Surface pretreatment for prolonged survival of cemented tibial prosthesis components: full- vs. surface-cementation technique

BACKGROUND: One of few persisting problems of cemented total knee arthroplasty (TKA) is aseptic loosening of tibial component due to degradation of the interface between bone cement and metallic tibial shaft component, particularly for surface cemented tibial components. Surface cementation technique has important clinical meaning in case of revision and for avoidance of stress shielding. Degradation of the interface between bone cement and bone may be a secondary effect due to excessive crack formation in bone cement starting at the opposite metallic surface. METHODS: This study was done to prove crack formation in the bone cement near the metallic surface when this is not coated. We propose a newly developed coating process by PVD layering with SiO(x )to avoid that crack formation in the bone cement. A biomechanical model for vibration fatigue test was done to simulate the physiological and biomechanical conditions of the human knee joint and to prove excessive crack formation. RESULTS: It was found that coated tibial components showed a highly significant reduction of cement cracking near the interface metal/bone cement (p < 0.01) and a significant reduction of gap formation in the interface metal-to-bone cement (p < 0.05). CONCLUSION: Coating dramatically reduces hydrolytic- and stress-related crack formation at the prosthesis interface metal/bone cement. This leads to a more homogenous load transfer into the cement mantle which should reduce the frequency of loosening in the interfaces metal/bone cement/bone. With surface coating of the tibial component it should become possible that surface cemented TKAs reveal similar loosening rates as TKAs both surface and stem cemented. This would be an important clinical advantage since it is believed that surface cementing reduces metaphyseal bone loss in case of revision and stress shielding for better bone health

Surface pretreatments for medical application of adhesion

Medical implants and prostheses (artificial hips, tendono- and ligament plasties) usually are multi-component systems that may be machined from one of three material classes: metals, plastics and ceramics. Typically, the body-sided bonding element is bone. The purpose of this contribution is to describe developments carried out to optimize the techniques , connecting prosthesis to bone, to be joined by an adhesive bone cement at their interface. Although bonding of organic polymers to inorganic or organic surfaces and to bone has a long history, there remains a serious obstacle in realizing long-term high-bonding strengths in the in vivo body environment of ever present high humidity. Therefore, different pretreatments, individually adapted to the actual combination of materials, are needed to assure long term adhesive strength and stability against hydrolysis. This pretreatment for metal alloys may be silica layering; for PE-plastics, a specific plasma activation; and for bone, amphiphilic layering systems such that the hydrophilic properties of bone become better adapted to the hydrophobic properties of the bone cement. Amphiphilic layering systems are related to those developed in dentistry for dentine bonding. Specific pretreatment can significantly increase bond strengths, particularly after long term immersion in water under conditions similar to those in the human body. The bond strength between bone and plastic for example can be increased by a factor approaching 50 (pealing work increasing from 30 N/m to 1500 N/m). This review article summarizes the multi-disciplined subject of adhesion and adhesives, considering the technology involved in the formation and mechanical performance of adhesives joints inside the human body

Enchantment in Business Ethics Research

This article draws attention to the importance of enchantment in business ethics research. Starting from a Weberian understanding of disenchantment, as a force that arises through modernity and scientific rationality, we show how rationalist business ethics research has become disenchanted as a consequence of the normalisation of positivist, quantitative methods of inquiry. Such methods absent the relational and lively nature of business ethics research and detract from the ethical meaning that can be generated through research encounters. To address this issue, we draw on the work of political theorist and philosopher, Jane Bennett, using this to show how interpretive qualitative research creates possibilities for enchantment. We identify three opportunities for reenchanting business ethics research related to: (i) moments of novelty or disruption; (ii) deep, meaningful attachments to things studied; and (iii) possibilities for embodied, affective encounters. In conclusion, we suggest that business ethics research needs to recognise and reorient scholarship towards an appreciation of the ethical value of interpretive, qualitative research as a source of potential enchantment

Healthism and the experiences of social, healthcare and self-stigma of women with higher weight

This study analyses how the discourse of healthism contributes to the social construction of weight stigma in women with higher-weight. In-depth semi-structured interviews were conducted with nine women who had undergone bariatric surgery and had lived with higher-weight during many years. A thematic analysis from a latent and constructionist perspective showed how the discourse of healthism was behind the experiences of stigma lived by the participants in the social and healthcare field. Even instances of self-stigma were found in our data. This study also illustrates how people influenced by healthism assumed individualism and the importance of body shape, core values of neoliberal consumer societies. In this way, people tended to blame women with higher-weight for their weight and to discriminate against for being far from the socially established ideal body. The findings can be useful to prevent weight stigmatization and to promote more appropriate and respectful strategies for obesity prevention and treatment

The strength of rigid and flexible adhesive joints at room temperature and after thermal shocks

The aim of the article was to determine the strength of the adhesive joints of the carbon steel and aluminium alloy. Two types of two-component epoxy adhesives were used in the tests: rigid and flexible. Rigid epoxy adhesive contains epoxy resin based on Bisphenol A and triethylenetetramine (TETA) curing agent, in a ratio of 100 g resin to 10 g curing agent. Flexible epoxy adhesive contains epoxy resin based on Bisphenol A and polimaminoamide curing agent, in a ratio of 100 g resin to 100 g curing agent. The tested adhesive joints were subjected to conditioning at room temperature (23 °C) and humidity 35% (the first version) and subjected to thermal shocks (500 cycles: + 60 °C/−40 °C)—the second version. Strength tests of different variants of adhesive joints were performed on the Zwick/Roell Z150 testing machine in compliance with the DIN EN 1465 standard. Shear strength and elongation at break were determination. The obtained results have shown that in some cases, depending on the type of adherend, the adhesive joints exhibit greater elongation after a specified time of thermal shocks compared to non-thermal adhesive joints