RESUMO
Objective To evaluate the accuracy and safety of screw placement position through second sacral alar -iliac(S2AI)with in-teroperative cone beam CT(CBCT)scan.Methods Collected 22 patients who underwent second sacral alar-iliac screw implant surgery in our hospital from June 2015 to June 2017.All the patients had intraoperative CBCT scan and conventional CT scan after operation.Regard the postoperative CT scan imageing as gold standard to assess the accuracy and safety of S 2AI screws position.The S2AI tract parameters were measured with intraoperative CBCT images and postoperative CT images respectively.Results There was no significant difference between the S2AI tract parameters which were measured with intraoperative CBCT images and postoperative CT images(P>0.05).Conclusion The intraoperative CBCT scan could accurately evaluate the position of S 2AI screws,as well as clarify the damage of the inner and outer plate of the iliac bone in the process of fixation.Compared with postoperative conventional CT scan,the intraoperative CBCT scan can potentially re-duce the reoperation rate.