Suitability of the Subaxial Cervical Laminae for Laminar Screws in the Pediatric Population: A Radiologic Anatomical Study

Abstract

Introduction: The laminar screw method was popularized during recent years. Since no data exist in the literature on its suitability for subaxial levels in the pediatric population, a radiologic anatomical study was planned to evaluate the suitability of the laminae for laminar screws in children. Methods: The laminar thicknesses from C3 to C7 were measured in axial sections in 120 pediatric patients using computed tomography. The patients were divided into 3 age-groups: ages 4–6, 7–9, and 10–12. Each age-group consisted of 20 boys and 20 girls. The suitability of the laminae was evaluated for 3.5-mm-thick commercially available screws and also for the 3-mm screws that could be produced in the future. If the height of the base of the spinous process is ≥ 9 mm, the segment was accepted as suitable for the bilateral screw, and ≥5 mm is for the unilateral screw. Additionally, laminar thickness and length were measured for possible short screws longer than 15 mm in the laminae that were distally thin but proximally thick. Results: The C4 and C5 levels had the thinnest (2.77 ± 0.6 mm and 2.81 ± 0.6 mm, respectively) and C7 had the thickest laminae (4.66 ± 0.6 mm) in all age-groups. No significant differences were found between boys and girls and right and left laminae. According to the age-groups, an increase in laminar thickness was possible by growing, but only C7 laminae thickness was statistically different between 10–12 and 4–6 age-groups (p < 0.001). The last rate of the suitability was 9.1% for the 3.5-mm-thick screws and 13.75% for the 3-mm-thick screws after deletion of the bilateral insertion due to the short base of the spinous process and adding the possible short screws in the distally thin but proximally thick laminae. The rates increased with age, but the only statistically significant difference was found between 4–6- and 10–12-year-old age-groups (p < 0.001). Conclusions: Laminar screws may be suitable for some levels of C7, C6, and C3 even in the young pediatric population. The use of thinner screws (3 mm) may increase the suitability rate. Therefore, laminar screw choice may be considered as a salvage method in pediatric patients, and all laminae may be evaluated individually for suitability. This study did not evaluate the safety and efficacy of the method in children, and these issues must be studied further.