Instituto Henriqueta Teixeira

The changes of the interspace angle after anterior correction and
instrumentation in adolescent idiopathic scoliosis patients
Yipeng Wang*, Guixing Qiu, Bin Yu, Jianguo Zhang, Jiayi Li, Xisheng Weng,
Jianxiong Shen, Qi Fei and Qiyi Li

Abstract

Background: In idiopathic scoliosis patients, after anterior spinal fusion and instrumentation, the discs (interspace angle) between the lowest instrumented vertebra (LIV) and the next caudal vertebra became more wedged. We reviewed these patients and analyzed the changes of the angle.
Methods: By reviewing the medical records and roentgenograms of adolescent idiopathic scoliosis patients underwent anterior spinal fusion and instrumentation, Cobb angle of the curve, correction rate, coronal balance, LIV rotation, interspace angle were measured and analyzed.

Results:
There were total 30 patients included. The mean coronal Cobb angle of the main curve thoracolumbar/lumbar curve) before and after surgery were 48.9° and 11.7°, respectively, with an
average correction rate of 76.1%. The average rotation of LIV before surgery was 2.1 degree, and
was improved to 1.2 degree after surgery. The interspace angle before surgery, on convex sidebending
films, after surgery, at final follow up were 3.2°, -2.3°, 1.8° and 4.9°, respectively. The difference between the interspace angle after surgery and that preoperatively was not significant (P= 0.261), while the interspace angle at final follow-up became larger than that after surgery, and the difference was significant(P = 0.012). The interspace angle after surgery was correlated with that on convex side-bending films (r = 0.418, P = 0.022), and the interspace angle at final follow-up was correlated with that after surgery (r = 0.625, P = 0.000). There was significant correlation between the loss of the interspace angle and the loss of coronal Cobb angle of the main curve during followup
(r = 0.483, P = 0.007).

Conclusion: The interspace angle could be improved after anterior correction and
instrumentation surgery, but it became larger during follow-up. The loss of the interspace angle was
correlated with the loss of coronal Cobb angle of the main curve during follow-up.

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