70
Anterior and Posterior Iliac Crest Bone Graft Harvesting
Michael A. Woods, Kristina M. Schmidt, and Brett A. Taylor
Description
To harvest autologous anterior or posterior iliac crest bone graft for spinal reconstructive surgery with the least morbidity and optimal structural integrity.
Expectations
The use of autogenous iliac crest bone grafting should lead to earlier fusion-site consolidation and decreased rates of fusion-site nonunion.
Indications
Harvesting iliac crest bone graft is indicated for anterior or posterior cervical, thoracic, or lumbar fusions.
Contraindications
Harvesting iliac crest bone graft is contraindicated in patients with metastatic disease to the pelvis, soft tissue compromise overlying the graft site, and in skeletally immature patients when bi- or tricortical graft is required. Caution should be taken in patients with pelvic fractures or ligamentous disruption, previous iliac crest bone graft harvesting, or in morbidly obese patients.
Special Considerations
Anterior
In patients who are positioned supine, a bump placed under the buttocks on the planned side will aid in graft harvest. In approximately 10% of patients the lateral femoral cutaneous nerve courses over the anterior crest 2 cm lateral to the anterior-superior iliac spine (ASIS). When harvesting a large structural graft from the iliac crest, try to stay at least 2.5 to 3 cm away from the ASIS to avoid creating a stress riser. Avoid using osteotomes to procure a bi- or tricortical graft, as they have been shown to weaken the structural integrity of the graft through microscopic stress fractures as compared with a saw. If using a retroperitoneal or tho-racoabdominal approach to the lumbar spine, subcutaneous dissection performed over the abdominal musculature may be used to access the iliac crest. Bovie cauterization should be kept at 25 or below to prevent thermal injury to the lateral femoral cutaneous nerve. Morphine infiltrated directly into the harvest site or 0.25% bupivacaine infiltrated in the incisional area can be used for postoperative analgesia. In bone grafting infected recipient sites, proper technique is paramount to avoid cross-contamination; use separate instruments, gowns, and gloves.
Posterior
The superior cluneal nerves provide cutaneous sensation to the buttocks and course over the posterior iliac crest beginning 8 cm lateral to the posterior-superior iliac spine (PSIS). They are oriented in a longitudinal direction, and therefore a limited vertically directed incision approximately two to three fingerbreadths from the midline should be made. The posterior iliac crest may be exposed through subcutaneous or fas-cial splitting dissection underneath the lumbodorsal fascia. However, in immunocompromised or diabetic patients, a separate incision may offer increased protection against a deep wound infection. Morphine infiltrated directly into the harvest site or 0.25% bupivacaine infiltrated in the incisional area can be used for postoperative analgesia. In bone grafting infected recipient sites, proper technique is paramount to avoid cross-contamination; use separate instruments, gowns, and gloves.
Tips, Pearls, and Lessons Learned
Anterior
When taping the shoulders down for radiographic visualization of the cervical spine, make sure to place the tape free of the harvest site. One may use a double-graft harvesting blade or a single blade when procuring a Smith-Robinson tricortical graft. The iliac crest is recommended for single-level corpectomy. Iliac crest may be used following a two-level cervical corpectomy; however, following a three-level or more corpectomy, iliac crest is not recommended. In the thoracic spine tricortical iliac crest is recommended for interbody fusion. In the lumbar spine cancellous bone can be harvested from the iliac crest using the “trapdoor” technique for packing interbody fusion cages.
If the abdominal compartment is entered during iliac crest harvest, a general surgery consult is recommended for exploration and closure of the peritoneal defect. If the lateral femoral cutaneous nerve is injured, repair should be attempted with 5-0 monofilament suture.
Posterior
Unicortical-cancellous strips or cancellous graft is most often harvested for posterior procedures. The “trapdoor” technique can be utilized for cancellous bone graft harvest utilizing straight and curved curettes. The sacroiliac (SI) joint is best avoided by standing on the opposite side of the table from where the graft is being taken. Avoid violating the inner table of the pelvis with either technique. Avoid overaggressive retraction into the sciatic notch due to potential injury to the gluteal vessels or sciatic nerve.
If the gluteal vessels are injured, do not attempt to blindly clamp them due to the proximity of neurologic and urologic structures. If vigorous bleeding occurs as a result of gluteal vessel injury, isolate the bleeding vessel and apply a vessel staple or ligature. If bleeding cannot be controlled due to retraction of the vessel into the true pelvis, the superior aspect of the sciatic notch can be resected to visualize the gluteal vessels. If this is unsuccessful, pack and close the wound and seek interventional angiography for embolization of the vessel.
Key Procedural Steps
Anterior
A 6- to 8-cm skin incision should be made at least 2.5 cm lateral to the ASIS inferior to the iliac crest to avoid compression by the belt line. Bluntly dissect through the subcutaneous fascia. Incise the deep fascia off the lateral edge of the iliac crest. Elevate the periosteum and deep fascia off of the iliac crest in line with the skin incision. When harvesting cancellous bone, use the “trapdoor” technique and replace the roof of crest before closing. If harvesting a structural bi- or tricortical graft, mark the depth of the saw cut on the blade. Thrombin-soaked Gelfoam can be applied for hemostasis. Sharp edges should be rounded off with a burr or rasp to decrease postoperative pain. Close the periosteum, deep fascia, and skin in layers. A drain may be placed in the deep or superficial layer of closure.
Posterior
A limited vertical incision should be made within 8 cm of the PSIS. Bluntly dissect through the subcutaneous fascia. Sharply dissect the iliolumbar fascia off the periosteum. Dissection should not extend medially to the SI joint or inferiorly to the sciatic notch. When harvesting cancellous bone use the “trapdoor” technique and replace the roof of crest before closing. If corticocancellous strips are necessary, straight or curved osteotomes may be used. Thrombin-soaked Gelfoam can be applied for hemostasis. Sharp edges should be rounded off with a burr or rasp to decrease postoperative pain. Close the periosteum, deep fascia, and skin in layers. A drain may be placed in the deep or superficial layer of closure.
Bailout, Rescue, Salvage Procedures
If the volume of the graft is inadequate, combine with an allograft source or the contralateral iliac crest.
Related posts:
Wound VAC Management for Spinal or Bone Graft Wound Infections
Reduction Techniques for Atlantoaxial Rotary Subluxation
Posterior Spinal Anchor Strategy Placement and Rod Reduction Techniques: Posterior (Rotation vs. In-Situ Translation)
Iliosacral Screw Fixation Techniques
Open Lumbar Microscopic Diskectomy
Spondylolysis Repair (Pars Interarticularis Repair)
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
