Bone Graft Case Study

Bone grafts

Even normal overlying soft tissues cannot hide a deficient or defective skeleton and thus it is imperative to restore the craniofacial skeleton in major facial clefts. In cases with minor bony deficits that do not displace key facial landmarks, bone grafts suffice. When bone grafts are used to bridge a critical-size bone defect, they are expected to become incorporated into the bed. Incorporation of the bone graft in the recipient site involves two essential steps: first is the bony union between the edges of the graft to the edges of native bone segments, and second is graft remodeling, or gradual resorption of the graft material itself, concomitant with its replacement by new bone.89 Bone grafting can be performed at any age and

However, the rate of successful union drops sharply when the defect is longer than 6 cm .90Posterior iliac crest graft can also be used for craniofacial reconstruction. However, the patient has to be tilted to the prone position, which eliminates the advantage of a simultaneous two-team approach. Donor site morbidity rate for anterior iliac crest grafts is around 23%, and much less for posterior iliac crest. Complications include postoperative pain, iliac or acetabular fractures or instability, persistent hematoma, herniation of abdominal contents, vascular injury, lateral femoral cutaneous nerve injury, and unsightly contour defects along the iliac crest91. Calvarial bone is also one of the most popular cortical bone grafts in craniofacial reconstruction, mainly for its mechanical properties and very slow resorption rate. This makes it ideal for facial augmentation, orbital roof and floor reconstruction, and covering cranial defects. Typically, only the outer cortex is used, although a full-thickness graft could be taken and split into two grafts. Typically, the skull continues to grow until the age of 8, continues to thicken until the age of 20, and is thickest at the parietal region. This area can provide 8 × 10 cm of bone and is considered the safest

If a craniotomy has already been performed, the inner cortex can be harvested from the bone flap and used in the reconstruction, leaving the outer cortex to be placed back in its original position. This technique maintains the contour of the calvarium. If large quantities of bone are needed, bicortical grafts may be harvested, followed by splitting of the two cortices to double the surface of the graft. It is obvious that harvesting a bicortical calvarial graft would have the most complications hazard.

Complications of calvarial grafts include surface deformity at the donor and/or recipient site and graft fracture during harvest. Less commonly, dural exposure or tear can occur. If the dura is injured, the tear should be totally exposed, by expanding the bone defect with a rongeur, and patched with a temporalis fascia or, more recently, a synthetic graft. Intracranial hemorrhage after calvarial bone harvesting has been reported but is extremely rare.92

The anterior surface of the tibial plateau can be a good source of cortical or corticocancellous bone grafts. Mechanical stiffness of the tibial cortex can be useful in facial bone augmentation, or bridging an osteotomy