Release of Chromium from Orthopaedic Arthroplasties

Many orthopaedic implants are composed of alloys containing chromium. Of particular relevance is the increasing number of Cobalt Chromium bearing arthroplasies being inserted into young patients with osteoarthritis. Such implants will release chromium ions. These patients will be exposed to the released chromium for over 50 years in some cases. The subsequent chromium ion metabolism and redistribution in fluid and tissue compartments is complex. In addition, the potential biological effects of chromium are also controversial, including DNA and chromosomal damage, reduction in CD8 lymphocyte levels and possible hypersensitivity reactions (ALVAL). The establishment of these issues and the measurement of chromium in biological fluids is the subject of this review

Global longitudinal strain is compromised in patients with elevated blood cobalt levels secondary to metal-on-metal hip implants

Metal-on-metal (MoM) hip arthroplasties are known to release metal ions including cobalt into the blood stream. Elevated blood cobalt at levels over 250µg/l have been shown to be a risk factor for developing systemic complications including neurological, endocrine and cardiovascular symptoms. Published case reports document cardiomyopathy, a need for cardiac transplantation and, in some cases, death in patients with severely elevated blood cobalt. Clinical studies have found conflicting evidence of cobalt-induced cardiomyopathy in patients with MoM hips. The extent of cardiovascular injury in patients with elevated blood cobalt levels above 250µg/l has not previously been examined and is the focus of the current study

Intra-articular injection composed of steroid, iohexol and local anaesthetic - is it stable?

The aim of this study is to determine the chemical stability of a suspension of steroid, radiographic contrast material and local anaesthetic. Image-guided steroid injection using a contrast material is widely used for several musculoskeletal conditions. Manufacturers of these agents do not advise mixture in a single syringe, as the chemical stability is unknown. They suggest that, if required, these agents should be injected separately. However, the agents will be mixed together when injected into a contained space within the body. it would seem unethical to continue this in clinical practice until the stability of such a mixture is established. High-performance liquid chromatographic (HPLC) analysis was used to assess the stability of combinations of steroids (triamcinolone and methylprednisolone) and Omnipaque (TM) (iohexol). Further analysis was also performed to test the stability of adding local anaesthetics (lidocaine and bupivacaine) to these mixtures. The results demonstrated that all combinations were stable when mixed together. in conclusion, these results support the continued safe use of these products in combination in clinical practice

The effect of anticoagulants on the distribution of chromium VI in blood fractions relevance to patients with metal orthopedic implants

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

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

Objectives: To investigate the influence of anticoagulants on the in vitro distribution pattern of hexavalent chromium in blood fractions. Many metallic implants used in orthopaedics are made of stainless steel or cobalt-chromium alloys which contain 18-30% chromium. Hexavalent chromium has been shown to be the predominant form of chromium released following in vivo and in vitro corrosion of these metal implants (Merritt & Brown 1995). Blood chromium levels may be elevated 50-250 times in patients with metal hip implants (Lhotka et al 2003). At physiological pH, hexavalent chromium exists predominantly as the chromate anion and as such can enter cells via non-specific anion channels. The anionic hexavalent chromium diffuses readily through the red blood cell (RBC) membrane and is bound by the haemoglobin probably after its rapid reduction to the cationic trivalent state within the RBC (Gray & Sterling 1950)

Osteoclastogenesis/osteoblastogenesis using human bone marrow-derived cocultures on nanotopographical polymer surfaces

BACKGROUND: Optimised nanotopography with controlled disorder (NSQ50) has been shown to stimulate osteogenesis and new bone formation in vitro. Following osteointegration the implant interface must undergo constant remodeling without inducing immune response. AIM: We aimed to assess the effect of nanotopography on bone remodelling using osteoclast and osteoblast cocultures. &lt;p&gt;&lt;/p&gt; MATERIALS &#38; METHODS: We developed a novel osteoblast/osteoclast coculture using solely human bone marrow derived mesenchymal and hematopeotic progenitor cells without extraneous supplementation. The coculture was been applied to NSQ50 or flat control polycarbonate substrates and assessed using immunohistochemical and immunofluorescent microscopy, scanning electron microscopy and quantitative reverse-transcription PCR methods.&lt;p&gt;&lt;/p&gt; RESULTS: These confirm the presence of mature osteoclasts, osteoblasts and bone formation in coculture. Osteoblast differentiation increased on NSQ50, with no significant difference in osteoclast differentiation.&lt;p&gt;&lt;/p&gt; CONCLUSION: Controlled disorder nanotopography appears to be selectively bioactive. We recommend this coculture method to be a better in vitro approximation of the osseous environment encountered by implants.&lt;p&gt;&lt;/p&gt

Late Dislocation after Total Hip Arthroplasty

Objectives: Instability after total hip arthroplasty is a troublesome complication. It commonly occurs in the first 3 postoperative months, but the risk continues over time.There are numerous treatment options, but they have relatively unpredictable outcomes. Numerous factors have been associated with dislocation, but research has mainly focused on the surgical ones. Epidemiological factors remain the subject of much debate.We aimed to establish the incidence of dislocation over time

Precision-Engineered Nanotopographical Surfaces to Control Osteoclast Differentiation

We have developed precision-engineered strontium eluting nanopatterned surfaces. Nanotopography has been shown to increase osteoblast differentiation, and strontium is an element similar to calcium, which has been proven to increase new bone formation and mineralization. This combination has great potential merit in fusion surgery and arthroplasty, as well as potential to reduce osteoporosis. However, osteoclast mediated osteolysis is responsible for the aseptic failure of implanted biomaterials, and there is a paucity of literature regarding osteoclast response to nanoscale surfaces. Furthermore, imbalance in osteoclast/osteoblast resorption is responsible for osteoporosis, a major healthcare burden. We aimed to assess the affect of strontium elution nanopatterned surfaces on osteoblast and osteoclast differentiation. We developed a novel human osteoblast/osteoclast co-culture system without extraneous supplementation to closely represent the in vivo environment. We assessed the surfaces using electron microscopy (SEM), protein expression using immunofluorescence and histochemical staining and gene expression using polymerase chain reaction (PCR). In complex co-culture significantly increased osteoblast differentiation and bone formation was noted on the strontium eluting, nanopatterned and nanopatterned strontium eluting surfaces, suggesting improved osteointegration. There was a reduction in macrophage attachment on these surfaces as well, suggesting specific anti-osteoclastogenic properties of this surface. Our results show that osteoblast and osteoclast differentiation can be controlled through use of nanopatterned and strontium eluting surface features, with significant bone formation seen on these uniquely designed surfaces

Precision-Engineered Nanotopographical Surfaces to Control Osteoclast Differentiation

We have developed precision-engineered strontium eluting nanopatterned surfaces. Nanotopography has been shown to increase osteoblast differentiation, and strontium is an element similar to calcium, which has been proven to increase new bone formation and mineralization. This combination has great potential merit in fusion surgery and arthroplasty, as well as potential to reduce osteoporosis. However, osteoclast mediated osteolysis is responsible for the aseptic failure of implanted biomaterials, and there is a paucity of literature regarding osteoclast response to nanoscale surfaces. Furthermore, imbalance in osteoclast/osteoblast resorption is responsible for osteoporosis, a major healthcare burden. We aimed to assess the affect of strontium elution nanopatterned surfaces on osteoblast and osteoclast differentiation. We developed a novel human osteoblast/osteoclast co-culture system without extraneous supplementation to closely represent the in vivo environment. We assessed the surfaces using electron microscopy (SEM), protein expression using immunofluorescence and histochemical staining and gene expression using polymerase chain reaction (PCR). In complex co-culture significantly increased osteoblast differentiation and bone formation was noted on the strontium eluting, nanopatterned and nanopatterned strontium eluting surfaces, suggesting improved osteointegration. There was a reduction in macrophage attachment on these surfaces as well, suggesting specific anti-osteoclastogenic properties of this surface. Our results show that osteoblast and osteoclast differentiation can be controlled through use of nanopatterned and strontium eluting surface features, with significant bone formation seen on these uniquely designed surfaces