May bending radiographs be replaced by recumbent CT scans in patients with adolescent idiopathic scoliosis?

Abstract

Purpose There is no data that show if it is possible to determine if a curve is structural or non-structural or to assess flexibility of an adolescent idiopathic scoliosis (AIS) by recumbent images like a CT scan (CTS) instead of bending radiographs (BR). We investigated if the results of BR may be compared to those of CTS. Methods We retrospectively analyzed prospectively collected data of patients with AIS in whom a selective spinal fusion was performed and in whom a CTS, BR, and full spine x-rays were made preoperatively. We measured the Cobb angles of the main and the minor curve in full spine x-ray, BR, and CTS. Results After applying inclusion and exclusion criteria, 39 patients were included. We found a strong correlation (r = 0.806, p < 0.01) between the Cobb angle of the main curve in BR and the Cobb angle of the main curve in the CTS and between the Cobb angle of the minor curve in BR and the Cobb angle of the minor curve in the CTS (r = 0.601, p < 0.01). All patients with a minor curve of less than 25 degrees in the BR had a Cobb angle of less than 35 degrees in the CTS. Conclusion Spinal curves showed a significant correlation between bending radiographs and recumbent images (CTS). In our group of patients, a Cobb angle of the minor curve of less than 35 degrees in the CTS indicated that this minor curve was non-structural.

Correlation between supine flexibility and postoperative correction in adolescent idiopathic scoliosis

“…The above technology was called the digitally reconstructed radiograph technique, which is a mature technique that has been used successfully in spine measurement [ 21 – 23 , 25 ]. Prost et al showed that Cobb angles measured in supine images reconstructed from CT images of the spine could render similar information on flexibility and type of curves as bending radiographs [ 26 ]. Because spinal flexibility is often used to predict surgical correction rates, we conducted this study to analyse whether supine flexibility could predict the extent of postoperative correction in AIS patients.…”

“…Cheh et al and Ramchandran et al showed that a single preoperative supine radiograph was highly predictive of side-bending radiographs and could be used as an adjunct to predict curve flexibility [ 15 , 16 ]. Prost et al compared Cobb angles of the main and minor curves in bending radiographs and supine images reconstructed from CT images and observed a significant correlation between bending radiographs and supine images [ 26 ]. Our results showed that supine flexibility can be used to predict the extent of postoperative correction in AIS patients.…”