Do Modic changes affect cervical sagittal alignment and motion in symptomatic patients?

The cervical segmental instability often occurs simultaneously with Modic changes (MCs). However, it is unknown whether there is a relation between the two diseases. The aim of this study was to evaluate the relationship between MCs and cervical segmental instability, cervical curvature and range of motion (ROM) in the cervical spine. A total of 464 patients with neck pain or cervical neurologic symptoms who underwent imaging examination were analyzed retrospectively. Based on MRI imaging cervical MCs were diagnosed, and patients were divided into with or without MCs groups. The cervical curvature and range of motion were measured. We compared the incidence of cervical instability, cervical curvature and ROM between the two group patients and their relationships with MCs were studied. Logistic regression was used to study the risk factors associated with MCs. MCs were observed in 94 of 464 patients and 122 of total 2320 cervical segments and were most frequent at C5-6 segment. The incidence of the cervical instability was significantly higher in patients with MCs than those without MCs at cervical level C3-7. In addition, cervical curvature and ROM in patients with MCs were less than those without MCs. Logistic regression analysis showed that the occurrence of cervical spine instability, less cervical curvature and ROM were risk factors for MCs. Patients with MCs were prone to have cervical instability at the same cervical level and may have a higher possibility of less cervical curvature and ROM.