Results: A formula of cervical vertebral bone age: CVBA= 1.92+ 0.04 * α2 + 0.03 * α4 - 1.12 * AB3/CB3 + 3.17 * h4 / w4 (CVBA I: CVBA < 2.55; CVBA II: 2.55 ≤ CVBA < 3.33; CVBA III: 3.33≤ CVBA <4.36; CVBA IV: 4.36 ≤ CVBA < 5.39; CVBA: CVBA ≥ 5.39 and α2: Anterior concavity angle of inferior border of C2; α4: Anterior concavity angle of inferior border of C4; AB3/BC3: Ratio of inferior and anterior length of C3; h4 / w4: Ratio of the middle height and width of C4).