Importance of Distal Fusion Level in Major Thoracolumbar and Lumbar Adolescent Idiopathic Scoliosis Treated by Rod Derotation and Direct Vertebral Rotation Following Pedicle Screw Instrumentation

STUDY DESIGN.A retrospective comparative study. OBJECTIVE.The aim of this study was to analyze the exact distal fusion level in the treatment of major thoracolumbar and lumbar (TL/L) adolescent idiopathic scoliosis (AIS) using rod derotation (RD) and direct vertebral rotation (DVR) following pedicle screw instrumentation (PSI). SUMMARY OF BACKGROUND DATA.Proper determination of distal fusion level is a very important factor in deformity correction and preservation of motion segments in the treatment of major TL/L AIS. METHODS.AIS patients with major TL/L curves (n = 64) treated by PSI with RD and DVR methods with a minimum 2-year follow-up were divided into AL3 (flexible) and BL3 (rigid) according to the flexibility and rotation by preoperative bending radiographs. RESULTS.There was no significant difference in TL/L (major) curve between the AL3 and BL3 groups postoperatively (P = 0.933) and at the last follow-up (P = 0.144). In addition, there was no significant difference in thoracic (minor) and compensatory (caudal) curve postoperatively (thoracic curveP = 0.828, compensatory curveP = 0.976); however, there was a significant difference in compensatory (caudal) curve at the last follow-up (P = 0.041). The overall prevalence of unsatisfactory results was 28.1% (18/64 patients), and the prevalence was 15.2% (7/46) in the AL3 group and 61.1% (11/18) in the BL3 group, which was significantly different (P