Customised maxillofacial prostheses
One exciting area of research at Sheffield is the development of bespoke cranial and maxillofacial implants. These assist surgeons re-building the faces of patients suffering either from facial deformities, due to extensive bone loss as a result of trauma or cancer, or for patients with congenital deformities. These patients require bespoke implants that are designed to meet their highly specific individual needs.
At present this involves the creation of an accurate 3D resin model of the patient's skull, constructed using CAD/CAM techniques from X-ray CT or MRI data. Highly skilled technicians then use these models to craft the implant, using the traditional methods used for creating dental restorations.
This process is expensive, time consuming and limited in the designs possible and materials available. By combining our skills with the CAD/CAM technology used by industry, however, we are developing processes which permit us to manufacture complex metallic and non-metallic bespoke implants with a high degree of accuracy of fit, whilst simultaneously reducing processing times and costs.
An industrial process of considerable interest to us is selective laser fusing of titanium being developed at AMRC in Sheffield. This technique builds the 3D model by laying down fine layers of titanium powder and selectively fusing areas of each layer together. After building up large numbers of these layers the loose titanium can be removed exposing a very complex finished object.
Above right: The sequence of events in developing a bespoke implant - in this instance both the condyle and fossa are being re-built. Top, the CAD process in which the implants are designed, followed by implantation (middle), bottom image shows an X-ray image of the implant in position.
As the technology develops we will couple it with our research into new biomaterials, which will allow us to extend the technology to other areas of application such as customised orthopaedic implants.
Customised soft tissue prostheses
A further potentially exciting area of research at Sheffield is the development of customised maxillofacial prostheses for patients suffering from facial deformities due to extensive tissue loss as a result of trauma, or cancer, or for patients with congenital deformities. These patients require a customised silicone facial prosthesis tailored to replace areas of facial soft tissue loss (e.g. eyes, ears and noses). Each of these prostheses has a working life of 6-12 months at an individual cost of approximately £1500.
Above: In the experimental technique a surface representation of the face of the patient is prepared from digital phootographs (left). This is used to create a digital model of the nasal area (centre), which can be used with rapid prototyping technologies to produce a prosthetic nose (right).
Traditional processes are expensive and the production route labour intensive and dependent upon skill of the individual technologist and the materials available. Preliminary work regarding these soft tissue prostheses indicates that by combining the technologists existing skills, with those of 3D digital camera images, computer generated virtual design and rapid prototyping technology we are able to develop a series of processes which enable us to manufacture complex surface shapes from both hard and flexible rubber-like materials.
Researchers active in this area include Prof. Rob Dwyer-Joyce (Mechanical Engineering) Prof. Richard van Noort, David Wildgoose and Dr Julian Yates.