Fig. 3.

a A stab incision was made at the entry point B which was determined according to the preoperative measurements. Then a guide tube containing a sharp tipped K-wire was placed through the incision aiming the pedicle of C2; b postoperative skin incision after percutaneous C2 transpedicular screw fixation; c the screw entry point on the open-mouth view; d the screw entry point on the lateral radiograph