The bones will be used to replace damaged or ceramic bones as part of reconstructive surgery. At present, the technology is limited to skulls, but tests are being carried out for other parts of the skeleton.

Using a system known as CT Bone, a 3-D image of the skull is taken using pictures and X-rays.

This image is sliced into a several cross-sections and the data is sent to a special 3-D inkjet printer, which works by transferring droplets of a water-based polymer adhesive onto a surface of powdered calcium phosphate to create a layer. This step is repeated to produce all the layers required for the prosthetic implant.

Calcium phosphate is a key material in human bones, allowing the custom-made part to be accepted by the body and eventually absorbed into the rest of the skeleton within a few years.

The polymer adhesive hardens the phosphate and the layering strengthens it and allows scientists to produce the required accuracy of bone size and shape – to an accuracy of 1mm.

In addition, the bespoke bone has a series of narrow holes running through it in order to encourage blood vessels and cells to flow through, in turn, strengthening the new structure.

The research has been undertaken by Tokyo-based firm Next 21 and the Tissue Engineering Department at the University of Tokyo Hospital.

It is expected that the breakthrough will be able to be used on the human skull by 2011 with plans for implementation for other parts of the body shortly after.