The Kerrison Ronguer
With the muscle retracted, the interspace is exposed. An operative microscope is then used to better see the laminae. The above instrument is then used to remove part of the lamina above and below the interspace, exposing the yellow ligament more widely. This instrument is very safe. The lip can be slipped under the edge of bone; squeezing the handles “bites” away pieces of bone, with are removed and discarded unless needed for graft material. After removal of enough bone, a window in the yellow ligament is made to expose the contents of the spinal canal – epidural fat, the dura mater and nerve root. The fat is moved to the middle and the edge of the dura carefully moved medially also, exposing the herniated disk.
A special self-retaining nerve root retractor is then placed to hold the dural sac and nerve root toward the midline, exposing the herniation. That will be described in Part 4.