Interspinous Spacers are implants that are inserted between the posterior spinous processes. Their purpose is to restore the tension of the ligaments between the spines and produce
- natrual tension in the ligamentum flavum between the laminae. This reverses the infolding of the ligament in to the spinal canal and restores some of the midline (axial) volume to the spinal canal and may reverse axial (cewntral) narrowing (stenosis).
- restore the alignment of the facet joints and normalise their alignment.
- an increase in the volume of the foramen and so counter the effects of facet joint overgrowth and narrowing of the exiting pathway of the nerve (lateral recess stenosis / narrowing).
The procedure using an X-stop can be performed under local anaesthesia and in the aware state.
It may be used in the elderly or infirm but application is normally limited to L3/4 and L4/5 and care must be employed in patients with osteoporosis. It can not be employed at L5/S1 unless there is an unusually large S1 spinous process. It may be performed on an ambulatory basis.
Patient selection must take in to account the degree of Lateral recess stenosis and foraminal tethering. In the Spinal Foundation the foramen is usually cleared, the nerve fully mobilised and osteophytes and ligaments resected by endoscopic lumbar decompression prior to the use of a spacer because this procedure may be sufficiently effective in its own right. The use of spacers is enhanced by specific treatment of the pathology in the causal segment foramen by endoscopic lumbar decompression. The X-stop is a valuable adjunct to this procedure.