For back pain sufferers, surgery isn't always the answer

The spine is a stack of bony vertebrae separated by gel-filled discs that act as shock absorbers. "It's one of the major ways the human body fails," says Dr. Aaron Filler, a spinal surgeon in Santa Monica. In part, back pain is the price mankind pays to stand upright. When the spine is horizontal, as it is in a four-legged animal, additional weight causes the vertebrae to spread out. But in people, more weight pushes the vertebrae and discs together -- and there is only so far the structure can compress.

Over time the effects of aging, use and gravity wear on the spine, making the 40-plus crowd most susceptible to back pain, though injury or stress can occur at any age.

Back pain is a symptom with many possible causes. Sprains, muscle tears and spasms are common. The discs, which cushion the vertebrae, can also suffer injury. In a herniated disc, the gel inside leaks out and irritates nearby nerves. Or the disc's outer layer merely thins, allowing the gel inside to form a bulge, which may also poke a nerve.

The joints between vertebrae, called facet joints, are susceptible to wear and tear, particularly in people with arthritis. The joint's cushioning cartilage can wear thin and the bone can jut out, causing pain in the back and thighs.

And as discs or bone protrude past their normal locations, the interior of the spine can narrow, putting pressure on nerves in a condition called stenosis.

Older people are more susceptible to back pain as are pregnant women, who carry added weight on the spine. Children, however, are not likely to suffer back pain without an obvious injury as the cause. "If I see a teenager with back pain, it really raises red flags," says chiropractor Robert Hayden of Griffin, Ga.

Hayden believes part of the rise in back pain patients has to do with the personal computer. Leaning over to type or peer at the screen strains the extensor muscles in the neck and the trapezius and rhomboid muscles that hold up the shoulders. The extensors, in particular, are small, thin muscles, and with too much use they can run out of oxygen, causing irritation or spasms.

The postural muscles in the lower spine, such as the quadratus lumborum, can also get sore if a person leans forward or slumps for a long time.

Being inactive can contribute to back problems because the body's core muscles -- the back and abdominal muscles that hold up the torso -- weaken and become more susceptible to tears or pulls. Weak muscles can also cause problems by forcing the spine to support extra weight -- as does obesity.