[In vitro evaluation of computer-assisted pedicle screw system].

GOAL

The goal of this study is to evaluate influence on the accuracy of pedicle hole positions when a surgeon uses a computer assisted system.

STUDY DESIGN

This comparative study was undertaken using dry thoraco-lumbar specimens in order to measure the position of drilled holes with and without computer assistance in the hands of an experienced surgeon as well as with a resident in training.

METHODS

Pedicle holes were drilled from D1 to L5 in identical dry thoraco- lumbar specimens. For half of the specimens a computer assisted pedicle screw installation system was used. Holes having been drilled for all specimens, we then measured the maximum distance between the axis of the drilled holes and the pedicle cortices All distances less or equal to 2 mm were classified as safe while all bigger distances were classified as unsafe for pedicle screw installation.

RESULTS

Nine specimens were drilled for a total of 306 holes, 170 of them with computer assistance. We have observed a 95% success rate with the computer assisted holes compared to a 62% success rate using conventional methods (p < 0.001). No difference was found between the results of an experienced surgeon and the results of a resident in training while using the computer assistance system. All holes drilled from D12 to L5 were found to be in optimal position, completely within the pedicles.

CONCLUSION

These results suggest that this computer assisted pedicle screw installation system could improve the accuracy of pedicle screw placement and enhance the safety of the procedure. Moreover, the computer system could become a valuable teaching tool for the training spine surgeons.