Study design: A prospective study was conducted to investigate the outcome of the Modic Type 1 inflammatory signal in magnetic resonance imaging (MRI) in 17 patients with chronic low back pain 6 months after instrumented posterior lumbar arthrodesis.
Objective: To assess the course of the inflammatory signal after stabilization of a painful intervertebral segment by posterior instrumentation alone visualized on MRI systematically performed 6 months after the operation.
Summary of background data: In 1988, Modic and colleagues described three degenerative stages of vertebral endplates and subchondral bone. The inflammatory stage, or Stage 1, is correlated with substantial functional disability. According to these authors, Stage 1 lesions naturally transform into Stage 2, the fatty stage. In the literature, patients with Modic 1 signal tend to have good results after arthrodesis, better than those with Modic 2 lesions.
Methods: This study included 17 patients (average age, 46 years) who had experienced chronic low back pain more than 1 year and showed Modic 1 changes in MRI and disc narrowing on plain radiographs. Every patient underwent posterior screw-rod osteosynthesis and posterolateral arthrodesis. Disc disease had occurred subsequently to discectomy (n = 7), rapidly destructive disc disease (n = 5), or spondylolisthesis resulting from spondylolysis (n = 5). Clinical results were assessed according to a visual analog scale for pain, a functional disability score for the evaluation of patients with low back pain (Eiffel), and the validated French version of the self-administered Dallas quality-of-life test (DRAD).
Results: Systematic MRI at 6 months showed transformation from Modic 1 to Modic 0 (normal endplate signal) in 4 patients and transformation from Modic 1 to Modic 2 in the remaining 13 patients. Clinical evaluation was performed at 6 months (at the same time as the MRI) and at 1 year. In every patient, there was improvement in the visual analog score and the functional score, which remained stable at 1 year.
Conclusions: According to the literature, most Modic 1 lesions change to become Stage 2 lesions in 18 to 24 months. In this study, 17 patients with Modic Type 1 signal had changes after 6 months. It appears that posterior osteosynthesis combined with posterolateral arthrodesis accelerates the course of Modic 1 lesions, probably by correcting mechanical instability.