Decompression and Placement of Interbody Spacer

After the tube is placed (with X-ray guidance to be sure we're focused on the correct level), as we look through the tube, we would see a thin layer of muscle which is removed for better visualization of the bony anatomy.  After removing this small amount of muscle, the facet joint (small joint on the back side of the lumbar spine) can be seen.  This diagram shows where the tube would contact the back part of the spine.  A spinal nerve (nerve root) exits deep to the region outlined by the circle on this diagram.

 

 

The facet joint is drilled (burred) away very carefully exposing the disc underneath and the exiting nerve root above.  Note that the nerve root getting ready to exit from the level below does not need to be retracted much to have good exposure to the disc

 

 

 

 

 

While drilling the facet joint away, the bone drillings are saved for use as bone graft.

This graft is combined with a special protein called BMP (stands for Bone Morphogenic Protein), which makes bone grow.

 

 

 

The spacer which goes between the vertebral bodies is pictured here.  This spacer, which is made of a special plastic that has the same mechanical properties as bone, is shaped like a small brick with rounded edges, with a hollow center to contain the bone graft and BMP.

The spacer is invisible on X-ray, but has metallic markers in it, so the position of the spacer can be noted.

 

This spacer, along with some additional bone graft, is placed between the vertebral bodies. This spacer helps keep the vertebral bodies from collapsing (which would lead to less room for the nerves and create nerve compression), and makes the local tissue environment favorable for fusion between the bones.

Additional bone graft is placed behind the nerve roots as well for what is called a posterolateral fusion.

 

To return to previous page:  Min Invasive Lumbar Fusion, page 1

To learn about pedicle screw fixation:   Min Invasive Lumbar Fusion, page 3

 

 

 

 

 

 

As the spacer is put in place, retractors are used to be sure the nerve root is not damaged.  All of the nerve work is done with the aid of an operating microscope for magnification.