Multifidus muscles (MF) atrophy are common in patients with Low back pain (LBP). Degenerative diseases of the lumbar spine, such as disc herniation, disc degeneration and facet joint osteoarthritis, are leading cause of LBP. Various studies have previously focused on the relationship between MF atrophy and disc degeneration, disc herniation. However, the results are inconsistent. Besides, no study for the correlation between MF atrophy and facet joint osteoarthritis has previously been conducted. This study will investigate the correlation between MF atrophy and disc degeneration, disc herniation, facet joint osteoarthritis using MRI.