PubMed | University of Basel, University of Applied Sciences and Arts Northwestern Switzerland and Medicoat AG
Type: Journal Article | Journal: Journal of biomedical materials research. Part B, Applied biomaterials | Year: 2015
Biomaterials with antimicrobial properties are now commonly used in different clinical specialties including orthopedics, endodontic, and traumatology. As a result, assessing the antimicrobial effect of coatings applied on implants is of critical importance. In this study, we demonstrate that isothermal microcalorimetry (IMC) can be used for monitoring bacterial growth and biofilm formation at the surface of such coatings and for determining their antimicrobial effects. The antibacterial effects of silver doped hydroxyapatite (HA) and calcium hydroxide coatings on Staphylococcus epidermidis were determined with a minimal workload. Using the Gompertz growth model we determined biofilm growth rates close to those values reported in the literature. Furthermore, we were able to estimate the reduction in the bacterial inocula originally applied at the surface of the coatings. Therefore, in addition to monitoring the antimicrobial effect of silver doped HA and calcium hydroxide coatings, we also demonstrate that IMC might be a valuable tool for assessing such antimicrobial properties of implant coatings at a minimal workload.
PubMed | Medicoat AG, TU Munich, Atesos medical AG and University of Applied Sciences and Arts Northwestern Switzerland
Type: | Journal: BMC musculoskeletal disorders | Year: 2016
Animal models serve as an important tool to understand peri-implant infection. Most of the models use high bacterial loads (>10(4) colony forming units, CFU) to provide high infection rates. Therefore these animals evolve rather similarly, making comparison between groups and statistical analysis possible. On the other hand, to mimic clinical constellation of surgery-related infections the use of low amounts of bacteria would be more advantageous.We developed a metaphyseal rat model of peri-implant bone infection with low amount of bacterial loads (10(2) and 10(3) CFU of Staphylococcus aureus) and investigated osseointegration of the implants coated with hydroxyapatite (HA) and low-dosed HA-silver (HA-Ag). Non-infected implants served as controls. After 6 weeks rats were sacrificed and implants evaluated for osseointegration and infection.Infection of implanted devices was reliably induced, independently whether 10(2) or 10(3) CFU of S. aureus were inoculated and HA or HA-Ag coated implants were used. No systemic infection was present in any of the animals at the time of sacrifice, and no animal developed acute infection requiring premature sacrifice. All CFU counts of the implant and the bone at sacrifice were significantly higher than the inoculated load (p <.05). All sterilely inserted implants showed excellent osseointegration and no infection.Our present study of a rat tibia model reliably induced osteomyelitis in the metaphysis with low-doses of bacteria. The addition of low-dosed Ag to the implant coating was not able to reduce the infection rates. The results demonstrate that it is possible to develop a model of implant-related osteomyelitis in rats with low amounts of bacteria to better mimic clinical constellations. No other promoters of infection besides insertion of the screw implant were used in this model.
PubMed | Medicoat AG, TU Munich, University of Applied Sciences and Arts Northwestern Switzerland and Atesos Medical AG
Type: Journal Article | Journal: Journal of applied biomaterials & functional materials | Year: 2016
Silver ions (Ag+) have strong antibacterial effects, and silver-coated materials are in widespread clinical use. However, the application of silver-coated medical devices is not without concerns: its use with direct bone contact is not established, and systemic toxic side effects of released Ag+ have been described. Therefore, alternative bactericidal coatings with a more localized way of acting - e.g., calcium dihydroxide, Ca(OH)2 (CH) - would be advantageous.A new rat model of the animals tibial metaphysis was developed. In the left proximal tibiae of 36 male Wistar rats, titanium screws were implanted. The screws were coated with hydroxyapatite (HA; 12 animals: group I), low-dosed HA silver (HA-Ag; 12 animals: group II) and CH (12 animals: group III). After 6 weeks, all rats were sacrificed. The implants were evaluated for morphological changes on their surfaces, by light microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy; for osteointegration, by measurement of resistance to removal; and for bacterial colonization, by quantitative culture analysis. Additionally, the tibial bone was investigated histologically for signs of osteomyelitis and sonicated to detect bacterial loads.(i) No microbiological or histological signs of infection could be determined on any of the screws or the surrounding bone. (ii) The bone-implant interface analysis revealed extensive bone formation and direct bone-implant contact on all HA, HA-Ag and HA-CH coated screws. (iii) HA and HA-Ag were partially, and CH was fully, degraded on the screw coating, allowing host bone to osteointegrate.
Mihm S.,Alstom |
Thomas G.,TU Berlin |
Kuhn R.,Medicoat AG
Proceedings of the International Thermal Spray Conference | Year: 2015
Characteristics of atmospheric plasma spraying based on single-cathode-anode-systems like the F4 gun with convergent- cylindrical nozzle designs, are voltage fluctuations caused by periodically changes of the arc length. As a result continuous varying plasma flow properties lead to inhomogeneities during energy transfer to injected powder particles and variations of coating quality and process efficiency. With an adjusted convergent-divergent nozzle design and optimized high energy plasma parameters it is proven that process efficiency and stability could be significantly increased, also due to the reduced arc movement. A drawback in this case is the increased anode wear which needs to be optimized to secure industrial usage. Aim of this work was to minimize the anode wear of contoured convergent-divergent nozzles by using high efficient plasma parameters. Therefore arc characteristics in different nozzle designs were analyzed and the influence of the geometry to arc anode attachment was investigated. Consequently a stepwise optimization of anode wear by keeping the plasma fluid dynamic properties almost constant could be achieved. The results contribute to understanding of the arc characteristics in atmospheric plasma spraying. Also a new concept of a "three-zone anode geometry", convergent-inlet- section, cone-shaped arc movement section and a divergent plasma fluid shape section was developed. © (2015) by ASM International All rights reserved.
Devine D.M.,AO Research Institute Davos |
Hahn J.,AO Research Institute Davos |
Richards R.G.,AO Research Institute Davos |
Richards R.G.,University of Cardiff |
And 3 more authors.
Journal of Biomedical Materials Research - Part B Applied Biomaterials | Year: 2013
Carbon fiber-reinforced polyetheretherketone (CF/ PEEK) is a thermoplastic composite biomaterial exhibiting properties suitable for load-bearing orthopedic implants. However, the hydrophobic surface of CF/PEEK implants induces the deposition of a peri-implant fibrous tissue capsule preventing bone apposition. However, if bone apposition was improved, the use of CF/PEEK in orthopedics could be increased as it has many advantages compared with metallic implants. In this study, CF/PEEK screws were coated with titanium (Ti) using two different techniques, namely vacuum plasma spraying (VPS) and physical vapor deposition (PVD) with uncoated screws as controls. These coatings were characterized and implanted in a loaded sheep tibia model. In the characterization of the screw surfaces using microscopy techniques, the uncoated screws were seen to have an irregular surface. The PVD coating appeared smooth and consistent, whereas the VPS coating appeared to be a rough coating with some inhomogeneities, which did not cover the entire surface area. Nevertheless, in the ex vivo analysis the VPS-coated screws had a screw removal torque which was statistically greater than uncoated and PVD-coated screws (p > 0.002 for both comparisons). Additionally, the VPS-coated screws had a statistically higher bone contact area than the uncoated screws (p = 0.006), whereas no statistical difference was detected between VPS and PVD coating types (p = 0.11). Thereby illustrating that Ti coating of CF/PEEK screws significantly improve bone apposition and removal torque compared with uncoated CF/ PEEK screws. © 2012 Wiley Periodicals, Inc.
Agency: Cordis | Branch: FP7 | Program: BSG-SME | Phase: SME-1 | Award Amount: 1.48M | Year: 2009
Each year in Europe there are:- 800000 hip operations costing approximately 1,942 per/implant, worth over 1.5 billion Hip implant operations are rising by approximately 15%. Currently 10% of all the prosthesis implanted are in patients under 55 years of age of which 33% of these will fail within 16 years with a further 20% of implant fitted to over 55s failing with in 20 years requiring revisional surgery costing 2.3 billion per annum. Treatment of younger patients with severe hip disease using a conventional THR presents a challenge with the rate of success being very low, (most failing within 16 years). To over come this Finsbury help develop the MoM BHR resurfacing hip with a survival rate of 93% over a conventional THR. However, studies have reported high concentrations of Co & Cr in the serum and/or urine of patients with MoM resurfacing implants. Studies have shown that increased levels of Co & Cr cause caners such as leukaemia and are linked with myocardiopathy. During the course of this project we intend to overcome these problems by developing a ceramic one ceramic or ceramic on polymer resurfacing hip. Like that of the MOM prosthesis will only cover the femoral head thus retaining all of the desirable properties associated with retaining an intact femur.
Mihm S.,Alstom |
Duda T.,Medicoat AG |
Gruner H.,Medicoat AG |
Thomas G.,Alstom |
Dzur B.,TU Ilmenau
Journal of Thermal Spray Technology | Year: 2012
Over the last few years, global economic growth has triggered a dramatic increase in the demand for resources, resulting in steady rise in prices for energy and raw materials. In the gas turbine manufacturing sector, process optimizations of cost-intensive production steps involve a heightened potential of savings and form the basis for securing future competitive advantages in the market. In this context, the atmospheric plasma spraying (APS) process for thermal barrier coatings (TBC) has been optimized. A constraint for the optimization of the APS coating process is the use of the existing coating equipment. Furthermore, the current coating quality and characteristics must not change so as to avoid new qualification and testing. Using experience in APS and empirically gained data, the process optimization plan included the variation of e.g. the plasma gas composition and flow-rate, the electrical power, the arrangement and angle of the powder injectors in relation to the plasma jet, the grain size distribution of the spray powder and the plasma torch movement procedures such as spray distance, offset and iteration. In particular, plasma properties (enthalpy, velocity and temperature), powder injection conditions (injection point, injection speed, grain size and distribution) and the coating lamination (coating pattern and spraying distance) are examined. The optimized process and resulting coating were compared to the current situation using several diagnostic methods. The improved process significantly reduces costs and achieves the requirement of comparable coating quality. Furthermore, a contribution was made towards better comprehension of the APS of ceramics and the definition of a better method for future process developments. © ASM International.
Medicoat AG | Date: 2010-05-12
The invention relates to an implant made of biocompatible materials, in particular a prosthesis implanted without cement for traumatology and/or orthopedics, which has a main body with an anchoring region which anchors in bone or tissue, with the anchoring region being provided at least partially with a covering layer, the covering layer being formed from a powder using a thermal spraying method, in particular a plasma spraying method. The powder consists essentially of calcium phosphate and comprises antibacterially effective active constituents.
PubMed | Medicoat AG, Fraunhofer Institute for Production Technology, Aurora Medical Ltd, Hunt Developments UK Ltd and 2 more.
Type: Journal Article | Journal: Journal of biomaterials applications | Year: 2014
Carbon-fibre-reinforced polyether ether ketone (CFR-PEEK) exhibits excellent biomechanical properties as it has an elastic modulus similar to bone. However, CFR-PEEK displays inferior biocompatibility compared with titanium alloy and coating techniques are therefore of interest in order to improve integration. In this paper, the early biological response to CFR-PEEK implants, with and without hydroxyapatite coating, was investigated. Furthermore, a hydroxyapatite-coated titanium alloy reference served as a clinically relevant control. The study was conducted in a rabbit model, both in femur trabecular bone as well as in tibia cortical bone. The results demonstrated that an hydroxyapatite coating significantly enhances the bone response to PEEK implants invivo. Moreover, in cortical bone, hydroxyapatite-coated PEEK implants induced superior bone response compared with hydroxyapatite-coated Ti ones. These results suggest that hydroxyapatite-coated CFR-PEEK is a suitable material for invivo implantation.
PubMed | University of Basel, Medicoat AG and Empa - Swiss Federal Laboratories for Materials Science and Technology
Type: Journal Article | Journal: Biointerphases | Year: 2016
Fast and efficient osseointegration of implants into bone is of crucial importance for their clinical success; a process that can be enhanced by coating the implant surface with hydroxyapatite (HA) using the vacuum plasma spray technology (VPS). However, bacterial infections, especially the biofilm formation on implant surfaces after a surgery, represent a serious complication. With ever-increasing numbers of antibiotic-resistant bacteria, there is great interest in silver (Ag) as an alternative to classical antibiotics due to its broad activity against Gram-positive and Gram-negative bacterial strains. In the present study, silver ions were introduced into HA spray powder by ion exchange and the HA-Ag powder was applied onto titanium samples by VPS. The Ag-containing surfaces were evaluated for the kinetics of the silver release, its antibacterial effect against Staphylococcus aureus as well as Escherichia coli, and possible cytotoxicity against human bone cells. The HA-Ag coatings with different concentrations of Ag displayed mechanical and compositional properties that fulfill the regulatory requirements. Evaluation of the Ag release kinetic showed a high release rate in the first 24 h followed by a decreasing release rate over the four subsequent days. The HA-Ag coatings showed no cytotoxicity to primary human bone cells while exhibiting antibacterial activity to E. coli and S. aureus.