An approach of percutaneous sacroiliac screw fixation guided by CT

Objective:To investigate the surgical location and approach for percutaneous sacroiliac screw fixation with multi-slice spiral CT.Methods:Bilateral sacroiliac joints of sixty healthy adult volunteers were scanned by multi-slice spiral CT.The angles between middle point of S1,S2 pedicle axis and median sagittal plane,as well as the width and height of S1,S2 pedicles,were measured on the CT films reconstruted on computer.The inserting point,ideal angle and the length of the screw within the S1,S2 pedicles were statistically analyzed and determined basing on the data presented.Results:The S1 inserting point was about(91.03±10.62) mm away from the median line,(41.16±8.80)mm from the homolateral posterior part of iliac crest in sacral transverse section,and(11.29 ±5.87)mm from the cranial sacral transverse section which passed through posterosuperior iliac spine.The angle between the screw and the horizontal plane of S1 was(30.76±5.34) °,and the sagittal plane(48.76±9.43) °.The ideal length of the screw for S1 was(84.59±5.29) mm.The S2 inserting point was(127.82±15.63)mm away from the median line,(59.34±9.03) mm from the homolateral posterior part of iliac crest in sacral transverse section,and(15.35±5.50)mm from the caudal sacral transverse section.The angle between the screw and the horizontal plane of S2 was(30.76±5.34) °,and the sagittal plane(61.15±8.38) °.The ideal length of screw for S2 was(64.04±6.65)mm.There were no statistically significant differences of sacral slant angle between dorsal and prone positions(P0.05).Conclusions:The data gained from this study reveal the approach that can quickly,accurately and harmlessly guide percutaneous sacroiliac screw fixation in both dorsal and prone position for clinical application.