Bilateral dual iliac screws in spinal deformity correction surgery.

BACKGROUND: Surgery for adult spinal deformity requires optimal patient-specific spino-pelvic-lower extremity alignment. Distal fixation in thoracolumbar spinal deformity surgery is crucial when arthrodesis to the sacrum is indicated. Although we had performed sacro-pelvic fixation with bilateral S1 and bilateral single iliac screws previously, iliac screw loosening and/or S1 screw loosening occurred frequently. So, the authors attempted to fuse spino-pelvic lesions with the dual iliac screws and S1 pedicle screws.

METHODS: Twenty-seven consecutive adult spinal deformity patients underwent thoracolumbar-pelvic correction surgery with bilateral double iliac screws between May 2014 and September 2015. Sagittal vertical axis, lumbar lordosis, pelvic tilt, sacral slope, T1 pelvic angle, and global tilt were assessed radiographically and by computed tomography both preoperatively and 24 months postoperatively. Iliac screw loosening, S1 pedicle screw loosening, and screw penetration of the ilium were evaluated 2 years postoperatively.

RESULTS: Only two patients (7.4%) at 1 year and three patients (11.1%) at 2 years presented with iliac screw loosening postoperatively. Loosening of the S1 screw occurred in three cases (11.1%) 2 years postoperatively. Displacement of the iliac screw occurred in eight cases (25%). Internal and external perforation of the ilium by the iliac screw occurred in six (22.2%) and three (11.1%) cases respectively. One reoperation was performed due to back-out of the iliac screw and rod breakage.

CONCLUSION: Bilateral dual iliac screws and an S1 pedicle screw system achieve longer stability for spinal and pelvic fusion in adult spinal deformity patients, with few severe complications.