Posterior Approach to Lumbar Spine

Axial drawing of the posterior midline approach to the lumbar spine, with the paraspinal muscles retracted laterally off the lamina and face
Axial drawing of the posterior midline approach to the lumbar spine, with the paraspinal muscles retracted laterally off the lamina and facet joints. In panel B both screw insertion and bone graft harvest are done through the one midline incision. Image from Ukeba D, Nagahama K, Hyugaji Y, Yamada K, Sudo H, Endo T, Ohnishi T, Fujita R, Koike Y, Fukushima A, Iwasaki N. Comparison of Cortical Bone Trajectory and Percutaneous Pedicle Screw Fixation in PETLIF, Short-Term Perioperative Muscle Injury and Pain Outcomes. J Clin Med. 2026, 15(18), 7174. CC BY 4.0.
Posterior Approach to Lumbar Spine, erector spinae, gray’s anatomy plate 389
Erector spinae, Gray’s Anatomy plate 389. Image by Henry Vandyke Carter, Wikimedia Commons, Public domain.

Indications

  • excision of herniated discs
  • exploration of nerve roots
  • spinal fusion
  • removal of tumours

Position

  • prone
  • bolsters longitudinally under patient’s sides
    • abdomen free
      • reduces venous plexus filling around the spinal cord by permitting the venous plexus to drain directly into the vena cava
  • Mayfield head rest
  • GA

Landmarks

  • Spinous processes
  • Iliac crest = L4-5 interspace
  • Identify Level with II

Incision

  • Midline longitudinal incision
  • Start: depends on numbers of levels to be explored

Internervous Plane

  • Between 2 paraspinal muscles (erector spinae)
    • Receive segmental nerve supply from posterior primary rami of lumbar nerves

Superficial Dissection

  • Inline with incision
    • Fat
    • Fascia
  • Reach spinous process
  • Detach paraspinal muscles subperiosteally using Cobb elevator
  • Dissect down the spinous process, lamina, facet joint
  • If needed
    • Strip facet joint capsule
    • Transverse process

Deep Dissection

  • Ligamentum flavum
    • Cutting attachment to the superior edge of the inferior lamina
    • Beneath it is
      • Epidural fat
      • Blue-white dura
    • Remove the rest of the ligamentum flavum & undersurface of lamina with a Kerrison Leskel
  • Stay lateral to dura
    • Identify nerve root

Dangers

  • Segmental vessels supplying paraspinal muscles
  • Posterior primary rami of lumbar nerves
  • Nerve roots
  • Venous plexus
    • Stop with gelfoam, cotton patties soaked in thrombin
    • Bipolar malis cautery
  • Iliac vessels
    • Injured if instruments pass through anterior portion of annulus fibrosus
  • Local measures
    • Remove additional portions of lamina
    • Remove portion of facet joint
    • Carry dissection far lateral onto transverse process
  • Extensile
    • From C1 to sacrum

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.