Kinematics of an intervertebral disc with type 1 Modic change: mechanical and non-mechanical causes

抄録

Purpose:Type 1 Modic change (MC) is associated with chronic low back pain and attributed to segmental instability. However, the relationship between type 1 MC and segmental instability is unclear. This study sought to clarify the role of mechanical abnormalities in type 1 MC. Method:Review of magnetic resonance images obtained for 727 patients over a 1-year period at our institution revealed 161 cases of type 1 MC. In 86 of these, the following indicators of mechanical abnormality could be evaluated on dynamic radiographs:segmental scoliosis (>5°), forward slippage (>1%), and posterior disc opening in flexion. Patients with one or more of these abnormalities were allocated to a mechanical group (n=62, 70%) and those with no abnormality to a non-mechanical group (n=26, 30%). The Pfirrmann grade of disc degeneration at the affected level was compared between the groups. Results:Segmental scoliosis, slippage, and posterior opening was observed in 34, 21 and 37 cases, respectively. Severe disc degeneration (grade IV or V) was present in 43 cases (69%) in the mechanical group and in 12 cases (46%) in the non-mechanical group;the difference was statistically significant (p=0.04). Conclusion:We propose that there are mechanical and non-mechanical variants of type 1 MC. J. Med. Invest. 72 : 385-389, August, 2025