RENSHAPESL TEMPLATES USED IN PROSTHETIC EAR SURGERY
31 January 2003 - Huntsman Advanced Materials

Working with researchers at the National Centre for Product Design & Development
Research (PDR), the surgeon and prosthetists used virtual imagery to evaluate
various options for the implant surgery. Once an operating plan was finalised, a
template to guide the surgeon to the precise drilling sites for ear implantation was
produced using stereolithography modelling and RenShape SL H-C 9100R
photopolymer.

Supplied by Vantico, this unique stereolithography material is sterilisable and can be used in patient contact during surgery.

With virtual surgical planning and RenShape SL templates, we achieved the
required accuracy and surgical time reduction without incurring the time and costs to produce anatomical SL models, said Dr. Richard Bibb, head of medical applications at PDR.

For the prosthetic ear implant, PDR and prosthetists began with a three-dimensional
Computed-Tomography (CT) scan. Data was used to create virtual models of the
soft head tissue, the healthy ear, and the bone structure at the implant site. With
these virtual models, implant planning was conducted as follows:

1. 3D software was used to create the mirror image of the patient s existing ear. The ear was then virtually positioned in an anatomically and aesthetically appropriate location for the implant.
2. Cylinders, representing the implants, were positioned on the virtual ear in the
location preferred by prosthetists. Soft tissue areas were then virtually removed
to expose the points at which the implants would intersect with the bone.
3. Bone quality at the implant sites was assessed to verify its suitability for
implantation. A cross-section view of the virtual model was used for this process,
allowing prosthetists to accurately measure bone thickness and density.
4. When the surgical team was satisfied with the implant sites, a virtual block was
created to overlap the implants and skull surface.
5. The skull and implant cylinders were then subtracted from the virtual block to
create the template design.
6. The template was produced from Vantico s RenShape SL H-C 9100R material in
PDR s stereolithography equipment.
7. After sterilisation, the template was placed on the patient s skull during surgery to indicate drilling holes that the surgeon used to install implants.

'We have worked with the Morriston Maxillofacial Unit team on several cases similar to this prosthetic ear implant and found that the virtual modelling and template approach fully exploits the advantages of modern technology. This process would not have been possible without Vantico s medically approved, sterilisable resin,' Bibb concluded.

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