Evaluation of vertical traction radiography for predicting the outcome of moderate to severe rigid scoliosis correction

Objective: To determine the efficacy of imaging patients in a state of traction (“traction imaging”) for selection of upper and lower vertebrae to undergo instrumentation (UIV and LIV, respectively) to correct moderate to severe, rigid scoliosis. Methods: Twenty‐seven patients aged 11–21 years (average, 15.5 years) who had been treated at our institution for scoliosis of the thoracic spine between 2004 and 2008 were retrospectively analyzed. All patients were treated with the third multiple hook‐screw and rod instrumentation system. Standardized radiographic measurements (anteroposterior, sagittal, bending, fulcrum, traction) were taken and Cobb's angles, apical vertebra translation (AVT), and traction‐stable vertebrae determined. Results: All patients were followed for 6–36 months (average, 14.7 months). The Cobb's angles under preoperative vertical traction correlated positively with those measured postoperatively in standing anteroposterior film (P < 0.01). Preoperative AVT under vertical traction was significantly different from that measured postoperatively in standing anteroposterior film (P < 0.01). The traction radiography‐determined UIV slant angles were significantly different from those preoperatively without traction and the postoperative values, whereas traction radiography‐determined LIV values were not significantly different from those found preoperatively without traction (P > 0.05). Conclusions: Traction radiographic imaging is an effective, feasible preoperative assessment for determining which vertebrae are stable, designing the surgical strategy and choosing the UIV and LIV for correcting moderate to severe, rigid scoliosis.