When arthritis affects the lower back, this is known as lumbar arthritis. The most common cause of lumbar arthritis is osteoarthritis (OA).
The spine is divided into five sections — the cervical, thoracic, lumbar, sacrum, and coccyx. Lumbar arthritis affects the lumbar portion of the spine, or lower back, which is situated just above the pelvis.
The lower back is the most common area for arthritis-related back pain.
Lumbar spine osteoarthritis is very common, affecting an estimated 30% of males and 28% of females aged 55–64 in the United States.