Cartilage‐on‐cartilage versus metal‐on‐cartilage impact characteristics and responses

A common in vitro model for studying acute mechanical damage in cartilage is to impact an isolated osteochondral or cartilage specimen with a metallic impactor. The mechanics of a cartilage‐on‐cartilage (COC) impact, as encountered in vivo, are likely different than those of a metal‐on‐cartilage (MOC) impact. The hypothesis of this study was that impacted in vitro COC and MOC specimens would differ in their impact behavior, mechanical properties, chondrocyte viability, cell metabolism, and histologic structural damage. Osteochondral specimens were impacted with either an osteochondral plug or a metallic cylinder at the same delivered impact energy per unit area, and processed after 14 days in culture. The COC impacts resulted in about half of the impact maximum stress and a quarter of the impact maximum stress rate of change, as compared to the MOC impacts. The impacted COC specimens had smaller changes in mechanical properties, smaller decreases in chondrocyte viability, higher total proteoglycan content, and less histologic structural damage, as compared to the impacted MOC specimens. If MOC impact conditions are to be used for modeling of articular injuries and post‐traumatic osteoarthritis, the differences between COC and MOC impacts must be kept in mind. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 887–893, 2013     

Optimism,self‐efficacy and information processing of threat‐ and well‐being‐related stimuli

The purpose of this study was to examine whether information bias associated with dispositional optimism and generalized self‐efficacy can account for the link between general expectations and well‐being. A modified Stroop task was used in this study. Our hypothesis was that individuals with high self‐efficacy expectations or dispositional optimism would show greater bias towards well‐being‐related stimuli, whereas individuals with low self‐efficacy or optimism would exhibit bias towards threat‐related stimuli. A secondary hypothesis was that both self‐efficacy and optimism would act as mediators of the latency, perceived distress relationship. One hundred and two undergraduate students participated in the study. After controlling for daily mood, the results showed that individuals high in optimism and self‐efficacy showed greater informational bias towards well‐being‐related stimuli. The low self‐efficacy group exhibited greater bias towards threat‐related stimuli. Also, consistent with our hypothesis, optimism and self‐efficacy mediated the relationship between the Stroop colour‐naming latencies and perceived distress. These findings suggest that associations, which refer to automatic processes, may form an additional way through which expectations are related to functioning. Copyright © 2007 John Wiley & Sons, Ltd.     

Investigation of High‐Speed Erythrocyte Flow and Erythrocyte‐Wall Impact in a Lab‐on‐a‐Chip

To better understand erythrocyte high‐speed motion, collision characteristics, and collision‐induced hemolysis probability in rotary blood pumps, a visual experimental investigation of high‐speed erythrocyte flow and erythrocyte‐wall collision in a lab‐on‐a‐chip was performed. The erythrocyte suspension was driven by a microsyringe pump connected to the microchip, and the erythrocyte flow and erythrocyte‐wall impact process were observed and imaged by an optical microscope and a high‐speed camera. Two types of microchips with different impact surfaces (flat and curved) were employed. The motion and deformation features before and after collision were studied in detail. The results show that erythrocytes not only move along the flow direction in the flow plane but also rotate and roll in three‐dimensional space. Erythrocytes keep discoid shape during the movement in the straight channel, but their deformations during collision are mainly classified into two types: erythrocyte structure is still stable and the erythrocyte performance can be ensured to a certain extent in the TypeA deformation, while the TypeB deformation makes the membrane more likely to fracture on the stretched side, increasing the probability of hemolysis. Furthermore, the movements and deformations of the erythrocytes after collision are analyzed and classified into two types: bouncing and slipping. Moreover, a simulation method for the flow in microchip was performed and validated through a comparison of the streamlines and experimental erythrocytes tracks, which can be further employed to predict the high‐speed blood flow, associated with collision process in mechanical blood pump.     

HIV‐Positive‐to‐HIV‐Positive Liver Transplantation

Most countries exclude human immunodeficiency virus (HIV)‐positive patients from organ donation because of concerns regarding donor‐derived HIV transmission. The Swiss Federal Act on Transplantation has allowed organ transplantation between HIV‐positive donors and recipients since 2007. We report the successful liver transplantation from an HIV‐positive donor to an HIV‐positive recipient. Both donor and recipient had been treated for many years with antiretroviral therapy and harbored multidrug‐resistant viruses. Five months after transplantation, HIV viremia remains undetectable. This observation supports the inclusion of appropriate HIV‐positive donors for transplants specifically allocated to HIV‐positive recipients.     

Sodium‐glucose co‐transporter type‐2 inhibitors: pharmacology and peri‐operative considerations

Sodium‐glucose co‐transporter 2 (SGLT2) inhibitors are an emerging class of oral hypoglycaemic agents with therapeutic benefits beyond better glycaemic control. A major concern of the sodium‐glucose co‐transporter 2 inhibitors is their propensity to cause euglycaemic ketoacidosis in the peri‐operative period and the potential for this critical diagnosis to be delayed or missed entirely. This review attempts to collate the case reports of sodium‐glucose co‐transporter 2 inhibitor ketoacidosis associated with surgery to highlight and put a perspective on this peri‐operative issue. Preventive strategies and the management of the ketoacidosis are discussed.     

Three‐decade‐delayed post‐traumatic small‐bowel stenosis

Injury to the small bowel is uncommon after trauma. There are rare reported cases of delayed post‐traumatic stenosis of the small bowel occurring weeks, months or even years later. In this study, we present a case of a delayed stenosis that caused a small‐bowel obstruction three decades after the trauma.     

Exploring performance of,and attitudes to,Stop‐ and Mock‐Before‐You‐Block in preventing wrong‐side blocks

We conducted an online survey to assess the career experiences of wrong side blocks, the practice of Stop‐Before‐You‐Block, the recently described method of Mock‐Before‐You‐Block and attitudes to these. Respondents were 208 anaesthetists across nine hospitals (173 consultants or Staff and Associate Specialist doctors'), representing 3623 years of collective anaesthetic practice. There had been a total of 62 wrong side blocks (by 51 anaesthetists and one current trainee). Predisposing factors for this were commonly ascribed to distractions (35 (69%), for example due to rushing or teaching), patient positioning (9 (18%)) or miscommunication (6 (12%)). Two (4%) respondents felt they had performed Stop‐Before‐You‐Block too early; 62 (41%) of all respondents stated they performed Stop‐Before‐You‐Block as early as preparing the skin or on arrival of the patient in the anaesthetic room, and not any later. Twenty (10%) respondents admitted to not performing Stop‐Before‐You‐Block at all or only occasionally (including 5 (2%) who had performed a wrong side block). Mock‐Before‐You‐Block was easily understood (by 169 out of 197 (86%)) and 14 out of 61 (23%) respondents felt it would have prevented the wrong side error in their case. However, free‐text comments indicated that many anaesthetists were reluctant to use a method that interrupted their performance of the block. We conclude that considerable work is needed to achieve full compliance with Stop‐Before‐You‐Block at the correct time.     

Bovine meniscal tissue exhibits age‐ and interleukin‐1 dose‐dependent degradation patterns and composition‐function relationships

Despite increasing evidence that meniscal degeneration is an early event in the development of knee osteoarthritis, relatively little is known regarding the sequence or functional implications of cytokine–induced meniscal degradation or how degradation varies with age. This study examined dose‐dependent patterns of interleukin‐1 (IL‐1)‐induced matrix degradation in explants from the radially middle regions of juvenile and adult bovine menisci. Tissue explants were cultured for 10 days in the presence of 0, 1.25, 5, or 20 ng/ml recombinant human IL‐1α. Juvenile explants exhibited immediate and extensive sulfated glycosaminoglycan (sGAG) loss and subsequent collagen release beginning after 4–6 days, with relatively little IL‐1 dose‐dependence. Adult explants exhibited a more graded response to IL‐1, with dose‐dependent sGAG release and a lower fraction of sGAG released (but greater absolute release) than juvenile explants. In contrast to juvenile explants, adult explants exhibited minimal collagen release over the 10‐day culture. Compressive and shear moduli reflected the changes in explant composition, with substantial decreases for both ages but a greater relative decrease in juvenile tissue. Dynamic moduli exhibited stronger dependence on explant sGAG content for juvenile tissue, likely reflecting concomitant changes to both proteoglycan and collagen tissue components. The patterns of tissue degradation suggest that, like in articular cartilage, meniscal proteoglycans may partially protect collagen from cell‐mediated degeneration. A more detailed view of functional changes in meniscal tissue mechanics with degeneration will help to establish the relevance of in vitro culture models and will advance understanding of how meniscal degeneration contributes to overall joint changes in early stage osteoarthritis. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:801–811, 2016.     

Opened end‐to‐side technique for end‐to‐side anastomosis and analyses by an elastic true‐to‐scale silicone rubber model

The end‐to‐side anastomosis is frequently used in microvascular free flap transfer, but detailed rheological analyses are not available. The purpose of this study was to introduce a new modified end‐to‐side (Opened End‐to‐Side, OES‐) technique and compare the resulting flow pattern to a conventional technique. The new technique was based on a bi‐triangulated preparation of the branching‐vessel end, resulting in a “fish‐mouthed” opening. We performed two different types of end‐to‐side anastomoses in forty pig coronary arteries and produced one elastic, true‐to‐scale silicone rubber model of each anastomosis. Then we installed the transparent models in a circulatory experimental setup that simulated the physiological human blood flow. Flow velocity was measured with the one‐component Laser‐Doppler‐Anemometer system, recording flow axial and perpendicular to the model at four defined cross‐sections for seven heart cycles in each model. Maximal and minimal axial velocities ranged in the conventional model between 0.269 and ?0.122 m/s and in the experimental model between 0.313 and ?0.153 m/s. A less disturbed flow velocity distribution was seen in the experimental model distal to the anastomosis. The OES‐technique showed superior flow profiles distal to the anastomosis with minor tendencies of flow separation and represents a new alternative for end‐to‐side anastomosis. © 2013 Wiley Periodicals, Inc. Microsurgery 34:28–36, 2014.     

Serum ion levels after ceramic‐on‐ceramic and metal‐on‐metal total hip arthroplasty: 8‐year minimum follow‐up

Alternative bearing surfaces for total hip arthroplasty, such as metal‐on‐metal and ceramic‐on‐ceramic, offer the potential to reduce mechanical wear and osteolysis. In the short and medium term, the second generation of metal‐on‐metal bearings demonstrated high systemic metal ion levels, whereas ceramic‐on‐ceramic bearings showed the lowest ones. We aimed to verify whether the long‐term ion release in metal‐on‐metal subjects was still relevant at a median 10‐year follow‐up, and whether a fretting process at the modular junctions occurred in ceramic‐on‐ceramic patients and induced an ion dissemination. Serum levels were measured in 32 patients with alumina‐on‐alumina implants (group A), in 16 subjects with metal‐on‐metal implants (group B), and in 47 healthy subjects (group C). Group B results were compared with medium‐term findings. Cobalt and chromium levels were significantly higher in metal‐on‐metal implants than in ceramic‐on‐ceramic ones and controls. Nevertheless, ion levels showed a tendency to decrease in comparison with medium‐term content. In ceramic‐on‐ceramic implants, ion values were not significantly different from controls. Both in groups A and B, aluminum and titanium release were not significantly different from controls. In conclusion, negligible serum metal ion content was revealed in ceramic‐on‐ceramic patients. On the contrary, due to the higher ion release, metal‐on‐metal coupling must be prudently considered, especially in young patients, in order to obtain definitive conclusions. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res     

Sex‐ and Site‐Specific Normative Data Curves for HR‐pQCT

The purpose of this study was to develop age‐, site‐, and sex‐specific centile curves for common high‐resolution peripheral quantitative computed tomography (HR‐pQCT) and finite‐element (FE) parameters for males and females older than 16 years. Participants (n = 866) from the Calgary cohort of the Canadian Multicentre Osteoporosis Study (CaMos) between the ages of 16 and 98 years were included in this study. Participants’ nondominant radius and left tibia were scanned using HR‐pQCT. Standard and automated segmentation methods were performed and FE analysis estimated apparent bone strength. Centile curves were generated for males and females at the tibia and radius using the generalized additive models for location, scale, and shape (GAMLSS) package in R. After GAMLSS analysis, age‐, sex‐, and site‐specific centiles (10th, 25th, 50th, 75th, 90th) for total bone mineral density and trabecular number as well as failure load have been calculated. Clinicians and researchers can use these reference curves as a tool to assess bone health and changes in bone quality. © 2016 American Society for Bone and Mineral Research.     

A randomised crossover comparison of mouth‐to‐face‐shield ventilation and mouth‐to‐pocket‐mask ventilation by surf lifeguards in a manikin

Thirty surf lifeguards (mean (SD) age: 25.1 (4.8) years; 21 male, 9 female) were randomly assigned to perform 2 × 3 min of cardiopulmonary resuscitation on a manikin using mouth‐to‐face‐shield ventilation (AMBU^® LifeKey) and mouth‐to‐pocket‐mask ventilation (Laerdal Pocket Mask?). Interruptions in chest compressions, effective ventilation (visible chest rise) ratio, tidal volume and inspiratory time were recorded. Interruptions in chest compressions per cycle were increased with mouth‐to‐face‐shield ventilation (mean (SD) 8.6 (1.7) s) compared with mouth‐to‐pocket‐mask ventilation (6.9 (1.2) s, p < 0.0001). The proportion of effective ventilations was less using mouth‐to‐face‐shield ventilation (199/242 (82%)) compared with mouth‐to‐pocket‐mask ventilation (239/240 (100%), p = 0.0002). Tidal volume was lower using mouth‐to‐face‐shield ventilation (mean (SD) 0.36 (0.20) l) compared with mouth‐to‐pocket‐mask ventilation (0.45 (0.20) l, p = 0.006). No differences in inspiratory times were observed between mouth‐to‐face‐shield ventilation and mouth‐to‐pocket‐mask ventilation. In conclusion, mouth‐to‐face‐shield ventilation increases interruptions in chest compressions, reduces the proportion of effective ventilations and decreases delivered tidal volumes compared with mouth‐to‐pocket‐mask ventilation.     

Short‐ and long‐term outcome of laparostomy following intra‐abdominal sepsis

Aim This study reports the short‐ and long‐term outcomes of laparostomy for intra‐abdominal sepsis. Method Twenty‐nine sequential patients with intra‐abdominal sepsis treated with a laparostomy over 6 years were included. Results The median age of the patients was 51 years, postoperative intensive care unit stay was 8 days, postoperative length of hospital stay was 87 days and follow up was 2 years. The expected mortality of 25% was insignificantly different from the observed mortality of 33% (P = 0.35). Seven per cent of patients required percutaneous drainage of intra‐abdominal collections. An enterocutaneous fistula developed in 31% of all patients and in 15% of those treated with vacuum dressings. Component‐separation fascial reconstruction was successful and uncomplicated in 83% of recipients compared with 25% of mesh repairs. Conclusion Laparostomy does not significantly reduce mortality from the expected rate and commits the patient to a prolonged recovery with a high risk of enterocutaneous fistulation. Component‐separation fascial reconstruction has a better outcome than mesh repair.