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Selective Laser Melting of Integrated Ti6Al4V ELI Permeable Walls for Controlled Drug Delivery of Vancomycin

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journal contribution
posted on 19.10.2018 by Martin B. Bezuidenhout, Elzaan Booysen, Anton D. van Staden, Emad H. Uheida, Philippus A. Hugo, Gert A. Oosthuizen, Dimiter M. Dimitrov, Leon M.T. Dicks
Bacteria colonizing the surface of orthopedic implants are responsible for most postoperative periprosthetic joint infections. A possible alternative route for drug delivery is described in this study by utilizing the bulk of the implant itself as a reservoir. Drug release is enabled by manufacturing of integrated permeable structures possessing high porosity through application of selective laser melting technology. The concept was evaluated in two paths, with 400 μm permeable thin walls and with dense reservoirs containing an integrated 950 μm permeable wall. Components were designed and preprocessed as separate parts, allowing for allocation of different settings of laser power and scanning speed. Lowering the energy input into the selective laser melting process to induce intermittent melting of the Ti6Al4V ELI powder produced porous components through which vancomycin was released with differing profiles. Static water contact angle measurements demonstrated a significant effect on the hydrophilicity by permeable wall thickness. Relative porosities of the 400 μm structures were determined with microcomputed tomography analyses. A transition zone of 21.17% porosity was identified where release profiles change from porosity-dependent to near free diffusion. Antimicrobial activity of released vancomycin was confirmed through evaluation against Staphylococcus aureus Xen 36 in two separate agar diffusion assays. The approach is promising for incorporation into the design and manufacturing of next-generation prosthetic implants with controlled release of antibiotics in situ and the subsequent prevention of periprosthetic joint infections.