Preoperative CT Determination of Angles for Sacral Screw Placement

Placement of screws in the sacrum is essential for assuring rigid fixation during instrumentation of the lumbosacral spine. However, the safest approach to obtaining sacral fixation has not been clearly delineated and is complicated by significant interpatient variation in sacral morphology. In the present study, CT evaluation of the S1 pedicle and sacral ala was performed in 10 cavaders and established average angles for screw placement. Placement of screws at the averages was undertaken and verified on CT