Defined as a defect or stress fracture in the pars interarticularis of the vertebral arch.


Slippage of one vertebra over another. The word “spondy” means vertebra and the word “olisthesis” means slippage in Ancient Greek. When a vertebra slips forward in relation to the vertebra below, it is called an anterolisthesis. If a vertebra slips backwards compared to the vertebra below, it is called a retrolisthesis. A spondylolisthesis is usually caused by degenerative conditions. A spondylolysis (pars fracture) can also cause a spondylolisthesis

Spinal Stenosis

The word “stenosis” means narrowing in Ancient Greek. Spinal stenosis is any condition that causes narrowing of the spinal canal or foramen. This term is usually used to refer to narrowing from bone spurs, a thickened ligamentum flavum, and cysts. However, disc herniations technically can cause spinal stenosis since they can narrow the spinal canal and/or foramen. 

Spinal Cord Stimulator

An electrical device surgically implanted to apply low voltage stimulation to the spinal cord to block the feeling of pain.

Sequestration (of Disc)

A specific type of herniated disc in which a large amount of disc material breaks through the outer rings of the annulus into the spinal canal, usually causing extreme pressure on nerve(s). In this type of herniation, the herniated fragment is completely separated from the intact portion of the nucleus pulposus.

Sciatic Nerve

The largest nerve in the body arising from the sacral plexus on both sides of the spine, passing from the pelvis through the sciatic foramen, down the back of the thigh where it divides into the lower leg, ankle, and foot.

Scar tissue

Fibrotic tissue that is vascular, pale, contracted and occurs with healing.


The large triangular bone at the bottom of the pelvis, inserted like a wedge between the two hip bones. It moves with the last lumbar vertebra and coccyx (tailbone).


Pertaining to the sacrum.