Custom implant design for large cranial defects

Purpose The aim of this work was to introduce a Computer Aided Design (CAD)tool that enables the design of large skull defects (> 100cm2) implants. Functional and aesthetically correct custom implants are extremely important for patients with large cranial defects. For these cases pre-operative fabrication of implants is recommended to avoid problems of donor site morbidity, sufficiencyof donor material and quality. Finally, crafting the correct shape is a non-trivial task increasingly complicated by defect size. Methods We present a Computer Aided Design (CAD) tool to design such implants for the neurocranium. A combination of Geometric Morphometrics (GM) and Radial Basis Functions (RBF), namely Thin Plate Splines (TPS), allows semiautomatic implant generation. The method uses symmetry and the best fitting shape to estimate missing data directly within the radiologic volume data. In addition, this approach delivers correct implant fitting via a boundary fitting approach. Results This method generates a smooth implant surface, free of sharp edges that follows the main contours of the boundary, enabling accurate implant placementin the defect site intraoperatively. The present approach is evaluated and compared to existing methods. A mean error of 89.29% (72.64% - 100%)missing landmarks with an error less or equal to 1 mm was obtained. Conclusion In conclusion, the results show that our Computer Aided Design (CAD)tool can generate patient specific implants with high accuracy.
Funding agencies: EU [MRTN-CT-2005-019564]
EVAN