Abstract
Introduction
The usefulness of markers of non-specific low back pain (NSLBP), including MRI derived measurements of cross-sectional area (CSA) and functional CSA (FCSA, fat free muscle area) of the lumbar musculature, is in doubt. To our knowledge, such markers remain unexplored in Lumbar Disc Degeneration (LDD), which is significantly associated with NSLBP, Modic change and symptom recurrence. This exploratory 3.0-T MRI study addresses this shortfall by comparing asymmetry and composition in asymptomatic older adults with and without Modic change.
Methods
A sample of 21 healthy, asymptomatic subjects participated (mean age 56.9 years). T2-weighted axial lumbar images were obtained (L3/L4 to L5/S1), with slices oriented through the centre of each disc. Scans were examined by a Consultant MRI specialist and divided into 2 groups dependent on Modic presence (M) or absence (NM). Bilateral measurements of the CSA and FCSA of the erector spinae, multifidus, psoas major and quadratus lumborum were made using Image-J software. Muscle composition was determined using the equation [(FCSA/CSA)*100] and asymmetry using the equation [(Largest FCSA-smallest FCSA)/largest FCSA*100]. Data were analysed using Mann-Whitney U tests (p value set at). Intrarater reliability was examined using Intraclass Correlations (ICCs).
Results
ICCs ranged between 0.74 and 0.96 for all area measurements, indicating excellent reliability. There was no significant difference in TCSA and FCSA asymmetry (P=0.1–1.0) and muscle composition (P=0.1–1.0) between M and NM groups.
Conclusion
Modic change in the absence of pain does not appear to influence cross-sectional asymmetry or composition of the lumbar musculature. CSA remains a controversial marker.
No conflicts of interest.
Funding: This work is funded by an Allied Health Professional Doctoral Fellowship awarded to Janet Deane by Arthritis Research U.K.
