2022, Vol. 26 ›› Issue (15): 2372-2376

Sensitivity and specificity of coronal computed tomography reconstruction and traditional methods for determining screw loosening in spinal internal fixation

Hu Weiran, Song Yuepeng, Shi Xinge, Ma Haohao, Wang Hongqiang, Zhang Kai, Gao Kun, Shao Jia, Gao Yanzheng   

Abstract: BACKGROUND: Pedicle screw loosening is a serious complication of spinal internal fixation, and previous reports on the determination of screw loosening still focused on computed tomography (CT) axial images.  
OBJECTIVE: To compare the sensitivity and specificity of coronal CT reconstruction using traditional methods, including X-ray and axial CT images, in determining screw loosening.
METHODS: This study enrolled a total of 23 patients who underwent spinal revision surgery in Henan Provincial People’s Hospital, including 17 patients with degenerative diseases and 6 patients with fractures. There were 14 patients with short segmental fixation and 9 patients with long segmental fixation. Coronal CT reconstruction and traditional X-ray and axial CT images were used to determine pedicle screw loosening preoperatively. Two doctors read the film independently without interfering with each other. Preoperative assessment was made for loosening of all fixation devices. A total of 171 screws were detected intraoperatively by digital torsion meter, and whether the screws were loose was determined according to the torsion. The sensitivity and specificity of the two methods were calculated separately. The clinical study was carried out in accordance with the Helsinki Declaration and the relevant ethical requirements of Henan Provincial People’s Hospital. Patients were informed of the treatment and signed an informed consent form.  
RESULTS AND CONCLUSION: A total of 171 screws were examined, of which 69 screws were loose, and the loosening rate was 40.1%. The torsion force was (13.9±17.2) Ncm for loose screws and (154.9±72.3) Ncm for unloosened screws. The sensitivity, specificity, and accuracy of coronal CT reconstruction were 76.2%, 89.8%, and 80.1%, respectively. The sensitivity, specificity, and accuracy of the traditional method were 63.7%, 79.3%, and 69.0%, respectively. The sensitivity, specificity, and accuracy of the coronal CT reconstruction were higher than those of the traditional method (P < 0.05). The intra-observer correlation coefficients of the two methods were both greater than 0.75, indicating a good consistency between the two methods. To conclude, coronal CT reconstruction is simple and convenient, which can improve the accuracy of screw loosening determination after spinal internal fixation.

Key words: computed tomography, coronal reconstruction image, spinal internal fixation, screw loosening, sensitivity, specificity