Dynamic measurement of axial vertebral rotation and rotational flexibility in scoliosis by flouroscopic method

The Pedriolle torsion meter is an established method of vertebral rotation assessment in scoliosis. However, the assessment of scoliosis by this method is static and indirect. The objective of this study is to compare the accuracy of a direct method of assessing scoliosis rotation by fluoroscopy compared to the Pedriolle torsion meter. Secondly, to determine that vertebral body rotation changes with supine posture compared to erect position. Eight volunteers with idiopathic scoliosis were assessed for the apical vertebral rotation with this method and the Pedriolle torsion meter. These patients were also assessed in the supine and erect position with the fluoroscopic method to determine if the apical vertebral rotation would change with posture. The mean Cobb angle of the curves was 62.8 degrees (range 45 degrees to 86 degrees). The mean apical vertebral rotation in a standing position was assessed to be 21.5 degrees by Pedriolle torsion meter and 29 degrees by the fluoroscopic method. This difference was not statistically significant by the student t-test. In most patient, the rotation of vertebrae improved by a varying degree ranging from none to 24 degrees in the supine position. In conclusion, the fluoroscopic method is an alternate mean of measuring vertebrae rotation in idiopathic scoliosis, with comparable accuracy to the Pedriolle torsion meter method. The amount of vertebral rotation changes with posture of the patient.