Pedicle screw placement with intraosseous endoscopy.

This study was undertaken to evaluate the efficiency of intraosseous endoscopy for the insertion of pedicle screws. Adult sheep served as an animal model. Under general anesthesia, the authors exposed the posterior lumbar elements through a midline spinal approach and cannulated six to eight pedicles in each sheep, without the use of radiographic or fluoroscopic guidance. Placement of properly located holes as well as intentionally misdirected holes was attempted. Using the fiber optic endoscope, direct examination of the interior of 22 pedicle screw holes was performed. Nine deliberate and 2 unintentional perforations, for a total of 11 defects in 22 pedicles, were easily recognized. These were confirmed by gross examination after specimens were harvested. Defects as small as 2 mm in diameter, not detected on palpation with a standard probe, were able to be closely inspected. The use of intraosseous endoscopy may serve as a useful adjunct in the placement of pedicle screws.