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Implant loosening, bone healing failure, implant-associated infections, and large bony defects remain challenges in orthopedic surgery. Implant surface modifications and coatings are being developed to promote osteointegration, prevent colonization by bacteria, and release bioactive factors. The following mini-review briefly discusses the clinical problem, explains the four "osteos", presents examples of coatings used for different orthopedic indications, and finally raises awareness of the coating and translational requirements.

Adhesives are not only being used increasingly in the design of medical devices, but also in the field of application, both directly on and in humans, for example as a replacement for the suturing and stapling of tissue through adhesive bonding. The advantages of using adhesives include less tissue damage, no incorporated materials that require removal, and a better biocompatibility. In this context, adhesives in the broader sense also perform functions that conventional methods cannot, for example as sealants or blood hemostats. In addition to fully synthetic and semi-synthetic adhesives, an increasing number of formulations are finding their way into research as well as clinical trials or clinical applications that are based on concepts taken from nature (biomimetic) or are a combination of biological and chemical components or are of completely biological origin. The importance of medical adhesives is evident not only in the almost double-digit annual growth rates, but also in the number of publications in this field. The constantly increasing requirements for the approval (CE marking in the EU, 510k or PMA in the USA) of new adhesives (fully synthetic, semi-synthetic, or biological) and the development of such systems in accordance with these requirements and those of the user (medical practitioners) still represent major challenges. This is partly due to the fact that development scenarios, such as the technology-push and market-pull approaches, are currently not being applied in a holistic and interdisciplinary manner.

Implant-associated infections represent a serious risk in human medicine and can lead to complications, revisions and in worst cases, amputations. To target these risks, the objective was to design a hybrid implant surface that allows a local burst release of antibiotics combined with long-term antimicrobial activity based on silver. The efficacy should be generated with simultaneous in vitro cytocompatibility. The investigations were performed on titanium K-wires and plates and gentamicin was selected as an illustrative antibiotic. A gentamicin depot (max 553 &micro, g/cm2) was created on the surface using laser structuring. The antibiotic was released within 15 min in phosphate buffered saline (PBS) or agar medium. Metallic silver particles (4 &micro, g/cm2) in a titanium dioxide layer were deposited using plasma vapor deposition (PVD). About 16% of the silver was released within 28 days in the agar medium. The local efficacy of the incorporated silver was demonstrated in a direct contact assay with a reduction of more than 99.99% (Escherichia coli). The local efficacy of the hybrid surface was confirmed in a zone of inhibition (ZOI) assay using Staphylococcus cohnii. The biocompatibility of the hybrid surface was proven using fibroblasts and osteoblasts as cell systems. The hybrid surface design seems to be promising as treatment of implant-associated infections, considering the achieved amount and release behavior of the active ingredients (gentamicin, silver). The generated in vitro results (efficacy, biocompatibility) proofed the concept. Further in vivo studies will be necessary translate the hybrid surface towards clinical applied research.