China
Africa
Explore chapters and articles related to this topic
Surface Modification Techniques
Published in S Santhosh Kumar, Somashekhar S. Hiremath, Role of Surface Modification on Bacterial Adhesion of Bio-Implant Materials, 2020
S Santhosh Kumar, Somashekhar S. Hiremath
Plasma spraying: The plasma-spraying physical surface modification technique involves the projection of precursor materials into the hot plasma jet generated by a plasma torch under vacuum pressure, reduced pressure, or atmospheric pressure. Argon and oxygen are the common gases used for these applications. Upon impingement of precursor materials (powders particles) onto the implant surface, an adherent coating is formed by melting and sintering. The main advantage of plasma-spraying is the possibility of coating various nanostructured films, for example, Au, Ti, and Ag, on a wide range of materials such as ceramics, metals, or polymers at a thickness <100 nm. For example, the stream of the HA powder is blown through a very high temperature flame that partially melts and ionizes the powder, which emerges from the flame, hitting the metallic surface, which has to be coated. This method uses carrier gas, which ionizes the forming plasma and superheats the particles of HA, which undergo partial melting and are propelled towards the surface that has to be coated, producing around 50 µm thick coatings (Garg et al., 2012; Rasouli et al., 2018).
Long-term migration of a cementless stem with different bioactive coatings. Data from a “prime” RSA study: lessons learned
Published in Acta Orthopaedica, 2020
Paul Van Der Voort, Martijn L D Klein Nulent, Edward R Valstar, Bart L Kaptein, Marta Fiocco, Rob G H H Nelissen
Bioactive coatings were introduced in the 1980s to enhance fixation by osseointegration, with HA used as the most common coating (Geesink 1989, Furlong and Osborn 1991). However, retrieval studies have shown resorption and delamination of the HA coating from the implant, which raised concerns regarding the induction of osteolysis and, ultimately, failure of the implant (Bloebaum et al. 1994, Bauer 1995). Fluorapatite (FA) was introduced as an alternative to HA with comparable biocompatibility and osteoconductive properties (Dhert et al. 1993), but with better thermostability (Lugscheider et al. 1989). Hence, FA might adhere better to the implant during the application process using a plasma-spraying technique, thereby possibly reducing resorption and delamination of the coating (Klein et al. 1994).
Enhanced osteogenic activity and antibacterial ability of manganese–titanium dioxide microporous coating on titanium surfaces
Published in Nanotoxicology, 2020
Quan-Ming Zhao, Yu-Yu Sun, Chun-Shuai Wu, Jian Yang, Guo-Feng Bao, Zhi-Ming Cui
In recent years, different surface modification techniques have been reported, such as ion implanting, plasma spraying, magnetron sputtering, laser cladding, electrophoretic deposition, alkali–heat treatment, anodic oxidation method, electrochemical deposition, and sol–gel method (Park et al. 2019; Hameed et al. 2019; Thangavel et al. 2019; Chen et al. 2017; Karimi, Kharaziha, and Raeissi 2019; de Souza et al. 2011; Kim and Ramaswamy 2009; Li et al. 2015; Chakrapani Venkatesan et al. 2018). Kim et al. (2013) implanted magnesium ions onto Ti surface via vacuum arc source ion implantation. In vitro studies have shown that Ti surfaces implanted with magnesium ions can promote cell adhesion, proliferation, differentiation, and mineralization, resulting in a marked improvement in osseointegration. Weidong et al. (2008) tested the biocompatibility of a functionally graded bioceramic coating prepared on the surface of Ti-6Al-4V using wide-band laser cladding; the coating contained β-tricalcium phosphate and hydroxyapatite, and it exhibited good biocompatibility with bone tissue and even promoted osteogenesis in vivo. Zhao et al. (2012) explored the effects of micropitted/nanotubular titania topographies on bone mesenchymal stem cell osteogenic differentiation. Via in vitro experiments, they showed that titanium dioxide (TiO2) nanotubes with a diameter of 20μm were effective in promoting the proliferation and osteogenic differentiation of mesenchymal stem cells. Of all methods, plasma spraying is the most widely used one for surface modification of Ti alloys, significantly improving the bioactive performance of Ti implants (Huang et al. 2010; Xiao et al. 2009). However, recent studies have revealed that plasma spraying can make coatings vulnerable to decomposition at high temperatures, resulting in low crystallinity degree and unstable performance of coatings. Moreover, the bond strength between the coating and matrix is low, and the coating may easily separate from the matrix. These problems have adversely affected the widespread clinical application of coatings.
Peri-apatite coating decreases uncemented tibial component migration: long-term RSA results of a randomized controlled trial and limitations of short-term results
Published in Acta Orthopaedica, 2018
Koen T Van Hamersveld, Perla J Marang-Van De Mheen, Rob G H H Nelissen, Sören Toksvig-Larsen
Most HA coatings are plasma sprayed onto the porous beaded implant surface area. Plasma spraying is a “line of sight” technique and therefore only able to coat the substrate surface (Hansson et al. 2008). Contrarily, Peri-Apatite HA (PA) (Stryker, Mahwah, NJ, USA)is an alternative technique to deposit HA from an aqueous solution at room temperature, thereby increasing the coverage of HA onto the 3D beaded implant surface (Serekian 2004). However, without the effect of high temperatures up to 20,000 °C associated with plasma spraying, the HA remains pure and 100% crystalline, while a lower crystallinity has been shown to improve the bioactivity and resorption profile of HA (Overgaard et al. 1999, Serekian 2004). In addition, the adhesion of the relatively thin PA layer (of 20 µm compared with 50–75 µm for most HA coatings) is fragile when touching the coated metal during implantation and, like any HA coating, might delaminate or release particles over time (Bloebaum et al. 1994, Morscher et al. 1998). Only a few randomized RSA studies have assessed the short-term (2-year follow-up) effect of PA on uncemented tibial component migration (van der Linde et al. 2006, Hansson et al. 2008, Therbo et al. 2008, Molt and Toksvig-Larsen 2014). All trials concluded that the PA coating appears to improve stabilization up to 2 years after implantation. However, no studies have examined long-term migration profiles of PA-coated tibial components. It is therefore unknown whether the found short-term effect on component fixation is sustained over time. Furthermore, in the short-term report of the current study (Molt and Toksvig-Larsen 2014), a number of both uncoated and PA-coated components showed continuous migration in the second postoperative year. It is unclear whether this leads to future aseptic loosening or if this high initial migration is merely part of a migration pattern typical for uncemented components. We therefore now report 10-year follow-up results of this double-blinded, randomized controlled trial comparing implant migration measured with RSA and clinical results of PA-coated with uncoated uncemented TKAs.