Clinical Applications of Rapid Prototyping Models in Cranio-Maxillofacial Surgery

Abstract

Medical models or bio-models represent portions of human anatomy at a scale of 1:1 obtained from three-dimensional (3D) medical imaging (CT scan, MRI). The procedure for the fabrication of medical models consists of multiple steps: 1) the acquisition of highquality volumetric 3D image data of the anatomical structure to be modelled, 2) 3D image processing to extract the region of interest from surrounding tissues, 3) mathematical surface modelling of the anatomic surfaces, 4) formatting of data for rapid prototyping (RP) (this includes the creation of model support structures that support the model during building, which are subsequently manually removed), 5) model building, and 6) quality assurance of the model and its dimensional accuracy. These steps require significant expertise and knowledge of medical imaging, 3D medical image processing, computerassisted design, and software manufacturing and engineering processes. The production of reliable, high-quality models requires a team of specialists that may include medical imaging specialists, engineers, and surgeons (Winder & Bibb, 2005). Rapid prototyping was introduced in the 1980’s to define new techniques for the manufacturing of physical models based on CAD-CAM (computer-aided design, computer-aided manufacturing). RP technology allows the building of a medical model layer by layer, reproducing almost every form of the external and internal anatomic structure. Other categories of RP technologies are solid freeform fabrication, layer additive manufacturing, and 3D printing. RP techniques are different from physical models obtained by milling. RP medical modelling in craniomaxillofacial (CMF) surgery has mainly been developed over the last ten years (Phidias European network), and concerns the following range of applications: 1) aiding in the production of surgical implants, 2) improving surgical planning, 3) acting as an orientation aid during surgery, 4) enhancing diagnostic quality, 5) using in preoperative simulation, 6) achieving a patient’s consent prior to surgery, and 7) preparing a template for resection for surgeons (Winder & Bibb, 2005).