Abstract
Objective
To introduce and validate the Anterior Tilt Slope (ATS) as a novel angular parameter for quantifying cervical forward inclination in asymptomatic young adults, and to examine its associations with cervical and global spinal sagittal parameters.Methods
In this single-center retrospective study, 341 asymptomatic subjects (18-45 years) who underwent standing full-spine radiographs (AP/Lateral) between May 2023 and May 2025 were analyzed. Cervical parameters (CL, O-C2, C1-7, T1S, cSVA, Borden, ATS), thoracic kyphosis (TK), and spinopelvic parameters (LL, SS, PI, PT, SVA) were measured on PACS by two spine surgeons (twice, averaged). ATS was graded as type I Results
The cohort included 119 males (39%) and 222 females (61%), mean age 25.17 years; overall ATS was 8.17 ± 4.63°. Distribution across ATS grades: I (n = 96), II (n = 134), III (n = 82), IV (n = 29). ATS correlated strongly with cSVA (r = 0.767, P 0.05). cSVA and T1S increased progressively with higher ATS grades (both P Conclusions
ATS provides a robust quantification of cervical forward inclination in asymptomatic individuals, closely linked to cSVA, T1S, and global sagittal alignment, with limited association to spinopelvic parameters-highlighting the pivotal role of the cervicothoracic junction in early sagittal compensation. ATS is a useful complement to cSVA for posture screening, outcome assessment, rehabilitation planning, and potentially surgical decision-making.