Mid-term progressive loosening of hydroxyapatite-coated femoral stems paired with a metal-on-metal bearing.

BACKGROUND: Several hydroxyapatite (HA)-coated femoral stems from a single manufacturer were identified to have aseptically loosened at mid-term follow-up despite prior radiographic appearance of osseointegration. Possible causes and associated risk factors for stem loosening were explored through radiographic review and implant retrieval analysis. METHODS: Forty-six retrieved hip stems (Corail, DePuy-Synthes) were identified and grouped by bearing type: metal-on-metal (MoM), metal-on-polyethylene, and ceramic-on-ceramic. Stem lucency was graded on post-operative radiographs up to the time of revision. Stems were examined for stripping of the HA coating, taper corrosion, and bearing wear in metal-on-metal cases. Patient demographics, implant design features, and perioperative data were collected from electronic databases and patient charts. RESULTS: Aseptic loosening occurred in 37% of cases examined. MoM bearings were associated with 7.25 times greater risk of loosening compared to other bearing types. Stem radiolucency was more prevalent for MoM cases and, although not statistically significant, demonstrated progressive lucency. Taper corrosion appeared more severe for MoM cases and correlated with proximal stem radiolucency. Removal of the HA coating from the stems was associated with both taper corrosion and MoM bearing wear. Length of implantation was a confounding factor for the MoM cases. CONCLUSION: This study has demonstrated a high risk of mid-term loosening of previously osseointegrated HA-coated femoral stems when paired with a MoM bearing. The mechanism of loosening appears progressive in nature and related to the MoM bearing, possibly interacting with the HA coating. If such loosening is recognized early, rapid revision may allow for retention of the femoral stem.

Characteristics of surgical prosthetic heart valves and problems around labeling: A document from the European Association for Cardio-Thoracic Surgery (EACTS)-The Society of Thoracic Surgeons (STS)-American Association for Thoracic Surgery (AATS) Valve Labelling Task Force.

Intraoperative surgical prosthetic heart valve (SHV) choice is a key determinant of successful surgery and positive postoperative outcomes. Currently, many controversies exist around the sizing and labeling of SHVs rendering the comparison of different valves difficult. To explore solutions, an expert Valve Labelling Task Force was jointly initiated by the European Association for Cardio-Thoracic Surgery (EACTS), The Society of Thoracic Surgeons (STS) and the American Association for Thoracic Surgery (AATS). The EACTS-STS-AATS Valve Labelling Task Force, comprising cardiac surgeons, cardiologists, engineers, regulators and representatives from the International Organization for Standardization (ISO), and major valve manufacturers, held its first in-person meeting in February 2018 in Paris, France. This article was derived from the meeting's discussions. The Task Force identified the following areas for improvement and clarification: reporting of physical dimensions and characteristics of SHVs determining and labeling of SHV size, in vivo and in vitro testing, and reporting of SHV hemodynamic performance and thrombogenicity. Furthermore, a thorough understanding of the regulatory background and the role of the applicable ISO standards, together with close cooperation between all stakeholders (including regulatory and standard- setting bodies), is necessary to improve the current situation. Cardiac surgeons should be provided with appropriate information to allow for optimal SHV choice. This first article from the EACTS-STS-AATS Valve Labelling Task Force summarizes the background of SHV sizing and labeling and identifies the most important elements where further standardization is necessary.

Capillary and Venous Blood Glucose Accuracy in Blood Glucose Meters Versus Reference Standards: The Impact of Study Design on Accuracy Evaluations.

BACKGROUND: Anecdotal blood glucose assessments conducted by health care professionals (HCPs) in the field have highlighted differences in results when methodology used is not according to best practices for measuring blood glucose. This study assessed the impact on accuracy of blood glucose measurements when methodology deviates from the recommended study design and recommended reference instrument. METHODS: Adults with type 1 or type 2 diabetes provided capillary and venous blood samples for accuracy assessments using OneTouch® Verio® (Verio) and OneTouch® Ultra 2® (Ultra) blood glucose meters (BGM) and two different reference instruments. RESULTS: Increases in mean bias were observed when comparing capillary to venous samples tested on the BGMs and the recommended reference instrument. Mean bias was even greater when a hospital blood glucose analyzer was used to measure venous plasma glucose. Increases in mean bias observed for Ultra BGM when testing venous blood on the meter compared to the recommended reference instrument was likely due to the interfering effects of low oxygen levels in the venous blood sample. Conversely, Verio meters, which are insensitive to low oxygen levels, showed little difference from baseline when testing venous blood on the meter compared to results from the same venous sample measured on a reference instrument. CONCLUSIONS: Deviations from the best practice study design of comparing capillary blood glucose results tested on the blood glucose meter with the manufacturer's stated reference instrument will affect accuracy of blood glucose measurements.

Bench testing and coronary artery bifurcations: a consensus document from the European Bifurcation Club.

This is a consensus document from the European Bifurcation Club concerning bench testing in coronary artery bifurcations. It is intended to provide guidelines for bench assessment of stents and other strategies in coronary bifurcation treatment where the United States Food and Drug Administration (FDA) or International Organization for Standardization (ISO) guidelines are limited or absent. These recommendations provide guidelines rather than a step-by-step manual. We provide data on the anatomy of bifurcations and elastic response of coronary arteries to aid model construction. We discuss testing apparatus, bench testing endpoints and bifurcation nomenclature.

Benchmarking for On-Scalp MEG Sensors.

OBJECTIVE: We present a benchmarking protocol for quantitatively comparing emerging on-scalp magnetoencephalography (MEG) sensor technologies to their counterparts in state-of-the-art MEG systems. METHODS: As a means of validation, we compare a high-critical-temperature superconducting quantum interference device (high Tc SQUID) with the low- Tc SQUIDs of an Elekta Neuromag TRIUX system in MEG recordings of auditory and somatosensory evoked fields (SEFs) on one human subject. RESULTS: We measure the expected signal gain for the auditory-evoked fields (deeper sources) and notice some unfamiliar features in the on-scalp sensor-based recordings of SEFs (shallower sources). CONCLUSION: The experimental results serve as a proof of principle for the benchmarking protocol. This approach is straightforward, general to various on-scalp MEG sensors, and convenient to use on human subjects. The unexpected features in the SEFs suggest on-scalp MEG sensors may reveal information about neuromagnetic sources that is otherwise difficult to extract from state-of-the-art MEG recordings. SIGNIFICANCE: As the first systematically established on-scalp MEG benchmarking protocol, magnetic sensor developers can employ this method to prove the utility of their technology in MEG recordings. Further exploration of the SEFs with on-scalp MEG sensors may reveal unique information about their sources.

A Novel 141Ce-Based Flood Field Phantom: Assessment of Suitability for Daily Uniformity Testing in a Clinical Nuclear Medicine Department.

Daily quality control testing of a γ-camera is of the utmost importance in assessing whether the camera is suitable for clinical use. The aim of our study was to assess the suitability of a fillable 141Ce-based flood field phantom developed in-house for daily quality control testing of γ-cameras. Methods: Daily uniformity testing was performed for 113 d using the fillable 141Ce phantom and a commercially available sheet-type 57Co phantom, and the results were compared. Results: The average integral uniformity obtained by the 141Ce and 57Co phantoms was 3.24% and 2.72%, respectively, for detector 1 and 3.31% and 2.78%, respectively, for detector 2. Conclusion: The 141Ce phantom we developed is a suitable alternative to the commercially available 57Co phantom.

Quality assurance guidelines for superficial hyperthermia clinical trials : II. Technical requirements for heating devices.

Quality assurance (QA) guidelines are essential to provide uniform execution of clinical trials with uniform quality hyperthermia treatments. This document outlines the requirements for appropriate QA of all current superficial heating equipment including electromagnetic (radiative and capacitive), ultrasound, and infrared heating techniques. Detailed instructions are provided how to characterize and document the performance of these hyperthermia applicators in order to apply reproducible hyperthermia treatments of uniform high quality. Earlier documents used specific absorption rate (SAR) to define and characterize applicator performance. In these QA guidelines, temperature rise is the leading parameter for characterization of applicator performance. The intention of this approach is that characterization can be achieved with affordable equipment and easy-to-implement procedures. These characteristics are essential to establish for each individual applicator the specific maximum size and depth of tumors that can be heated adequately. The guidelines in this document are supplemented with a second set of guidelines focusing on the clinical application. Both sets of guidelines were developed by the European Society for Hyperthermic Oncology (ESHO) Technical Committee with participation of senior Society of Thermal Medicine (STM) members and members of the Atzelsberg Circle.

Classifying Alarms: Seeking Durability, Credibility, Consistency, and Simplicity.

Alongside the development and testing of new audible alarms intended to support International Electrotechnical Commission 60601-1-8, a global standard concerned with alarm safety, the categories of risk that the standard denotes require further thought and possible updating. In this article, we revisit the origins of the categories covered by the standard. These categories were based on the ways that tissue damage can be caused. We consider these categories from the varied professional perspectives of the authors: human factors, semiotics, clinical practice, and the patient or family (layperson). We conclude that while the categories possess many clinically applicable and defensible features from our range of perspectives, the advances in alarm design now available may allow a more flexible approach. We present a three-tier system with superordinate, basic, and subordinate levels that fit both within the thinking embodied in the current standard and possible new developments.

137Cs Dosimeter Irradiation Facilities: Calibration Frequency, Precision, and Accuracy.

Many dosimeter and instrument calibration sources, especially Cs irradiators permanently installed in facilities, are infrequently calibrated since their geometry is not subject to large variation, their mechanisms are simple, and their operation can be visibly error-free for decades. Only decay corrections are needed to know delivered doses at fixed locations once a thorough characterization of such facilities is completed. For one such Cs source, however, collected current values in a span of a few days were found to drop significantly. Malfunction of the internal positioning mechanisms through wear were found to be the cause. This paper suggests periodic source calibrations for the timely identification of source failures that could cause gross errors in dose delivery. In addition, a rigorous analysis of the magnitude of uncertainties and errors in dose delivery using a calibration source is included, which is based upon newly collected experimental data. This provides a technical basis for calibration procedures to ensure a given accuracy and precision of dose delivery.

Evaluation of the Potential Optical Radiation Hazards with Led Lamps Intended for Home Use.

The authors evaluated the potential for ocular damage from optical radiation emitted by Light Emitting Diode (LED) based lamps used for general illumination. Ten LED lamps were randomly selected off the shelf from a local home improvement store. The LEDs were behind diffusers in half of these lamps, while in the other half, the LEDs were clearly visible. In addition, a battery powered LED lantern having a LED source behind a diffuser was measured. The optical radiation emissions from two common incandescent lamps were also measured to compare the relative hazards of LED and incandescent lamps. All lamp samples were evaluated in accordance with procedures specified in the American National Standards Institute/Illuminating Engineering Society of North America (ANSI/IESNA) Standard RP-27.3. For comparison purposes, the lantern and 100 W incandescent lamps were also evaluated according to ANSI RP-27.1. These measurements indicate that no lamp evaluated poses any photobiological hazard, and therefore, all lamps fall in the RP-27.3 category of Exempt Group. However, when evaluated in accordance with RP-27.1, the 100 W incandescent lamp would be classified in Risk Group 1 (low risk), while the LED lantern would be classified in Risk Group 2 (moderate risk).

Radiation Protection Clothing in X-Ray Diagnostics - Influence of the Different Methods of Measurement on the Lead Equivalent and the Required Mass.

PURPOSE: The determination of attenuation compared to lead for lead-free and lead-reduced protective clothing depends strongly on the different methods of measurement. The standards EN 61331-1 (2002), DIN 6857-1 und IEC 61331-1 (2014) are now available for the testing of protective clothing. These standards define methods in the narrow beam and in the inverse broad beam geometry with partially different radiation qualities. In the narrow beam the scattered radiation and fluorescence are not considered due to the arrangement. Therefore, the protective effect of lead-free materials will be incorrectly estimated compared to lead material. The influence of the different methods of measurement on the lead equivalent and the required mass of radiation protection clothing was examined. MATERIALS AND METHODS: The lead equivalents for material samples for commercially available protective clothing were determined. These samples were made of lead and lead-reduced and lead-free materials. For determination of the attenuation equivalents, certified lead foils with high purity and a precise thickness of 0.05 to 1.25 mm were used. RESULTS: The measurements indicate that the lead equivalent depends on the method of measurement and the radiation quality. For X-ray tube voltages below 110 kV, lead-free or lead-reduced materials show a higher lead equivalent compared to lead material in some cases. Significant mass reductions of more than 10 % compared to lead material are only achievable with a limited range of use up to 100 kV. CONCLUSION: The implementation of an internationally accepted measuring standard for radiation protection clothing is reasonable and necessary. If standard IEC 61331-1 (2014) can fill this role is unknown. Key points • The attenuation factor and the lead equivalent depend strongly on the method of measurement.• The used X-ray spectra are only partially comparable with the spectra of scattered radiation.• Mass reductions for protective clothing are only achievable with a limited range of use. Citation Format: • Schöpf T, Pichler T. Radiation Protection Clothing in X-Ray Diagnostics - Influence of the Different Methods of Measurement on the Lead Equivalent and the Required Mass. Fortschr Röntgenstr 2016; 188: 768 - 775.

Integrating Cerebrospinal Fluid Shunt Quality Checks into the World Health Organization's Safe Surgery Checklist: A Pilot Study.

BACKGROUND: Despite efforts for improvement, cerebrospinal fluid (CSF) shunt failure rates remain high. Recent studies have shown promising reductions in failure rates and infection rates with the routine use of perioperative checklists. This study was conducted to pilot test the feasibility and efficacy of integrating specific CSF shunt surgery quality checks into the World Health Organization (WHO) Surgical Safety Checklist. METHODS: We designed CSF shunt checklist quality items according to a previously established methodology, including solicitation of best practices by a national multidisciplinary expert panel. We examined adherence to key processes before and after implementation as a measure of the efficacy of the integrated checklist. We then surveyed users regarding perceived checklist utility. RESULTS: Overall adherence to shunt-specific key processes increased from 8.6 (95% confidence interval [CI], 7.9-9.2) to 9.9 (95% CI, 9.3-10.4; P = 0.0070) per 12 items, driven by the infection control items (4.7 [95% CI, 4.1-5.3] to 6.0 [95% CI, 5.4-6.4] per 8 items; P = 0.0056). All of the survey respondents indicated that the checklist was easy to use. The majority stated that it helped them feel better prepared to perform the procedure consistently according to evidence-based practice, and that if they were to adhere to the checklist consistently, their rate of shunt failure would be expected to decrease. CONCLUSIONS: The integration of specialty-specific checks into the WHO Safe Surgery Checklist improved adherence to quality processes and generally was well accepted in our pilot study. A larger clinical trial is needed to assess whether this approach could improve shunt outcomes.