Preoperative Planning for Cervical Pedicle Screw Placement: Identifying Key Morphological Parameters

Area of Science:

• Spine surgery
• Orthopedic surgery
• Neurosurgery

Background:

• Cervical pedicle screw (CPS) placement is vital for posterior cervical fusion, offering strong fixation.
• CPS insertion carries risks like screw perforation, potentially causing vertebral artery injury and neurological deficits.
• Limited data exists on specific morphological factors predicting CPS perforation.

Purpose of the Study:

• To investigate cervical vertebrae features associated with CPS perforation.
• To establish threshold values for key morphological parameters to improve preoperative planning.

Main Methods:

• Retrospective analysis of 36 patients undergoing posterior cervical fusion with CPS placement (C3-C7).
• Measurement of optimal screw trajectory angle, pedicle diameter, and distance from entry point to pedicle isthmus (DEP) using CT-based navigation.
• Receiver operating characteristic (ROC) curve analysis to determine cutoff values for predicting perforation.

Main Results:

• Overall perforation rate was 25.5% (102 screws). C3 had the highest (45.5%), C7 the lowest (3.1%).
• Perforated screws were associated with larger optimal screw trajectory angles (45.5° vs. 38.0°), smaller pedicle diameters (4.2 mm vs. 5.2 mm), and longer DEPs (13.2 mm vs. 11.9 mm).
• ROC analysis identified cutoff values: 44.0° for angle, 4.35 mm for diameter, and 12.7 mm for DEP, predicting perforation risk.

Conclusions:

• Key morphological thresholds for cervical vertebrae can be established.
• These thresholds enhance preoperative planning for CPS placement.
• Improved planning can increase accuracy, patient safety, and minimize complications.