Cervical lateral mass screw length analysis in men versus women

2021 ◽  
Author(s):  
Kohei Morita ◽  
Hiroki Ohashi ◽  
Daichi Kawamura ◽  
Satoshi Tani ◽  
Kostadin Karagiozov ◽  
...  
Keyword(s):  
Lateral Mass ◽  
Lateral Mass Screw ◽  
Screw Length ◽  
Length Analysis

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

2012 ◽  
Vol 17 (5) ◽  
pp. 390-396 ◽  
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.

Computed tomography morphometric analysis for C-1 lateral mass screw placement in children

2009 ◽  
Vol 3 (1) ◽  
pp. 20-23 ◽  
Author(s):  
Roukoz B. Chamoun ◽  
William E. Whitehead ◽  
Daniel J. Curry ◽  
Thomas G. Luerssen ◽  
Andrew Jea
Keyword(s):  
Morphometric Analysis ◽  
Entry Point ◽  
Posterior Arch ◽  
Lateral Mass ◽  
Confined Space ◽  
Lateral Mass Screw ◽  
Screw Length ◽  
Entry Points ◽  
Left And Right ◽  
The Mean

Object 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. Methods 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. Results 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° (range 4 to 27°). 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). Conclusions 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.

Factors affecting lateral mass screw placement at C-7

2011 ◽  
Vol 14 (3) ◽  
pp. 405-411 ◽  
Author(s):  
Kalil G. Abdullah ◽  
Amy S. Nowacki ◽  
Michael P. Steinmetz ◽  
Jeffrey C. Wang ◽  
Thomas E. Mroz
Keyword(s):  
Sagittal Plane ◽  
Anatomical Variation ◽  
Axial Plane ◽  
Screw Placement ◽  
Lateral Mass ◽  
Lateral Mass Screw ◽  
Modified Technique ◽  
Modified Method ◽  
Starting Point ◽  
Lateral Mass Screws

Object The C-7 lateral mass has been considered difficult to fit with instrumentation because of its unique anatomy. Of the methods that exist for placing lateral mass screws, none particularly accommodates this anatomical variation. The authors have related 12 distinct morphological measures of the C-7 lateral mass to the ability to place a lateral mass screw using the Magerl, Roy-Camille, and a modified Roy-Camille method. Methods Using CT scans, the authors performed virtual screw placement of lateral mass screws at the C-7 level in 25 male and 25 female patients. Complications recorded included foraminal and articular process violations, inability to achieve bony purchase, and inability to place a screw longer than 6 mm. Violations were monitored in the coronal, axial, and sagittal planes. The Roy-Camille technique was applied starting directly in the middle of the lateral mass, as defined by Pait's quadrants, with an axial angle of 15° lateral and a sagittal angle of 90°. The Magerl technique was performed by starting in the inferior portion of the top right square of Pait's quadrants and angling 25° laterally in the axial plane with a 45° cephalad angle in the sagittal plane. In a modified method, the starting point is similar to the Magerl technique in the top right square of Pait's quadrant and then angling 15° laterally in the axial plane. In the sagittal plane, a 90° angle is taken perpendicular to the dorsal portion of the lateral mass, as in the traditional Roy-Camille technique. Results Of all the morphological methods analyzed, only a combined measure of intrusion of the T-1 facet and the overall length of the C-7 lateral mass was statistically associated with screw placement, and only in the Roy-Camille technique. Use of the Magerl technique allowed screw placement in 28 patients; use of the Roy-Camille technique allowed placement in 24 patients; and use of the modified technique allowed placement in 46 patients. No screw placement by any method was possible in 4 patients. Conclusions There is only one distinct anatomical ratio that was shown to affect lateral mass screw placement at C-7. This ratio incorporates the overall length of the lateral mass and the amount of space occupied by the T-1 facet at C-7. Based on this virtual study, a modified Roy-Camille technique that utilizes a higher starting point may decrease the complication rate at C-7 by avoiding placement of the lateral mass screw into the T1 facet.

Lateral Radiologic Evaluation of Lateral Mass Screw Placement in the Cervical Spine

Spine ◽  
1998 ◽  
Vol 23 (4) ◽  
pp. 458-462 ◽  
Author(s):  
Nabil A. Ebraheim ◽  
Micheal R. Tremains ◽  
Rongming Xu ◽  
Richard A. Yeasting
Keyword(s):  
Cervical Spine ◽  
Screw Placement ◽  
Lateral Mass ◽  
Lateral Mass Screw ◽  
Radiologic Evaluation

scholarly journals Load sharing properties of cervical pedicle screw-rod constructs versus lateral mass screw-rod constructs

2010 ◽  
Vol 19 (5) ◽  
pp. 803-808 ◽  
Author(s):  
Bradley J. Dunlap ◽  
Eldin E. Karaikovic ◽  
Hyung-Soon Park ◽  
Mark J. Sokolowski ◽  
Li-Qun Zhang
Keyword(s):  
Pedicle Screw ◽  
Load Sharing ◽  
Lateral Mass ◽  
Lateral Mass Screw ◽  
Cervical Pedicle Screw ◽  
Cervical Pedicle
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