Morphological observation of occipital condyle position in Chinese skulls and potential clinical significance

BACKGROUND: We aimed to study the anatomy of the Chinese occipital condyle and its position relative to the occipital foramen and skull. MATERIALS AND METHODS: Measurements were taken from 106 adult Chinese skulls using a Cartesian coordinate system centred on the foramen magnum. Measurements included the longitudinal diameter of the foramen magnum, distances from various points on the occipital condyles to the foramen magnum and skull landmarks, and the occipital condyle classification index (OCI) and skull-occipital condyle classification index (SOCI). RESULTS: Occipital condyle index classified the position of the foramen magnum and occipital condyles into three groups: OCI ≤ 0.40 (3 cases, 2.83%); 0.40 < OCI ≤ 0.50 (75 cases, 70.75%); and OCI > 0.50 (28 cases, 26.42%). SOCI classified the relationship between the skull and occipital condyles into two groups: 0.5 < SOCI ≤ 0.6 (49 cases, 46.23%); and 0.6 < SOCI ≤ 0.7 (57 cases, 53.77%). Four relationship types were identified based on specific measurements: Type I (23 cases, 21.70%); Type II (42 cases, 39.62%); Type III (four cases, 3.77%); and Type IV (37 cases, 34.91%). CONCLUSIONS: Sagittal movement of the occipital condyle affects the cervical spine’s curvature. Asymmetry between the occipital condyles and the foramen magnum can misalign the skull with the body’s coronal plane.