| Introduction |
- T11-L5
- most common approach
- provides access to the following
- cauda equina
- intervertebral discs
- posterior elements
- spinous processes
- laminae
- facet joints
- pedicles
- Common uses
- disc decompression
- nerve root exploration
- spinal fusion
- tumor debulking
|
| Intermuscular plane |
- Between 2 paraspinal muscles
- each has segmental supply from posterior rami of lumbar nerves
|
| Approach |
- Position
- prone (most common)
- abdomen free with bolsters
- reduces venous plexus filling
- avoid pressure points at hip, chest
- Incision
- midline incision
- tip of superior spinous process to spinous process of affected level
- Position
- lateral decubitus, affected side upwards & over break
- hip flexed
- opens interspinous spaces
- Incision
- from tip of superior spinous process to spinous process of caudal affected level
- midline incision
- Landmarks
- tip of iliac crest: L4/5 interspace
- posterior superior iliac spince: S2
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|
- Superficial dissection
- skin
- subcutaneous fat
- fascial layer (lumbodorsal)
- spinous processes
- cartilagious tip in pediatric patients
- paraspinal muscles stripped off lamina (subperiosteal)
- superficial (erector spinae)
- course: transverse & spinous process of inferior vertebrae to spinous processes of superior vertebrae
- function: extend and stabilize back
- deep: transversospinalis (multifidis & rotators)
- facet joint
- dissection laterally to tip of mamillary process
- lateral dissection taken to transverse process
- transverse process of lower vertebra is at level of facet joint
- Deep dissection
- ligamentum flavum
- travels from superior aspect of inferior lamina to midway point of superior lamina
- removed with kerrison from leading edge of lower lamina
- epidural fat
- dural covering (seen as blue-white covering)
- dissection is kept lateral to protect dura & visualize roots
- Extension
- proximal
- continue midline with incision as above
- can be taken to C1
- distal:
- continue with midline incision as above
- can be taken to sacrum
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| Dangers |
- vascular area between transverse processes
- venous plexus surrounding nerves
- nerve roots
- exiting nerve root exits foramen below the same level pedicle and above the disc
- posterior rami
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