Neurotrophin-eluting hydrogel coatings for neural stimulating electrodes

Surgical cup placement affects the heating up of total joint hip replacements

The long-term success of highly effective total hip arthroplasty (THA) is mainly restricted by aseptic loosening, which is widely associated with friction between the head and cup liner. However, knowledge of the in vivo joint friction and resulting temperature increase is limited. Employing a novel combination of in vivo and in silico technologies, we analyzed the hypothesis that the intraoperatively defined implant orientation defines the individual joint roofing, friction and its associated temperature increase. A total of 38,000 in vivo activity trials from a special group of 10 subjects with instrumented THA implants with an identical material combination were analyzed and showed a significant link between implant orientation, joint kinematics, joint roofing and friction-induced temperature increase but surprisingly not with acting joint contact force magnitude. This combined in vivo and in silico analysis revealed that cup placement in relation to the stem is key to the in vivo joint friction and heating-up of THA. Thus, intraoperative placement, and not only articulating materials, should be the focus of further improvements, especially for young and more active patients.

Indirect Rapid Prototyping: Opening Up Unprecedented Opportunities in Scaffold Design and Applications

Over the past decades, solid freeform fabrication (SFF) has emerged as the main technology for the production of scaffolds for tissue engineering applications as a result of the architectural versatility. However, certain limitations have also arisen, primarily associated with the available, rather limited range of materials suitable for processing. To overcome these limitations, several research groups have been exploring novel methodologies through which a construct, generated via SFF, is applied as a sacrificial mould for production of the final construct. The technique combines the benefits of SFF techniques in terms of controlled, patient-specific design with a large freedom in material selection associated with conventional scaffold production techniques. Consequently, well-defined 3D scaffolds can be generated in a straightforward manner from previously difficult to print and even "unprintable" materials due to thermomechanical properties that do not match the often strict temperature and pressure requirements for direct rapid prototyping. These include several biomaterials, thermally degradable materials, ceramics and composites. Since it can be combined with conventional pore forming techniques, indirect rapid prototyping (iRP) enables the creation of a hierarchical porosity in the final scaffold with micropores inside the struts. Consequently, scaffolds and implants for applications in both soft and hard tissue regeneration have been reported. In this review, an overview of different iRP strategies and materials are presented from the first reports of the approach at the turn of the century until now.

Materials approaches for modulating neural tissue responses to implanted microelectrodes through mechanical and biochemical means

Implantable intracortical microelectrodes face an uphill struggle for widespread clinical use. Their potential for treating a wide range of traumatic and degenerative neural disease is hampered by their unreliability in chronic settings. A major factor in this decline in chronic performance is a reactive response of brain tissue, which aims to isolate the implanted device from the rest of the healthy tissue. In this review we present a discussion of materials approaches aimed at modulating the reactive tissue response through mechanical and biochemical means. Benefits and challenges associated with these approaches are analyzed, and the importance of multimodal solutions tested in emerging animal models are presented.