Geography of lumbar paravertebral muscle fatty infiltration

Study Design: Cross-sectional Objective: We quantified fatty infiltration (FI) geography of the lumbar spine to identify whether demographics, temporal low back pain (LBP), and disability influence FI patterns. Summary of Background Data: Lumbar paravertebral muscle FI has been associated with age, sex, LBP, and disability; yet, FI accumulation patterns are inadequately described to optimise interventions. Methods: This cross-sectional study employed lumbar axial T1-weighted MRI in 107 Southern-Chinese adults (54 females, 53 males). Single-slices at the vertebral inferior end-plate per lumbar level were measured for quartiled-FI, and analysed against demographics, LBP, and disability (ODI: Oswestry Disability Index). Results: Mean FI% was higher in females, on the right, increased per level caudally, and from medial to lateral in men (p 0.05). Conclusions: Lumbar paravertebral muscle FI predominates in the lower lumbar spine, notably for those aged 40-65, and depends more on sagittal than transverse distribution. Higher FI in females and differences of mean FI between sexes for BMI, LBP, and disabling ODI suggest sex-differential accumulation patterns. Our study contradicts pain models rationalising lumbar muscle FI and may reflect a normative sex-dependent feature of the natural history of lumbar paravertebral muscles