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Ideal Starting Point & Trajectory for C2 Pedicle Screw Placement: a 3D Computed Tomography Analysis Using Perioperative Measurement

Scientific Paper

Chin KR1, Mills MV2, Seale J3, Cumming V4.

Interested medical professionals can read through the full paper, as published in The Spine Journal, here.


C2 pedicle screws provide stable fixation for posterior cervical fusion. Placing C2 pedicle screws is fraught with risks, and a misplaced screw can result in cortical breach of the pedicle, resulting in injury to the vertebral artery or spinal cord.


We sought to identify a reproducible starting point and trajectory for C2 pedicle screw placement using three-dimensional (3D) computed tomography (CT) imaging. Our aims included identifying correct cephalad and mediolateral angles used for determining the most accurate trajectory through the C2 pedicle.


A radiographic analysis of the anatomy of the C2 pedicle using CT.


A random sample of 34 cervical spine CT scans in patients without medical or surgical pathology of the cervical spine.


Normal anatomic measurements made in the axial and sagittal planes of the CT scans. Angles and measures in millimeters were recorded.


The C2 pedicles were evaluated using CT scanning with a 3D imaging application. The ideal trajectory through each pedicle was plotted. The mediolateral and cephalad angles were measured using the midline sagittal plane and the inferior vertebral body border as references. Other measurements made were the distances through the pedicle and vertebral bodies, and the surface distances along the laminae between the isthmus and the starting point of the chosen trajectories. Other measurements involving the height of the laminae were also made. The mean values, standard deviations, and intraobserver variations are presented.


CT scans from 34 patients were reviewed. The sex of the patient did not predict angle measurements (p=.2038), so combined male and female patient measures are presented. The mean mediolateral angle measured was 29.2°, and the mean cephalad angle was 23.0°. The mean distance along the lamina surface between the isthmus and the starting point was 8.1 mm. The mean distance from the superior border of the lamina to the starting point was 5.7 mm. There were no statistically significant differences between the dataset collected in duplicate by the same observer (p=.74); as such, we present one data analysis on combined data from the two datasets collected.


It is possible to determine an ideal trajectory through the C2 pedicle. These measurements may facilitate C2 pedicle screw fixation decreasing the risk of injury to the vertebral artery, spinal cord, or nerve roots. Delineating the individual anatomy in each case with imaging before surgery is recommended.

Copyright © 2014 Elsevier Inc. All rights reserved.


Dr. Kingsley R. Chin, Founder of philosophy and practice of The LES Society and The LESS Institute

Dr. Kingsley R. Chin is a board-certified Harvard-trained Orthopedic Spine Surgeon and Professor with copious business and information technology exposure. He sees a niche opportunity where medicine, business and info. tech meet – and is uniquely educated at the intersection of these three professions. He has experience as Professor of Clinical Biomedical Sciences & Admissions Committee Member at the Charles E. Schmidt College of Medicine at Florida Atlantic University, Professor of Clinical Orthopedic Surgery at the Herbert Wertheim College of Medicine at Florida International University, Assistant Professor of Orthopaedics at the University of Pennsylvania Medical School, Visiting Spine Surgeon & Professor at the University of the West Indies, Mona, and Adjunct Professor of Clinical Biomedical Sciences at the University of Technology, Jamaica.

Learn more about Dr. Chin here and connect via LinkedIn.


Less Exposure Surgery (LES) is based on a new philosophy of performing surgery, leading the charge to prove through bench and clinical outcomes research that LES treatment options are the best solutions – to lowering the cost of healthcare, improving outcomes and increasing patient satisfaction. Learn more at LESSociety.org.

The LES Society philosophy: “Tailor treatment to the individual aiding in the quickest recovery and return to a pain-free lifestyle, using LES® techniques that lessen exposure, preserve unoffending anatomy and utilize new technologies which are safe, easy to adopt and reproducible. These LES®techniques lessen blood loss, surgical time and exposure to radiation and can be safely performed in an outpatient center. Less is more.” – Kingsley R. Chin, MD


The LESS Institute is the world leader center of excellence in Less Exposure Surgery. Our safe, effective outpatient treatments help patients recover quickly, avoid expensive hospital stays and return home to their family the same day. Watch our patient stories, follow us on Facebook and visit TheLESSInstitute.com to learn more.


The above study utilized LES Technology from SpineFrontier – leading provider of LES Technologies and instruments – offering surgeons and patients superior technology and services.



Chin KR1, Mills MV2, Seale J3, Cumming V4.

Author information

  1. Charles E. Schmidt College of Medicine at Florida Atlantic University and LESS (LESSurgeons) Institute, Division LESSpine Institute, 1100 W. Oakland Park Blvd., Suite #3, Fort Lauderdale, FL 33311, USA. Electronic address: [email protected]

  2. Department of Orthopedic Surgery, Howard University Hospital, Washington, DC, USA.

  3. LESS (LESSurgeons) Institute, Division, LESSpine Institute, 1100 W. Oakland Park Blvd., Suite #3, Fort Lauderdale, FL 33311, USA.

  4. Less Exposure Surgery (LES) Society, 300 E. Oakland Park Blvd., Suite 502, Fort Lauderdale, FL 33334, USA.

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