Abstract
Introduction: Compared with open instrumented anterior spinal fusion for adolescent idiopathic scoliosis (AIS), endoscopic surgery offers clinical benefits that include reduced pulmonary morbidity and improved cosmesis. However, quantitative data on the radiological improvement of vertebral rotation using this method is limited. The aim of this study was to measure pre-operative and postoperative axial vertebral rotational deformity at the curve apex in endoscopic anterior instrumented scoliosis surgery patients using computed tomography (CT), and assess the relevance of these findings to clinically measured chest wall rib hump deformity correction.
Methods: Between November 2002 and August 2005, twenty patients with right-sided thoracic curves underwent endoscopic single-rod anterior instrumented fusion. Pre and post surgical axial vertebral rotation was measured at the curve apex on preoperative and two-year postoperative CT using Aaro and Dahlborn’s method. Rib hump deformity correction was retrieved from a surgical database and correlated to the CT findings. Linear regression was used to investigate the correlation between apical vertebral rotation measured on CT and rib hump measured using a scoliometer.
Results: The mean angle of correction achieved in axial vertebral body derotation at the apical vertebra as measured by CT was 7.9°. This equated to a 43% improvement (range 20–90%). The preoperative and postoperative clinical measurements i.e. rib hump deformity correction, correlated significantly with CT measurements using regression analysis (p=0.03) and the mean improvement in rib hump deformity was 55%.
Conclusion: To our knowledge, this is the first quantitative CT study to confirm that endoscopic anterior instrumented fusion for AIS substantially improves the axial vertebral body rotational deformity at the apex of the curve. The margin of correction of 43% compares favourably historically published figures for all-hook-rod constructs in posterior spinal fusion. In addition, the CT measurements obtained significantly correlated to the clinical outcome of rib hump deformity correction.
The abstracts were prepared by Mr Matt Costa and Mr Ben Ollivere. Correspondence should be addressed to Mr Costa at Clinical Sciences Research Institute, University of Warwick, Clifford Bridge Road, Coventry CV2 2DX, UK.
