Assessment of Percutaneous “K-wireless” Pedicle Screw Fixation Technique

Percutaneous spinal pedicle screw fixation is a mini invasive technique initially described by Magerl in 1977 [1] using guide wires. The original technique is decribed with use of k-wires which is frequently associated with breakage or recoil during tapping which can extend operating time in often fragile patients and increase radiation exposure in the medical team. Faced with these challenges, we detail our experience with percutaneous k-wireless pedicle screw fixation.

We carried out a retrospective study from January 2018 to December 2020. We collected K-wireless percutaneous pedicle screw fixation performed between the thoracolumbar hinges including T11 up to L5. The positioning of the screws was judged by a postoperative CT scan with grades ranging from A to D: A = intra-pedicle path or "in out in" extra canal. B = Intra-canal path <2 mm, C = Intra-canal path between 2-4mm, and D = Intra-canal path> 4 mm. The operating time, the exposure dose of irradiation and the complications related to the path of the screws were also noted.

A total of 200 screws in 42 patients were collected. A postoperative CT scan was performed in all our patients. 188 screws were grade A. 9 screws were grade B. 2 screws were grade C without clinical consequences and 1grade D symptomatic by an irritation of the left L5 root having required a surgical resumption and the change of the path of the screw. The average time for screw placement was 5.62 minutes with an average exposure dose of 7.6 +/- 1.2 mRem and an irradiation time of 1.2 minutes.

Results of this study showed that lumbur percutaneous k-wireless pedicule screw fixation under fluoroscopic control is achievable with improved operating time and reduced exposure of the medical team.