Through a midline incision, the muscles are retracted and the entire lamina and underlying ligaments are removed from the vertebrae above and below the level or levels of stenosis.  That weakens the spine a little, but most people with stenosis severe enough to cause symptoms have a stable spine because of the increased stiffness produced by calcium spurs that have built up around the vertebrae

Micro-operative Intersegmental Lumbar Decompression

Using the operative microscope, lumbar spinal stenosis can be treated through a small incision, similar to MLD.  The key is to not do a laminectomy but only remove the lower part of the upper lamina and the upper part of the lower lamina on one side, leaving the spinous processes and intact hemi-laminae on the other side.  Then by holding the dura out of the way, the scope allows visibility to safely reach across the spinal canal to remove thick ligament over there and thus relieve the stenosis. By angling the retractor up and down, the segments above and below can also be decompressed if necessary.  If a fusion is needed, a metal clamp between two spinous processes can be inserted through this small skin incision (Aspen MIS Fusion System).