Large Image Display: Prosthetic Jaw Hinging

One of the most important aspects when working with any skeletal system, is the joint where bones connect. If you don't get this area right, then bone will grind against prosthesis, and the bone is likely to take critical damage first. You inflame a joint, that did not have a problem in the first place, and spread further complications throughout the body.

This image is of the LayerWise jaw, a prosthetic replacement jaw made from titanium, whose central claim to fame is that it was custom made to fit the skull of the patient, by running a CT scan of her skull, assembling the slices into a 3D map of her head bones, and using that as CAD data to precisely contour the new jaw to the contours of her skull - and other systems.

It illustrates an elegant solution very well. This jawbone was created using an exact picture of the old bone before it was removed due to osteomyelitis. The infection had not reached the joint, so the old bone's shape could be replicated exactly. Even if this was not possible, the rest of the skull was also mapped exactly, so the new joint could be modelled based on that - and then animated in the computer system to be certain there were no clashes.

In essence, this is a new use for virtual reality, as is going on here. The new prosthetic is being modelled as a working hinge joint, to see if the hinge is going to cause problems with existing bone structures. It is about a third heavier than the old bone as well, so that is factored in. Many tests like this one were run on the data in simulation, before the technical team were confident the joint would be fine. Then the 3D printer was engaged, and the prosthetic printed out straight from this VR data, creating the final form exactly as it was in the simulation.

That jaw has now been implanted in the patient, and time will tell if the joint is as perfect a match as it seems.

Further Reading

Large Image Display: Making a Bespoke Jaw


Form Fitting Prosthetics Using DICOM Data

Standards > DICOM