Correlation between kinematic sagittal parameters of the cervical lordosis or head posture and disc degeneration in patients with posterior neck pain

The purpose of this retrospective cross-sectional study was to examine the degrees of the cervical disc degeneration and the parameters of cervical sagittal balance in plain radiographs, representing cervical lordosis or head posture in subjects with posterior neck pain. A total of 113 patients with posterior neck pain with or without radiating pain were analyzed. The kinematic sagittal parameters of cervical radiographs were obtained at the occipito–cervical (O–C2) angle, sagittal Cobb’s angles of C1–C2, C2–C7, and sagittal vertical axis (SVA) of C1–C7 and C2–C7. Cervical disc degeneration was evaluated using the sum of Pfirrmann grades and total modified Matsumoto scores calculated from MRI of the cervical spine. A significant positive correlation was found for the C2–C7 angle using the sum of the Pfirrmann grades and total modified Matsumoto scores, whereas the O–C2 angle and the C1–C2 angle were negatively correlated. The sagittal cervical parameters representing cervical kyphosis and jaw lifting posture were found to be significantly correlated with the degree of cervical disc degeneration. These findings suggest that the loss of the natural sagittal lordosis of the cervical spine may contribute to the progression of disc degeneration, rather than the forward head posture.