Eversion-based robots can enable safe access,steering and endoscopic imaging within the spinal subarachnoid space

2026-07-21

AI Summary

This study addresses the challenges of navigating the spinal subarachnoid space, where conventional catheters and continuum robots generate friction and shear forces due to proximal pushing, leading to poor distal control and heightened risk of neural injury. To overcome this, the authors propose a 2-mm-diameter eversion-based growing robot that advances via pressure-driven local eversion at its tip, substantially minimizing sliding of the deployed body. The system integrates a miniature endoscope for real-time intrathecal visualization. For the first time, the robot’s navigational feasibility is demonstrated within intact human spinal anatomy. Phantom experiments show a 65.2% reduction in average interaction force and a 48.0% decrease in peak force. In human cadaveric trials, the robot achieved 150 mm of controlled extension across multiple vertebral levels without causing macroscopic damage to the dura or neural structures, confirming its low tissue stress and high safety profile.

Abstract

Safe navigation within the spinal subarachnoid space is constrained by its narrow, compliant, and delicate anatomy. Conventional catheters and continuum robots rely on proximal pushing, generating friction and shear along the tissue device interface that limit distal controllability and increase the risk of neural injury. Here, we present a 2 mm diameter eversion-growing robotic platform that enables friction minimised extension and steering within the human spinal subarachnoid space, validated through computational modelling, phantom experiments, and intact human cadaver studies. The robot integrates a miniature endoscope for real time intrathecal visualisation and advances by pressure driven tip eversion, localising motion to the distal tip while minimising translational sliding of the deployed body. Phantom experiments demonstrated reductions of 65.2% in mean interaction force and 48.0% in peak interaction force compared with matched push-based insertion. Physics based modelling showed that eversion based growth redistributed tissue loading, reducing local stress concentrations and interfacial shear relative to conventional insertion. In an intact human cadaver, the system achieved 150 mm of controlled intrathecal extension with concurrent fluoroscopic and endoscopic visualisation, providing access across multiple vertebral levels from a standard lumbar entry point. Postprocedural laminectomy and durotomy revealed no observable macroscopic disruption of the dura mater or surrounding neural structures. These results provide the first mechanically characterised and multimodally validated demonstration of eversion-based robotic navigation in intact human spinal anatomy, establishing a quantitative and procedural foundation for future intrathecal interventions. Further validation in larger anatomical cohorts and under physiological conditions will be required before clinical translation.

Problem

• spinal subarachnoid space
• safe navigation
• neural injury
• friction minimization
• intrathecal access

Innovation

• eversion-based robot
• minimally invasive navigation
• spinal subarachnoid space
• friction-minimized steering
• intrathecal endoscopy