LAUSR

BACKGROUND This study aimed to investigate the anatomical morphology of the C2 to C7 spinous process bifurcation (SPB) in the Chinese population and reveal its potential clinical significance. MATERIALS AND METHODS Measurement parameters of the three-dimensional (3D) reconstructions of neck computed tomography (CT) scans (N=92 scans) were retrospectively analyzed. The 3D reconstruction and measurements were performed using Mimics Research 19.0 and 3-Matic Research 11.0. Two independent investigators reviewed all the data, including parameters such as the length and angle of the SPB. The effects of age and sex were also analyzed. RESULTS We identified four morphological types of SPB: Fully bifid (n=252, 45.65%), Partially bifid (n=65, 11.78%), Non-bifid (n=226, 40.94%) and Unilateral branch (n=9, 1.63%). The Kappa coefficients indicated good inter-observer reproducibility (0.776), and the ICC values demonstrated excellent intra-rater reliability (ICC=0.9, P<0.0001) in the classification and measurement of SPB parameters. The percentage of general bifid SP was more than 70% in C2-5 and about 21% in C6, while all C7 SPs presented non-bifid. Morphology was symmetrical in bifid and partially bifid SP, while unilateral SP was not. CONCLUSIONS The classification system of SPB in this study proved consistent and reliable, despite the subjective bias. Identifying the cervical level by C6 bifurcation is unreliable, as nearly 80% of C6 SP is non-bifid. Our work provides an accurate and effective anatomical reference for SPB studies in the Chinese population.