Discectomy
Indications
- excision of herniated discs
- exploration of nerve roots
- spinal fusion
Position
- Supine with bolsters (Gillerspie pillow) placed longitudinally under the patient’s sides
- To allow abdomen to be entirely free
- ¯ venous plexus filling
- Arms placed forward
- Head supported by Mayfield Headrest
- Prep & drape
Landmarks
- Spinous processes
- Iliac crests L45 interspace
- Identify level under II
Incision
- 8 cm Midline longitudinal incision over spinous processes
- centred over the interspace where the disc herniation is located
Internervous Plane
- Paraspinal muscles
- Segmental nerve supply from the posterior primary rami of lumbar nerves
Superficial Dissection
- Deepen through fat & fascia until spinous processes are reached
- Using Cobb elevator
- Detach the paraspinal muscles subperiosteally off the spinous process
- Along the lamina
- To the facet joint
- Retract muscles with self retaining retractor
- Secure haemostasis with electrocautery, bone wax, packs
- Leave a portion of each pack completely outside the wound for ready identification
Deep Dissection
- Identify ligamentum flavum
- Cut its attachment to the superior edge of the Inferior Lamina
- Insert a blunt dissector under the cut edge of the ligamentum flavum
- Use a Kerrison rongreur (with thin footplate) to remove the distal end of the lamina & ligamentum flavum
- NB. Ligament Flavum attaches half way up the lamina
- Often no lamina is needed to be removed for exposure
- But hesistation is performing laminotomy or laminectomy to ↑ exposure
- Identify
- epidural fat
- blue white dura
- nerve root
- ↑ exposure if needed
- Retract dura & nerve root medially
- Stop bleeding with Gelfoam or cotton patties soaked in thrombin
Dangers
Nerves
Vessels
Procedure
- Identify the disc & posterior longitudinal ligament
- Gently remove disc fragments
- Pituitary forceps
- Do not penetrate beyond 15mm to avoid injury to anterior viscera
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