The cranial vertical angle (CVA) and cranial rotation angle (CRA) are used in clinical settings because they can be measured on lateral photographs of the head and neck. We aimed to clarify the relationship between CVA and CRA photographic measurements and radiographic cervical spine alignment. Twenty-six healthy volunteers were recruited for this study. Lateral photographs and cervical spine radiographs were obtained in the sitting position. The CVA and CRA were measured using lateral photographs of the head and neck. The C2-7 sagittal vertical axis (SVA), cervical lordosis (C2-7), and occipito-C2 lordosis (O-C2) were measured using radiographic imaging as a standard method of evaluating cervical spine alignment. Correlations between the CVA and CRA on photographs and cervical spine alignment on radiographs were analyzed. The CVA and SVA were significantly negatively correlated (ρ = −0.51; p < 0.05). Significant positive correlations were found between CVA and C2-7 (ρ = 0.59; p < 0.01) and between CRA and O-C2 (ρ = 0.65; p < 0.01). Evaluating the CVA and CRA on photographs may be useful for ascertaining head and neck alignment in the mid-lower and upper parts of the sagittal plane.
Keywords: cervical alignment; cranial rotation angle; cranial vertical angle; head posture assessment; neck alignment; neck posture; non-radiographic measurement; photogrammetry; spine position; vertical alignment.