FLEXIBILITY IN THE SCOLIOTIC SPINE - 3-DIMENSIONAL ANALYSIS

The purpose of this study was to measure the three-dimensional geometr y of scoliosis by using biplane radiographic photogrammetry and to eva luate the flexibility of the deformed spine. Thirty-one patients with idiopathic scoliosis underwent analysis. Then was a significant correl ation between the degree of the scoliotic angle in the frontal plane, kyphotic angle in the sagittal plane, and the rotational angle of the apical vertebra. Hypokyphosis was associated with a scoliotic angle >4 0 degrees in the frontal plane. Similarly, hypokyphosis was related to increased rotation of the apical vertebra (p < 0.01). Although the sc oliotic angle was decreased by traction in all cases, axial rotation w as less corrected in those patients with scoliotic angle >40 degrees. This suggests that the rotational stiffness at the apex is related to the degree of the rotational angle of the apical vertebra and to the d egree of the frontal curve.