A Novel Perspective for Analyzing Craniocervical Sagittal Balance and Horizontal Gaze

This study aimed to analyze craniocervical sagittal balance parameters in an asymptomatic population revealing the interaction of craniocervical compensation with the horizontal gaze and to identify a new parameter that can be evaluated more easily with the horizontal gaze.

Lateral radiographs were taken of the 75 asymptomatic volunteers. Two independent observers measured the pelvic, spinal, and cranial parameters, spinocranial angle, and C2-7 sagittal vertical axis (C2-7SVA) distances. The correlations between these parameters and the differences in the created subgroups were analyzed.

Correlations were found between the sacral slope and L1-L5 lordosis (r = 0.700), between L1-L5 lordosis and thoracic kyphosis (r = 0.363), between thoracic kyphosis and C2-7 lordosis (r = 0.425), and between C2-7 lordosis and C2 slope (C2S) (r = -0.735). In addition, this chain was extended to include the cranium, showing a strong correlation between the C2S and the cranial slope (CS) (r = -0.827). Strong correlations were observed between the CS and C2S (r = -0.827), C2-C7 lordosis (r = 0.583), C2-7 SVA (r = -0.437). The importance of O-C2 lordosis was significantly increased in the patient cohort with a prominent C2S (≥13) and became the main determinant of the CS (r = 0.667) together with the C2S (r = -0.800).

The factors affecting horizontal gaze are C2S, C2-7 lordosis, O-C2 lordosis, and C2-7 SVA. C2S can be used as an indicator of the horizontal gaze in preoperative surgical planning and postoperative evaluation.