Fig. 4

Cadaveric C2TOPI with PDT A and B. a Three 2.0-mm-diameter and one 2.5-mm-diameter K-wires were inserted through the guide tubes of the PDT A. b A TRS was then inserted. The upper two holes of the TARP were fixed to C1 with lateral mass screws. c A special reduction instrument was used to relocate C1 and C2 by applying force between the TARP and TRS. In the figure, (1) indicates the TARP, (2) indicates the reduction instrument, and (3) indicates the TRS. d When the inferior border of the TARP reached the midpoint of the TRS and the two entry points of C2TOPI were detected at the center of the pedicle screw holes of the TARP, the inferior two holes of the TARP were fixed to C2 with VBSs. e After removing the TRS, a K-wire was inserted into the pedicle with the assistance of the PDT B. f Two 3.5-mm-diameter screws were inserted