Change of Deformity due to Position and Anesthesia in Adolescent Idiopathic Scoliosis

Abstract

Purpose: To determine changes in the end vertebra and neutral vertebra as well as in the magnitudes of coronal and rotational deformities according to position and anesthesia in patients with adolescent idiopathic scoliosis. Materials and Methods: Sixty-two structural curves in 31 patients were evaluated using standing, supine, side bending, post-anesthesia, and postoperative anteroposterior plain radiographs. Cobb angles and rotation angles by perdriolle torsionmeter were measured, and the end vertebra and neutral vertebra were identified in each radiograph. Results: Coronal cobb angles decreased significantly with correction rates of 25.0%, 31.7%, 59.5%, and 74.0%, and rotational deformities decreased with correction ratesof 6.1%, 24.5%, 6.2%, and 25.7% by supine position, anesthesia, side bending and surgery, respectively.The end vertebrae changed in 18 patients (58.1%) in both supine and post-anesthesia radiographs, and the neutral vertebrae changed in 10 patients (32.3%) in supine radiographs and in 20 patients (64.5%) in post-anesthesia radiographs. Conclusion: Coronal deformities are significantly corrected by supine position and anesthesia. Anesthesia significantly corrects axial rotation, but more correction cannot be achieved by rod derotation. The end vertebra and neutral vertebra have a tendency to vary by position and anesthesia, which gives rise to confusion in the determination of fusion level.