Periprosthetic infection via skin-implant interface is a leading cause of failures and revisions in direct skeletal attachment of limb prostheses. Implants with deep porosity fabricated with skin and bone integrated pylons (SBIP) technology allow for skin ingrowth through the implant's structure creating natural barrier against infection. However, until the skin cells remodel in all pores of the implant, additional care is required to prevent from entering bacteria to the still nonoccupied pores. Temporary silver coating was evaluated in this work as a means to provide protection from infection immediately after implantation followed by dissolution of silver layer in few weeks. A sputtering coating with 1 µm thickness was selected to be sufficient for fighting infection until the deep ingrowth of skin in the porous structure of the pylon is completed. In vitro study showed less bacterial (Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa) growth on silver coated tablets compared to the control group. Analysis of cellular density of MG-63 cells, fibroblasts, and mesenchymal stem cells (MSCs) showed that silver coating did not inhibit the cell growth on the implants and did not affect cellular functional activity. The in vivo study did not show any postoperative complications during the 6-month observation period in the model of above-knee amputation in rabbits when SBIP implants, either silver-coated or untreated were inserted into the bone residuum. Three-phase scintigraphy demonstrated angiogenesis in the pores of the pylons. The findings suggest that a silver coating with well-chosen specifications can increase the safety of porous implants for direct skeletal attachment. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018.

Angio- and osteogenesis following the two-stage implantation of the Skin and Bone Integrated Pylon (SBIP) seeded with autologous fibroblasts was evaluated. Two consecutive animal substudies were undertaken: intramedullary subcutaneous implantation (fifteen rabbits) and a two-stage transcutaneous implantation (twelve rabbits). We observed enhanced osseointegrative properties of the intramedullary porous component seeded with fibroblasts induced into osteoblast differentiation, as compared to the untreated porous titanium pylon. The three-phase scintigraphy and subsequent histological analysis showed that the level of osteogenesis was 1.5-fold higher than in the control group, and significantly so (P<0.05). The biocompatibility was further proved by the absence of inflammatory response or encapsulation and sequestration on the histology assay. Treatment of the transcutaneous component with autologous fibroblasts was associated with nearly a 2-fold decrease in the period required for the ingrowth of dermal and subdermal soft tissues into the implant surface, as compared to the untreated porous titanium component. Direct dermal attachment to the transcutaneous implant prevented superficial and deep periprosthetic infections in rabbits in vivo.

Composite threads based on polylactide (PLA) containing up to 20 wt% carbon nanofibers (CNF) were produced using melt technology. The formation of a percolation cluster was studied in composite filaments with various morphologies (non‐oriented, subjected to isothermal crystallization, and oriented by six times). By adding 20 wt% CNF, a specific resistance of 100 Ohm m was achieved in the PLA filament. With orientation stretching, the specific resistance was 107 Ohm m, regardless of the CNF concentration. The scanning electron microscopy study showed poor adhesion between PLA and CNF. Threads containing 1 wt% CNF demonstrated stable conductive characteristics under dynamic loading for 24 h (50% of their breaking load). Studies of the creep of composite fibers have shown that small amounts of CNFs promote the sliding of polymer fibrils. In vivo tests showed that the addition of 5 wt% CNF led to an increase in the rate of bioresorption of PLA filaments. Additionally, the conductive properties were maintained for 12 months after implantation. The prepared filaments can be used in flexible electronics for biomedical applications.

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