Bone grafting is a surgical procedure that transplants bone tissue to repair bones damaged by trauma, disease, or congenital defects. This process provides a framework for new bone growth and helps restore structural integrity to the skeletal system. The transplanted bone can be sourced from the patient’s own body (autograft), a donor (allograft), or synthetic materials.
Defining the Tricortical Iliac Crest Graft
A tricortical iliac crest bone graft is a type of autograft, meaning it is harvested from the patient’s own body. The term “iliac crest” refers to the curved, superior border of the ilium, the largest bone of the pelvis. This area is a frequent donor site because it contains a rich supply of bone that is relatively easy to access.
The graft is called “tricortical” because it includes three layers of bone tissue. It is composed of a dense outer cortical layer, a spongy inner cancellous layer, and a second dense cortical layer. The two hard, outer layers provide immediate structural support, while the inner cancellous bone is rich in marrow and the cells that form new bone. This combination of structural support and regenerative capacity makes the graft highly effective.
Common Clinical Applications
This graft is used in surgeries where both structural support and active bone healing are required. One of the most frequent uses is in spinal fusion, particularly in the neck. In an anterior cervical discectomy and fusion (ACDF), a damaged disc is removed, and the graft is inserted between the vertebrae to maintain space and facilitate the fusion of the two bones into a single, stable unit.
The graft is also used in dental and maxillofacial surgery for jawbone reconstruction after trauma, tumor removal, or to augment the alveolar ridge, which is the bone that supports the teeth. If a patient has insufficient bone mass for dental implants, a tricortical graft can build up the area to provide a solid foundation for them.
Orthopedic trauma is another area of application. The graft repairs complex fractures with significant bone loss or addresses non-unions, which are fractures that have failed to heal. The structural strength of the graft provides immediate stability, while its biological components encourage the bone to heal.
The Graft Harvesting Procedure
Harvesting the graft begins with positioning the patient, often face-up with a bolster under the hip to make the iliac crest more prominent. After prepping the surgical site, an incision is made along the iliac crest. The incision starts about 2 to 3 centimeters behind the anterior superior iliac spine (the bony prominence at the front of the hip) to avoid nerve injury.
The surgeon dissects through soft tissue to expose the bony crest. The fascia, a thin casing of connective tissue, is opened to reveal the top of the ilium. To protect surrounding tissues, muscle attachments are stripped from the bone’s surface in a subperiosteal fashion, where the periosteum (the membrane covering the bone) is lifted with the muscle.
With the bone exposed, the surgeon uses an osteotome (a specialized chisel) or a power saw to make controlled cuts through the iliac bone. These cuts outline a block of bone sized for the recipient site. The graft is then carefully lifted from the donor site. After harvesting, the wound is filled with an absorbable gelatin sponge to help control bleeding before the incision is closed in layers.
Recovery and Donor Site Considerations
The donor site can be a source of considerable discomfort, with patients often reporting that pain from the hip is more intense than at the primary surgical site. This pain is managed with medication, ice packs, and a short period of limited weight-bearing activities.
Potential complications can arise from the donor site. These include:
- Nerve irritation, which can lead to numbness or persistent pain over the buttock area.
- Formation of a hematoma (a collection of blood under the skin).
- Infection at the incision site.
- Gait disturbances, such as limping, for at least a week.
More serious, though less frequent, complications include fractures of the iliac wing or herniation of abdominal contents if the pelvic bone is weakened. Recovery involves using crutches or a walker, with a gradual return to normal activities over several weeks. Most patients resume unlimited physical activity within a month, though some may have persistent numbness.
Alternative Bone Grafting Options
Due to the potential for donor site pain and complications, several alternatives to autografts have been developed. These options eliminate the need for a second surgical site, which reduces surgical time, blood loss, and post-operative issues.
One alternative is an allograft, which is bone tissue harvested from a deceased human donor. The bone is processed and sterilized to remove cellular components, minimizing the risk of disease transmission and immune rejection. Allografts provide a scaffold for new bone but lack the live, bone-forming cells found in autografts.
A xenograft is bone tissue from a different species, such as a cow, that is treated to leave only the mineral structure. Synthetic grafts are man-made materials, like ceramics or polymers, engineered to mimic natural bone. These materials are biocompatible and are eventually resorbed and replaced by the patient’s own bone.