Comparative Study of Bilateral Dual Sacral-Alar-Iliac Screws versus Bilateral Single Sacral-Alar-Iliac Screw for Adult Spine Deformities

Abstract

To evaluate the feasibility of O-arm navigation of bilateral dual sacral-alar-iliac (SAI) screws compared with conventional bilateral single SAI and S1 pedicle screws for pelvic anchors in cases of adult spinal deformity. This retrospective, comparative study included 39 patients who underwent corrective fusion using SAI screws from T10 to the pelvis. Patients were divided into 2 groups according to the number of SAI screws placed during adult spinal deformity surgery: single SAI screw (group S, 17 cases) and dual SAI screws (group D, 22 cases). The incidence of rod breakage, proximal junctional kyphosis, screw loosening, reoperation, and global alignment in each group was estimated. Postoperative patient-reported outcomes were measured using the Oswestry Disability Index, Japanese Orthopaedic Association Back Pain Evaluation Questionnaire, and visual analog scale. The incidence of SAI screw loosening was significantly lower in group D than in group S (23% vs. 65%, P= 0.011). The rod breakage incidence was 0% and 12% in groups D and S, respectively (P= 0.17). There were no significant differences in the postoperative global alignment and clinical outcomes between the 2 groups. Dual SAI screws were associated with a significantly reduced incidence of screw loosening compared with single SAI screws. The bilateral dual SAI screws technique for pelvic anchors is feasible for the treatment of patients with adult spinal deformity.