Pain is considered chronic once it lasts for more than three months. Chronic back pain often involves a disc problem, a joint problem, and/or an irritated nerve root.
Common causes can be:
Lumbar herniated disc.
The soft center of a lumbar disc can break through the tough outer layer and irritate a nearby nerve root. The herniated portion of the disc contains proteins that cause inflammation when they reach a nerve root, and nerve compression cause nerve root pain. The disc wall is also supplied by nerve fibers, and a tear through the wall can cause pain.
Degenerative disc disease.
As people grow older, discs lose water content and wear down. As the disc loses hydration, it less pliable to forces and transfers force to the disc wall that may develop degeneration and cause pain or weakening that can lead to a herniation. The disc can also collapse and add to stenosis.
Facet joint dysfunction.
There are two facet joints behind each disc in the lumbar spine. These joints have cartilage between the bones and are surrounded by a capsule, which is innervated by nerves. These joints can be painful if injured in conjunction with disc pain.
Sacroiliac joint dysfunction.
The sacroiliac joint connects the sacrum at the bottom of the spine to each side of the pelvis ring. It is a strong joint that primarily absorbs shock and tension between the upper body and the lower. The sacroiliac joint can become painful if it becomes inflamed or if there abnormal motion of the joint.
Spinal stenosis.
This condition causes pain through narrowing of the spine where the nerve roots are located. The narrowing can be at a single or multiple levels in the lower back.
Spondylolisthesis.
This condition occurs when one vertebra slips over the one above or below. There are 5 types of spondylolisthesis that can cause mechanical instability of the facet joints. The pain can be caused by instability or compression of the nerves.