Definition

Back pain is a common complaint. Four out of five people in the United States will experience low back pain at least once during their lives. It's one of the most common reasons people go to the doctor or miss work.

On the bright side, you can prevent most back pain. If prevention fails, simple home treatment and proper body mechanics will often heal your back within a few weeks and keep it functional for the long haul. Surgery is rarely needed to treat back pain.

Causes

Your back is an intricate structure composed of bones, muscles, ligaments, tendons and disks — the cartilage-like pads that act as cushions between the segments of your spine. Back pain can arise from problems with any of these component parts. In some people, no specific cause for their back pain can be found.

Strains
Back pain most often occurs from strained muscles and ligaments, from improper or heavy lifting, or after a sudden awkward movement. Sometimes a muscle spasm can cause back pain.

Structural problems
In some cases, back pain may be caused by structural problems, such as:

• Bulging or ruptured disks. Disks act as cushions between the vertebrae in your spine. Sometimes, the soft material inside a disk may bulge out of place or rupture and press on a nerve. But many people who have bulging or herniated disks experience no pain from the condition.
• Sciatica. If a bulging or herniated disk presses on the main nerve that travels down your leg, it can cause sciatica — sharp, shooting pain through the buttock and back of the leg.
• Arthritis. The joints most commonly affected by osteoarthritis are the hips, hands, knees and lower back. In some cases arthritis in the spine can lead to a narrowing of the space around the spinal cord, a condition called spinal stenosis.
• Skeletal irregularities. Back pain can occur if your spine curves in an abnormal way. If the natural curves in your spine become exaggerated, your upper back may look abnormally rounded or your lower back may arch excessively. Scoliosis, a condition in which your spine curves to the side, also may lead to back pain.
• Osteoporosis. Compression fractures of your spine's vertebrae can occur if your bones become porous and brittle.

Rare but serious conditions
In rare cases, back pain may be related to:

• Cauda equina syndrome. This is a serious neurological problem affecting a bundle of nerve roots that serve your lower back and legs. It can cause weakness in the legs, numbness in the "saddle" or groin area, and loss of bowel or bladder control.
• Cancer in the spine. A tumor on the spine can press on a nerve, causing back pain.
• Infection of the spine. If a fever and a tender, warm area accompany back pain, the cause could be an infection.