Estimated kyphosis and lordosis changes at follow-up in patients with idiopathic scoliosis.

Abstract

The objective of this study was to verify the accuracy of surface measurements to estimate the magnitude of sagittal curvature changes at follow-up. Ninety-seven patients with idiopathic scoliosis were evaluated at two different visits (interval: 15.7 months). Kyphosis and lordosis were measured on the lateral radiograph. Surface measurements rely on localization of spinous process landmarks using a video-based system. Multiple regression analyses were performed to estimate the sagittal curvatures on the second visit. The regression was significant for both kyphosis and lordosis. The mean absolute difference between the estimate and the radiologic measurement was 3.3 degrees for kyphosis and 3.2 degrees for lordosis. The difference between the estimated change and the observed change between visits showed mean absolute differences of 3.4 degrees and 2.7 degrees, respectively. The proposed strategy could be used during follow-up to reduce patient irradiation without loss of sagittal information.