Posterior Approach to the Iliac Crest indications:

  • The Posterior Approach to the Iliac Crest is used to harvest a bone graft from iliac crest.
  • Posterior iliac crest bone grafts usually are taken during any posterior spine surgery that requires additional autogenous bone to supplement the area to be fused.
  • The grafts also may be used as corticocancellous grafts for any part of the skeleton that needs fusion or refusion.

Position of the Patient

  • Place the patient prone on the operating table, with bolsters running longitudinally to support the chest wall and pelvis, allowing the chest wall and abdomen to expand without touching the table.
  • Place drapes distally enough so that the beginning of the gluteal cleft and the posterior superior iliac spine can be seen.

Landmarks and Incision

  • Landmarks:
    • Palpate the posterior superior iliac spine
    • posterior part of the iliac crest
  • Incision:
    • Make an 8-cm oblique incision, centered over the posterior superior iliac spine and in line with the iliac crest.
Posterior Approach to the Iliac Crest
Posterior Approach to the Iliac Crest Incision

Internervous plane

  • The outer border of the iliac crest is truly an internervous plane because muscles insert into or take origin from the iliac crest, but do not cross it.
  • The gluteus medius, minimus, and maximus muscles take their origins from the outer surface of the ilium.
  • The gluteus medius and minimus are supplied by the superior gluteal nerve and the gluteus maximus is supplied by the inferior gluteal nerve.

Superficial dissection

  • The subcutaneous tissues should be dissected until the iliac crest is reached.
  • In children, the iliac apophysis is white and quite visible; it may be incised or split in line with the iliac crest, using it as an avascular plane.
  • In adults, the apophysis is ossified and fused to the crest; the incision lands directly on the crest itself.
  • The Cobb elevator should be used to remove the apophysis or muscles from the iliac crest both medially and laterally, to bare the surface of the posterior portion of the crest.

Deep dissection

  • Strip the musculature completely off the posterior portion of the lateral surface of the ilium so that a large enough graft can be obtained.
  • Proceeding 1.5 cm down the ilium in the area of the posterior superior spine, the elevated posterior gluteal line can be seen and felt.
  • pass subperiosteally up over the line and then down its other side. 

Approach Extension

  • The Posterior Approach to the Iliac Crest cannot be extended.
  • It is designed specifically for removing bone for graft material from the posterior outer cortex of the ilium. Inner cortex also may be taken, but soft tissues should not be stripped off the anterior (deep) aspect of the ilium.

Dangers

The structures at risk during Posterior Approach to the Iliac Crest include:

  1. Sciatic nerve:
    • Sciatic nerve runs close to the distal end of the wound deep to the sciatic notch.
    • It is remotely possible that an osteotome will hit it during harvesting.
  2. The superior gluteal vessel:
    • The superior gluteal vessel is a branch of the internal iliac (hypogastric) artery.
    • It leaves the pelvis via the sciatic notch, staying against the bone and proximal to the piriformis muscle. If a graft is taken too close to the sciatic notch, the vessel may be cut and may retract into the pelvis.
  3. The sciatic notch:
    • Breaking through the thick portion of the bone that forms the notch disrupts the stability of the pelvis.

References

  • Surgical Exposures in Orthopaedics book – 4th Edition
  • Campbel’s Operative Orthopaedics book 12th