5/2/15
Vertebral subchondral bone marrow changes visible on magnetic resonance imaging (MRI), known as modic changes, of the M1 type are positively correlated with low back symptoms. Type 1 modic changes show decreased signal intensity on T1-weighted images and increased signal intensity on T2-weighted images.
In a 2-year study examining modic changes and low back symptoms, Finnish researchers led by Jyri Jarvinen at Oulu University Hospital, found positive associations between M1 type changes and changes in the intensity of low back pain and in disability.
“Our results suggest a statistically significant association between M1 and low back symptoms … Our findings support the observation that M1 has a stronger association with low back pain than other types of modic changes,” they state online in BMC Musculoskeletal Disorders.
The findings “lend support to the hypothesis that low back pain patients with M1 represent a specific subgroup of patients with low back pain,” they conclude.
Sixty-four patients with chronic low back pain with M1 in the lumbar spine on MRI were followed for 2 years. The size and type of modic changes on sagittal lumbar MRI and low back symptoms were recorded at baseline and at the 2-year follow-up. The Oswestry Disability Index was obtained by patient-completed questionnaire. Patients’ mean age at baseline was 43.8 years.
At baseline, most modic changes were located at L4/5 or L5/S1 (39% and 49%, respectively). The mean size of the modic change in relation to vertebral volume at baseline was 20.7%, and at the 2-year follow-up, the mean size was 24.4%. The mean proportion of the M1 component within the modic change was 74.2% at baseline and 40.6% at follow-up, and the mean proportion of the M2 component was 23.9% at baseline and 56.2% at follow-up.
At baseline, the mean low back pain intensity was 6.5 using a visual analog scale (VAS) of 0 (no pain) to 10 (worst pain possible). The mean Oswestry Disability Index at baseline was 33%, which uses a scale of 0% (no disability) to 100% (very severe disability).
Both low back pain intensity and Oswestry Disability Index were more likely to decrease than increase during follow-up. At 2 years, the mean low back pain intensity declined to 5.2 and the mean Oswestry Disability Index dropped to 28%. The intensity of low back pain increased in 15 patients (23%) and decreased in 41 patients (64%), and the Oswestry Disability Index increased in 19 patients (30%) and decreased in 44 patients (69%).
Change in the extent of M1 had positive associations with changes in low back pain intensity (beta 0.26, P=0.036) and Oswestry Disability Index (beta 0.30, P=0.017). For a 50% decrease in the extent of M1, low back pain intensity decreased 2.4 units on the VAS, and disability decreased 11.7 units on the Oswestry Disability Index. For a 10% decrease in the extent of M1, the corresponding estimates were -1.3 on the VAS and -5.3 on the Oswestry Disability Index.
When adjusted for age, gender, and size of modic change at baseline, the association between the change in the extent of M1 and low back pain intensity became nonsignificant (P=0.284), whereas the association between the change in the extent of M1 and Oswestry Disability Index remained significant (P=0.003).
Conversely, change in the extent of M2 had a negative association with changes in low back pain intensity (beta -0.24,P=0.054) and Oswestry Disability Index (beta -0.125, P=0.306), although neither were statistically significant.
In patients with low back pain and modic changes, treatment with amoxicillin-clavulanate and zoledronic acid was effective in reducing pain intensity in separate studies, but “more research must be carried out to replicate both treatment interventions,” the authors of the current study wrote.
Limitations include the small study population and the exclusion of potentially relevant changes from other disc levels, requiring recruitment of patients from multiple sites with different MRI equipment. Also, the potential influence of other degenerative findings, pain medications and treatments, education level, comorbidities, and other psychosocial elements on low back pain symptoms was not analyzed.
The authors declare no competing interests.
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