Spatial Spinal Fixation: A Transformative Approach Using a Unique Robot-Assisted Steerable Drilling System and Flexible Pedicle Screw

TL;DR

This paper introduces a novel robotic-assisted spinal fixation system that allows flexible, multi-directional placement of pedicle screws within vertebral bodies, aiming to improve fixation success and reduce failures.

Contribution

It presents the Spatial Spinal Fixation approach using a steerable drilling robot and a flexible screw, enabling in-plane and out-of-plane, linear and non-linear screw placements.

Findings

Successful drilling of various trajectories in vertebral phantoms

High accuracy in screw placement demonstrated

Potential to reduce fixation failures

Abstract

Spinal fixation procedures are currently limited by the rigidity of the existing instruments and pedicle screws leading to fixation failures and rigid pedicle screw pull out. Leveraging our recently developed Concentric Tube Steerable Drilling Robot (CT-SDR) in integration with a robotic manipulator, to address the aforementioned issue, here we introduce the transformative concept of Spatial Spinal Fixation (SSF) using a unique Flexible Pedicle Screw (FPS). The proposed SSF procedure enables planar and out-of-plane placement of the FPS throughout the full volume of the vertebral body. In other words, not only does our fixation system provide the option of drilling in-plane and out-of-plane trajectories, it also enables implanting the FPS inside linear (represented by an I-shape) and/or non-linear (represented by J-shape) trajectories. To thoroughly evaluate the functionality of our proposed robotic system and the SSF procedure, we have performed various experiments by drilling different I-J and J-J drilling trajectory pairs into our custom-designed L3 vertebral phantoms and analyzed the accuracy of the procedure using various metrics.