Three-Dimensional Implant Reconstruction for the Cranial Vault

DEFINITION

Three-dimensional (3D) implant reconstruction of the cranial vault involves the reconstruction of full-thickness skull defects with implants of various materials made from a 3D computed tomography (CT) scan and by computer design.¹

ANATOMY

The external shape of the skull is composed of six bones— the frontal, parietal (two bones), temporal (two bones), and occipital.
The only soft tissues of relevance to the external skull shape are the temporal muscles on the side of the head.
The front to back shape of the skull is a convexity, whereas the sides of the skull are more linear or slightly concave.
The thickness of the skull and its three layers (two cortices and diploid space) vary widely at different positions of the skull as well as among different genders and ethnicities.

PATHOGENESIS

Full-thickness skull defects can occur due to the following:
- Craniotomy/surgical defects
- Traumatic injuries
- Congenital skull deformities

NATURAL HISTORY

Skull growth is complex and the result of both endochondral and intramembranous ossification.
It becomes a more united and solid structure when both the fontanelles close and the sutures become more rigid.
This occurs as early as 2 years of age; the thickness of the skull continues to increase up until adulthood to accommodate brain growth and expansion.

FIG 1 • Three-dimensional total custom skull implant replacement design.

PATIENT HISTORY AND PHYSICAL FINDINGS

IMAGING

High-resolution (slices of 1 mm or less) 3D CT scan is essential to evaluate the size and thickness of the skull defect as well as for computer design of the reconstructive implant (FIG 1).

NONOPERATIVE MANAGEMENT

There are no nonoperative methods to recreate the shape of the skull.
In large nonoperative skull defects, protective headwear may be recommended for protection of the brain.

SURGICAL MANAGEMENT