Abstract: ［Abstract］〓Objective〖HTSS〗〓To explore a more accurate and simple method which measures the screwing trajectory′s parameters of the sacroiliac screw by the computed tomography, so as to provide the related theoretical basis for the safty of the sacroiliac screw path during the iliosacral screw fixation for iliosacral joint disruption.
〖HTH〗〖WTHZ〗Methods〖HTSS〗〓Twenty pelvis specimens(40 sacroiliac joint) of native adults were studied. The iliosacral screw fixation had been taken on all pelvis specimens, and then the CT scans were done. The screwing trajectory′s parameters of the sacroiliac screw were measured, including the distances from the inserting point to various structures of pelvis, such as the inserting direction of the guidewire, the length from the inserting point and the safety angle.
〖HTH〗〖WTHZ〗Results〖HTSS〗〓The diameter of the deal screw was(86.927±1.813) mm, and the maximum length was(20.541±1.412) mm. The diatance from the entry point to the crista glutea, the greater sciatic notch, the posterior superior iliac spinethe, posterior inferior iliac spine, the contrary anterior cortex of vertebral body, the central part of vertebral body, and the most narrow part of pedicle of vertebral arch were(20.121±2.986) mm, (40.424±2.018) mm, (36.987±1.596) mm, (37.412±1.328) mm, (86.967±4.210) mm, (71.615±3.932) mm, and(52.428±2.981) mm, respectively. The angles of the ideal screw was(25.065±1.121) ° to coronal plane, and(20.019±1.524) ° to the horizontal plane. The angles between guide wire and iliac surface in axial CT scans and in coronal CT scans were(90.621±3.672) ° and (90.476±2.993) °. The safe angle of the screw trajectory was(24.514±1.672) °to the axial plane, and (19.623±1.617) ° to the coronal plane.
〖HTH〗〖WTHZ〗Conclusion〖HTSS〗〓The techinque of the sacroiliac screw fixation for iliosacral joint disruption has the advantage of good results, mall trauma, and little cost, which was a simple and accurate method. The measurement of the screwing trajectory′s parameters of the sacroiliac screw through the computed tomography before the operation of internal fixtion, could provide a safe, simple and accurate method for the percutaneous placement of sacroiliac screw fixation for iliosacral joint disruption.

Key words: sacroiliac joint, wounds and injuries, helical computed tomography