectional study of the neural ossification centers of vertebrae C1–S5 in the human fetus

Cross-sectional study of the neural ossification centers of vertebrae C1–S5 in the human fetus

Posterior second sacral alar iliac screw insertion: anatomic study in a Chinese population

Evidence-based support for S1 transpedicular screw entry point modification

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