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Metals and alloys have been used in the human body as biomaterials to repair, replace, or augment tissues and structures for many decades. A principal concern in the use of metals in the body is the corrosion behavior of these materials. Titanium-based, cobalt-chromium-molybdenum-based, and stainless steel-based alloys comprise the preponderant metals used in orthopedic, dental, and cardiovascular medical devices across a wide range of applications. Each experiences challenging and unique environments. These environments include the electrochemical environment developed by the living system (i.e., the biological environment) and the mechanical environment. This article will provide a brief overview of the nature of the corrosion and tribocorrosion processes present in the human body by focusing on implant retrievals. Examples of corrosion damage in retrieved medical devices will be described and some of the underlying mechanisms and processes of corrosion will be presented. These include tribocorrosion processes and the role that inflammatory species play on corrosion attack. Some unique elements of corrosion in the human body will be discussed including the active response of the biological system to corrosion reactions (oxidation and reduction), and the effect of biological processes on corrosion will be presented.

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are the newest class of antihyperglycemic agents available on the market. Regulator warnings and concerns regarding the risk of developing diabetic ketoacidosis (DKA), however, have dampened enthusiasm for the class despite the combined glycemic, blood pressure, and occasional weight benefits of SGLT2 inhibitors. With the goal of improving patient safety, a cross-Canada expert panel and writing group were convened to review the evidence to-date on reported SGLT2 inhibitor–related DKA incidents and to offer recommendations for preventing and recognizing patients with SGLT2 inhibitor–associated DKA. Reports covering DKA events in subjects taking SGLT2 inhibitors that were published in PubMed, presented at professional conferences, or in the public domain from January 2013 to mid-August 2016 were reviewed by the group independently and collectively. Practical recommendations for diagnosis and prevention were established by the panel. DKA is rarely associated with SGLT2 inhibitor therapy. Patients with SGLT2 inhibitor–associated DKA may be euglycemic (plasma glucose level <14 mmol/L). DKA is more likely in patients with insulin-deficient diabetes, including those with type 2 diabetes, and is typically precipitated by insulin omission or dose reduction, severe acute illness, dehydration, extensive exercise, surgery, low-carbohydrate diets, or excessive alcohol intake. SGLT2 inhibitor–associated DKA may be prevented by withholding SGLT2 inhibitors when precipitants develop, avoiding insulin omission or inappropriate insulin dose reduction, and by following sick day protocols as recommended. Preventive strategies should help avoid SGLT2 inhibitor–associated DKA. All SGLT2 inhibitor–treated patients presenting with signs or symptoms of DKA should be suspected to have DKA and be investigated for DKA, especially euglycemic patients. If DKA is diagnosed, SGLT2 inhibitor treatment should be stopped, and the DKA should be treated with a traditional treatment protocol.

What does 'anticapitalism' really mean for the politics and culture of the twenty-first century?Anticapitalism is an idea which, despite going global, remains rooted in the local, persisting as a loose collection of grassroots movements and actions. Anticapitalism needs to develop a coherent and cohering philosophy, something which cultural theory and the intellectual legacy of the New Left can help to provide, notably through the work of key radical thinkers, such as Ernesto Laclau, Stuart Hall, Antonio Negri, Gilles Deleuze and Judith Butler. Anticapitalism and Culture argues that there is a strong relationship between the radical tradition of cultural studies and the new political movements which try to resist corporate globalization. Indeed, the two need each other: whilst theory can shape and direct the huge diversity of anticapitalist activism, the energy and sheer political engagement of the anticapitalist movement can breathe new life into cultural studies.

Background Metal release resulting from taper fretting and corrosion is a clinical concern, because wear and corrosion products may stimulate adverse local tissue reactions. Unimodular hip arthroplasties have a conical taper between the femoral head (head bore taper) and the femoral stem (stem cone taper). The use of ceramic heads has been suggested as a way of reducing the generation of wear and corrosion products from the head bore/stem cone taper junction. A previous semiquantitative study found that ceramic heads had less visual evidence of fretting-corrosion damage compared with CoCr heads; but, to our knowledge, no studies have quantified the volumetric material loss from the head bore and stem cone tapers of a matched cohort of ceramic and metal heads. Questions/purposes We asked: (1) Do ceramic heads result in less volume of material loss at the head-stem junction compared with CoCr heads; (2) do stem cone tapers have less volumetric material loss compared with CoCr head bore tapers; (3) do visual fretting-corrosion scores correlate with volumetric material loss; and (4) are device, patient, or intraoperative factors associated with volumetric material loss? Methods A quantitative method was developed to estimate volumetric material loss from the head and stem taper in previously matched cohorts of 50 ceramic and 50 CoCr head-stem pairs retrieved during revision surgery for causes not related to adverse reactions to metal particles. The cohorts were matched according to (1) implantation time, (2) stem flexural rigidity, and (3) lateral offset. Fretting corrosion was assessed visually using a previously published four-point, semiquantitative scoring system. The volumetric loss was measured using a precision roundness machine. Using 24 equally spaced axial traces, the volumetric loss was estimated using a linear least squares fit to interpolate the as-manufactured surfaces. The results of this analysis were considered in the context of device (taper angle clearance, head size, head offset, lateral offset, stem material, and stem surface finish) and patient factors that were obtained from the patients’ operative records (implantation time, age at insertion, activity level, and BMI). Results The cumulative volumetric material losses estimated for the ceramic cohort had a median of 0.0 mm 3 per year (range, 0.0–0.4 mm 3 ). The cumulative volumetric material losses estimated for the CoCr cohort had a median of 0.1 mm 3 per year (range, 0.0–8.8 mm 3 ). An order of magnitude reduction in volumetric material loss was found when a ceramic head was used instead of a CoCr head (p < 0.0001). In the CoCr cohort, the femoral head bore tapers had a median material loss of 0.02 mm 3 (range, 0.0–8.7 mm 3 ) and the stem cone tapers had a median material loss of 0.0 mm 3 (range, 0.0–0.32 mm 3 /year). There was greater material loss from femoral head bore tapers compared with stem cone tapers in the CoCr cohort (p < 0.001). There was a positive correlation between visual scoring and volumetric material loss (Spearman’s ρ = 0.67, p < 0.01). Although visual scoring was effective for preliminary screening to separate tapers with no or mild damage from tapers with moderate to severe damage, it was not capable of discriminating in the large range of material loss observed at the taper surfaces with moderate to severe fretting-corrosion damage, indicated with a score of 3 or 4. We observed no correlations between volumetric material loss and device and patient factors. Conclusions The majority of estimated material loss from the head bore-stem cone junctions resulting from taper fretting and corrosion was from the CoCr head bore tapers as opposed to the stem cone tapers. Additionally, the total material loss from the ceramic cohort showed a reduction in the amount of metal released by an order of magnitude compared with the CoCr cohort. Clinical Relevance We found that ceramic femoral heads may be an effective means by which to reduce metal release caused by taper fretting and corrosion at the head bore-stem cone modular interface in THAs.

Additive manufacturing (AM) of orthopedic implants has increased in recent years, providing benefits to surgeons, patients, and implant companies. Both traditional and new titanium alloys are under consideration for AM-manufactured implants. However, concerns remain about their wear and corrosion (tribocorrosion) performance. In this study, the effects of fretting corrosion were investigated on AM Ti-29Nb-21Zr (pre-alloyed and admixed) and AM Ti-6Al-4V with 1% nano yttria-stabilized zirconia (nYSZ). Low cycle (100 cycles, 3 Hz, 100 mN) fretting and fretting corrosion (potentiostatic, 0 V vs. Ag/AgCl) methods were used to compare these AM alloys to traditionally manufactured AM Ti-6Al-4V. Alloy and admixture surfaces were subjected to (1) fretting in the air (i.e., small-scale reciprocal sliding) and (2) fretting corrosion in phosphate-buffered saline (PBS) using a single diamond asperity (17 µm radius). Wear track depth measurements, fretting currents and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) analysis of oxide debris revealed that pre-alloyed AM Ti-29Nb-21Zr generally had greater wear depths after 100 cycles (4.67 +/− 0.55 µm dry and 5.78 +/− 0.83 µm in solution) and higher fretting currents (0.58 +/− 0.07 µA). A correlation (R2 = 0.67) was found between wear depth and the average fretting currents with different alloys located in different regions of the relationship. No statistically significant differences were observed in wear depth between in-air and in-PBS tests. However, significantly higher amounts of oxygen (measured by oxygen weight % by EDS analysis of the debris) were embedded within the wear track for tests performed in PBS compared to air for all samples except the ad-mixed Ti-29Nb-21Zr (p = 0.21). For traditional and AM Ti-6Al-4V, the wear track depths (dry fretting: 2.90 +/− 0.32 µm vs. 2.51 +/− 0.51 μm, respectively; fretting corrosion: 2.09 +/− 0.59 μm vs. 1.16 +/− 0.79 μm, respectively) and fretting current measurements (0.37 +/− 0.05 μA vs. 0.34 +/− 0.05 μA, respectively) showed no significant differences. The dominant wear deformation process was plastic deformation followed by cyclic extrusion of plate-like wear debris at the end of the stroke, resulting in ribbon-like extruded material for all alloys. While previous work documented improved corrosion resistance of Ti-29Nb-21Zr in simulated inflammatory solutions over Ti-6Al-4V, this work does not show similar improvements in the relative fretting corrosion resistance of these alloys compared to Ti-6Al-4V.

Background Previous studies regarding modular head-neck taper corrosion were largely based on cobalt chrome (CoCr) alloy femoral heads. Less is known about head-neck taper corrosion with ceramic femoral heads. Questions/purposes We asked (1) whether ceramic heads resulted in less taper corrosion than CoCr heads; (2) what device and patient factors influence taper fretting corrosion; and (3) whether the mechanism of taper fretting corrosion in ceramic heads differs from that in CoCr heads. Methods One hundred femoral head-stem pairs were analyzed for evidence of fretting and corrosion using a visual scoring technique based on the severity and extent of fretting and corrosion damage observed at the taper. A matched cohort design was used in which 50 ceramic head-stem pairs were matched with 50 CoCr head-stem pairs based on implantation time, lateral offset, stem design, and flexural rigidity. Results Fretting and corrosion scores were lower for the stems in the ceramic head cohort (p = 0.03). Stem alloy (p = 0.004) and lower stem flexural rigidity (Spearman’s rho = −0.32, p = 0.02) predicted stem fretting and corrosion damage in the ceramic head cohort but not in the metal head cohort. The mechanism of mechanically assisted crevice corrosion was similar in both cohorts although in the case of ceramic femoral heads, only one of the two surfaces (the male metal taper) engaged in the oxide abrasion and repassivation process. Conclusions The results suggest that by using a ceramic femoral head, CoCr fretting and corrosion from the modular head-neck taper may be mitigated but not eliminated. Clinical Relevance The findings of this study support further study of the role of ceramic heads in potentially reducing femoral taper corrosion.

Background There is renewed concern surrounding the potential for corrosion at the modular head-neck junction to cause early failure in contemporary THAs. Although taper corrosion involves a complex interplay of many factors, a previous study suggested that a decrease in flexural rigidity of the femoral trunnion may be associated with an increased likelihood of corrosion at retrieval. Questions/purposes By analyzing a large revision retrieval database of femoral stems released during a span of three decades, we asked: (1) how much does flexural rigidity vary among different taper designs; (2) what is the contribution of taper geometry alone to flexural rigidity of the femoral trunnion; and (3) how have flexural rigidity and taper length changed with time in this group of revised retrievals? Methods A dual-center retrieval analysis of 85 modular femoral stems released between 1983 and 2012 was performed, and the flexural rigidity and length of the femoral trunnions were determined. These stems were implanted between 1991 and 2012 and retrieved at revision or removal surgery between 2004 and 2012. There were 10 different taper designs made from five different metal alloys from 16 manufacturers. Digital calipers were used to measure taper geometries by two independent observers. Results Median flexural rigidity was 228 N-m 2 ; however, there was a wide range of values among the various stems spanning nearly an order of magnitude between the most flexible (80 N-m 2 ) and most rigid (623 N-m 2 ) trunnions, which was partly attributable to the taper geometry and to the material properties of the base alloy. There was a negative correlation between flexural rigidity and length of the trunnion and release date of the stem. Conclusions There is wide variability in flexural rigidity of various taper designs, with a trend toward trunnions becoming shorter and less rigid with time. Clinical Relevance This temporal trend may partly explain why taper corrosion is being seen with increasing frequency in modern THAs.

Mechanically-assisted crevice corrosion of modular tapers continues to be a concern in total joint replacements. Surgical factors that may affect taper seating mechanics include seating load magnitude and load orientation. Seating mechanics is defined as the seating load versus displacement behavior. In this study, mixed-alloy (CoCrMo/Ti-6Al-4V) modular head-neck 5°40′ taper junctions were seated over a range of axially-oriented loads and off-axis orientations, capturing load-displacement during seating. The goals of the study were to assess the effects of seating load magnitude and load orientation on seating mechanics and correlate those findings with the taper pull-off load. A testing fixture measured head-neck seating displacement as the load was quasistatically applied. Motion was captured using two non-contact differential variable reluctance transducers which were mounted to the neck targeting the head. Seating experiments ranged from 1000 N to 8000 N. Load orientation ranged from 0° to 20° at 4000 N. Seating load-displacement behavior at different seating loads showed a consistent characteristic behavior. Testing demonstrated increased seating displacement with seating load. Pull-off loads increased with seating load and were approximately 44% of the seating load across the range of seating loads investigated. Seating load orientation up to 20° had no significant effect on seating displacement and taper pull-off load. Increased seating load magnitude increased seating displacement, work of seating and pull-off loads in mixed-alloy 5°40′ head-neck tapers. Altering load orientation up to 20° off-axis had no significant effect. Direct measurements of seating mechanics provides insights into the locking of taper junctions.

Background Individuals with type 2 diabetes (T2D) have a high prevalence of cardiovascular and renal comorbidities. Despite clinical practice guidelines recommending the use of cardiorenal protective medications, many people with T2D are not prescribed these medications. A clinical decision support system called Exandra was developed to provide treatment recommendations for individuals with T2D based on current clinical practice guidelines from Diabetes Canada. The current study aimed to medically validate Exandra via review by external medical experts in T2D. Methods Validation of Exandra took place in two phases. Test cases using simulated clinical scenarios and recommendations were generated by Exandra. In Phase 1 of the validation, reviewers evaluated whether they agreed with Exandra’s recommendations with a “yes,” “no,” or “not sure” response. In Phase 2, reviewers were interviewed about their “no” and “not sure” responses to determine possible reasons and potential fixes to the Exandra system. The primary outcome was the precision rate of Exandra following the interviews and final adjudication of the cases. The target precision rate was 90%. Results Exandra displayed an overall precision rate of 95.5%. A large proportion of cases that were initially labeled “no” or “not sure” by reviewers were changed to “yes” following the interview phase. This was largely due to the validation using a simplified user interface compared with the complexity of the actual Exandra system, and reviewers needing clarification of how the outputs would be displayed on the Exandra platform. Conclusion Exandra displayed a high level of accuracy and precision in providing guideline-directed recommendations for managing T2D and its common comorbidities. The results of this study indicate that Exandra is a promising tool for improving the management of T2D and its comorbidities.

Continuous glucose monitoring (CGM) in diabetes improves outcomes and enhances patient self management. Compared with traditional fingerstick testing, CGM improves glycemic control and quality of life, and is now recommended for people with type 1 and type 2 diabetes using basal--bolus insulin. Use of CGM improves glycemic outcomes among people with type 2 diabetes treated with basal insulin alone in the primary care setting. It alerts users to hypo- or hyperglycemia, and promotes healthy behaviors by providing immediate data on lifestyle choices like diet and exercise. Real-time CGM automatically collects and displays glucose data, while intermittently scanned CGM requires manual scanning at least every 8 hours. Real-time CGM has a predictive alert that warns of impending hypoglycemia, an important feature for patients with frequent hypoglycemia or hypoglycemia unawareness. Choosing between systems should be based on patient needs and preferences. Reports can be easily accessed by smartphone, receiver or CGM specific software. These provide easy-to-read glycemic data to identify patterns that can enable effective therapeutic adjustments and reduce clinical inertia. Continuous glucose monitoring can be successfully implemented in primary care, and numerous resources are available to support this.