A photoacoustics-enhanced drilling probe for radiation-free pedicle screw implantation in spinal surgery

Li Liu; Yongjian Zhao; Ang Li; Xianghu Yu; Xiao Xiao; Siyu Liu; Max Q-H Meng

doi:10.3389/fbioe.2022.1000950

A photoacoustics-enhanced drilling probe for radiation-free pedicle screw implantation in spinal surgery

Front Bioeng Biotechnol. 2022 Sep 15:10:1000950. doi: 10.3389/fbioe.2022.1000950. eCollection 2022.

Authors

Li Liu¹, Yongjian Zhao¹, Ang Li¹, Xianghu Yu², Xiao Xiao², Siyu Liu³, Max Q-H Meng^{1

2}

Affiliations

¹ Department of Electronic Engineering, The Chinese University of Hong Kong, Hong Kong SAR, China.
² Department of Electronic and Electrical Engineering, Southern University of Science and Technology, Shenzhen, China.
³ School of Science, Nanjing University of Science and Technology, Nanjing, China.

Abstract

This article proposes a novel intra-operative navigation and sensing system that optimizes the functional accuracy of spinal pedicle screw implantation. It does so by incorporating radiation-free and multi-scale macroscopic 3D ultrasound (US) imaging and local tissue-awareness from in situ photoacoustic (PA) sensing at a clinically relevant mesoscopic scale. More specifically, 3D US imaging is employed for online status updates of spinal segment posture to determine the appropriate entry point and coarse drilling path once non-negligible or relative patient motion occurs between inter-vertebral segments in the intra-operative phase. Furthermore, a sophisticated sensor-enhanced drilling probe has been developed to facilitate fine-grained local navigation that integrates a PA endoscopic imaging component for in situ tissue sensing. The PA signals from a sideways direction to differentiate cancellous bone from harder cortical bone, or to indicate weakened osteoporotic bone within the vertebrae. In so doing it prevents cortical breaches, strengthens implant stability, and mitigates iatrogenic injuries of the neighboring artery and nerves. To optimize this PA-enhanced endoscopic probe design, the light absorption spectrum of cortical bone and cancellous bone are measured in vitro, and the associated PA signals are characterized. Ultimately, a pilot study is performed on an ex vivo bovine spine to validate our developed multi-scale navigation and sensing system. The experimental results demonstrate the clinical feasibility, and hence the great potential, for functionally accurate screw implantation in complex spinal stabilization interventions.

Keywords: cancellous bone characterization; in situ tissue sensing; multi-scale navigation and sensing; pedicle screw implantation; photoacoustic endoscopy; robotic-assisted spinal surgery; ultrasound-based surgical navigation.