SUNConferences, COMA '13

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Advances in Customized Medical Prostheses through Additive Manufacturing with an Emphasis on Hip Replacement and Cervical Implants
Dimitar Dimitrov, Martin Bezuidenhout, Graziano Marcantonio

Last modified: 2013-08-21

Abstract


The evolution of rapid prototyping technologies into additive manufacturing (AM) enables the direct manufacturing of functional parts from various metallic powders.  The layer by layer approach of AM ensures optimal use of material.  It also allows the development of complex three dimensional geometries for mass customization of medical implants.  Near net shape parts of almost 99.9% density and comparable mechanical properties can be obtained with appropriate process parameters.

An annual increase in hip replacement surgeries emphasizes the importance of implant longevity.  Obstacles that impair the life expectancy of hip implants are the large mismatch of elastic moduli between metallic implants and natural bone, and the occurrence of prosthetic infection, the latter being the worst.  Prosthetic infection is currently treated with complex surgical procedures, which cause much discomfort for the patient.  Severe cases can end in amputation or even mortality. 

In standard cervical cage implants currently used in anterior cervical discectomy and fusion (ACDF) surgery, subsidence is a major issue.  Factors affecting subsidence are notably the shape of the implant and the preparation of the endplates during surgery.  The development of a customized implant aims to reduce the risk of subsidence by distributing the load more effectively across the end-plate/implant interface.

This paper analyses the state-of-the-art in customised medical prosthesis with a focus on hip replacement and cervical implants. Based on this analysis, the Selective Laser Melting process in the proprietary form of LaserCUSING is applied to investigate the enhancement on certain properties of hip and cervical cage implants. A special attention is given to the possibilities for the manufacture of a hip implant with surface features, from which antimicrobial loaded bone cement can be eluted. Discussed is also the suitability of the surfaces obtained by LaserCUSING for osteointegration, which forms the prerequisite for successful fusion of cervical cage implants.


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