Feasibility of Translaminar Screw Placement in Korean Population: Morphometric Analysis of Cervical Spine

Object There are rare indications for upper cervical spine fusion in young children. Compared with nonrigid constructs, rigid instrumentation with screw fixation increases the fusion rate and reduces the need for halo fixation. Instrumentation may be technically challenging in younger children. A number of screw placement techniques have been described. Use of C-2 translaminar screws has been shown to be anatomically feasible, even in the youngest of children. However, there are few data detailing the clinical outcome. In this study, the authors describe the clinical and radiographic follow-up of 18 children 5 years of age or younger who had at least one C-2 translaminar screw as part of an occipitocervical or C1–2 fusion construct. Methods A retrospective review of all children treated with instrumented occipitocervical or C1–2 fusion between July 1, 2007, and June 30, 2013, at Riley Children's Hospital and Texas Children's Hospital was performed. All children 5 years of age or younger with incorporation of at least one C-2 translaminar screw were identified. Results Eighteen children were studied (7 boys and 11 girls). The mean age at surgery was 38.1 months (range 10–68 months). Indications for surgery included traumatic instability (6), os odontoideum (3), destructive processes (2), and congenital instability (7). A total of 24 C-2 translaminar screws were placed; 23 (95.8%) of 24 were satisfactorily placed (completely contained within the cortical walls). There was one medial cortex breach without neurological impingement. There were no complications with screw placement. Three patients required wound revisions. Two patients died as a result of their original condition (trauma, malignant tumor). The mean follow-up duration for the surviving patients was 17.5 months (range 3–60 months). Eleven (91.7%) of the 12 patients followed for 6 months or longer showed radiographic stability or completed fusion. Conclusions Use of C-2 translaminar screws provides an effective anchor for internal fixation of the upper cervical spine. In this study of children 5 years of age or younger, the authors found a high rate of radiographic fusion with a low rate of complications.

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Computed tomography morphometric analysis of C2 translaminar screw fixation of Wright’s technique and a modified technique in the pediatric cervical spine

European Spine Journal ◽

10.1007/s00586-013-3130-9 ◽

2013 ◽

Vol 23 (3) ◽

pp. 606-612 ◽

Cited By ~ 13

Author(s):

Dong-Dong Xia ◽

Sheng-Lei Lin ◽

Wei Chen ◽

Zhong-Hai Shen ◽

Yao Li ◽

...

Keyword(s):

Computed Tomography ◽

Cervical Spine ◽

Morphometric Analysis ◽

Screw Fixation ◽

Modified Technique ◽

Translaminar Screw Fixation ◽

Translaminar Screw

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Morphometric Analysis and Classification of the Cross-Sectional Shape of the C2 Lamina

BioMed Research International ◽

10.1155/2017/7276946 ◽

2017 ◽

Vol 2017 ◽

pp. 1-7

Author(s):

Soyeon Kim ◽

Dai-Soon Kwak ◽

In-Beom Kim

Keyword(s):

Individual Differences ◽

Morphometric Analysis ◽

Three Dimensional ◽

Cervical Vertebra ◽

Screw Placement ◽

Cross Sectional ◽

Translaminar Screw ◽

Korean Adult ◽

The Cross ◽

Sectional Shape

A thorough understanding of the morphology of the lamina of the second cervical vertebra (C2) is important for safe C2 translaminar screw placement. Although anatomical characteristics of the C2 lamina have been widely documented, individual differences in morphology have not been addressed. The aim of this study was to morphometrically analyze the cross-sectional shape of the C2 lamina and classify the shape to describe individual differences. Morphometric analysis was conducted on 145 three-dimensional C2 models based on computerized tomography images from Korean adult cadavers. Several parameters were measured on a cross-section image of the lamina model. Based on numerical criteria, all of the C2 lamina’s cross-sectional shapes could be categorized into three distinctive morphological types: pyriform, ellipse, and obpyriform shapes. We confirmed that most Koreans can accommodate C2 translaminar screw placement with a lower limit of the 95% confidence interval of thickness measured at 6.26 mm. Morphometric analysis suggested that the obpyriform-shaped lamina (4.48%) is likely to require screw trajectory adjustment to avoid cortical breakout of the screw. Our results will enhance current anatomical understanding of the C2 lamina and thus facilitate safer C2 translaminar screw placement.

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Computed tomography morphometric analysis for lateral mass screw placement in the pediatric subaxial cervical spine

Journal of Neurosurgery Spine ◽

10.3171/2012.8.spine12767 ◽

2012 ◽

Vol 17 (5) ◽

pp. 390-396 ◽

Cited By ~ 8

Author(s):

George Al-Shamy ◽

Jacob Cherian ◽

Javier A. Mata ◽

Akash J. Patel ◽

Steven W. Hwang ◽

...

Keyword(s):

Cervical Spine ◽

Morphometric Analysis ◽

Pediatric Patients ◽

Screw Fixation ◽

Screw Placement ◽

Lateral Mass ◽

Lateral Mass Screw ◽

Subaxial Cervical Spine ◽

Screw Length ◽

Lateral Mass Screws

Object Lateral mass screws are routinely placed throughout the subaxial cervical spine in adults, but there are few clinical or radiographic studies regarding lateral mass fixation in children. The morphology of pediatric cervical lateral masses may be associated with greater difficulty in obtaining adequate purchase. The authors examined the lateral masses of the subaxial cervical spine in pediatric patients to define morphometric differences compared with adults, establish guidelines for lateral mass instrumentation in children, and define potential limitations of this technique in the pediatric age group. Methods Morphometric analysis was performed on CT of the lateral masses of C3–7 in 56 boys and 14 girls. Measurements were obtained in the axial, coronal, and sagittal planes. Results For most levels and measurements, results in boys and girls did not differ significantly; the few values that were significantly different are not likely to be clinically significant. On the other hand, younger (< 8 years of age) and older children (≥ 8 years of age) differed significantly at every level and measurement except for facet angularity. Sagittal diagonal, a measurement that closely estimates screw length, was found to increase at each successive caudal level from C-3 to C-7, similar to the adult population. A screw acceptance analysis found that all patients ≥ 4 years of age could accept at least a 3.5 × 10 mm lateral mass screw. Conclusions Lateral mass screw fixation is feasible in the pediatric cervical spine, particularly in children age 4 years old or older. Lateral mass screw fixation is feasible even at the C-7 level, where pedicle screw placement has been advised in lieu of lateral mass screws because of the small size and steep trajectory of the C-7 lateral mass. Nonetheless, all pediatric patients should undergo high-resolution, thin-slice CT preoperatively to assess suitability for lateral mass screw fixation.

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Computed tomography morphometric analysis for axial and subaxial translaminar screw placement in the pediatric cervical spine

Journal of Neurosurgery Pediatrics ◽

10.3171/2008.11.peds08277 ◽

2009 ◽

Vol 3 (2) ◽

pp. 121-128 ◽

Cited By ~ 30

Author(s):

Joshua J. Chern ◽

Roukoz B. Chamoun ◽

William E. Whitehead ◽

Daniel J. Curry ◽

Thomas G. Luerssen ◽

...

Keyword(s):

Cervical Spine ◽

Pediatric Population ◽

Cervical Vertebrae ◽

Linear Regression Analysis ◽

Screw Placement ◽

Published Data ◽

Rigid Fixation ◽

Translaminar Screw ◽

Laminar Thickness ◽

Translaminar Screws

Object 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. Methods 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. Results 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 ≥ 4 mm). Conclusions 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.

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Endonasal Surgery of the Upper Cervical Spine: A Morphometric Analysis

Skull Base ◽

10.1055/s-2008-1093170 ◽

2008 ◽

Vol 18 (S 01) ◽

Author(s):

Harminder Singh ◽

Bartosz Grobelny ◽

Adam Flanders ◽

Marc Rosen ◽

Paul Schiffmacher ◽

...

Keyword(s):

Cervical Spine ◽

Morphometric Analysis ◽

Upper Cervical Spine ◽

Endonasal Surgery ◽

Upper Cervical

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CADAVERIC MORPHOMETRIC ANALYSIS FOR ATLANTAL LATERAL MASS SCREW PLACEMENT

Neurosurgery ◽

10.1227/01.neu.0000124753.74864.07 ◽

2004 ◽

Vol 54 (6) ◽

pp. 1436-1440 ◽

Cited By ~ 54

Author(s):

Michael Y. Wang ◽

Srinath Samudrala

Keyword(s):

Morphometric Analysis ◽

Screw Placement ◽

Lateral Mass ◽

Lateral Mass Screw

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Utility of intraoperative electromyography in placing C7 pedicle screws

Journal of Neurosurgery Spine ◽

10.3171/2019.11.spine191120 ◽

2020 ◽

Vol 32 (6) ◽

pp. 891-899 ◽

Cited By ~ 1

Author(s):

Jonathan J. Rasouli ◽

Brooke T. Kennamer ◽

Frank M. Moore ◽

Alfred Steinberger ◽

Kevin C. Yao ◽

...

Keyword(s):

Cervical Spine ◽

Pedicle Screw ◽

Thoracolumbar Spine ◽

Pedicle Screws ◽

Neurological Injury ◽

Screw Placement ◽

Pedicle Screw Placement ◽

Data Set ◽

Subaxial Cervical Spine ◽

Increased Risk

OBJECTIVEThe C7 vertebral body is morphometrically unique; it represents the transition from the subaxial cervical spine to the upper thoracic spine. It has larger pedicles but relatively small lateral masses compared to other levels of the subaxial cervical spine. Although the biomechanical properties of C7 pedicle screws are superior to those of lateral mass screws, they are rarely placed due to increased risk of neurological injury. Although pedicle screw stimulation has been shown to be safe and effective in determining satisfactory screw placement in the thoracolumbar spine, there are few studies determining its utility in the cervical spine. Thus, the purpose of this study was to determine the feasibility, clinical reliability, and threshold characteristics of intraoperative evoked electromyographic (EMG) stimulation in determining satisfactory pedicle screw placement at C7.METHODSThe authors retrospectively reviewed a prospectively collected data set. All adult patients who underwent posterior cervical decompression and fusion with placement of C7 pedicle screws at the authors’ institution between January 2015 and March 2019 were identified. Demographic, clinical, neurophysiological, operative, and radiographic data were gathered. All patients underwent postoperative CT scanning, and the position of C7 pedicle screws was compared to intraoperative neurophysiological data.RESULTSFifty-one consecutive C7 pedicle screws were stimulated and recorded intraoperatively in 25 consecutive patients. Based on EMG findings, 1 patient underwent intraoperative repositioning of a C7 pedicle screw, and 1 underwent removal of a C7 pedicle screw. CT scans demonstrated ideal placement of the C7 pedicle screw in 40 of 43 instances in which EMG stimulation thresholds were > 15 mA. In the remaining 3 cases the trajectories were suboptimal but safe. When the screw stimulation thresholds were between 11 and 15 mA, 5 of 6 screws were suboptimal but safe, and in 1 instance was potentially dangerous. In instances in which the screw stimulated at thresholds ≤ 10 mA, all trajectories were potentially dangerous with neural compression.CONCLUSIONSIdeal C7 pedicle screw position strongly correlated with EMG stimulation thresholds > 15 mA. In instances, in which the screw stimulates at values between 11 and 15 mA, screw trajectory exploration is recommended. Screws with thresholds ≤ 10 mA should always be explored, and possibly repositioned or removed. In conjunction with other techniques, EMG threshold testing is a useful and safe modality in determining appropriate C7 pedicle screw placement.

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