Fig. 4From: Biomechanical study of C1 posterior arch crossing screw and C2 lamina screw fixations for atlantoaxial joint instabilityStress distribution nephograms of implants for the three fixation models when tested in a flexion, b extension, c lateral bending, and d axial rotation after applying a 40-N vertical downward force and a 1.5-N m momentBack to article page