[CD instrumentation in pelvic tilt]

Our realistic definition of pelvic obliquity is: any fixed malalignment existing between the spinal and pelvic structure in the frontal, sagittal and horizontal plane. The pelvic unit--with rare exceptions--must be considered one unique vertebra, an intercalary bone between the trunk and lower limbs. Like a structural vertebra in a scoliotic spine, the pelvic unit can be distorted in structure. The etiologies of pelvic obliquity can be divided into three major levels: below, inside and above the pelvis. Preoperative surgical planning must consider the position of the pelvis in the three dimensions. The technical options of pelvic fixation are described: alar staples, sacral screws, the cannulated iliosacral screw and finally the Galveston technique. The surgical technique is described. The results are presented in about 80 cases of CD instrumentation with pelvic fixation. For preoperative hyperlordosis a mean correction of 40 degree was achieved and for preoperative hyperkyphosis a mean correction of 66 degree.