This work investigated a novel process for improving the reliability of load-bearing joint prosthetics, in which electrical discharge machining (EDM) is used to create pores with sub-surface continuity on a conventionally-fabricated prosthetic material. The first part of this investigation utilized in vitro studies to verify the biocompatibility of deep, high-aspect-ratio EDM-produced pores. Mesenchymal stem cells were seeded onto Grade 4 titanium samples with EDM-created pores, and osteodifferentiation and mineralization were induced and assessed. It was found that such pores allowed for cell proliferation and mineralization indicating good biocompatibility. The second part of this work utilized three dimensional finite element modeling (FEM) to characterize simulated porous implant interfaces under stress. Interlocking strengths of selected structures were verified, interface separation under applied stress was measured for these structures with implications for wear particle intrusion in the interfaces, and stress shielding analysis was performed on simulated implants containing intersecting and non-intersecting pores.

This work was supported in part by the National Science Foundation under Grant Number CMMI-0733522.