Pitfalls of 2D and 3D navigation in spine surgery

Both 2D and 3D computer navigation systems have become important tools in the operative treatment of spinal injuries. 2D navigation utilizes a modality-based dataset from the C-arm, while 3D-navigation is based on a non-modality-based dataset from conventional computed tomography or on 3D modality-based ascertainment of data by an isocentric C-arm equipped with an appropriate computer. Experimental and clinical studies have shown increasing accuracy of transpedicular screw placement with all types of computer navigation than with traditional implantation, but unsatisfactory levels of precision are still recorded even when computer navigation is used. Before computer navigation systems can be used with sufficient precision it is necessary to know the potential sources of error for each of the various modalities. These extend from the data acquisition through data transfer and preparation of the dataset for use in computer navigation to intraoperative use of each navigation system. Those who are starting to use such systems must undergo a specialized course of instruction followed by supervised training, and any surgeon who applies them must be sufficiently experienced and well informed to be able to view them with a well-founded criticism; only then are identification and consequent avoidance of complications of computer navigation possible.