Lower back pain becomes more common with age. In fact, they affect more than half of people over 60 years old. They are very expensive in terms of reimbursement of medical expenses, disability benefits and absenteeism at work. The number of work-related back injuries is decreasing, perhaps due to an awareness of this problem and the improvement of preventive measures.

The spine (vertebral column) is composed of vertebrae. The vertebrae are covered with a thin layer of cartilage, separated and protected by shock-absorbing disks consisting of a gelatinous material and fibrocartilage. They are held in place by ligaments and muscles, namely:

• Two iliopsoas muscles, which run along both sides of the column
• Two erector muscles of the spine, which run along the back of the spine
• Many short paraspinal muscles that pass between the vertebrae

These muscles help stabilize the column. The abdominal muscles (which extend from the lower part of the rib cage to the pelvis) also help stabilize the spine by supporting the abdominal contents.

Inside the spine is the spinal cord. Along the spinal cord laterally emerge the spinal nerves through spaces formed between the vertebrae to connect to all the nerves of the body. The part of the spinal nerve closest to the spinal cord is called the root. Given their situation, the roots of the spinal nerves can be compressed (compressed) in case of injury of the spine, inducing pain.

Lower back pain is only one symptom whose causes are very varied. In nearly 90% of cases, low back pain is benign, or “nonspecific”. This means that there is no major lesion that can explain the pain. These can then be linked to the intervertebral discs, vertebrae, muscles, etc. Most of the time, it is impossible to accurately determine the origin of pain, which disappear spontaneously in a few weeks.

For this reason, the doctor will not prescribe imaging tests (x-ray, scan, magnetic resonance) when the situation is clearly nonspecific, with no disturbing features. In other cases, especially in the presence of neurological symptoms, imaging is indicated. In rare cases, low back pain can be a sign of serious illness.

Here are the most common causes of pain.

An injury to a muscle, tendon or ligament. It can come from an effort, an unusual twist or the accumulation of microlesions caused by repetitive movements. People in bad physical shape or exercising physical trades (construction, carrying heavy loads …) are most at risk.

Disc degeneration. With aging, the intervertebral discs lose their elasticity. There is disc degeneration in almost all people over 60 years. Some athletes also experience this problem around midlife, especially those who practice an activity resulting in pressure on the spine. This degeneration is not always associated with pain, but it can be involved in some low back pain.

A herniated disc. It occurs when a portion of the gel contained in the intervertebral disc protrudes outwardly and compresses the nerve roots. Poor postures, excess weight, pregnancy and disc degeneration are the main causes of disc herniation.

A gynecological problem. Many women have periodic or constant back pain due to painful periods, endometriosis, etc. The source of the pain is not located in the lumbar region, but the pain still radiates in the lower back.

The sliding of a vertebra on another vertebra (spondylolisthesis). This situation can occur because of congenital weakness in the vertebral structures or as a result of trauma.

Arthritis, osteoarthritis or osteoporosis. These health problems are common in the elderly. If osteoporosis of the spine is important, it can cause a vertebral fracture. Some inflammatory rheumatism, such as ankylosing spondylitis, can also cause pain and stiffness in the lower back.

In rare cases, low back pain can be caused by an abdominal aortic aneurysm, tumor, osteoporosis-related fracture, or infection.

Regardless of the origin of the back pain, there is often a contraction of muscles located near the sore area. This is a protective reflex. This contraction can itself cause pain. A vicious circle can then trigger and contribute to chronic pain.