Intraosseous Ultrasound Evaluation of Thoracolumbar Pedicle Screw Holes

Overview

This experimental study demonstrates the feasibility of using endoscopic ultrasound (EUS) probes for intraosseous ultrasound (IOUS) assessment of pedicle screw holes in the thoracolumbar spine. The technique offers real-time imaging to detect cortical breaches and screw misplacements with potential advantages over existing intraoperative technologies.

Background

Misplacement of pedicle screws in spinal surgery can cause cortical bone damage leading to spinal instability and injury to adjacent neurovascular structures. Various intraoperative technologies such as 3D printed templates, dynamic surgical guidance, cone-beam CT, robotic navigation, augmented reality, and photoacoustic imaging have been developed to reduce screw malposition rates. However, these methods often require extensive exposure, involve radiation, are costly, or lack rapid feedback. Intraosseous ultrasound (IOUS) using miniature probes placed within bone channels offers a simple, real-time, and cost-effective alternative for assessing screw hole integrity during surgery.

Data Highlights

In this study, 76 pedicle screw holes (3 mm diameter, 30–35 mm length) were created in caprine thoracolumbar spines from T2 to S1. The EUS probe (2.4 mm diameter, 12 MHz frequency) provided 360° 2D transverse ultrasound images of the screw holes. Most holes were intentionally malpositioned to simulate cortical breaches and spinal canal penetration. The study evaluated the ability of IOUS with EUS probes to identify correct versus misplaced screw trajectories.

Key Findings

• IOUS using an EUS probe successfully visualized pedicle screw holes in fresh caprine thoracolumbar spines.
• The 360° transverse ultrasound imaging allowed detection of cortical breaches and deviations in screw hole trajectories.
• The EUS probe’s small diameter and lateral transducer placement facilitated insertion into narrow pedicle channels without bending artifacts.
• Compared to previously used intravascular ultrasound catheters, the EUS probe is reusable and lower cost, enhancing feasibility for clinical application.
• The technique requires minimal additional training and equipment, potentially integrating easily into surgical workflows.
• Experimental data support the potential of IOUS with EUS probes to improve intraoperative assessment of pedicle screw placement accuracy.

Clinical Implications

Intraosseous ultrasound with EUS probes may provide spine surgeons with a rapid, real-time method to verify pedicle screw hole integrity and detect cortical breaches intraoperatively. This technique could reduce reliance on radiation-based imaging and complex navigation systems, lowering costs and operative time. Its ease of use and minimal training requirements may facilitate adoption in various surgical settings, including minimally invasive spine surgery.

Conclusion

The study validates the feasibility of using EUS-based IOUS to assess pedicle screw holes in the thoracolumbar spine experimentally. This approach holds promise as a practical intraoperative tool to enhance screw placement accuracy and patient safety.

References

1. Kantelhardt SR et al. 2009/2010 -- Feasibility of Intravascular Ultrasound for Pedicle Screw Hole Assessment
2. Sonoscape Jupiter System -- EU10 Console and TP10 Controller with UM2412 Probe