The posterior surgical approach to the spine has been developed from open laminectomy into microscope assisted discectomy (Microdiscectomy) to gain access to posterior disc protrusions or decompression of axial (central) stenosis (narrowing) afflicting the spinal canal.
The objective of the posterior decompression technique has been to remove disc protrusions causal of sciatica or to enlarge the narrowing of the dimensions of the epidural canal caused by overgrowth of the facet joint and infolding of the inter-laminar ligaments and causal of claudicant (limping or leg weakness or leg pain) symptoms arising from lateral recess stenosis or axial stenosis.
The problem with the conventional midline approach is that the muscles must be widely mobilised with impairment of their blood supply. The removal of the lamina deprives these muscles of their blood supply and the wide surgical track may result in extensive scarring. The technique carries all the risks that attend a General Anaesthetic, paralysis, dural tears, infection, blood clot formation and subsequent instability which may develop over a few years.
Endoscopic Interlaminar Decompression has been developed from a bilateral approach into a unilateral approach with a single 9mm endoscope inserted between the laminae. After elevation of the lateral ligamentum flavum from the laminae, the dura may be displaced and a disc protrusion may be removed or the medial (inner) facet joint is undercut and the remaining ligamentum flavum is removed across the midline to remove the midline narrowing (stenosis).
This technique may be used in preference to Transforaminal Endoscopic Lumbar Decompression & Foraminoplasty at L5/S1 where anatomic considerations significantly impede access to the L5/S1 foramen or disc protrusions at this level. It may be used to decompress axial stenosis at cervical and lumbar discal levels.
Endoscopic Interlaminar Decompression is safest performed under General Anaesthesia to minimise patient movement. The technique spreads the fibres of the deep muscles rather than undermine them and so facilitates postoperative rehabilitation. The risk of infection is minimised by intravenous antibiosis during the operation and the saline wound irrigation but the risk of dural tear persists as the working cannula is turned. If this occurs then the wound needs to be opened in a conventional fashion should the dural tear need to be sutured. The risk of an intraspinal blood clot is also reduced because the overall surgical area is kept to a minimum.
Komp et al 2011 reported clearance axial stenosis leg symptoms in 70.8% at 2 years review with 22.2% suffering occasional pain. The decompression results equate to those of conventional procedures but with reduced complications and rapid rehabilitation.
Martin Komp, Sebastien Rueten et al 2009 using a combination of Transforaminal discectomy and / or Endoscopic Interlaminar Decompression reported a clearance of pain in 74.5% with occasional symptoms in 14 – 20.5% of patients and a recurrent disc protrusion rate of 6.2%
