A spinal disc herniation, informally and misleadingly called a “slipped disc”, is a medical condition affecting the spine due to trauma, lifting injuries, a tear in the outer fibrous ring of an intervertebral disc.
Tears are almost always postero-lateral in nature owing to the presence of the posterior longitudinal ligament in the spinal canal. This tear in the disc ring may result in the release of inflammatory chemical mediators which may directly cause severe pain, even in the absence of nerve root compression. This is the rationale for the use of anti-inflammatory treatments for pain associated with disc herniation, protrusion, bulge, or disc tear.
It is usually a further development of a previously existing disc protrusion, a condition in which the outermost layers of the annulus fibrosus are still intact, but can bulge when the disc is under pressure.