Low back pain (sometimes referred to generally as lumbago) is a common symptom of musculoskeletal disorders or of disorders involving the lumbar vertebrae and related soft tissue structures such as muscles, ligaments, nerves and intervertebral discs. It can be either acute, subacute or chronic in its clinical presentation. Most often, the symptoms of low back pain show significant improvement within a few days to a few weeks from onset. In a significant number of individuals, low back pain can be recurrent in nature with a waxing and waning quality to it. In a small proportion of individuals this condition can become chronic. Population studies show that back pain affects most adults at some stage in their life and accounts for more sick leave and disability than any other single medical condition.
An acute lower back injury may be caused by a traumatic event, like a car accident or a fall. It occurs suddenly and its victims will usually be able to pinpoint exactly when it happened. In acute cases, the structures damaged will more than likely be soft tissue. With a serious accident, osteoporosis or other causes of weakened vertebral bones, vertebral fractures in the lumbar spine may also occur. At the lowest end of the spine, some patients may have tailbone pain (also called coccyx pain or coccydynia). Others may have pain from their sacroiliac joint at the bottom of the lumbar spine, called sacroiliac joint dysfunction (see sacroiliac joint for more information). Chronic lower back pain usually has a more insidious onset, occurring over a long period of time. Physical causes may include osteoarthritis, rheumatoid arthritis, degeneration of the discs between the vertebrae, or a spinal disc herniation, a vertebral fracture (such as from osteoporosis), or rarely, a tumor (including cancer) or infection.