Pelvic Obliquity Correction in Distraction-Based Growth Friendly Implants

Abstract Design Multicenter retrospective review. Objective To evaluate radiographic outcomes and complication rates of patients treated with distraction based implants and pelvic fixation with either screws (sacral-alar-iliac [SAI] screws or iliac screws) or hooks (S hook iliac fixation). Summary of Background Data Multiple options exist for pelvic fixation in distraction-based growing rod systems; however, limited comparative data are available. Methods Early-onset scoliosis (EOS) patients of all diagnoses with distraction-based implants that had pelvic fixation from 2000 to 2013 were reviewed from two EOS multicenter databases. Patients were divided into two groups by type of pelvic fixation: (1) screw group (SAI screws or iliac screws) or (2) S hooks. Exclusion criteria were as follows: index instrumentation ≥10 years old and follow up Results Pelvic fixation in the 153 patients was as follows: screw group = 42 and S hook group = 111. When comparing patients with >20° of initial pelvic obliquity, the screw group had significantly more correction; mean 26° ± 13° for the screw group versus mean 17° ± 7° in the S hook group (p = .039). There was no significant difference in change in T1–S1 length (40 vs. 39 mm, p = .89) or correction of Cobb angle (30° vs. 24°, p = .24). The total complication rate for the screw group was 14% (6/42) versus 25% (28/111) in the S hook group, though this did not achieve significance (p = .25). The most common complications were device migration (13), implant failure (8), and implant prominence (4) for S hooks and implant failure (3), implant prominence (2), and device migration (1) for the screw group. Conclusion In distraction-based growth-friendly constructs, pelvic fixation with screws achieved better correction of pelvic obliquity than S hooks. Complications were almost twice as common with S hooks than screws, though this did not reach statistical significance.