Musculoskeletal strain: This is the most common cause of non-traumatic low back pain, often resulting from overuse, poor posture, or sudden awkward movements. It affects the muscles and ligaments in the back.

Herniated disc: A condition where the soft inner gel of the disc leaks out through a tear in the outer layer, putting pressure on nerves and causing pain.
Degenerative disc disease: A condition where the spinal discs lose their cushioning ability and can cause pain due to the reduced space between the vertebrae.
Spondylosis: A defect in the pars interarticularis, the thin piece of bone that connects the superior and inferior articular facets of the spine, which can lead to low back pain.
Osteoarthritis: Wear and tear of the spinal joints, leading to pain and stiffness in the lower back.

Cauda equina syndrome: A serious condition where the nerves in the spinal canal are compressed, leading to severe pain, numbness, and potentially permanent nerve damage if not promptly treated.
Spinal infection (e.g., osteomyelitis, discitis): Infections of the spine that can cause severe pain and have serious consequences if not treated promptly.
Spinal tumor: Abnormal cell growth in the spine, which can compress nerves and cause pain.
Abdominal aortic aneurysm: A bulge in the main blood vessel that leads from the heart and passes through the abdomen, which can cause back pain if it ruptures.

Spondylolisthesis: A condition where one of the vertebrae slips forward over the bone below it, which can cause low back pain.
Paget's disease of bone: A chronic condition that can result in enlarged and misshapen bones, leading to pain and potential nerve compression.
Osteoporotic compression fracture: A fracture in a vertebra caused by osteoporosis, leading to sudden back pain.
Inflammatory diseases (e.g., ankylosing spondylitis): Chronic inflammatory diseases that can cause pain and stiffness in the lower back.