Iliac Crest Graft in Maxillofacial Surgery: Jaw Reconstruction

Overview and Historical Significance

• Osteogenesis: Contains viable osteoblasts, osteocytes, and bone marrow stromal cells (approximately 15% of transplanted osteoblasts survive the procedure)
• Osteoinduction: Rich in bone morphogenetic proteins (BMPs) and growth factors that stimulate local mesenchymal stem cell differentiation
• Osteoconduction: The cancellous scaffold allows ingrowth of new vessels and bone cells

Anatomy of the Iliac Crest Relevant to Harvest

Bony Architecture

• The iliac crest runs from the anterior superior iliac spine (ASIS) anteriorly to the posterior superior iliac spine (PSIS) posteriorly
• It has an inner table (medial cortex), outer table (lateral cortex), and a large cancellous (medullary) compartment between them - this three-layer architecture allows harvesting of cortical-only, cancellous-only, or full-thickness corticocancellous blocks
• The iliac tubercle (the widest point of the crest, approximately 5 cm posterior to the ASIS) marks the boundary of safe harvest - staying 2-3 cm posterior to the ASIS avoids risk to the ASIS itself

Vascular Supply

1. Superficial circumflex iliac artery (SCIA) - a branch of the femoral artery, runs parallel to the inguinal ligament toward the ASIS and supplies the skin over the crest
2. Deep circumflex iliac artery (DCIA) - a branch of the external iliac artery, courses approximately 2.5 cm below the inner table of the iliac crest in a tunnel along the transversus abdominis and iliacus fascia, and provides the dominant endosteal blood supply to the iliac bone. This vessel is the pedicle for the vascularized iliac crest free flap
3. Muscular attachments (tensor fasciae latae laterally, iliacus medially, gluteal muscles posteriorly) contribute to periosteal supply

Nerves at Risk

• Lateral femoral cutaneous nerve (LFCN): Emerges just medial to the ASIS and passes under or through the inguinal ligament. It is the most commonly injured nerve during anterior iliac crest harvest, causing meralgia paraesthetica (anterior-lateral thigh numbness/burning). It lies approximately 1-2 cm medial to the ASIS
• Ilioinguinal nerve: Runs in the inguinal canal; at risk with deep medial dissection
• Iliohypogastric nerve: Risk if incision extends too far medially
• Genitofemoral nerve: At risk with posterior deep dissection

Muscles Attached

• Tensor fasciae latae: Lateral surface, anterior
• Iliacus: Inner table (medial surface)
• Gluteus medius and minimus: Lateral surface, posterior
• Sartorius: Originates from ASIS - must not be detached
• Abdominal muscles (external oblique, internal oblique, transversus abdominis): Attach to the iliac crest superiorly - must be incised and repaired

Types of Graft Obtainable from the Iliac Crest

Indications for Iliac Crest Graft in Maxillofacial Surgery

1. Mandibular reconstruction - segmental defects from tumor ablation (benign), trauma, osteomyelitis, osteoradionecrosis (smaller defects)
2. Alveolar cleft bone grafting - secondary bone grafting in cleft lip and palate patients at age 9-11 (mixed dentition stage)
3. Alveolar ridge augmentation - pre-implant augmentation of atrophic ridges
4. Maxillary reconstruction - post-resection defects, midface augmentation
5. Sinus floor elevation - lateral window sinus lift with large volume cancellous bone
6. Orbital floor/wall reconstruction - corticocancellous blocks
7. TMJ reconstruction - as costochondral rib graft substitute in selected cases
8. Augmentation of free flap reconstructions - supplementing fibular flaps where alveolar height is insufficient for implant placement
9. Non-union repair - mandibular non-unions after trauma

Approaches: Anterior vs. Posterior Iliac Crest

Anterior Iliac Crest (Most Common in Maxillofacial Surgery)

• Patient remains supine - allows two-team surgery (one at jaw, one at hip)
• Familiar anatomy, accessible in most patients
• Can harvest cancellous chips, corticocancellous blocks, or full tricortical grafts
• Quicker patient positioning

• Smaller volume than posterior crest
• Higher risk to lateral femoral cutaneous nerve
• More visible scar
• Risk of contour deformity (hip dip)

Posterior Iliac Crest

• Much larger volume of cancellous bone (preferred for particulate grafts - approximately 5 g wet weight per linear cm of mandibular defect needed)
• Better bone quality and density in many patients
• Lower neurovascular complication rate
• Allows harvest of true large-volume particulate grafts

• Requires prone or lateral decubitus positioning - cannot run simultaneously with oral surgery team
• Longer operating time
• More postoperative pain with ambulation
• Less familiar to some surgeons

Detailed Surgical Procedure: Anterior Iliac Crest Harvest

Pre-operative Planning

• Mark the ASIS, iliac tubercle, and the planned incision on the skin preoperatively
• The incision should be placed at least 2-3 cm posterior to the ASIS to protect the ASIS and avoid the lateral femoral cutaneous nerve
• Plan the volume and type of graft required (cancellous chips, block, or combination)
• Ensure patient is positioned with a bump/roll under the ipsilateral hip (usually right side, to free the left hand for oral surgery) to rotate the hip slightly medially and bring the crest into prominence

Patient Positioning

• Supine position with a folded sheet or sandbag placed under the ipsilateral buttock/hip
• This elevates the iliac crest and makes it more prominent and accessible
• Both the oral and iliac crest sites are prepped and draped simultaneously to allow two-team surgery

Step-by-Step Operative Technique

• Palpate the ASIS and mark a point 2-3 cm posterior to the ASIS to begin the incision
• Make a skin incision approximately 5-8 cm long along or just below the iliac crest (bikini line incision placed 2-3 cm below the crest is cosmetically preferable and avoids the nerve)
• Alternatively, an incision directly over the crest ridge is used for larger harvests
• Incise through skin and subcutaneous fat

• Incise the fat down to the fascia overlying the crest
• Identify and protect the lateral femoral cutaneous nerve (runs medially near the ASIS - strictly avoid dissection within 2 cm of the ASIS)
• Expose the periosteum of the iliac crest

• Incise the periosteum along the top (superior border) of the iliac crest using a sharp blade
• Using a periosteal elevator (Cobb or Langenbeck), strip the periosteum from the outer table (laterally, elevating gluteal and tensor fasciae latae attachments) and the inner table (medially, elevating the iliacus attachment)
• The degree of periosteal stripping depends on the volume of bone required
• Maintain the periosteum as intact as possible to allow good wound closure and minimize dead space

• Using a straight osteotome or oscillating saw, make an initial cut along the outer cortex parallel to the crest (keeping the superior iliac border intact if possible)
• Make a second cut on the inner table parallel to the first
• Make transverse (perpendicular) cuts at each end to free the block
• The cuts are typically made 1-2 cm below the superior border of the crest to preserve the crest contour
• Rock the osteotome gently to free the block - avoid sudden forceful levering which risks fracturing through to the sciatic notch

• After removing the outer cortical block, cancellous bone is accessible
• Use bone curettes (sharp Volkmann curettes) to scoop out cancellous bone from the medullary space between the two cortices
• Work from anterior to posterior, staying within safe boundaries
• Do NOT extend harvest to within 2 cm of the ASIS (avoids ASIS avulsion) and do not approach the sciatic notch posteriorly (risk of superior gluteal artery injury)

• The superior cortex (iliac crest rim) is first lifted as a "mayo-osseous flap" with its soft tissue attachments by making a shallow cut 1-2 mm deep with an osteotome and hinging it medially
• Both cortices (inner and outer tables) are then cut with osteotomes
• The mayo-osseous flap is held with an Ellis forceps to prevent retraction
• After graft harvest, this flap is replaced and sutured to restore crest contour

• Critical step: The cancellous bone bleeds profusely from the medullary space
• Pack the donor cavity with bone wax applied to cut bone surfaces
• Use electrocautery for soft tissue bleeding
• Oxidized cellulose (Surgicel) or thrombin-soaked gelatin sponge (Gelfoam) may be placed in the cavity
• Perforating vessels in the medullary space are the most common source of significant hemorrhage

• The periosteum is reapproximated with interrupted absorbable sutures - this is the most important layer for closing dead space and restoring crest contour
• A suction drain is placed at the bone graft site (maintained for only ~30 minutes to prevent excessive blood loss, then discontinued; a second drain in the soft tissue mantle is maintained for 2-3 days)
• Deep fascial layer (abdominal muscles if incised) is closed with heavy absorbable sutures
• Subcutaneous tissue closed with absorbable sutures
• Skin closed with subcuticular suture or staples
• Pressure dressing applied over the wound

Vascularized Iliac Crest Free Flap (DCIA Flap)

1. Two surgical teams work simultaneously - one at the jaw, one at the hip
2. Doppler probe is used to map the course of the superficial circumflex iliac artery along the inguinal ligament
3. The skin flap (if osteocutaneous design is used) is outlined, then the dissection proceeds from inferior to superior, identifying the SCIA/inferior epigastric vein
4. The fascia is incised at vessel penetration points near the lateral border of the sartorius muscle
5. The skin/soft tissue flap is elevated superficial to fascia while maintaining attachments to the iliac crest
6. The deep circumflex iliac artery is identified as it arises from the external iliac artery (the DCIA courses approximately 2.5 cm inferior to the iliac crest along the transversus abdominis-iliacus fascia plane)
7. The external oblique, internal oblique, and transversus abdominis muscles are divided transversely
8. The preperitoneal fascia is exposed and posterior iliacus attachment preserved
9. The iliac crest is osteotomized using oscillating saw or osteotome - maximum harvestable length is 10-12 cm due to the curvature of the ilium
10. The internal oblique muscle paddle can be raised as a separate soft tissue component for intraoral lining
11. Vessels are transected, flap transferred, and microvascular anastomosis performed at the jaw
12. Fixation at recipient site with plates and screws (note: plate application to iliac bone can be technically difficult due to the curved, irregular shape)
13. Donor site is closed primarily by hip flexion

Graft Fixation at the Jaw

• Non-vascularized block grafts: Lag screw fixation directly through the graft into the mandible; perforating the recipient bed cortex improves vascularity and graft integration
• Particulate grafts: Packed into titanium mesh cribs or barrier membranes (for defects >6 cm or those involving the symphysis/condylar region)
• Vascularized flap: Titanium reconstruction plates with screws; fixation is more demanding than fibula due to shorter graft length and irregular bone shape
• For alveolar defects: Block graft fixed with 1-2 lag screws and covered with resorbable membrane

Complications and Surgical Implications

Donor Site Complications

Recipient Site / Graft Complications

• Graft resorption: Non-vascularized grafts undergo some resorption during incorporation (20-40%); planning accounts for this
• Infection: Requires removal of graft and debridement
• Non-union / failure of integration: Higher risk in irradiated fields, active infection, poor soft tissue coverage
• Relapse: Bone remodeling may reduce final volume

General Surgical Implications for Planning

1. Volume limitation: Anterior iliac crest can provide up to 30-40 mL cancellous bone; posterior crest yields larger quantities. Defects >7 cm generally exceed non-vascularized graft capacity
2. Radiation history: Previous radiation to the jaw significantly increases graft failure rates; hyperbaric oxygen therapy pre and post-operatively is recommended in some protocols; vascularized grafts are preferred
3. Patient age: Younger patients have better bone quality and marrow cellularity; elderly patients and those on bisphosphonates may have compromised graft biology
4. Timing: Immediate (primary) reconstruction in the same operation as tumor removal has higher infection risk but single-stage advantage; delayed reconstruction (after wound healing) has better success rates for non-vascularized grafts
5. Soft tissue envelope: A healthy, tension-free soft tissue envelope at the recipient site is essential - without adequate soft tissue, even a good bone graft will fail
6. Continuity vs. marginal defects: Continuity (through-and-through) defects require rigid fixation and often a crib/container for particulate graft; marginal defects are more forgiving
7. Maxillomandibular fixation (MMF): Used intraoperatively to establish proper occlusion before final graft placement and fixation

Comparison: Iliac Crest vs. Free Fibula in Jaw Reconstruction

Post-operative Care (Donor Site)

• Ambulation: Encouraged from day 1 with physiotherapy support; most patients walk with assistance by 24-48 hours
• Analgesia: Multimodal - NSAIDs (if not contraindicated), acetaminophen, local bupivacaine infiltration at closure significantly reduces early pain
• Drain management: Remove bone site drain within 30 minutes; soft tissue drain at 24-48 hours
• Weight-bearing: Usually full weight-bearing by 2-3 weeks
• Return to normal activity: 4-6 weeks typically
• Hip exercises: Gentle range-of-motion exercises from day 2 to prevent stiffness