A comparative study of C2 screw placement parameters between CT-based and anatomical measurements during TARP-Ⅲprocedure
LI Xueshi
WU Zenghui
XIA Hong
MA Xiangyang
AI Fuzhi
WANG Jianhua
MAI Xiaohong
YIN Qingshui
Abstract：Objective To compare the differences between CT-based parameters of C2 transoral articular mass screw (C2TOAMS)/C2 transoral transpedicular screw (C2TOTPS) placement and their anatomical measurement data during transoral atlantoaxial reduction plate (TARP)-Ⅲ procedure, and to analyze the existing problems in the process of actual screws placement. Methods Postoperative CT thin-slice data from 75 adult patients underwent TARP-Ⅲ procedure from March 2008 to August 2012 in Guangzhou General Hospital of Guangzhou Military Command were collected, and then parameters of the clinically placing C2TOAMS/C2TOTPS were measured by 2 observers from different planes. The intraclass correlation coefficient (ICC) was calculated to access the intra-observer reliability and the inter-observer repeatability of the measurement results, and the differences between these clinical parameters and the previous measured anatomical parameters were compared, simultaneously, the variance between two sides was also analyzed. Results The mean distance between the screw entry point of C2TOAMS/C2TOTPS and the lateral articular surface of C2 was 4.6 mm on both sides. The average distance from the screw entry point on the left and the right side to the mid-sagittal plane was 7.6 mm and 9.3 mm respectively, and the average length of intraosseous screw trajectory was 16.3 mm on the left, and 17.3 mm on the right. The mean transverse angle was 16.9° on the left side and 15.8° on the right side, and the average declination angles were-1.2° on the left side and 0.2° on the right side respectively. Reliability test of CT image measurement showed that intra-observer ICC was 0.94, 0.95, and inter-observer ICC was 0.94. Conclusions During TARP-Ⅲ procedure, entry point locations and angles of C2TOAMS/C2TOTPS are highly variable with insufficient declination angles. As a result, individualized preoperative planning and intraoperative X-ray guiding are not necessary for accurate screw placement. Other guidance methods should be accompanied so as to enhance the accuracy and safety of transoral C2 screw placement.
Keywords：Atlanto-axial jointAxisJoint instabilityTransoral procedureBone platesBone screwsCT measurementAnatomical measurement
Publication Date：2015-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：9( 95-103 )