About Low Back Pain: Causes
There are hundreds of diseases and injuries that can cause back pain. If back pain comes on suddenly, it's usually a sign of a muscle tear, sprained ligament, or ruptured disc. The spine contains intervertebral discs, a kind of cushion made of cartilage that fits between two vertebrae (bone segments). A slipped disc is a condition in which pressure on a disc causes it to rupture, pushing cartilage sideways. The cartilage presses on the spinal cord nerves, causing intense pain.
Pregnancy can also cause back pain, both because of the extra weight and because the baby's head can compress spinal nerves. Overweight people are also more prone to back pain due to the extra strain on discs and muscle.
In older people, the vertebrae themselves may spontaneously fracture. This can be the result of diseases that affect the bone, the most common being osteoporosis. That's why these diseases can make people shorter with age. Sometimes these fractures cause no pain.
Because of the wiring of the nervous system, diseases in other parts of the body can manifest themselves as back pain. Pyelonephritis, the most common kidney disease, causes back pain as well as fever.
Sciatica is not a disease, but rather pain that follows the path of the sciatic nerve into the lower back. It can be triggered by a slipped disc, or more rarely by a degenerative disease like osteoarthritis.
Young people, especially men, who start to develop recurring back pain in their 20s, 30s, or 40s may have ankylosing spondylitis or a similar disease. Ankylosing spondylitis causes the vertebrae to slowly fuse together, causing pain and stiffness. Fortunately, it responds well to modern treatments, and is less likely to cause disability than in the past.