Robot-assisted percutaneous placement of K-wires during minimally invasive interventions of the spine.

Purpose: To assess the accuracy and time requirements of image-guided percutaneous K-wire insertion in the spine using an advanced robot assistance device for needle guidance and to demonstrate a radiation-free workflow for the physician. Material and methods: A planning CT-scan was acquired of a cadaver specimen and analyzed using a 3D-interventional software integrated in the robotic device. The optimal needle path was simulated and the needle holder of the robot was used for guidance during K-wire insertion. Twenty-four K-wires were inserted percutaneously in a transpedicular approach in the following vertebrae: thoracic (T) 2, 7-12 and lumbar (L) 1-5. A post-procedural CT scan was performed to analyze the accuracy of the K-wire insertion. Results: All procedures were carried out without any perforation of the pedicle wall. The mean duration of planning the intervention path was 2:54 ± 2:22 min, mean positioning time was 2:04 ± 0:42 min and the mean time for K-wire insertion was 2:13 ± 0:54 min. In total, the average intervention time was 7:10 ± 3:06 min per pedicle. Compared to the planning, the K-wire position showed a mean deviation of 0.5 mm in the vertical-axis and 1.2 mm in the horizontal-axis. The average intervention path length was 8.1 cm. Conclusion: Our findings show a high accuracy in robot-assisted K-wire insertion during spinal interventions without any exposure of the operator to radiation.

Combining C-arm CT with a new remote operated positioning and guidance system for guidance of minimally invasive spine interventions.

OBJECTIVE: To report our experience using C-arm cone beam CT (C-arm CBCT) combined with the new remote operated positioning and guidance system, iSYS1, for needle guidance during spinal interventions. METHODS: A C-arm CBCT with a flat panel angiography system was acquired (Artis Zeego; Siemens Healthcare Sector, Forchheim, Germany). Reconstruction of CT-like images and planning of the needle path were performed using a common workstation. The needle holder of iSYS1 acted as a guide during insertion of Kirschner (K) wires. 20 percutaneous K wires were placed in the pedicles at T2-T3, T7-T12, and L1-L2 in a cadaver specimen. Postprocedure C-arm CBCT scans were obtained to confirm the accuracy of the K wire placement. RESULTS: All K wire placements were successfully performed. Mean planning time with Syngo iGuide was 4:16 min, mean positioning time of iSYS1 was 3:35 min, and mean placement time of the K wires was 2:22 min. Mean total intervention time was 10:13 min per pedicle. A mean deviation of 0.35 mm between the planned path and the placed K wire with a mean path length of 6.73 cm was documented. CONCLUSIONS: Our results demonstrate the potential of combining C-arm CBCT with iSYS1 for safe and accurate percutaneous placement of pedicle K wires in spinal interventions.