The Cotrel-Dubousset (CD) scoliosis surgery was simulated for 10 patients with idiopathic scoliosis using a 3D finite element model (FEM) of the patient's entire spine. The geometry of the FEM was extracted from a 3D stereo-radiographic reconstruction, and mechanical properties were personalized using lateral bending films. Finally, each step of the CD correction was simulated and results were compared with the post-operative 3D stereo-radiographic reconstruction. The whole procedure was applied for 10 patients, and quantitative comparison was performed between post-operative spine configuration and predicted configuration. For all patients, mean differences between post-operative measurements and predicted values of vertebral rotation were estimated at 5 degrees (max: 13 degrees) and those for linear position at 6 mm (max: 12 mm). Furthermore, intermediate steps of surgery simulation were consistent with the literature. Then, for one scoliotic patient, the model was used to investigate three alternative surgical strategies. It was found that a one-level change in the instrumentation limit may have a significant effect on spine alignment and correction.