A lumbar laminectomy is also known as an open decompression and is typically performed to alleviate pain caused by neural impingement that can result from lumbar spinal stenosis. A condition that primarily afflicts elderly patients, spinal stenosis is caused by degenerative changes that result in enlargement of the facet joints. The enlarged joints then place pressure on the nerves, and this pressure may be effectively relieved with the laminectomy.
The lumbar laminectomy is designed to remove a small portion of the bone over the nerve root and/or disc material from under the nerve root to give the nerve root more space and a better healing environment.
This procedure is done through a skin incision along the middle of the low back. After the incision through the skin, the lumbar muscles are visualized and these are pushed to the sides to visualize the back of the spinal bones. The most prominent bone initially seen is the spinous process which flows down towards the spinal lamina. After completion of the exposure, a sharp cutting instrument called a Leksell rongeur is used to remove the spinous processes and a portion of the spinal lamina. By thinning down the lamina, small angled instruments called curettes can be used to find the space in between the undersurface of the lamina and the covering of the spinal nerves. Once this space is found, an instrument called a Kerrison rongeur is used to remove the spinal lamina in small pieces. Care is taken at all times not to damage the dura or the spinal nerves themselves. The lamina are usually quite thick due to arthritic changes and this thick bone can compress the nerves. Another source of compression on the nerves is a yellow ligament called the ligamentum flavum which is normally found between the lamina and the spinal nerves. Thickenings of this ligament leads to pressure on the nerves and this ligament is usually also removed with a Kerrison rongeur. After removal of the central portion of the lamina, as well as the thickened ligamentum flavum, the dura is easily seen and the spinal nerves are free of compression.