K-line tilt as a novel potential risk factor for cervical Modic change: a retrospective study

BACKGROUND: Cervical sagittal parameters are important parameters that reflect the mechanical stress in the sagittal plane of the cervical spine and are an important basis for predicting the clinical status and prognosis of patients. Although it has been confirmed that there is a significant correlation between cervical Modic changes and some sagittal parameters. However, as a newly discovered sagittal parameter, there is no report on the relationship between the K-line tilt and the Modic changes of cervical spine. METHODS: A retrospective analysis was performed for 240 patients who underwent cervical magnetic resonance imaging scan for neck and shoulder pain. Among them, 120 patients with Modic changes, namely the MC(+) group, were evenly divided into three subgroups of 40 patients in each group according to different subtypes, namely MCI subgroup, MCII subgroup and MCIII subgroup. One hundred twenty patients without Modic changes were included in MC(−) group. We measured and compared the sagittal parameters of cervical spine among different groups, including K-line tilt, C2–C7 sagittal axial vertical distance (C2–C7 SVA), T1 slope and C2–7 lordosis. Logistic regression was used to analyse the risk factors of cervical Modic changes. RESULTS: The K-line tilt and C2–7 lordosis were significantly different between MC(+) group and MC(−) group (P < 0.05). The K-line tilt greater than 6.72° is a risk factor for Modic changes in cervical spine (P < 0.05). At the same time, the receiver operating characteristic curve showed that this change had moderate diagnostic value when the area under the curve was 0.77. CONCLUSION: This study shows that the K-line tilt greater than 6.72° is a potential risk factor for Modic changes in cervical spine. When the K-line tilt is greater than 6.72°, we should be alert to the occurrence of Modic changes. Trial registration number: 2022ER023-1.