Inflammatory cell-induced corrosion in total knee arthroplasty: A retrieval study.

Metal release in patients with joint replacements is associated with local tissue reactions, pain, and ultimately revision of implants. One of the causes of this metal loss is speculated to be due to a mechanism of inflammatory cell-induced corrosion (ICIC). In this knee retrieval study, we aimed to: (1) identify the extent and location of ICI corrosion patterns on our femoral and tibial components and (2) correlate our findings with implant and clinical information. We investigated 28 femoral and 9 tibial components made of polished CoCr for presence of ICIC, using macroscopic and microscopic screening and statistical analyses to identify any significant correlations between our results and clinical information. We found that 71% of femoral and 100% of tibial components showed evidence of ICIC and significantly more was present on non-contacting regions (p < 0.0001). We found a significant correlation between the presence of ICIC and instability (p = 0.0113) and a significant difference between poster stabilized and cruciate retaining designs in the amount of ICIC on internal edges (p = 0.0375). This corrosion pattern was prevalent in our series of knee retrievals and may help explain some of the mechanisms of material loss that may occur in vivo. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 460-467, 2018.

Toxicology of wear particles of cobalt-chromium alloy metal-on-metal hip implants Part II: Importance of physicochemical properties and dose in animal and in vitro studies as a basis for risk assessment.

The objective of the Part II analysis was to evaluate animal and in vitro toxicology studies of CoCr particles with respect to their physicochemistry and dose relevance to metal-on-metal (MoM) implant patients as derived from Part I. In the various toxicology studies, physicochemical characteristics were infrequently considered and administered doses were orders of magnitude higher than what occurs in patients. Co was consistently shown to rapidly release from CoCr particles for distribution and elimination from the body. CoCr micron sized particles appear more biopersistent in vivo resulting in inflammatory responses that are not seen with similar mass concentrations of nanoparticles. We conclude, that in an attempt to obtain data for a complete risk assessment, future studies need to focus on physicochemical characteristics of nano and micron sized particles and on doses and dose metrics relevant to those generated in patients or in properly conducted hip simulator studies.

Blood levels of cobalt and chromium are inversely correlated to head size after metal-on-metal resurfacing arthroplasty.

Resurfacing arthroplasty has fallen out of favour in recent years due to unfavourable survivorship in joint registries and alarming reports of soft tissue reactions around metal on metal prostheses. Our aim was to assess the effect of head size, implant design and component positioning on metal production by resurfacing arthroplasties. We measured whole blood cobalt and chromium and component position in matched populations implanted with two designs of resurfacing arthroplasty over a two-year period. Both implants resulted in a significant increase in blood metal levels (p<0.001) though the ASR design generated significantly higher metal levels (p = 0.041). A significant inverse correlation was seen between component size and blood cobalt levels (p = 0.032) and blood chromium levels (p<0.001). No correlation was identified between component position and blood metal levels. Small diameter metal resurfacing components result in increased metal generation compared with larger components. As increased metal generation has been correlated to wear and therefore failure, caution must be used on implantation of smaller components and indeed, in those who require smaller components, alternative bearing materials should be considered. These results contrast with recent findings which have demonstrated early failure for larger diameter stemmed metal-on-metal prostheses.

Growth, mechanical, thermal and spectral properties of Cr3+:MgMoO4 crystal.

This paper reports the growth, mechanical, thermal and spectral properties of Cr(3+):MgMoO(4) crystals. The Cr(3+):MgMoO(4) crystals with dimensions up to 30 mm×18 mm×14 mm were obtained by TSSG method. The absorption cross-sections of (4)A(2)→(4)T(1) and (4)A(2)→(4)T(2) transitions are 12.94×10(-20) cm(2) at 493 nm and 7.89×10(-20) cm(2) at 705 nm for E//N(g), respectively. The Cr(3+):MgMoO(4) crystal shows broad band emission extending from 750 nm to 1300 nm with peak at about 705 nm. The emission cross-section with FWHM of 188 nm is 119.88×10(-20) cm(2) at 963 nm for E//N(g). The investigated results showed that the Cr(3+):MgMoO(4) crystal may be regarded as a potential tunable laser gain medium.

Effect of different cleansers on the weight and ion release of removable partial denture: an in vitro study.

OBJECTIVE: Removable partial dentures (RPD) require different hygiene care, and association of brushing and chemical cleansing is the most recommended to control biofilm formation. However, the effect of cleansers has not been evaluated in RPD metallic components. The aim of this study was to evaluate in vitro the effect of different denture cleansers on the weight and ion release of RPD. MATERIAL AND METHODS: Five specimens (12x3 mm metallic disc positioned in a 38x18x4 mm mould filled with resin), 7 cleanser agents [Periogard (PE), Cepacol (CE), Corega Tabs (CT), Medical Interporous (MI), Polident (PO), 0.05% sodium hypochlorite (NaOCl), and distilled water (DW) (control)] and 2 cobalt-chromium alloys [DeguDent (DD), and VeraPDI (VPDI)] were used for each experimental situation. One hundred and eighty immersions were performed and the weight was analyzed with a high precision analytic balance. Data were recorded before and after the immersions. The ion release was analyzed using mass spectrometry with inductively coupled plasma. Data were analyzed by two-way ANOVA and Tukey HSD post hoc test at 5% significance level. RESULTS: Statistical analysis showed that CT and MI had higher values of weight loss with higher change in VPDI alloy compared to DD. The solutions that caused more ion release were NaOCl and MI. CONCLUSIONS: It may be concluded that 0.05% NaOCl and Medical Interporous tablets are not suitable as auxiliary chemical solutions for RPD care.

Effect of different cleansers on the weight and ion release of removable partial denture: an in vitro study

OBJECTIVE: Removable partial dentures (RPD) require different hygiene care, and association of brushing and chemical cleansing is the most recommended to control biofilm formation. However, the effect of cleansers has not been evaluated in RPD metallic components. The aim of this study was to evaluate in vitro the effect of different denture cleansers on the weight and ion release of RPD. MATERIAL AND METHODS: Five specimens (12x3 mm metallic disc positioned in a 38x18x4 mm mould filled with resin), 7 cleanser agents [Periogard (PE), Cepacol (CE), Corega Tabs (CT), Medical Interporous (MI), Polident (PO), 0.05 percent sodium hypochlorite (NaOCl), and distilled water (DW) (control)] and 2 cobalt-chromium alloys [DeguDent (DD), and VeraPDI (VPDI)] were used for each experimental situation. One hundred and eighty immersions were performed and the weight was analyzed with a high precision analytic balance. Data were recorded before and after the immersions. The ion release was analyzed using mass spectrometry with inductively coupled plasma. Data were analyzed by two-way ANOVA and Tukey HSD post hoc test at 5 percent significance level. RESULTS: Statistical analysis showed that CT and MI had higher values of weight loss with higher change in VPDI alloy compared to DD. The solutions that caused more ion release were NaOCl and MI. CONCLUSIONS: It may be concluded that 0.05 percent NaOCl and Medical Interporous tablets are not suitable as auxiliary chemical solutions for RPD care.

The effect of anticoagulants on the distribution of chromium VI in blood fractions.

Metal-on-metal resurfacing arthroplasty is associated with elevated circulating levels of cobalt and chromium ions. To establish the long-term safety of metal-on-metal resurfacing arthroplasty, it has been recommended that during clinical follow-up of these patients, the levels of these metal ions in blood be monitored. In this article, we provide information on the distribution of chromium VI ions (the predominant form of chromium released by cobalt-chrome alloys in vivo and in vitro) in blood fractions. Chromium VI is predominantly partitioned into red blood cells compared with plasma (analysis of variance, P < .05). The extent of accumulation in red blood cells is influenced by the anticoagulant used to collect the blood, with EDTA giving a lower partitioning into red cells compared with sodium citrate and sodium heparin.

Cobalt-chromium-molybdenum alloy causes metal accumulation and metallothionein up-regulation in rat liver and kidney.

Cobalt-chromium-molybdenum (CoCrMo) metal-on-metal hip prosthesis has had a revival due to their excellent wear properties. However, particulate wear debris and metal ions liberated from the CoCrMo alloys might cause carcinogenicity, hypersensitivity, local and general tissue toxicity, genotoxicity and inflammation-generating qualities. Nine months after implanting small pieces of CoCrMo alloy intramuscularly and intraperitoneally in rats, we analysed the accumulation of metals with a multi-element analysis, and the levels of metallothionein I/II with real-time reverse transcriptase-polymerase chain reaction in liver and kidney. We found that metal ions are liberated from CoCrMo alloys and suggest that they are released by dissolucytosis, a process where macrophages causes the metallic surface to release metal ions. Animals with intramuscular implants accumulated metal in liver and kidney and metallohionein I/II were elevated in liver tissue. The present data do not tell whether kidney and liver are the primary target organs or what possible toxicological effect the different metal ions might have, but they show that metal ions are liberated from CoCrMo alloys that are not subjected to mechanical wear and that they accumulate in liver and kidney tissue. That the liberated metal ions affect the tissues is supported by an up-regulation of the detoxifying/pacifying metalloprotein I/II in the liver.

Environmental impact of ferrochrome slag in road construction.

Vargon Alloys in Western Sweden is one of the largest producers of ferrochrome slag in Europe. Ferrochrome slag is a by-product from the production of ferrochrome, an essential component in stainless steel. Extensive tests have been carried out on the physical properties of the ferrochrome slag from Vargon Alloys and it was found to be highly suitable as road construction material. The composition and leaching tests of the ferrochrome slag show that the chromium content is high, 1-3%, although leaching under normal conditions is very low. With the exception of potassium (K), which had a potential leaching capacity (availability test) of around 16%, the leaching of chromium, nickel, zinc and other elements was just a few per cent. However, all these tests were conducted in the laboratory. What happens out in the field, under the influence of acid rain and biological activity, and how does this compare with the laboratory results? To answer this question an investigation was carried out to study the environmental impact of ferrochrome slag in roads that were built in 1994. The investigation includes soil sampling (total content and leachable amounts of metals) and groundwater analysis (filtered and non-filtered samples). In addition, a new method involving the bio-uptake of chromium and other metals by the roots of the dandelion (Taraxacum officinale) was tested. The results show that there was a low migration of particles from the slag to the underlying soil and that the leaching into the groundwater was also low for all the elements analysed. However, there seemed to be a significant uptake of Cr by plants growing with their roots in the slag. An investigation of plant uptake was an important complement to laboratory leaching tests on alternative materials.

In vivo transport and excretion of corrosion products from accelerated anodic corrosion of porous coated F75 alloy.

Corrosion of porous coated cobalt chromium specimens surgically implanted subcutaneously in hamsters was accelerated by application of a fixed anodic potential. Corrosion current measurements were utilized for prediction of metal ion release based on Faraday's law. Daily urine samples were collected pre- and post-stimulation, and, at animal sacrifice, organs and blood samples were taken for chemical analysis. By using in vitro release data from previous studies, and efficiency correction factors, the amount of metal ion release was calculated. The results demonstrated rapid and complete excretion of nickel and molybdenum. Most of the cobalt was excreted, with elevation of cobalt levels in liver, kidney, and lung. Chromium excretion was much lower due to significant red cell binding and in vivo storage, especially in the kidney and spleen.