The Former Path Anatomy Of The Atlantoaxial Facet Screw Fixation

Objective.To provide anatomic data for anterior transarticular atlantoaxial screw fixation. Methods. Direct measurements using an electronic digital caliper and a goniometer were taken from50 pairs of dried human C1 and C2 vertebrae. The parameters related to anterior transarticular atlantoaxial screw fixation between the C1 lateral mass and the C2 vertebral body were measured. Results. The anterior transarticular C1-C2 screw insertion point lies in the lateral 4 mm of the C2 vertebral body inferior midpoint. In the anterior transarticular atlantoaxial screw placement, lateral angulation of the screw placement relative to sagittal plane ranged from11.36°±1.51° to 29.34°±1.96°. The posterior angulation of the screw placement relative to the coronal plane ranged from 13.90°±2.99° to 28.78°±4.27°. The length of the medial screw path ranged from 23.14±3.06 mm(male)/21.93±1.28 mm(woman) to 41.05±3.28 mm(male)/ 39.14±2.15 mm(woman). Conclusions. An anterior transarticular atlantoaxial screw 25 mm -35 mm long can be inserted with a lateral angulation of 15°-25° relative to the sagittal plane and a posterior angulation of 15-25° relative to the coronal plane.