Feasibility of a Cannula-Mounted Piezo Robot for Image-Guided Vertebral Augmentation: Toward a Low Cost, Semi-Autonomous Approach

Abstract

Vertebral compression fractures (VCFs), the most common fragility fractures secondary to osteoporosis, affect more than 200 million individuals worldwide. Percutaneous vertebral augmentation is an effective interventional treatment option that is routinely performed across the world. Because fluoroscopy-guided vertebral augmentation is a well-established and safe minimally invasive technique, automating its delivery is among the most important next steps. In this work, we describe the design and evaluation of a novel cannula mounted vertebral augmentation robot in a simulated X-ray environment as a first step toward autonomous vertebral augmentation. The cannula robot employs a piezo stack with inchworm control to place surgical tools within the vertebral body, while X-ray imaging verifies the robot does not interfere with imaging. Finite element analysis of the robot confirms that radiolucent materials were rigid enough to be used in the robot design as expected deformations for the cannula drive, accessory drive, and locking mechanisms $(1.299 \pm 0.034 \ um, 1.280 \pm 0.027\ um$, and $1.960 \pm 0.218\ um$, respectively) did not exceed the stroke lengths of the piezo stacks. An in silico clinical trial based on a human anatomy model suffering from VCF validates that the cannula robot does not impede visualization of the critical anatomy and tool-to-tissue positioning. Together these results demonstrate the feasibility of a cannula mounted robot for vertebral augmentation.