Radiological assessment of cervical lateral mass screw angulations in Asian patients

Sureisen, M. and Saw, L.B. and Chan, C.Y.W. and Singh, D.A. and Kwan, M.K. (2011) Radiological assessment of cervical lateral mass screw angulations in Asian patients. Indian Journal of Orthopaedics, 45 (6). pp. 504-507. ISSN 0019-5413,

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Background: Various lateral mass screw fixation methods have been described in the literature with various levels of safety in relation to the anterior neurovascular structures. This study was designed to radiologically determine the minimum lateral angulations of the screw to avoid penetration of the vertebral artery canalusing three of the most common techniques: Roy-Camille, An, and Magerl. s and Methods: Sixty normal cervical CT scans were reviewed. A minimum lateral angulation of a 3.5 mm lateral mass screw which was required to avoid penetration of the vertebral artery canal at each level of vertebra were measured. Results: The mean lateral angulations of the lateral mass screws (with 95 confidence interval) to avoid vertebral artery canal penetration, in relation to the starting point at the midpoint (Roy-Camille), 1 mm medial (An), and 2 mm medial (Magerl) to the midpoint of lateral mass were 6.8 degrees (range, 6.3-7.4 degrees), 10.3 degrees (range, 9.8-10.8 degrees), and 14.1 degrees (range, 13.6-14.6 degrees) at C3 vertebrae; 6.8 degrees (range, 6.2-7.5 degrees), 10.7 degrees (range, 10.0-11.5 degrees), and 14.1 degrees (range, 13.4-14.8 degrees) at C4 vertebrae; 6.6 degrees (range, 6.0-7.2 degrees), 10.1 degrees (range, 9.3-10.8 degrees), and 13.5 degrees (range, 12.8-14.3 degrees) at C5 vertebrae and 7.6 degrees (range, 6.9-8.3 degrees), 10.9 degrees (range, 10.3-11.6 degrees), and 14.3 degrees (range, 13.7-15.0 degrees) at C6 vertebrae. The recommended lateral angulations for Roy-Camille, Magerl, and An are 10 degrees, 25 degrees, and 30 degrees, respectively. Statistically, there is a higher risk of vertebral foramen violation with the Roy-Camille technique at C3, C4 and C6 levels, P < 0.05. Conclusions: Magerl and An techniques have a wide margin of safety. Caution should be practised with Roy-Camille's technique at C3, C4, and C6 levels to avoid vertebral vessels injury in Asian population.

Item Type: Article
Additional Information: ISI Document Delivery No.: 850BD Times Cited: 0 Cited Reference Count: 15 Sureisen, Mariapan Saw, Lim Beng Chan, Chris Yin Wei Singh, Deepak Ajit Kwan, Mun-Keong Medknow publications Mumbai
Uncontrolled Keywords: Asians cervical spine lateral mass screw angulation spinal stabilization methods biomechanical evaluation magerl model
Subjects: R Medicine
Divisions: Faculty of Medicine
Depositing User: Ms azrahani halim
Date Deposited: 14 Oct 2014 01:47
Last Modified: 14 Oct 2014 01:47

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