# Redefining the Cervical Pedicle Entry Point (CPEP) in the Insertion of Cervical Pedicle Screw Using O-Arm Navigation: A Prospective Radiological Study From India

## TL;DR

This study introduces a new, safer method for inserting cervical spine screws using advanced imaging technology, showing high accuracy and safety.

## Contribution

A novel medially-shifted cervical pedicle entry point technique using O-arm navigation is proposed and validated.

## Key findings

- The novel CPEP technique achieved a 97.24% accuracy rate in cervical pedicle screw placement.
- Only 2.76% of screws had breaches, with no neurovascular complications observed.
- The technique reduces soft tissue dissection and lateral malposition risks compared to conventional methods.

## Abstract

Introduction

Cervical pedicle screw (CPS) fixation offers superior biomechanical stability in the management of cervical spine pathologies. However, the technique is associated with a significant risk of screw malposition due to the small pedicle dimensions and the lateralized trajectory of conventional entry points, often complicated by medial paraspinal muscular force. This study aimed to evaluate the safety and accuracy of a novel, medially-shifted cervical pedicle entry point (CPEP) for sub-axial CPS placement utilizing intraoperative O-arm™-based navigation (Medtronic, Minneapolis, USA).

Methods and materials

A prospective cohort study was conducted on 50 patients undergoing sub-axial CPS fixation between July 2021 and January 2023. All procedures employed an intraoperative O-arm imaging system integrated with the StealthStation S8 Navigation Platform (Medtronic, Minneapolis, USA). The CPEP was defined as the intersection of a vertical line bisecting the lateral mass and a horizontal line 2 mm inferior to its superior margin. Screw trajectory was planned and executed entirely under navigation guidance. Screw accuracy was assessed postoperatively using multiplanar computed tomography and classified according to the Neo grading system.

Results

A total of 218 CPSs were inserted using the proposed CPEP technique. The overall accuracy rate was 97.24%, with a total breach rate of 2.76%. Specifically, four screws exhibited Grade 1 breaches, one screw exhibited a Grade 2 breach, and one a Grade 3 breach; the latter two were revised intraoperatively. No intraoperative or postoperative neurovascular complications were observed.

Conclusion

The novel CPEP technique, characterized by a medially positioned entry point and executed under O-arm navigation, demonstrated high accuracy and safety in CPS placement. The approach effectively reduces soft tissue dissection and mitigates lateral malposition risks associated with conventional lateral entry points. These findings support the adoption of CPEP as a viable alternative to traditional CPS techniques, warranting further investigation in larger, multi-center cohorts.