[Computer assisted pedicle screw installation. Our first 3 cases].

Pedicle screw fixation is sometimes a difficult surgical procedure relying on anatomical landmarks that may be modified by vertebral asymmetries. A significant incidence of cortex penetration and neuro-vascular complications have been documented. Our study evaluates the usefulness of a computer-aided pedicle installation system and analyses the results for our first 3 clinical cases. The system was used for 3 adolescent patients with idiopathic scoliosis undergoing surgical correction and instrumentation. In all cases, selected vertebrae were reconstructed in 3D pre-operatively. At surgery, the surgeon compared the computer-suggested pedicle location to his own opinion. After pedicular hole drilling was done in the usual fashion, hole positions were confirmed per-operatively with the computer software. Post-operatively, software hole positions were measured and compared to the actual screw axis using CT-Scans. Three dimensional models produced for all selected vertebrae allowed visualization of asymmetrical deformations of the scoliotic vertebrae. All pedicles were correctly detected by the software. Pedicular hole measurements agreed with the actual screws positions on post-op CT-Scans. The computerized surgical assistant can be of value in a clinical situation. These initial results warrant a large scale trial in order to establish accuracy and reliability.