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Updated: Jul 15, 2026
A Teleoperated Robotic System-Assisted Percutaneous Transiliac-Transsacral Screw Fixation Technique
Published on: January 6, 2023
C1 anatomy and dimensions relative to lateral mass screw placement
David M Christensen1, Robert K Eastlack, James J Lynch
1Intermountain Spine and Orthopaedics, Twin Falls, ID, USA.
Study Design:
An anatomic surface osteometric analysis of cadaveric cervical spines.
Objective:
To assess the feasibility of placing a 3.5-mm cortical screw in the lateral mass of C1 in a large number of specimens for the purpose of gaining internal fixation for various conditions.
Summary Of Background Data:
Previous studies have addressed surface dimensions of the atlas vertebra and computerized tomography-measured dimensions of the lateral masses of the atlas. These studies used a limited number of specimens with potentially homogeneous origins.
Methods:
A total of 120 atlas (C1) vertebrae for a total of 240 lateral masses were examined and external measurements obtained to assess the feasibility of placing a 3.5-mm cortical screw in the lateral mass.
Results:
The minimum lateral mass dimensions found from 240 C1 lateral masses were 13.15 mm anterior-posterior, 4.22 mm medial-lateral, and 4.73 mm cephalocaudal. The height of the posterior arch at the groove for the vertebral artery (pedicle analog) was less than 4 mm in 46 of 240 (19.2%) arches.
Conclusions:
It is feasible to safely and reproducibly place a 3.5-mm cortical screw in the lateral mass of C1 when the appropriate starting point and trajectory of the screw are chosen.
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