Der Orthopäde
-
Comparative Study
[Accuracy of fluoroscopic navigation of pedicle screws. CT-based evaluation of bone screw placement].
While the advantages of C-arm navigation in computer-assisted spine surgery are obvious, the accuracy of pedicle screw placement with virtual fluoroscopy still needs to be verified. The C-arm-based ION system (Medtronic Sofamor Danek) was used to navigate pedicle screw insertion in patients undergoing spinal surgery for various conditions. ⋯ Computed tomography (CT) scans were performed postoperatively by two independent radiologists to control the accuracy of screw placement at the level of the pedicles after reconstruction of axial images according to Laine et al. The comparison of the calculated accuracy rate of pedicle screw placement using virtual fluoroscopy with reported results achieved with CT-based navigation shows similar results for virtual fluoroscopy and a remarkable increase of accuracy in comparison to reports on conventional pedicle screw placement.
-
Comparative Study
[Placement of pedicle screws using different navigation systems. A laboratory trial with 12 spinal preparations].
A well-known problem occurring with thoracolumbar spondylodesis is the perforation of pedicle screws through the pedicle wall. It occurs in up to 40% of the implanted screws. To reduce this problem, computed tomography (CT)-based navigation systems have been introduced, which allow the surgeon multidimensional control of the screw position in virtual reality and real time during insertion. ⋯ We inserted 77 pedicle screws in human lumbar cadaveric spine specimens either without navigation, with CT-based navigation, or with fluoroscopy-based navigation. In the critical sizes of pedicles between 6.5 and 9 mm, we found the best results with CT-based navigation, but there was no significant difference between the three methods. The minimal pedicle and the screw diameters should be reported in every study on pedicle screw misplacement and spine navigation since they represent the most important factor in pedicle wall perforations.
-
There is a rapid increase of computer-assisted surgery (CAS) in the spine for insertion of pedicle screws. In contrast to the traditional technique using fluoroscopy, CT is the primary source for surgical navigation systems. ⋯ In experienced hands open pedicle screw insertion in the thoracic and lumbar spine using fluoroscopy-control requires a fifteen times lower radiation dose than do CT scans necessary for computer-assisted surgery. Regarding the published small percentage of neurological complications in traditional screw insertion technique the use of computer-assisted surgery in pedicle screw insertion using CT scan should be limited to carefully chosen indications. The development of navigation systems based on other data sources than CT should be encouraged.