This retrospective study aimed to quantitatively evaluate the effects of improved facial asymmetry on cervical spine deviation in patients who had undergone orthognathic surgery. This study enrolled 51 female patients who underwent orthognathic surgery at the University of Yamanashi Hospital. Preoperative and 1-year postoperative cephalometric analysis and three-dimensional computed tomography (3D-CT) image analysis were performed. Facial asymmetry was evaluated using cephalometric analysis. In 3D-CT analysis, cervical spine deviation was assessed by first plotting anatomical landmarks (external occipital protuberance, spinous processes, and transverse processes of C1–C5) on 3D-reconstructed head and neck images. The distances between these landmarks were then measured. The angle formed by the external occipital protuberance, spinous process of the atlas (C1), and spinous process of the fifth cervical vertebra (C5) was measured as a continuous variable to define the cervical deviation angle. Cephalometric analysis showed a significant improvement in the facial asymmetry (Mx-Md midline angle) in all patients postoperatively (Pre: 2.7 ± 2.3 vs. Post: 1.7 ± 1.3, p = 0.013). The cervical deviation angle was also significantly reduced postoperatively (Pre: 10.79 ± 8.28 vs. Post: 5.10 ± 2.58, p < 0.0001). While there was no significant difference in the interspinous process distances, a significant decrease was observed in the intertransverse process distances between the atlas (C1) and axis (C2), and between the third (C3) and fourth (C4) cervical vertebrae (p < 0.05). These findings suggest that the correction of facial asymmetry by orthognathic surgery may contribute to the improvement of cervical spine deviation in female patients. This retrospective study was registered at the the Clinical Research Ethics Committee of the University of Yamanashi Hospital (Trial Resistration Number: 2751; Date of registration: November 8th, 2023).
Gomi et al. (2026) studied this question.