3D visualization contribution to the spine surgery

Merloz P., Tonetti J., Milaire M., Kerschbaumer G., Ruatti S., Dao-Lena S.

Abstract


The basic principle of systems for computer-assisted surgery (CAS – «Computer Assisted Surgery») consists in the possibility of three-dimensional determining the position of surgical instruments both in the operative field, and in preoperative or operating images. The first CAS systems for the spine were introduced in the late 90s in order to optimize the placement of transpedicle screws. Two technologioes are used: navigation based on computer tomograph (CT) images and fluoronavigation which is an alternative system. New intraoperative navigation technologies became to be used in the spine surgery at the end of the first decade of the XXI century. 3D electron-optical converters are used for three-dimensional visualization like CT. In view of individual anatomical parameters of vertebrae this thechnology allows to choose the optimal intrapedicle trajectory properly both at the stage of preoperative planning and in the process of surgery. It involves digital processing of CT-examination data, and construction of trajectories for implantation thereby allowing to determine the correct entry point and the vector of the screw being implanted intraoperatively. Such mini-robots as «Bone Mounted Robot» (a robot with bone fixation) are more assistants during auxiliary instrumentation placement than real robots. They are fixed directly on the vertebral spinous process, and modeling the trajectory of implantation is carried out on the base of CT-model. Navigation provides the accuracy of high degree for choosing projection and vectors of transpedicle screw implantation comparing with traditional surgical methods. The advantage of navigation systems becomes evident when transpedicle implants are used for correction of the spine large deformities or through locking the spine segments. Meta-analysis demonstrates that among often used navigation systems CT-based navigators provide somewhat greater accuracy than fluoronavigation 2D systems. However, the accuracy level of these two systems is a little lower than that of the new systems of fluoronavigation 3D. As for the degree of exposure (radiation), these methods can be arranged in descending order as follows: traditional fluoroscopy, fluoronavigation 2D, CT-based navigation, and fluoronavigation 3D. Moreover, the surgery duration when using fluoronavigation 3D system is comparable with traditional surgery.

Keywords


computer-assisted surgery of the spine; navigation in surgery; orthopedic surgery with computer assistance; spine surgery; computerassisted surgery

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