P0831 - Has the Evolution of Pelvic Fixation in Neuromuscular Scoliosis Improved Outcomes?

Background/Purpose
Spinal fusion for treatment of neuromuscular scoliosis often involves fusion to the pelvis. Pelvic fixation techniques for neuromuscular scoliosis have evolved from rod-based to mostly screw-based fixation. The Marchesi technique is a hybrid method described for Duchenne's-associated scoliosis involving the placement of S1 pedicle screws combined with the insertion of L shaped rods into the Ilium. We present a retrospective series of neuromuscular scoliosis patients to evaluate the efficacy of 3 pelvic fixation methods in obtaining and maintaining pelvic obliquity correction.

Methods
We performed a single center retrospective review of pediatric neuromuscular scoliosis patients undergoing posterior spinal fusion to the pelvis from 2012 to 2017. Over time, surgeons transitioned from primarily using the Marchesi technique to Iliac screws to S2 Alar-Iliac (S2AI) screws. We divided patients into 3 groups based on pelvic fixation technique and compared radiographic data.

Results
We identified 56 patients: 18 Marchesi, 29 Iliac, and 9 S2SAI, the majority (52%) of which had cerebral palsy. Mean follow-up was 26 months. 36 patients (64%) had minimum 2 year follow-up. There were no significant differences in mean preoperative pelvic obliquity and mean preoperative major Cobb angle among the three groups. Initial postoperative pelvic obliquity correction was not significantly different among the groups: Marchesi (64%), Iliac (51%), S2AI (52%)(p=0.448), as was initial Cobb angle percent correction: Marchesi (52%), Iliac (53%), S2AI (53%)(p=0.979). In all 3 groups, pelvic obliquity correction was maintained at 1 year, and at 2 years in the Marchesi and Iliac groups. At 1 year, major Cobb correction was maintained in the Marchesi and S2AI groups but the Iliac group had a loss of correction at 1 (9.4% loss, p=0.016) and 2 years (10.3% loss, p=0.027).

Conclusion
The Marchesi method is equivalent to Iliac screws and S2AI screws at obtaining and maintaining pelvic obliquity correction. As costs and frequency of imaging associated with newer pelvic fixation techniques have increased, there has not been a concurrent improvement in obtaining and maintaining pelvic obliquity correction.