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A new tool to improve pedicle screw placement accuracy in navigated spine surgery: a monocentric study.

OBJECTIVE
Navigated instrumented spine surgery is burden by a low but significant screw mispositioning risks, respectively, for the 2D imaging system from 15 to 40% and, for the 3D imaging system, ranging from 4.1 to 11.5%. The primary objective of this study was to demonstrate the efficacy of a new "screw-like" tool in order to further decrease pedicle screws mispositioning rate during vertebral navigated spine surgery.


MATERIALS AND METHODS
Between January and June 2019 an initial case series of 18 patients were enrolled. All patients underwent a pedicle screw fixation, both in thoracic (Th10-Th12) and lumbosacral (L1-S1) spine, using O-arm (Medtronic Navigation, Louisville, Colorado) and StealthStation S7 surgical navigation system (Medtronic Navigation, Louisville, CO). Evaluation of pedicle screws placement accuracy using the new tool in adjunct to the classic reference frame, was performed following the Gertzbein and Robbins classification.


RESULTS
A total of 94 screws have been placed. Among them, the 98.9% were completely inside cortical bone (Grade A) and only the 1.1% with a breach of less than 2 mm (Grade B).


CONCLUSIONS
Our new "screw-like" tool coupled to the classic reference frame device could improve accuracy during navigated spine surgery and potentially reducing to zero the risks for screw mispositioning.