Accurate pedicle screw insertion under the control of a computer-assisted image guiding system: laboratory test and clinical study.

We used a commercially available computer-assisted navigation system (StealthStation; Sofamor Danek, Memphis, TN, USA) in both an in-vitro and a clinical study performed in 1996-1998. The basic data used for navigation were preoperative computed tomography (CT) scan imaging data. The position of the probe or drill guide was superimposed in real-time on a monitor. For the in-vitro study, ten plastic lumbar spine models (50 vertebrae) were used. The entrance hole for the screw was made by drilling, following navigation. Using the navigation system, we drilled 88 holes through the pedicles into the vertebral bodies of 44 vertebral models. All 88 pedicle holes were contained within the pedicle without perforation. The mean deviation of the hole positions from the surgical plan was 1.78 +/- 0.81 mm, and the mean angular deviation was 2.28 degrees +/- 1.92 degrees. In 29 patients, using the navigation system, we introduced 169 pedicle screws at the planned position. Fifty-one screws were used for thoracic and 118 screws for lumbar spinal fixation. All screws correctly passed through the pedicles. There were no neurological complications after surgery. Using this guided surgery system, we achieved satisfactory results both in the laboratory and in a clinical setting.