The sagittal alignment of the cervical spine in adolescent idiopathic scoliosis.

To assess the sagittal orientation of the cervical and thoracolumbar spine, 38 adolescents with idiopathic scoliosis were studied. The C7 plumb line and Cobb angles from C2-6, T1-12, and L1-S1 were measured on preoperative films. Lateral radiographs with > 1-year follow-up after surgical correction were available for the same measurements in 28 patients. The preoperative curve from C2-6 was 6 +/- 11 degrees of kyphosis. There was a significant correlation between the loss of thoracic kyphosis and the development of cervical kyphosis for the entire group preoperatively (p = 0.009). Postoperatively, cervical kyphosis increased to 11 +/- 9 degrees at 1-year follow-up (p = 0.05). There was no progression of cervical kyphosis in patients with "thoracic hypokyphosis" (kyphosis < 20 degrees). Cervical kyphosis increased in patients with "normal" thoracic kyphosis (20-40 degrees) and in patients with hyperkyphosis (kyphosis > 40 degrees) after surgery, despite preservation of thoracolumbar sagittal contour. There were no significant differences between the sagittal contour of patients treated with Cotrel-Dubousset or Harrington instrumentation.