CORRELATION BETWEEN THE MODIC I SIGN AND IMAGES OF VERTEBRAL INSTABILITY

ABSTRACT The lumbar region is highly affected by degenerative diseases and can be symptomatic as a result of inflammatory processes of the disc or segmental vertebral instability (SVI), according to concepts by White and Panjabi. Magnetic resonance imaging (MRI) and dynamic radiographs can be used to evaluate it. Objective: To determine whether images of Modic type I lesions are compatible with radiological vertebral instability. Methods: The MRIs and dynamic radiographs of 100 patients with a mean age of 46.94 years, 65 of whom were women and 35 of whom were men, were studied to evaluate the reaction of endplates according to Modic and SVI at levels L2-L3, L3-L4, L4-L5 and L5-S1. They were divided into 3 groups: A- Modic I and SVI; B- Modic I without SVI; and C- Without Modic I and SVI. Sex, age and type of disc were evaluated. Result: 46 Modic I lesions and 24 cases of SVI were recognized. There were 5 patients in Group A (OR 0.23, p=0.006), 38 in Group B; and 19 in Group C. No direct relationship between age and Modic I and/or SVI was observed. Pfirrmann grade 5 discs are 4.6 times more likely to present a Modic I signal. The most affected disc was L3-L4 for the Modic signal and L4-L5 with respect to the SVI, translational instability being more frequent. Conclusions: Modic type changes, identified by magnetic resonance, are clinically relevant in relation to low back pain, but their presence does not confirm either translational or angular instability. Level of evidence III; Cross-sectional cohort.