Computed Tomographic Measurement of Screw Fixation in Atlas via Posterior Arch and Lateral Mass

Objective:Normal anatomic properties of atlas were measured in radiology to evaluate the feasibility of screw fixation in atlas via posterior arch and lateral mass.Methods:Fifty dry atlas of Chinese origin were measured with computed tomography scanning aiming at the path of screw fixation.Results:The point of screw penetration was 18～20mm lateral to the midpoint of posterior tubercle and 2mm superior to the inferior edge of posterior arch.The screw directioin chosen was parallel with sagittal plane and about 5° cephalad to the transverse plane.Conclusion:Atlas has the condition of screw fixation via posterior arch and lateral mass.