Computer-aided manufacturing of implants for the repair of large cranial defects: An improvement of the stereolithography technique

Abstract

The objective of this study is to demonstrate the utility of geometric modeling in cranioplasty; in other words, to use geometric modeling to generate a prototype that will be used as the base structure of a composite prosthesis for covering cranial defects. This geometric model is easy to manipulate and can be modified. To achieve this goal, the top surface of a cranial bone flap is digitized using a portable coordinate measurement machine. Intentionally, a sub-surface of the bone flap, representing the skull defect, was not digitized. A geometric model of the bone flap is generated that includes the undigitized region. With the technique described in this paper the authors generated the geometric model of the undigitized region (the skull defect). The geometric model of the bone flap is further manipulated and a series of conical cavities are introduced. Prototypes of the geometric models are manufactured using stereolithography. The clinical implications of this technique are discussed.

Congenital Scalp and Calvarial Deficiencies: Principles for Classification and Surgical Management

“…66 One interesting application of this modality is the manufacturing of methylmethacrylate implants that contain cavities to be filled with an osseointegrating material such as hydroxyapatite with or without bone morphogenetic protein. 63 The perfect alloplastic cranioplasty material has not yet been found.…”

“…62 A major advance in the use of alloplastic materials is the association with stereolithographic techniques for custom-made implants. 63 Using data acquired from threedimensional computed tomographic scans, 64,65 a "perfect-fit" implant can be manufactured either by generating a skull/defect facsimile or designing the implant within the computer software itself. 66 One interesting application of this modality is the manufacturing of methylmethacrylate implants that contain cavities to be filled with an osseointegrating material such as hydroxyapatite with or without bone morphogenetic protein.…”

Biomodels of Bone: A Review

“…25,36 Jans et al 36 applied filters and algorithms to these curves, and reduced the amount of data to a level which could be used to generate the model with Non-Uniform Rational B-Spline (NURBS) surfaces for the region of interest. One disadvantage of NURBS surfaces is that they are not suitable for complex structures.…”

Engineering Assisted Surgery™: A route for digital design and manufacturing of customised maxillofacial implants

“…Many EAS TM related publications discuss the use of biomodels generated using rapid prototyping for diagnostics, operation planning [10] and preparation of implants [11,12], even in a virtual environment [2,5,[13][14][15]. Some studies have been performed using digital design and RP techniques for direct manufacturing of an implant model [6]; but not with respect to material suitable for implantation.…”