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The effective conductivity of a contact system is an important characteristic used to link the microstructure of the contact system to its performance. A resistor network model has been developed from the cross-sectional slices of a given electrical contact system. This allows the total resistance across the model and hence the total conductance of the system to be calculated. This resistor network model development is based on the contact interface, of the contact system, which is presented as a 3-D contact map. The 3-D contact map consists of contact spots that have been extended across the two bodies of the contact system as asperities. In this modeling process, a technique is developed that pictures any cross-sectional slice of the contact system and shows in which voxels the electric current flows. An X-ray computed tomography method is used to collect the data for visualizing the contact system and preparing the 3-D contact map. A 250-V, 16-A rated ac single-pole rocker switch is used as the contact system for investigation.

A 3D contact analysis and modeling suite of tools are developed and introduced in this work. The “3D Contact Map” of an electrical contact interface is presented demonstrating the 3D nature of the contact. It gives information on where the electrical contact spots in a 3D surface profile are located. An X-ray Computer Tomography (CT) technique is used to collect the 3D data to a resolution of around 5 μ m of a real un-dismantled contact interface for analysis. Previous work by Lalechos and Swingler presented “2D Contact Map” on a 2D contact profile from collected 3D data to a resolution of around 8 μ m . The main advantages of both 3D and 2D mapping techniques focus on the fact that they are non-destructive and there is no need to dismantle the component of interest. This current work focuses on the 3D mapping technique showing its advantages over the 2D mapping technique. For test purposes, a 16 A rated AC single pole switch is scanned after two different current loading tests (0 A and 16 A). A comparison for the total mechanical area of contact, the number of contact spots and the total contact resistance is conducted using both the 2D and 3D mapping techniques to a resolution of around 5 μ m .

Objective Detailed assessment of activity before and after total hip arthroplasty (THA) including a long-term followup period is lacking. Our objectives were to evaluate patient activity levels prior to disease onset, prior to THA, and at 5 and 10 years after surgery, and to determine the predictors of high activity 5 years after surgery. Methods We included elective primary THAs performed between 1996 and 2012. A cross-sectional analysis compared mean University of California, Los Angeles (UCLA) activity scores over 4 periods: prior to symptom onset of osteoarthritis, prior to surgery, 5 years after surgery, and 10 years after surgery. Analyses of activity levels were performed and stratified by sex, age, body mass index (BMI), American Society of Anesthesiology (ASA) classes, and preoperative activity level. A prospective study was conducted to identify baseline characteristics associated with a high activity level (UCLA score ≥7) 5 years after surgery using logistic regression. Results The mean UCLA activity scores prior to symptom onset (n = 189), prior to THA (n = 203), 5 years after surgery (n = 1,085), and 10 years after surgery (n = 757) were 6.9, 3.5, 5.7, and 5.5, respectively. Postoperative scores were close to values prior to symptom onset in patients ages ≥55 years, but were lower in those who were younger. High activity was reported by 49% of patients prior to symptom onset, 5% of patients prior to surgery, and 28% of patients at both 5 and 10 years after surgery. The predictors of high activity at 5 years were younger age, male sex, a lower BMI, a lower ASA score, and an active lifestyle prior to surgery. Conclusion Five and 10 years after primary THA, physical activity levels were substantially higher in men and women and in all age categories as compared to before surgery.

In experimental studies, statin use has been associated with reduction of osteoclastic activity and promotion of bone formation around implants. Moreover, a large clinical study recently reported a substantially reduced risk of revision for aseptic loosening among statin users with THA. Our objective was to evaluate the influence of statin use on the development of femoral osteolysis within 5 years after THA. We conducted a case-cohort study including all THAs presenting with femoral osteolysis at the 5 year visit (cases) and compared them with those without osteolysis (controls). Cases and controls were identified from a cohort of primary THAs operated between 2001 and 2005. Seven hundred thirty-five THAs were included, mean age 68 years. Five years after surgery osteolysis had developed around the femoral component of 40 THAs (5.4%). Ever-use of statins was much less frequent among cases (5 of 40, 12.5%) than among controls (199 of 695, 28.6%). The crude risk ratio of femoral osteolysis among statin users was 0.36 (95% CI 0.14; 0.92). After adjusting for age, sex, activity level, BMI, diagnosis, bearing surface, and type of stem, the adjusted risk ratio was 0.38 (95% CI 0.15; 0.99). In conclusion, statin use was associated with a reduced risk of developing femoral osteolysis 5 years after THA. Statins may be useful for reducing the risk of implant failure following THA.

BACKGROUND: The most important long-term complication following total hip arthroplasty is periprosthetic femoral osteolysis. A sizeable proportion of patients who undergo arthroplasty are obese. While patient activity, implant type, and quality of fixation are known risk factors for osteolysis, the literature concerning obesity is sparse and controversial. Our primary objective was to evaluate the influence of obesity on the risk of osteolysis five and ten years after primary total hip arthroplasty with a cemented stem. Secondary objectives were to evaluate clinical outcome and patient satisfaction. METHODS: We conducted a prospective cohort study of patients undergoing hip arthroplasty with a third-generation stem-cementing technique from 1996 to 2003. All patients were seen at five or ten years postoperatively. Radiographs and information regarding body-mass index (

Electrical contact is an essential factor that should be considered to achieve better performance and long term reliability for the design of devices. In this work, an electrical contact interface is visualized as a “3D Contact Map” using X-Ray Computed Tomography (CT) which acquires 3D views of the sample keeping the features intact. The “3D Contact Map” contains information on where the electrical contact spots in a 3D surface profile are located with each voxel relating to 5 µm × 5 µm x 5 µm volume at the interface. Contact analysis techniques are developed and implemented with a suite of tools in Matlab in order to calculate electrical parameters (voltage, current, resistance) of each contact spot and contact asperity located between the conductors of a single pole switch rated at 16A AC.

Electrical contact is an important parameter for the reliability of electrical devices. Due to the limitation of optical imaging, methods available for the contact measurement characteristics are only suitable for open or transparent systems. For most of the practical situations that require contact measurement characteristics in non-transparent or enclosed systems, the traditional methods are not effective. Based upon these requirements, a method suitable for the electrical contact characteristics in non-transparent systems is developed by using X-ray computer tomography (CT). The main advantage of this visualisation method is the ability to acquire three-dimensional (3D) views of systems keeping the features intact. In this work, the method is demonstrated by measuring the contact area and the average contact angle in each contact spot which is held between the conductors of 16A AC single pole switch after two different current tests (0 and 16A AC). The distances between the contact spots are also calculated.

Detailed assessment of activity before and after total hip arthroplasty (THA) including a long-term followup period is lacking. Our objectives were to evaluate patient activity levels prior to disease onset, prior to THA, and at 5 and 10 years after surgery, and to determine the predictors of high activity 5 years after surgery.We included elective primary THAs performed between 1996 and 2012. A cross-sectional analysis compared mean University of California, Los Angeles (UCLA) activity scores over 4 periods: prior to symptom onset of osteoarthritis, prior to surgery, 5 years after surgery, and 10 years after surgery. Analyses of activity levels were performed and stratified by sex, age, body mass index (BMI), American Society of Anesthesiology (ASA) classes, and preoperative activity level. A prospective study was conducted to identify baseline characteristics associated with a high activity level (UCLA score ≥7) 5 years after surgery using logistic regression.The mean UCLA activity scores prior to symptom onset (n = 189), prior to THA (n = 203), 5 years after surgery (n = 1,085), and 10 years after surgery (n = 757) were 6.9, 3.5, 5.7, and 5.5, respectively. Postoperative scores were close to values prior to symptom onset in patients ages ≥55 years, but were lower in those who were younger. High activity was reported by 49% of patients prior to symptom onset, 5% of patients prior to surgery, and 28% of patients at both 5 and 10 years after surgery. The predictors of high activity at 5 years were younger age, male sex, a lower BMI, a lower ASA score, and an active lifestyle prior to surgery.Five and 10 years after primary THA, physical activity levels were substantially higher in men and women and in all age categories as compared to before surgery.

Large-head metal-on-metal (MoM) total hip replacements (THR) have given rise to concern. Comparative studies of small-head MoM THRs over a longer follow-up period are lacking. Our objective was to compare the incidence of complications such as infection, dislocation, revision, adverse local tissue reactions, mortality and radiological and clinical outcomes in small-head (28 mm) MoM and ceramic-on-polyethylene (CoP) THRs up to 12 years post-operatively. A prospective cohort study included 3341 THRs in 2714 patients. The mean age was 69.1 years (range 24 to 98) and 1848 (55.3%) were performed in women, with a mean follow-up of 115 months (18 to 201). There were 883 MoM and 2458 CoP bearings. Crude incidence rates (cases/1000 person-years) were: infection 1.3 vs 0.8; dislocation 3.3 vs 3.1 and all-cause revision 4.3 vs 2.2, respectively. There was a significantly higher revision rate after ten years (adjusted hazard ratio 9.4; 95% CI 2.6 to 33.6) in the MoM group, and ten of 26 patients presented with an adverse local tissue reaction at revision. No differences in mortality, osteolysis or clinical outcome were seen. In conclusion, we found similar results for small-head MoM and CoP bearings up to ten years post-operatively, but after ten years MoM THRs had a higher risk of all-cause revision. Furthermore, the presence of an adverse response to metal debris seen in the small-head MOM group at revision is a cause for concern. Cite this article: Bone Joint J 2014; 96-B:868–75.

The electrical contact is an important phenomenon that should be given into consideration to achieve better performance and long term reliability for the design of devices. Based upon this importance, the electrical contact interface has been visualized as a ‘‘3D Contact Map’’ and used in order to investigate the contact asperities. The contact asperities describe the structures above and below the contact spots (the contact spots define the 3D contact map) to the two conductors which make the contact system. The contact asperities require the discretization of the 3D microstructures of the contact system into voxels. A contact analysis approach has been developed and introduced in this paper which shows the way to the 3D visualization of the contact asperities of a given contact system. For the discretization of 3D microstructure of contact system into voxels, X-ray Computed Tomography (CT) method is used in order to collect the data of a 250 V, 16 A rated AC single pole rocker switch which is used as a contact system for investigation.

In experimental studies, statin use has been associated with reduction of osteoclastic activity and promotion of bone formation around implants. Moreover, a large clinical study recently reported a substantially reduced risk of revision for aseptic loosening among statin users with THA. Our objective was to evaluate the influence of statin use on the development of femoral osteolysis within 5 years after THA. We conducted a case-cohort study including all THAs presenting with femoral osteolysis at the 5 year visit (cases) and compared them with those without osteolysis (controls). Cases and controls were identified from a cohort of primary THAs operated between 2001 and 2005. Seven hundred thirty-five THAs were included, mean age 68 years. Five years after surgery osteolysis had developed around the femoral component of 40 THAs (5.4%). Ever-use of statins was much less frequent among cases (5 of 40, 12.5%) than among controls (199 of 695, 28.6%). The crude risk ratio of femoral osteolysis among statin users was 0.36 (95% CI 0.14; 0.92). After adjusting for age, sex, activity level, BMI, diagnosis, bearing surface, and type of stem, the adjusted risk ratio was 0.38 (95% CI 0.15; 0.99). In conclusion, statin use was associated with a reduced risk of developing femoral osteolysis 5 years after THA. Statins may be useful for reducing the risk of implant failure following THA.

Introduction: Large-diameter metal-on-metal (LDMOM) cups have been used in total hip arthroplasty (THA) advocating superior results with respect to dislocation rates, range of motion, and long-term survival. The Durom cup used as part of the Durom hip resurfacing system has been incriminated with poor short-term results sometimes correlated to incorrect positioning of either the femoral or acetabular component due to poor exposure during this procedure. Our objective was to evaluate short-term results of the Durom cup used in conjunction with standard stems.

We evaluated all revisions performed from March 1996 to December 2008 and compared complications, mortality, and clinical outcomes between patients 80 years and older and patients younger than 80 years. Data were collected prospectively. There were 325 revisions, 84 (25.8%) in patients 80 years and older and 241 in patients younger than 80 years (62% revision for aseptic loosening in both groups). The mean follow-up was 4.3 years. The results, 80 years and older vs younger than 80 years, revealed the following: mortality, 5% vs 0% 3 months postoperatively; medical complications in 23.8% vs 6.2%; postoperative fractures, 9.5% vs 2.5%; and improved Merle d'Aubigne scores from 9.6 to 13.0 vs 10.4 to 14.3. Revision total hip arthroplasty in patients 80 years and older was associated with substantial clinical improvement and patient satisfaction. However, medical complications and 90-day mortality were higher, and postoperative fractures occurred more frequently.

Total hip arthroplasty (THA) with well designed cementless acetabular implants has shown excellent results. The purpose of this study was to assess our clinical and radiological outcomes using an uncemented cup. We conducted a prospective cohort study including all consecutive primary THAs performed with the Morscher press-fit cup, an uncemented non-modular acetabular component, between March 1996 and December 1998. Patients were evaluated at ten years with clinical and radiological follow-up, patient satisfaction and questionnaire assessment using the Harris hip score (HHS), Merle d'Aubigné and Postel score, the UCLA score, the 12-item short-form health survey (SF-12) and a visual analog scale. Five hundred sixty-one THAs were performed in 518 patients. At 120 months (± 7.3 months), 303 patients with 335 THAs were still available for follow-up. None of the patients had required cup revision for aseptic loosening. At ten years, the cup survivorship was 98.8% (95% CI 97.4-99.5) with cup revision for any cause as an endpoint. No radiolucencies were seen around the cups, but osteolytic defects involved 21 stems (8.3%). Mean total linear polyethylene wear was 0.9 mm. The Morscher acetabular replacement cup provides excellent results at ten years. There were no revisions for aseptic loosening of the cup, and no osteolytic defects were found around the cup. Patient satisfaction was high and the clinical results were very good.

Objective: We hypothesized that pretreatment with atorvastatin improves alveolar capillary permeability and hemodynamics and, thus, confers protection against lung injury caused by high-stretch mechanical ventilation. Methods: Twenty-four isolated sets of normal rabbit lungs were utilized. Treated animals received atorvastatin (20 mg/kg body weight/day by mouth) for 3 days before surgery. Lungs were perfused constantly (300 mL/min) and ventilated for 1 hr with pressure-control ventilation at either 23 (high pressure; resulting in tidal volume approximately 22 mL/kg) or 11 (low pressure; tidal volume approximately 10 mL/kg) cm H2O peak inspiratory pressure and positive end-expiratory pressure of 3 cm H2O. Four groups were examined: high pressure-no statin, high pressure-statin pretreatment, low pressure-no statin, and low pressure-statin pretreatment. Results: The high-pressure-no statin group sustained more damage than the low-pressure groups. In high-pressure groups, lungs of statin-pretreated vs. no statin-pretreated animals sustained a significantly lower increase in ultrafiltration coefficient (an accurate marker of alveolar capillary permeability; high-pressure-statin pretreatment vs. high-pressure-no statin, -0.013 +/- 0.017 g/min/ mm Hg/100g vs. 1.723 +/- 0.495 g/min/mm Hg/100g; p < .001), lower weight gain (i.e., less edema formation; 4.62 +/- 1.50 grams vs. 17.75 +/- 4.71 grams; p = .005), improved hemodynamics (i.e., lower increase in mean pulmonary artery pressure; 0.56 +/- 0.51 mm Hg vs. 5.62 +/- 1.52 mm Hg; p = .04), lower protein concentration in bronchoalveolar lavage fluid (p < .001), and fewer histologic lesions (p = .013). Apoptosis of lung parenchyma cells was not different (p = .97). There was no difference between low-pressure-statin pretreatment and low-pressure-no statin groups regarding these outcomes. Conclusion: In this model, atorvastatin improves alveolar capillary permeability and hemodynamics and, thus, attenuates lung injury caused by high-stretch mechanical ventilation. (Crit Care Med 2010; 38:1321-1328)

Background: DRESS syndrome (drug rash with eosinophilia and systemic symptoms) is a hypersensitivity reaction with skin rashes, eosinophilia, fever, lymph node enlargement and internal organ involvement. Case Report: A 60-year-old diabetic woman was hospitalized at the University Hospitals of Geneva for mid-leg amputation due to peripheral arterial occlusive disease. No drug allergy was reported. Because of a wound infection by methicillin-resistant Staphylococcus aureus, treatment with vancomycin (2 g/day) in continuous perfusion was initiated. Approximately 2 weeks later, she developed a toxidermia with fever, a progressive maculopapular skin rash, eosinophilia and acute renal insufficiency. The skin biopsy revealed a necrosis with lymphocytic and eosinophilic infiltrations, supporting the suspicion of DRESS syndrome. A cure was achieved by the withdrawal of vancomycin and the administration of methylprednisolone (1 g/day), antihistaminics and topical mometasone, without the introduction of other antibiotics. Conclusion: Vancomycin can be a cause of DRESS syndrome. A high index of suspicion is warranted in order not to miss this potentially lethal disease.

Right ventricular (RV) infarction, which is now recognized to occur in approximately 50% of all inferior myocardial infarctions (MIs), has a significant early mortality in patients with RV dysfunction. In this article we report the midterm results of 3 patients who had isolated RV failure after acute inferior MI and in whom a cavobipulmonary shunt was carried out to reestablish an adequate left ventricular (LV) filling and decrease the RV volume overload in the presence of significant tricuspid regurgitation.