Placement of transpedicular vertebral screws close to anterior vertebral cortex. Description of methods

Strengthening of the screw-vertebra interface has been shown to occur with implantation of longer transpedicular screws, the tips of which are placed closer to the anterior cortex of the vertebral body. Such implantation probably results in increased risk for anterior cortex penetration and associated vascular or pulmonary damage. Typically recommended lateral and posterior-anterior radiography is shown here to provide potentially misleading visualization during implantation. To reduce the risk of anterior cortical penetration, presented here are 1) a radiographic method ("near approach view") that avoids this problem and allows direct visualization of the relationship between drill bit or screw tip and anterior vertebral cortex, and 2) a surgical technique ("mallet method") that provides both an audible and a palpable change when the drill bit contacts the anterior cortex.