Split Calvarial Graft

Introduction

Calvarial graft may be the preferred bone graft for reconstruction of much of the craniofacial skeleton. Both cortical and cancellous bone can be harvested in relative abundance. Cortical calvarial bone graft is pliable, allowing for reconstruction of the complex three-dimensional contours of the facial skeleton. It is thin for orbital grafting and strong for recreation of the facial buttresses. These attributes make it ideal for both primary and secondary reconstruction after facial trauma and for reconstruction after tumor extirpation. Furthermore, when a coronal incision is already being used for exposure of the fracture or defect, using calvarial bone graft for reconstruction requires no additional donor site incisions.

Calvarial bone graft may be harvested in several different fashions depending on the needs of the operation and the patient. We will review the standard harvest of a parietal bone graft through a coronal incision. Other incisions may be used, such as a parasagittal incision in the hair-bearing frontoparietal scalp. We discuss harvesting cortical and cancellous graft as a split graft in situ, via an intracranial approach in which the graft is split ex vivo, and our preferred methods for harvesting particulate bone graft. A large quantity of particulate bone graft is available from the calvarium, which we have found particularly effective in reconstructing calvarial defects.

Using calvarial graft to reconstruct calvarial defects allows one to replace like with like. This is nearly always favorable to prosthetic reconstruction when possible, especially in the growing skeleton. Split calvarial bone graft can be used in older children and adults who have a well-developed diploic space. Using a template from the contralateral skull leads to a symmetric autologous reconstruction. In the infant and young child, full-thickness calvarial bone graft may be harvested to reconstruct a defect. Young infants may regenerate the donor site defect fully when there is an intact, healthy dura below. Although regenerative capacity is thought to diminish with age, we have been successful reconstructing full-thickness defects with particulate bone graft in all ages using protected bony regeneration.

Key Operative Learning Points

• 1.

  Parietal bone is usually thick with less curvature than other areas of the calvarium. Parietal bone is therefore the most common calvarial graft donor site.

• 2.

  Calvarial graft may be split in situ or ex vivo. When splitting calvarium ex vivo an intracranial approach is used and neurosurgical assistance is recommended.

• 3.

  Full-thickness calvarial bone graft may be used for reconstruction of the zygoma in trauma or in congenital anomalies.

• 4.

  Calvarium may also be used as particulate bone graft. Cortical bone may be harvested for particulate graft, or cancellous bone from the diploic space may be used when splitting the bone.

Preoperative Period