SURGICAL-CORRECTION OF VERTEBRAL AXIAL ROTATION IN ADOLESCENT IDIOPATHIC SCOLIOSIS - PREDICTION BY LATERAL BENDING FILMS

The pre- and postoperative radiographs of 45 patients with scoliosis w ere compared with the preoperative lateral bending radiographs. The pu rpose was to compare correction of Cobb angle and apical vertebral rot ation between preoperative lateral bending and operative spinal instru mentation. Twenty-one patients had Harrington instrumentation, 12 had Drummond/Wisconsin spinous process segmental instrumentation, and 12 h ad Texas Scottish Rite Hospital instrumentation From the pre- and post operative radiographs, each vertebra was marked and digitized for comp uterized measurements of Cobb angle and apical vertebral rotation. Cor rection of Cobb angle on the lateral bending radiograph averaged 22 +/ - 10 degrees, which was less than that achieved at operation (Harringt on 23 +/- 7 degrees, Drummond/Wisconsin 29 +/- 10 degrees, and Texas S cottish Rite Hospital 36 +/- 6 degrees; p < 0.01, paired t test). In c ontrast, correction of apical vertebral rotation on the lateral bendin g radiograph averaged 4 +/- 8 degrees, which was not significantly dif ferent from that achieved at operation (Harrington 1 +/- 8 degrees, Dr ummond/Wisconsin 1 +/- 7 degrees, and Texas Scottish Rite Hospital 4 /- 8 degrees). Spinal instrumentation markedly corrected the Cobb angl e but minimally corrected apical vertebral rotation. In contrast, preo perative lateral bending produced a similar proportional correction of both.