Cranioplasty - how to fix a hole in the skull

A ‘craniotomy’ is a surgery to remove a portion of the skull (called a ‘bone flap’), typically done to reach a brain tumour or manage a bleed on the brain (read more here or here).

Sometimes it is not possible to replace the bone flap after surgery, e.g. if surgeons are concerned about ongoing brain swelling. In these cases, the hole left in the skull will eventually need reconstructed. This is important as it both protects the brain and restores the natural shape of the skull (an important psychological consideration).

How is this skull reconstructed?

Over the centuries surgeons have tried many materials to cover holes in the skull including coconut shells, bone grafts, metals, and more recently ceramics and biosynthetic materials. 3D printing technology has brought new opportunities for custom reconstruction. 3D data from CT scans can be used to design implants that are tailored to fit a patient exactly, built from strong and non-reactive materials. These have been shown to reduce complications such as infection, protrusion of ill-fitting materials, and resorption, compared to traditional techniques.

OssDsign is one such company leading this field who manufacture a patient-customised titanium implant with calcium phosphate mosaic tiles to reconstruct the skull. Here’s an illustrated overview of the surgery which can be done to fit one of these custom implants:

Note the dip in the skull where a large section of bone is missing following a previous surgery.

The surgical site is shaved and opened along the scar

Scar tissue is removed to reveal the bone edge

The custom cranioplasty is fitted and screwed into place

Next, the temporalis muscle is identified and freed

The temporalis is affixed to the implant, helping reconstruct the contour of the skull.

Bone grows between the calcium phosphate matrix over time, integrating the implant into the skull.

The natural contour of the skull is restored.

3D printing technology is creating exciting new possibilities to adapt surgery to individual patients. I look forward to seeing it continues to evolve in the coming years. To see a real case video of this surgery explained by a neurosurgeon and illustrated by me, check out the Artibiotics x Brainbook collaboration here or below:

A big thanks goes out to OssDsign whose support of this project made it possible to shed light on this developing area of neurosurgery in an open way.