Three-dimensional quantitative segmental analysis of scoliosis corrected by the in situ contouring technique

Study Design. A three-dimensional analysis of right thoracic scoliosis before and after surgical correction was performed. Objective. To compare the orientations of the vertebrae in apical and junctional zones before and after surgery. Summary and Background Data. Three-dimensional segmental analysis considering the lateral, sagittal, and axial (vertebral and intervertebral) rotations that can define apical and junctional zones has been described previously. Modern surgical techniques have been designed to correct scoliosis three-dimensionally. Therefore, the effect of the surgery must be evaluated in three dimensions. Methods. The three-dimensional reconstruction of the spine and pelvis of 10 patients with right thoracic scoliosis was obtained by a stereoradiographic method before and after surgery. The orientations of all vertebrae were computed, and the apical and junctional zones were defined. The correction of these characteristic vertebrae obtained by the in situ contouring technique was evaluated. Results. The mean three-dimensional pattern for the 10 patients was 20degrees of vertebral axial rotation with 6degrees of intervertebral extension in the thoracic apex and 30degrees of vertebral lateral rotation with 10degrees of intervertebral axial rotation in the junctional zones of the thoracic curve. The correction obtained by in situ contouring was 52% to 79% for all these three-dimensional vertebral orientations. Conclusions. Three-dimensional reconstruction of the spine allows quantitative segmental analysis of the deformity. This could be used as a reliable tool to evaluate both the severity of the scoliosis and the effects of the surgical correction.