CHAPTER 53
Anterior Iliac Crest Bone Graft

Michael Carson

Department of Oral and Maxillofacial Surgery, Naval Medical Center Portsmouth, Portsmouth, Virginia, USA

A surgical procedure for harvesting a cortical, cancellous, or corticocancellous block graft from the anterior ilium.

Indications

When autogenous grafting is desired that requires a high ratio of cancellous to cortical bone (a high volume of osteocompetent cells)
Hard tissue maxillofacial defects requiring 50 mL or less of cancellous bone

Contraindications

Reconstruction of maxillofacial defects requiring more than 50 mL of cancellous bone
Patients with previous head and neck radiation involving the graft recipient site

Anatomy

Anterior ilium: Located between the anterior iliac spine and the ilium tubercle. The ilium serves as a site for numerous muscular attachments responsible for normal gait and core stability.
Anterior superior iliac spine: Serves as the attachment of the external abdominal oblique muscle medially and the tensor fascia lata laterally.
Tensor fascia lata: Originates at the anterior superior iliac spine and the antero-lateral portion of the anterior iliac crest, and inserts into the iliotibial tract of the lateral thigh. The iliotibial tract (band) continues inferiorly and inserts along the lateral condyle of the tibia. Damage or excessive retraction of this muscle is the most common cause of postoperative gait disturbances.
Iliacus muscle: Originates along the superior half of the iliac fossa (medial iliac crest). The iliacus muscle joins the psoas major muscle and inserts along the lesser trochanter of the femur.
Sensory cutaneous nerves (3):
- Iliohypogastric nerve (L1, L2): The lateral cutaneous branch of the iliohypogastric nerve is located overlying the ilium tubercle and is the most commonly injured nerve during an anterior iliac crest bone graft (AICBG). The iliohypogastric nerve provides sensory innervation to the skin of the pubis and lateral aspect of the buttock.
- Lateral branch of the subcostal nerve (T12, L1): Located overlying the anterior superior iliac spine. The subcostal nerve is located medial to the iliohypogastric nerve and provides sensory innervation to the lateral buttock.
- Lateral femoral cutaneous nerve: Located between the psoas major and the iliacus muscle, medial to the subcostal nerve. In 2.5% of the population, the lateral femoral cutaneous nerve can be found within 1 cm of the anterior superior iliac spine. The lateral femoral cutaneous nerve provides sensory innervation to the skin of the anterior and lateral thigh. Damage to this nerve may result in a meralgia paresthetica.

Anterior Iliac Crest Bone Graft (AICBG) Harvesting Technique (Medial Approach)

Preoperative intravenous antibiotics are administered. The patient is intubated and positioned supine on the operating room table. A hip roll is placed under the pelvis to accentuate the anterior iliac crest anatomy. Surgical markings are made to include the locations of the anterior superior iliac spine, the ilium tubercle, and the anterior iliac crest (Figure 53.1).
A hand is used to place medial (toward the abdomen) pressure, and the anticipated incision line is marked 2–4 cm lateral to the height of the anterior iliac crest (Figure 53.1). Incisions placed directly overlying the anterior ilium will cause postoperative pain along the beltline. Local anesthetic containing a vasoconstrictor is injected within the area of the proposed skin incision within the subcutaneous tissue.
The patient is prepped and draped in a sterile fashion. An iodoban antimicrobial incise drape (3M, St. Paul, MN, USA) may be used if desired.
A 4–6 cm skin incision is made with a #10 blade 1 cm posterior to the anterior superior iliac spine and terminating 1–2 cm anterior to the ilium tubercle.
The dissection proceeds through the subcutaneous tissue until Scarpa's fascia is reached. A 4 × 4 sterile gauze is used to bluntly dissect Scarpa's fascia (Figure 53.2) from the overlying subcutaneous fat. Prior to transversing Scarpa's fascia, electrocautery is used to control all hemorrhaging subcutaneous vessels.
A #15 blade is used to transect Scarpa's fascia. A hypovascular tissue plane is identified overlying the anterior iliac crest between the insertions of the tensor fascia lata laterally and the external and transverse abdominal muscles medially. Elevating within this hypovascular tissue plane will minimize bleeding and postoperative pain or gait disturbances. The periosteum is released, and dissection proceeds within a subperiosteal tissue plane over the medial (inner) iliac cortical plate. The iliacus muscle is identified and reflected to expose the medial iliac crest (iliac fossa).
A blunt retractor (i.e., a Bennett retractor) is placed to retract the musculoperiosteal layer and to protect the intra-abdominal contents during the medial approach to the anterior ileum.
Osteotomies are made utilizing combinations of saws, burs, and chisels based on the type of graft required (corticocancellous block or cancellous graft) and the size of the defect requiring reconstruction. Regardless of the osteotomy design, it is imperative to preserve the attachments to the anterior superior iliac spine and to maintain a minimum safe distance of 1 cm from the anterior superior iliac spine and 1–2 cm from the ilium tubercle.
For standard medial (inner) AICBG harvest, the author marks the proposed osteotomy site with either a sterile marking pen or electrocautery (Figure 53.3). A reciprocating saw with copious irrigation is used to outline the osteotomy (Figure 53.4). If only cancellous bone is required, the medial cortical plate is outfractured with a chisel, marrow is removed with curettes and bone gouges, and the medial plate is repositioned (clamshell technique). If a corticocancellous block graft is required, the inferior aspect of the medial cortical plate (just superior to the fusion of the inner and outer iliac plates) is scored with either a reciprocating or a sagittal saw, and a sharp chisel is used to outfracture the medial plate (Figures 53.5). The chisel is directed against the outer (lateral) cortical plate to maximize the amount of cancellous bone attached to the inner (medial) cortical bone (Figures 53.6 and 53.7). Additional marrow is removed with curettes and bone gouges to increase the amount of graft material and to minimize marrow oozing.
After the harvest is completed, the wound site is irrigated copiously and inspected for hemostasis. Marrow bleeding is minimized with the removal of all bone marrow from the harvest site and with the placement of hemostatic agents (i.e., microfibrillar collagen, gelfoam, bone wax, and topical thrombin). If minor to moderate marrow oozing is present that is refractory to marrow removal and hemostatic agents, a drain may be placed within the bony defect, placed to low suction, and monitored closely postoperatively.
Meticulous layered closure is required to minimize postoperative hematoma and seroma formation.
A long-lasting local anesthetic agent may be infiltrated within the soft tissues overlying the donor site, and/or an ON-Q C-bloc continuous nerve block system (I-Flow Corporation, Lake Forest, CA, USA) (Figure 53.8) may be placed.
A thin layer of antibiotic ointment is placed over the wound, and an external dressing is placed.

images — **Figure 53.1.** After palpation of the anterior superior iliac spine and the ileum tubercle, the anterior iliac crest is palpated and drawn. The inferior-lateral marking represents the location of the proposed skin incision (inferior and lateral to the anterior iliac crest) to minimize postoperative pain along the beltline.

Postoperative Management

Nonsteroidal anti-inflammatory drugs and narcotics are utilized postoperatively. A pain-controlled analgesia pump (PCA) may be required in the immediate postoperative period.
Drains are typically removed when they become nonproductive for a 24-hour period.
Antibiotics are recommended for 5–7 days.
Ambulation is initiated within 24 hours postoperatively. Ambulation should be closely monitored with the assistance of a physical therapist and nursing support prior to discharge from the hospital. Ambulation aids (cane and walker) may be required for short periods of time postoperatively.
Moderate– to high-impact physical activity is restricted for a period of 6 weeks.

Complications

Early Complications

Pain and gait disturbances: Minimized with preservation of the muscular attachments to the anterior superior iliac spine (tensor fascia lata and external abdominal oblique) and the lateral iliac crest (tensor fascia lata and gluteus medius).
Nerve injury: Involved areas are dependent on the specific nerve(s) injured (i.e., iliohypogastric, subcostal, and lateral femoral cutaneous).
Hematoma formation: Minimized with meticulous dissection, hemostasis prior to wound closure, and the use of local hemostatic agents and drains when applicable.
Infection: Infections rates from AICBG harvests coincide with infection rates from similar orthopedic procedures (1–3%). Appropriate preoperative antibiotic administration, proper site preparation, maintenance of a sterile field, and meticulous wound closure will minimize infection occurrences. Infection management is aimed toward incision and drainage procedures, with antibiotic coverage based on culture and sensitivity results.
Cosmetic deformity: Avoided by taking split-thickness grafts (avoiding harvesting of both the medial and lateral cortical plates) and maintaining an intact supero-lateral rim of the anterior iliac crest.
Peritoneal perforation: Minimized by maintaining an intact musculoperiosteal layer during medial reflection, using blunt abdominal retractors (i.e., a Bennett retractor), avoiding excessive retraction, and judiciously using periosteal elevators and electrocautery during initial dissection of the medial crest (iliac fossa).
Fracture: Minimized by maintaining a minimum safe distance of 1 cm from the anterior superior iliac spine and 1–2 cm from the ilium tubercle, and by avoidance of moderate– to high-impact activity for 6 weeks postoperatively. Treatment typically consists of bed rest followed by activity restriction and assisted ambulation.
Meralgia paresthetica: Numbness and/or pain to the outer thigh caused by injury to the lateral femoral cutaneous nerve.

Key Points

When evaluating a maxillofacial defect prior to definitive reconstruction, typically 10 mL of uncompressed bone is required to reconstruct a 1 cm bony defect. For mandibular continuity defects where a reconstruction plate will be placed or has already been placed, each screw hole span is roughly 1 cm. A mandibular continuity defect with a four–screw hole span would require a minimum of 40 mL of uncompressed marrow to appropriately reconstruct the defect.
AICBGs are ideal for segmental and marginal defects in which less than 50 mL of bone are required.
For continuity defects spanning greater than 5 cm and for patients who have undergone previous head and neck radiation therapy, microvascular reconstruction is recommended.
The harvest of AICBG can be performed in a two-team manner for most oral and maxillofacial reconstructions. Using a second team to harvest the AICBG decreases the overall procedure time significantly.
The overall infection rate of the recipient site can be decreased by minimized contamination with oral microbes. For secondary reconstruction of mandibular continuity defects, transcervical approaches should be utilized when possible.
The defect/recipient site should always be exposed prior to harvesting the AICBG. For reconstructing mandibular continuity defects through an extraoral approach, large intraoral perforations often preclude the placement of the graft. Small intraoral perforations may be treated with a tension-free watertight closure (4-0 Vicryl interrupted horizontal mattress sutures) and copious irrigation prior to graft placement.
The size of the graft harvested or the osteotomy design is based on the defect size. The maximum size of the graft is limited anteriorly-posteriorly by maintaining a minimum safe distance of 1 cm from the anterior superior iliac spine and 1–2 cm from the ilium tubercle. The maximum vertical height is traditionally 4–5 cm and coincides with the fusion of the medial and lateral cortical plates.
The graft harvest to recipient placement time should be minimized in order to preserve the viability of osteocompetent cells.
For pediatric patients, the cartilaginous cap overlying the iliac crest is bisected longitudinally, preserved, and reapproximated with suture after completion of bone harvesting.

References

American Association of Oral and Maxillofacial Surgeons (AAOMS), 1994. OMFS knowledge update. Vol. 1. Rosemont, IL: AAOMS.
Kademani, D. and Keller, E., 2006. Iliac crest grafting for mandibular reconstruction. Atlas of Oral and Maxillofacial Surgery Clinics of North America, 14, 161.
Maus, U., 2008. How to store autogenous bone graft perioperatively. Archives of Orthopedic Trauma Surgery, 128, 1007–11.
Wilk, R.M., 2004. Bony reconstruction of the jaws. In: M. Miloro, G.E. Ghali, P. Larsen and P. Waite, eds. Peterson's principles of oral and maxillofacial surgery. 2nd ed. Shelton, CT: PMPH- USA.