The purpose of this paper was development of patient-specific femoral prosthesis using rapid prototyping (RP), a part of additive manufacturing (AM) technology, and comparison of its merits or demerits over CNC machining route.
The customized femoral prosthesis was developed through computed tomography (CT)-3D CAD-RP-rapid tooling (RT)-investment casting (IC) route using a stereolithography apparatus (SLA-250) RP machine. A similar prosthesis was also developed through conventional CT-CAD-CAM-CNC, using RP models to check the fit before machining. The dimensional accuracy, surface finish, cost and time involvement were compared between these two routes.
In both the routes, RP had an important role in checking the fit. Through the conventional machining route, higher-dimensional accuracies and surface finish were achieved. On the contrary, RP route involved lesser time and cost, with rougher surface finish on the prosthesis surface and less internal shrinkage porosity. The rougher surface finish of the prosthesis is favourable for bone ingrowths after implantation and porosity reduce the effective stiffness of the prosthesis, leading to reduced stress shielding effect after implantation.
As there is no AM machine for direct fabrication of metallic component like laser engineered net shaping and electron beam melting in our Institute, the metallic prosthesis was developed through RP-RT-IC route using the SLA-250 machine.
The patient-specific prosthesis always provides better fit and favourable stress distribution, leading to longer life of the prosthesis. The described RP route can be followed to develop the customized prosthesis at lower price within the shortest time.
The described methodology of customized prosthesis development through the AM route and its advantages are applicable for development of any metallic prostheses.
The authors are thankful to the Council of Scientific and Industrial Research (CSIR), New Delhi, for providing financial grant to this investigation work, in the form of research project. The authors are grateful to the Director, CSIR-CMERI, for his kind permission to undertake this work and publish this paper. Authors are thankful to the officials of MTG and CAMP of CMERI, who have helped a lot during this development work. Finally, authors wish to thank all the technical and non-technical staff of CMERI for their coordination in carrying out this investigative work.
Maji, P.K., Banerjee, A.J., Banerjee, P.S. and Karmakar, S. (2014), "Additive manufacturing in prosthesis development – a case study", Rapid Prototyping Journal, Vol. 20 No. 6, pp. 480-489. https://doi.org/10.1108/RPJ-07-2012-0066
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