Comparison of Apical Axial Derotation between Adolescent Idiopathic and Neuromuscular Scoliosis with Pedicle Screw Instrumentation

STUDY DESIGN: A retrospective study. PURPOSE: To compare outcomes of apical derotation with pedicle screws in idiopathic and neuromuscular scoliosis (NMS). OVERVIEW OF LITERATURE: No information about apical derotation in NMS with pedicle screws is available. METHODS: We performed deformity correcting surgery using pedicle screw constructs on 12 adolescent idiopathic scoliosis (AIS) patients (mean age 14.1 years) and 16 NMS patients (mean age 16.5 years). Preoperative, postoperative, and final follow-up radiographs were analyzed for Cobb's angle and pelvic obliquity, while apical rotation was measured on CT scans using the Aaro-Dahlborn method. RESULTS: For AIS, the mean preoperative Cobb's angle, pelvic obliquity, and apical rotation values were 57.3°, 2.8°, and 20.4°, respectively, and postoperatively they were 16.8°, 1.1° and 14.7°, respectively, showing significant correction. For NMS, the mean preoperative Cobb's angle, pelvic obliquity, and apical rotation values were 75.6°, 13.7°, and 42.9°, respectively, and postoperatively they were 27.1°, 5.8°, and 34.1°, respectively, also showing significant correction. There were no significant differences between AIS and NMS patients Cobb's angle p=0.306, pelvic obliquity p=0.887 and apical derotation p=0.113°. There were no differences in curve severity in the three groups (AIS, NMS >80°and NMS <80°); or the correction of apical rotation (p=0.25), although less correction was achieved in the Cobb's angle in the >80 NMS group (p=0.04). CONCLUSIONS: Apical axial derotation can be achieved with posterior only pedicle screw fixation in NMS without anterior release, with comparable results in idiopathic scoliosis.