Towards an Autonomous Minimally Invasive Spinal Fixation Surgery Using a Concentric Tube Steerable Drilling Robot

TL;DR

The paper tackles autonomous minimally invasive spinal fixation by integrating a Concentric Tube Steerable Drilling robot with a seven-DOF robotic arm, complemented by calibration procedures and a biomechanically informed trajectory planning module. The proposed framework employs pivot and hand-eye calibrations to enable precise, safe autonomous drilling, demonstrated through Sawbone experiments with varied mounting angles. Key findings show a maximum rotation error of $2.41°$ and a curvature radius deviation of $3.20$ mm from the target, while positional errors reach up to $5.15$ mm at steep angles, highlighting calibration as a critical factor. The work suggests that this architecture improves surgeon capability and paves the way for cadaveric and clinical validation, offering enhanced strength, dexterity, and safety for autonomous spinal drilling with flexible implants.

Abstract

Towards performing a realistic autonomous minimally invasive spinal fixation procedure, in this paper, we introduce a unique robotic drilling system utilizing a concentric tube steerable drilling robot (CT-SDR) integrated with a seven degree-of-freedom robotic manipulator. The CT-SDR in integration with the robotic arm enables creating precise J-shape trajectories enabling access to the areas within the vertebral body that currently are not accessible utilizing existing rigid instruments. To ensure safety and accuracy of the autonomous drilling procedure, we also performed required calibration procedures. The performance of the proposed robotic system and the calibration steps were thoroughly evaluated by performing various drilling experiments on simulated Sawbone samples.

Figures (3)

• Figure 1: An outline of the overall framework for surgeon care of a patient. A Biomechanics-Aware Trajectory Planning Module provides a desired Trajectory to both the Flexible Pedicle Screw Design/Fabrication Module and the Autonomous Robotic Drilling Module (highlighted as the focus of this paper). The performed fixation by these two modules is then passed to the Trajectory/Placement Analysis Module for evaluation.
• Figure 2: Experimental set-up for the CT-SDR System. Including the Optical Tracking Camera, KUKA LBR Med, and the CT-SDR(subfigure D). Marked in green are the known transforms present in our system, used for calculations of the system. Marked in red are the unknown transforms required to establish positions of any given object in space at all times. Solid dashed lines indicate pivot calibration, full lines indicate $AX=ZB$ calibration. The entry points for each test are in subfigures A-C, showing the angles that the test sample blocks were mounted at (0°, 30°, and 60° respectively).
• Figure 3: Cross Sectional View of several of the tests performed with the CT-SDR System with a 30° mounting angle.