Article
Preoperative implant fabrication by fused deposition modeling and virtual simulation of implant fit for cranioplasty
Präoperative Erstellung von Implantaten durch Fused Deposition Modeling und virtueller Simulation der Passgenauigkeit für die Kranioplastie
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Published: | May 8, 2006 |
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Objective: Trauma, calvarian tumors and defects following surgery are the main reasons for large cranial defects. Indications for reconstruction of these defects are cosmetic and protection against mechanical impact. We report a technique of Rapid Prototyping (RP) for custom reconstruction of cranial defects using Fused Deposition Modeling (FDM) and virtual simulation of implant fit and cosmetic result.
Methods: In a cadaver specimen a craniectomy was performed and a model of the defect was built using FDM. Implant design was based on the postoperative imaging data using a mirror image of the contralateral side modified by “free hand” CAD. The CAD data were transformed to a STL format to generate a negative mold by 3D printing using FDM. PMMA implants were formed using the mold and the influence of sterilization techniques on implant form and stability were investigated by optical 3D scanning. The fit of 3D scanned implants into the virtual defect of preoperative CCT reconstructions was studied on colour coded images and compared to preoperative images.
Results: CAD designed 3D printed PMMA implants showed a significantly better fit and cosmetic results than free hand modeled implants. The intraoperative modeling times were more than four times longer than implantation of prefabricated implants and ranged from 26-44 minutes. Sterilization of prefabricated implants by irradiation, gas- and plasma sterilization did not result in changes of the spatial configuration of the implants and had no significant influence on implant stability. Virtual implantation into preoperative CCT 3D reconstructions allowed the visualization of implant fit and the cosmetic result, which was verified by post implantation CCT.
Conclusions: Our results demonstrate that FDM generated anatomical models and negative molds of the defects provide a rapid and highly accurate method of custom implants of skull defect reconstructions. 3D simulation of the implant fit allows preoperative verification of the post operative cosmetic result. Our technique based offers a cost-effective alternative to industrially produced implants.