Comparison of S2-Alar and traditional iliac screw pelvic fixation for pediatric neuromuscular deformity.

Abstract

Many pelvic fixation options exist for posterior spinal fusion of pediatric neuromuscular scoliosis, including standard iliac screws (SISs) or a more recently introduced S2-Alar (S2A) technique. However, little data exist comparing the clinical and radiographic outcomes of these techniques. This study aimed to dentify differences in clinical and radiographic outcomes for pediatric neuromuscular scoliosis patients treated with SIS or S2A pelvic fixation. This was a retrospective cohort study at a pediatric orthopedic clinic. Patients aged 8-19 years undergoing posterior spinal fusion to the pelvis for neuromuscular scoliosis using SIS or S2A technique, with Gross Motor Function Classification System (GMFCS) Level 4 or 5 were included. Postoperative complication rates associated with pelvic fixation method were the outcome measures. Charts and radiographs were reviewed for demographics, intra- and postoperative course, levels of instrumentation, operative correction, and implant failure (IF). Postoperative complications were classified according to the Accordion scale. We studied 50 patients (28 SIS, 22 S2A) aged 14.0±2.8 years and an average follow-up of 3.5±1.7 years. The average number of levels fused was 16.5±1.1 with an average curve correction of 48°±21° postoperatively. A significant difference in radiographic IF rates was noted between SIS and S2A groups (57% vs. 27%, p=.02). No difference was noted between groups for frequency or severity of postoperative complications, inclusive of wound infections. Subgroup analysis demonstrated equivalent IF rates when comparing the S2A group with the SIS group with cross-links. The S2A group generally demonstrated improved rates of radiographic IF compared with the SIS group, but the rates became equivalent when a cross-link was added to an SIS construct. Further, no difference in postoperative complication rates were identified between SIS and S2A groups.