Laminectomy
Laminectomy is one of the most common procedures performed in patients over 50 years of age. It is used to treat spinal stenosis. An incision is made over the interspace, and the muscles are moved to the side. Approximately half of the spinous process of the upper vertebra is removed in order to open the space around the nerves. The ligamentum flavum and facet overgrowths are carefully removed. This procedure typically includes a “partial facetectomy” (removal of the anterior facet bone spurs) and “foraminotomy” (opening the space where the nerves exit). The thecal sac (containing the nerves) can move posteriorly away from the disc protrusions.
  Moderate Spinal Stenosis  
Laminotomy
Laminotomy is essentially half of a laminectomy. The spinous process is left intact with the interspinous ligaments. Typically only one side of the vertebra is exposed, although both sides can be treated through the same or separate incisions.
Laminectomy     Laminotomy
In a laminectomy, the area in green is removed. The biggest area of narrowing is the ligamentum flavum. In a laminotomy, the area in orange is removed. The spinous process is left intact.