Translaminar screw fixation of the cervical spine in Asian population: feasibility and safety consideration based on computerized tomographic measurements

Abstract

Cervical translaminar screw fixation has been shown to be safe, efficient and provides alternative for cervical fixation. However, its use in the Asian population should be considered cautiously because the cervical lamina diameter may not be adequate to accommodate the standard lamina screw size. We studied the average transverse lamina diameter of the cervical spine in the Malaysian population to evaluate the feasibility and safety of lamina screw fixation in this population. The measurements of the cervical lamina were performed on CT images. The diameters were defined as the most inner or outer diameter of the lamina, taken perpendicular to the axis of the lamina and measured in millimeters up to 0.1 mm. The mean transverse inner diameter of the lamina of C2, C3, C4, C5, C6 and C7 was 3.4, 2.0, 1.7, 1.9, 2.3 and 3.4 mm, respectively. The lamina of C2 and C7 has the largest transverse inner diameter and the lamina of C4 the smallest. The mean transverse outer diameter of the lamina of C2, C3, C4, C5, C6 and C7 was 5.6, 3.5, 3.1, 3.1, 3.9 and 5.8 mm, respectively. The lamina of C7 has the largest transverse outer diameter and the lamina of C4 and C5 the smallest. Translaminar fixation using a 3.5 screw should be attempted with caution in Asian population. Pre-operative CT scan evaluation is mandatory before translaminar screw fixation is attempted.