The American Academy of Orthopaedic Surgeons explains that a herniated disc in the L5-S1 section of the spine consists of ruptured material between two vertebrae: the lumbar in the lower back and the sacrum in the pelvic area. This lumbosacral joint is most prone to injury because it bears the most weight, according to Spine Health.
Vertebrae are bony structures that support the spine. They are separated by softer material in the form of discs that act as shock absorbers. When a disc ruptures, the jelly-like nucleus pushes against the outer-ring, called the annulus fibrosus, and causes inflammation and pain. Once the nucleus of the disc breaks through the outer-ring, the pain often lessens. However, if the disc material continues to irritate the sciatic nerve, the pain can persist. Although 60 to 80 percent of people experience lower-back pain at some point, most recover without surgery, notes the American Academy of Orthopaedic Surgeons.
Aging discs are more apt to become herniated, as they lose water content over time, and the space between the vertebrae shrinks. Other risk factors include lifting heavy objects improperly and repetitive actions that put strain on the lower back. Sitting for long periods of time, sedentary lifestyles and smoking are also associated with herniated discs, according to the American Academy of Orthopaedic Surgeons.