First, Let’s Understand The Normal Disc For Lumbar

All disc injuries begin with a traumatic tear of the annulus fibrosus ring. An annular tear occurs when traumatic forces on the disc exceed its elastic property limits and cause structural failure of the annulus fibrosus and nucleus pulposus. At the moment of structural failure, linear annular tears occur in the wall of the disc while the adjacent nucleus pulposus is crushed into multiple fragments. Although not all annular tears immediately result in a disc herniation, the tear is a weakened area of the disc wall prone to herniations of the adjacent fragmented nucleus pulposus.

Disc herniations occur when fragments of damaged nucleus pulposus are pushed into the annular tear during physical activities like bending, lifting, twisting, sports, and work. Once herniation of a fragment of nucleus pulposus into the annular tear occurs, the annular tear can no longer heal itself closed. In fact, fragments of nucleus pulposus embedded within the annular tear prevent healing and closure of the annular tear. Over time more pieces of the damaged nucleus pulposus push out into the non-healed annular tear and the herniation gets bigger.

Discogenic back pain may occur once the herniated fragments of nucleus pulposus reach the outer 1/3 of the posterior annulus fibrosus. The inner 2/3 of the annulus fibrosus normally has no blood vessels, no blood supply and no innervation. Nucleus pulposus fragments present within the outer 1/3 of the annular tear will trigger the body’s inflammatory defense system to turn “on” and begin to attack the pieces of herniated nucleus pulposus. The resulting inflammation within the walls of the posterior annular tear of an injured disc is the source of discogenic back pain (pain generator). When the inflammation spreads to nearby nerve roots it causes sciatica (radiculitis). Inflammation lasting weeks or months within the annular tear further weakens the wall and makes the disc more susceptible to reherniation. Untreated, the annular tear remains open and vulnerable to additional herniation, inflammation and pain occurring in cycles over a lifetime.

Discogenic pain is localized pain that originates from a specific injured spinal disc. The source of discogenic pain is inflammation within the posterior annular tear of the injured disc. Inflammation is a normal part of healing any injury. In this case, the annular tear is the injury that needs to heal. Unfortunately, the fragments of herniated nucleus pulposus stuck within the walls of the posterior annular tear prevent the tear from healing completely. Because the annular tear remains unhealed and “open”, more herniations occur and the cycle of inflammation and pain goes on. Discogenic pain can last for decades and is the most common cause of chronic lower back pain.