Cranioplasty (Autogenous, Cadaveric, and Alloplastic)

Indications

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We prefer to use autologous calvarial bone grafts as the primary material for cranioplasty and skull reconstruction. Autogenous graft has a lower incidence of infection, grows with the child, and heals the best of all other alternatives. It is generally close to the operative site, and resorption tends to be minimal. We prefer autologous calvarial bone when the defect size is not larger than the amount of remaining diploic bone available for harvest.
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We use split rib or iliac crest grafts in patients with large defects who are opposed to alloplastic reconstruction or in whom a prior infection has occurred. Autogenous bone is our first choice in patients with a history of scalp irradiation, provided that the scalp blood supply is intact. In patients with compromised soft tissue coverage, free tissue transfer may be necessary for coverage of autogenous or alloplastic calvarial reconstruction.
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In large defects in which an inadequate amount of bone is available, we prefer to use alloplastic reconstruction over split rib or iliac crest bone grafts to avoid donor site issues. Occasionally, patients may prefer autogenous reconstruction, however, or in heavily scarred tissue in which infection or dehiscence may occur, autogenous grafting with split rib or split iliac bone may still be preferable.
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When the defect is larger than the amount of remaining diploic bone available for harvest, we prefer to use prefabricated implants made of various synthetic materials, such as methyl methacrylate and porous, linear high-density polyethylene (MEDPOR, Porex Surgical, Inc., Newnan, GA). These implants are constructed using three-dimensional reconstructed images derived from “fine-cut” computed tomography (CT) scans.
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We prefer to use a calcium phosphate bone void filler when smaller gaps in bone are present (<2 to 3 cm) or when contour abnormalities require augmentation. Cadaveric bone and demineralized bone paste are viable options for filling in small bony gaps. In children younger than 5 years old, in whom the diploic space is not fully formed, demineralized bone grafts are also useful to fill moderately large defects. In using calcium phosphate bone cements or similar products, dural pulsations may be disruptive to the material before it hardens. In smaller defects, resorbable mesh may be used to cover the dura, dampening pulsations, and the bone cement is then overlaid on the mesh to fill the defect.

Contraindications

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We do not use autologous calvarial bone when the defect is larger than the bone available. In smaller children with large defects, we avoid using rib and iliac crest grafts.
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Cranioplasty should not be performed if there is questionable soft tissue coverage present over the calvaria, or if there is active infection present in any of the layers of the scalp. Free tissue coverage should be considered in cases of questionable scalp viability or in the presence of irradiated tissue.