Analysis of the intervertebral angle following anterior spinal fusion of thoracolumbar/lumbar adolescent idiopathic scoliosis

Abstract

To investigate the changes of intervertebral angle and relative factors after anterior correction and instrumentation in thoracolumbar/lumbar (PUMCIb, Ic) adolescent idiopathic scoliosis patients. The clinical data, including roentgenograms of 18 PUMCIb, Ic adolescent idiopathic scoliosis patients, including 13 patients of Ib type, 2 males and 11 females, and 5 patients of Ic type, all females, 1 who underwent anterior correction and instrumentation, were collected. The Cobb angle of the coronal curve, correction rate, trunk shift, apical vertebra translation, intervertebral angle, and so on, were measured and analyzed. The average coronal Cobb angle were 44.72 +/- 10.20 degrees and 6.51 +/- 7.54 degrees before and after surgery respectively, with an average correction rate of 81.2%. The average preoperative intervertebral angle was 3.57 +/- 3.48 degrees , and 2.02 +/- 4.37 degrees and 5.26 +/- 5.92 degrees 1 week and 1 year postoperatively. The changes were of significance in the intervertebral angle between preoperative and 1-week postoperative values (P = 0.035), and between the 1-week and 1-year postoperative values (P = 0.029). All 18 patients were grouped to Group A (n = 12) and Group B (n = 6) according to the fusion levels. In Group A the preoperative intervertebral angle was 4.07 +/- 3.98 degrees ; the intervertebral angle 1-week and 1-year postoperatively were 1.23 +/- 3.46 degrees and 4.01 +/- 4.72 degrees respectively. In Group B, the preoperative intervertebral angle was 1.97 +/- 1.76 degrees ; and the intervertebral angle 1-week, and 1-year postoperatively were 4.21 +/- 4.47 degrees and 7.12 +/- 5.09 degrees respectively. There were significant changes between the two groups about the intervertebral angle in different stages (P < 0.05). The analysis and comparison of the other variables between these two groups revealed significant changes in the preoperative apical vertebra translocation, number of fused segments and T12 approximately LI lordosis (all P < 0.05). The intervertebral angle is much improved after anterior correction and instrumentation surgery, but it increases gradually during the follow-up. The fusion levels, the preoperative apical vertebra translocation, T12 approximately LIV lordosis, and the preoperative intervertebral angle may be correlated with the changes of postoperative intervertebral angle. In the current opinion, it's unworthy of preventing postoperative intervertebral angle changes by decreasing the correction rate or sacrificing the motion segment.