The touched vertebra method for lower instrumented vertebra selection in adult idiopathic scoliosis using preoperative upright and supine radiographs
摘要
The aim of this study was to evaluate the use of the touched vertebra (TV) on upright and supine radiographs for determining the lower instrumented vertebra (LIV) in Adult Idiopathic Scoliosis (AdIS) patients undergoing fusion short of the sacrum, and to assess how “substantial contact” (CSVL intersecting at or medial to the pedicle) influences radiographic and clinical outcomes.
MethodsA retrospective longitudinal cohort study of AdIS patients ≥ 18 years fused proximal to the sacrum with ≥ 2-year follow-up was analyzed. Upright and supine radiographs were reviewed to identify the TV. Patients were categorized into four groups: (1) upright = supine TV used as LIV; (2A) supine TV more cephalad but upright TV used; (2B) supine TV used with substantial contact; (2C) supine TV used without substantial contact. Radiographic outcomes included C7–SVA, C7–Trunk Shift, Cobb correction, and distal disc angle. Patient-reported outcomes included SRS-22 domains and ODI.
Results66 patients (mean age 28) were included, with 70% demonstrating a cephalad shift in supine TV. Significant improvements occurred in C7–SVA (24.0 mm to 11.0 mm), C7–Trunk Shift (17.1 mm to 6.9 mm), and distal disc angle (2.6° to 0.9°) at 2 years (all p < 0.01). No distal adding-on, junctional kyphosis, or revisions occurred. Group 2C showed persistently higher distal disc angles (p < 0.01) but the strongest SRS-22 improvement. ODI improved across all groups, converging by 2 years.
ConclusionThe touched vertebra provides a reliable method for LIV selection in AdIS. Supine TV may safely guide LIV selection when substantial pedicle contact is present, often preserving an additional lumbar segment. Lack of substantial contact results in less optimal radiographic alignment but does not impair clinical outcomes.