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.