Complex pediatric cervical spine surgery using smaller nonspinal screws and plates and intraoperative computed tomography: Clinical article
Department of Neurological Surgery, Harborview Medical Center, University of Washington School of Medicine, Seattle Children’s Hospital, Seattle, WA, USA. Journal of Neurosurgery Pediatrics
(Impact Factor: 1.48).
06/2012; 9(6):594-601. DOI: 10.3171/2012.2.PEDS11329
The treatment of craniocervical instability in children is often challenging due to their small spine bones, complex anatomy, and unique syndromes. The authors discuss their surgical experience with 33 cases in the treatment of 31 children (≤ 17 years of age) with craniocervical spine instability using smaller nontraditional titanium screws and plates, as well as intraoperative CT.
All craniocervical fusion procedures were performed using intraoperative fluoroscopic imaging and electrophysiological monitoring. Nontraditional spine hardware included smaller screw sizes (2.4 and 2.7 mm) from the orthopedic hand/foot set and mandibular plates. Twenty-three of the 33 surgical procedures were performed with intraoperative CT, which was used to confirm adequate position of the spine hardware and alignment of the spine.
The mean patient age was 9.5 years (range 2-17 years). Eleven children underwent a posterior C1-2 transarticular screw fusion, 17 had an occipitocervical fusion, and 3 had a posterior subaxial cervical fusion. The follow-up duration ranged from 9 to 72 months (mean 53 months). All children demonstrated successful fusion at their 3-month follow-up visit, except 1 patient whose unilateral C1-2 transarticular screw fusion required a repeat surgery before proper fusion was achieved. Of the 47 C1-2 transarticular screws that were placed, 13 were 2.4 mm, 15 were 2.7 mm, 7 were 3.5 mm, and 12 were 4.0 mm. Eighteen of the 47 C1-2 transarticular screws were suboptimally placed. Eleven of these misplaced screws were removed and redirected within the same operation because these surgeries benefitted from the use of intraoperative CT; 6 of the 7 remaining suboptimally placed screws were left in place because a second surgery for screw replacement was not warranted. The other suboptimally placed C1-2 screw was replaced during a repeat operation due to failure of fusion. Use of intraoperative CT was invaluable because it enabled the authors to reposition suboptimal C1-2 transarticular screws without necessitating a second operation.
Successful craniocervical fusion procedures were achieved using smaller nontraditional titanium screws and plates. Intraoperative CT was a helpful adjunct for confirming and readjusting the trajectory of the screws prior to leaving the operating room, which decreases overall treatment costs and reduces complications.
Available from: Joshua J Chern
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ABSTRACT: The management of upper cervical spinal instability in children continues to represent a technical challenge. Traditionally, a number of wiring techniques followed by halo orthosis have been applied; however, they have been associated with a high rate of nonunion and poor tolerance for the halo. Alternatively, C1-2 transarticular screws and C-2 pars/pedicle screws allow more rigid fixation, but their placement is technically demanding and associated with vertebral artery injuries. Recently, C-2 translaminar screws have been added to the armamentarium of the pediatric spine surgeon as a technically simple and biomechanically efficient means of fixation. However, the use of subaxial translaminar screws have not been described in the general pediatric population. There are no published data that describe the anatomical considerations and potential limitations of this technique in the pediatric population.
The cervical vertebrae of 69 pediatric patients were studied on CT scans. Laminar height and thickness were measured. Statistical analysis was performed using unpaired Student t-tests (p<0.05) and linear regression analysis.
The mean laminar heights at C-2, C-3, C-4, C-5, C-6, and C-7, respectively, were 9.76+/-2.22 mm, 8.22+/-2.24 mm, 8.09+/-2.38 mm, 8.51+/-2.34 mm, 9.30+/-2.54 mm, and 11.65+/-2.65 mm. Mean laminar thickness at C-2, C-3, C-4, C-5, C-6, and C-7, respectively, were 5.07+/-1.07 mm, 2.67+/-0.79 mm, 2.18+/-0.73 mm, 2.04+/-0.60 mm, 2.52 +/- 0.66 mm, and 3.84+/-0.96 mm. In 50.7% of C-2 laminae, the anatomy could accept at least 1 translaminar screw (laminar thickness>or=4 mm).
Overall, the anatomy in 30.4% of patients younger than 16 years old could accept bilateral C-2 translaminar screws. However, the anatomy of the subaxial cervical spine only rarely could accept translaminar screws. This study establishes anatomical guidelines to allow for accurate and safe screw selection and insertion. Preoperative planning with thin-cut CT and sagittal reconstruction is essential for safe screw placement using this technique.
Journal of Neurosurgery Pediatrics 02/2009; 3(2):121-8. DOI:10.3171/2008.11.PEDS08277 · 1.48 Impact Factor
Available from: thejns.org
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ABSTRACT: The use of C-1 lateral mass screws provides an alternative to C1-2 transarticular screws in the pediatric population. However, the confined space of the local anatomy and unfamiliarity with the technique may make the placement of a C-1 lateral mass screw more challenging, especially in the juvenile or growing spine.
A CT morphometric analysis was performed in 76 pediatric atlases imaged at Texas Children's Hospital from October 1, 2007 until April 30, 2008. Critical measurements were determined for potential screw entry points, trajectories, and lengths, with the goal of replicating the operative technique described by Harms and Melcher for adult patients.
The mean height and width for screw entry on the posterior surface of the lateral mass were 2.6 and 8.5 mm, respectively. The mean medially angled screw trajectory from an idealized entry point on the lateral mass was 16 degrees (range 4 to 27 degrees ). The mean maximal screw depth from this same ideal entry point was 20.3 mm. The overhang of the posterior arch averaged 6.3 mm (range 2.1-12.4 mm). The measurement between the left- and right-side lateral masses was significantly different for the maximum medially angled screw trajectory (p = 0.003) and the maximum inferiorly directed angle (p = 0.045). Those measurements in children < 8 years of age were statistically significant for the entry point height (p = 0.038) and maximum laterally angled screw trajectory (p = 0.025) compared with older children. The differences between boys and girls were statistically significant for the minimum screw length (p = 0.04) and the anterior lateral mass height (p < 0.001).
A significant variation in the morphological features of C-1 exists, especially between the left and right sides and in younger children. The differences between boys and girls are clinically insignificant. The critical measurement of whether the C-1 lateral mass in a child could accommodate a 3.5-mm-diameter screw is the width of the lateral mass and its proximity to the vertebral artery. Only 1 of 152 lateral masses studied would not have been able to accommodate a lateral mass screw. This study reemphasizes the importance of a preoperative CT scan of the upper cervical spine to assure safe and effective placement of the instrumentation at this level.
Journal of Neurosurgery Pediatrics 02/2009; 3(1):20-3. DOI:10.3171/2008.10.PEDS08224 · 1.48 Impact Factor
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ABSTRACT: Cone beam CT (CBCT) has been widely accepted as an imaging tool for a variety of dental and nondental applications. Although dental CBCT has evolved considerably in the last decade, there is still a lot of room for optimization of this modality at different levels. In this perspective, an overview is given of various hardware and software innovations that could be implemented in CBCT imaging in the foreseeable future. Some have already been applied to clinical practice but require further validation; others are being commonly applied by other imaging modalities and could be adapted for use in dental CBCT. The overview covers the X-ray tube, adaptive exposure techniques, beam and rotation geometry, detector technology and reconstruction algorithms. Furthermore, the combination of CBCT with optical imaging is discussed, the possibility of using these devices for nondental applications is evaluated, and the potential use of phase-contrast tomography is discussed.
Imaging in medicine 10/2012; 4(5):551-563. DOI:10.2217/iim.12.45
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