The vertebrae provide the structural support for the back. The facet joints attached to the vertebrae control the amount and direction of movement. The discs are soft cushions that separate the vertebrae and absorb shock as we move. Each disc has a spongy center (nucleus) and a tough outer ring which contains pain fibers.
Movement of fluid within the nucleus allows the vertebrae to rock back and forth on the discs. Over time, the discs wear out from natural aging. Poor posture, slumped sitting, forward bending and lifting can cause them to wear out early.
As the discs narrow and dry out, the vertebrae move closer together and become irritated. The nerves exit the openings between the vertebrae. Bony outgrowths (spurs) may form, narrowing the opening for nerves, a process called “stenosis” thus irritating the nearby nerve.
Muscles surrounding the vertebrae can become shortened and tight, causing irritation of the nerves exiting the spine as they form the sciatic nerve, passing through the buttocks to branch off to the feet.
Discs can develop bulges due to weakness of the outer rings of the disc, placing pressure on the nerves along with muscle tightness, thus causing leg pain. The prevalence of bulges increases with age.
A disc bulge is similar to a bulge in your car tire. You can drive the car, but not at 75 mph over bumpy roads. The same goes for your body – excessive activity can cause leg pain. A bulge that herniates loses fluid from the disc, becoming like a flat tire.
Pain and paresthesia (tingling and numbness) radiating to the leg may be an indication of sciatic involvement of a bulging or herniation of a disc. Severe back and leg pain may occur without associated disc herniation, as well as leg pain only.
The sciatic nerve passes through muscles which may be extremely tight,placing pressure on the nerve. It is estimated that only 5% to 10 % of individuals with sciatica require surgery.
Avoid positions that increase leg pain. Positions and exercises that decrease leg pain and do not significantly increase low back pain should be emphasized. Back pain may increase as leg symptoms decrease. This is a sign of improvement.