Instrument Alignment Research Articles

Retropatellar Accessory Portals for Improved Access to the Patella; Anatomic Description and Evaluation of Safety

Current arthroscopic techniques are limited in their ability to achieve the appropriate orientation necessary to address deep chondral defects of the patella. We describe novel retropatellar portals to offer improved access to critical areas of the retropatellar region for the treatment of chondral defects. A descriptive anatomic study was performed on 10 cadaveric knees. Novel retropatellar portals were created to access the undersurface of the patella, and the distance to adjacent neurovascular structures (common peroneal nerve (CPN) and infrapatellar branch of the saphenous nerve (IPBSN)) was assessed. Distances to these structures, in addition to bony landmarks (medial & lateral epicondyles and margins of the mid-patella), were recorded to describe the precise location of the portals for their safe use. Safe placement can confidently be established on the lateral aspect of the knee guided by palpation of bony landmarks. The lateral retropatellar portal was separated by the CPN by an average of 53.8 ± 7.2mm. Further, on the medial aspect of the knee, the IPBSN was an average distance of 15.8 ± 15.5 mm from the portal site. No nerves were transected or contacted in any specimens. The new retropatellar portals markedly improve visualization and achieve near perpendicular alignment of arthroscopic instruments to the posterior patella. We believe these portals are safe to use and thus clinically acceptable.

Micro/nanoparticle separation via curved nano-gap device with enhanced size resolution

Micro/nanoparticles are widely found in industry and biological field to play important roles and particle size distribution is an important factor to evaluate these particles. Nano-gap device has advantages in size determination for particles in diverse size and/or shape, but it has difficulty in practical use due to severe requirement on instrumental alignment to reproduce the gap profile and non-quantitative sample injection based on capillary action. To solve these problems, curved nano-gap device (CGD) was fabricated from two flat glass plates via a simple microfabrication process to gain enhanced size resolution, and pressure-driven liquid delivery system was coupled to CGD. The gap was precisely controlled by wet etching with hydrofluoric acid on a glass plate to obtain the depth of 35.5±15.0nm on average. CGD utilized glass deflection with 18.1nm elevation/μm lateral distance that achieved practical size resolutions of 14.5nm, which was 15.7% smaller than that of conventional linear nano-gap device. Using CGD, particles from 0.5 to 10μm diameter were trapped and separated. The estimated sizes of the trapped particles matched the suggested values well. Cell sizes were also measured by CGD and the measured values matched with the values found by microscope observation. CGD acquired reproducible instrumental setup that resulted in robust analysis on size of micro/nanoparticles.

X-ray Scattering from Semiconductors and Other Materials. 3rd Ed. By Paul F. Fewster. Singapore: World Scientific Press, 2015. Pp. 493. Price GBP 65.00, USD 99.00. ISBN 9789814436922.

X-ray scattering has now become a standard metrology within the semiconductor industry and as such is regularly used by analytical scientists and engineers who are not experts in X-ray physics, but who rely on the validity of the data that are coming from commercial X-ray instruments. For them, this is an ideal book, which distils the knowledge accrued by Paul Fewster over a long and distinguished career into a compact account of how the techniques may be used to understand the structure of advanced materials. Fewster, as one of the best experimentalists of his generation, gives insights into the subtleties of data extraction, instrument alignment and choice of configuration to obtain optimal performance from a system. Like the first two editions, the book begins with an introduction to semiconducting materials and the influence of distortions on their structure, emphasizing the importance of epitaxial relationships in modern device materials. The second chapter contains the theory of X-ray scattering. This, as with the fourth chapter on instrument selection, is a mine of information and it provides a detailed exposition of the physics needed to understand how materials properties can be deduced from the collected data. These two chapters are not ‘novice friendly’; the mixing of quantum and classical ideas is not helpful and the reader is taken to quite recent research work before the basics will have been grasped. Use of text boxes to differentiate complex and second-order ideas from the main exposition would have been helpful. The great value of these chapters is for the diffractometer user who, having thought that understanding of Bragg ’s law and thickness fringes was all that was necessary, encounters apparent anomalies in data that need a deeper understanding. For such analytical scientists this book is an essential tool. The third chapter describes the properties of X-ray optical components used for scattering measurements and shows clearly how different devices can be combined to select appropriate instrument functions. The last chapter gives a number of excellent case studies of how materials parameters can be extracted confidently from scattering data. This is set out in sequence of increasing complexity of interpretation and includes valuable information on how to treat imperfect systems, extending from single crystals to polycrystalline materials. It is a pity that the criticisms of Ullrich Pietsch (2005) relating to the second edition have not been heeded. The presentation is poor in several respects. Fonts of equations vary wildly and unexpectedly. Graph axes are still missing units; diagrams, equations and tables still appear without definition of symbols. The book is deliberately focused at laboratory instrument users and the huge advances made at synchrotron radiation sources get barely a mention. Nevertheless for the specific audience, this new edition is a most valuable resource. The extra material included does make the purchase of another edition worthwhile.

The influence of osteophyte depiction in CT for patient-specific guided hip resurfacing procedures.

An accurate fit of a patient-specific instrument guide during an intervention is one of the critical factors affecting accuracy of the surgical procedure. In this study, we investigated how well osteophytes, which are abnormal bone growths that form along joints, are depicted in clinical preoperative CT scans and estimated the influence of such depiction errors on the intraoperative accuracy of the guide. In 34 hip resurfacing patients, 227 osteophyte surface points on the anterior aspect of the femoral neck were collected intraoperatively, using an optoelectronic navigation system. These points were registered to a preoperative CT scan of the patient, and distances between collected points and segmented virtual bone surface, as well as Hounsfield units for these points, were determined. We simulated the registration error of a patient-specific guide, using a modified registration algorithm, to test placement on the anterior aspect of the femoral neck without removing any osteophytes. This error was then applied to the surgical plan of the femoral central-pin position and orientation for evaluation. The average distance between the collected points and the segmented surface was 2.6 mm. We estimated the average error for the entrance point of the central-pin to be 0.7 mm in the distal direction and 3.2 mm in the anterior direction. The average orientation error was 2.8° in anteversion. The depiction of osteophytes in clinical preoperative CT scans for proximal femurs can be unreliable and can possibly result in significant intraoperative instrument alignment errors during image-guided surgeries.

Development of a laboratory-based transmission diffraction technique forin situdeformation studies of Mg alloys

A laboratory-based transmission X-ray diffraction technique was developed to measure elastic lattice strains parallel to the loading direction duringin situtensile deformation. High-quality transmission X-ray diffraction data were acquired in a time frame suitable forin situloading experiments by application of a polycapillary X-ray optic with a conventional laboratory Cu X-ray source. Based on the measurement of two standard reference materials [lanthanum hexaboride (NIST SRM 660b) and silicon (NIST SRM 640c)], precise instrumental alignment and calibration of the transmission diffraction geometry were realized. These results were also confirmed by the equivalent data acquired using the standard Bragg–Brentano measurement geometry. An empirical Caglioti function was employed to describe the instrumental broadening, while an axis of rotation correction was used to measure and correct the specimen displacement from the centre of the goniometer axis. For precise Bragg peak position andhkilintensity information, a line profile fitting methodology was implemented, with Pawley refinement used to measure the sample reference lattice spacings (do(hkil)). It is shown that the relatively large X-ray probe size available (7 × 7 mm) provides a relatively straightforward approach for improving the grain statistics for the study of metal alloys, where grain sizes in excess of 1 µm can become problematic for synchrotron-based measurements. This new laboratory-based capability was applied to study the lattice strain evolution during the elastic–plastic transition in extruded and rolled magnesium alloys. A strain resolution of 2 × 10−4at relatively low 2θ angles (20–65° 2θ) was achieved for thein situtensile deformation studies.In situmeasurement of the elastic lattice strain accommodation with applied stress in the magnesium alloys indicated the activation of dislocation slip and twin deformation mechanisms. Furthermore, measurement of the relative change in the intensity of 0002 and 10\overline 13 was used to quantify {10\overline 12}〈\overline 1011〉 tensile twin onset and growth with applied load.

Perspectivas de la cooperación internacional y el desarrollo sostenible después de 2015

Este ensayo analiza los elementos que condicionan ese proceso de adecuación de los objetivos e instrumentos del sistema o arquitectura de la cooperación a las nuevas realidades internacionales del mundo interpolar y posoccidental, en el que Europa y sus vástagos occidentales han perdido la centralidad del poder material e ideacional/normativo. En ese contexto, se exploran las alternativas de gobernanza de un sistema renovado de cooperación que está sujeto a enormes incertidumbres por la competencia de dos plataformas, denominadas en cacofonía “Alianza Global”, y se hace un balance del concepto de desarrollo sostenible contenido en la nueva propuesta de Objetivos de Desarrollo Sostenible en la perspectiva crítica de los Objetivos de Desarrollo del Milenio.

Determining sample alignment in x-ray reflectometry using thickness and density from GaAs/AlAs multilayer certified reference materials

X-ray reflectometry (XRR) provides researchers and manufacturers with a non-destructive way to determine thickness, roughness and density of thin films deposited on smooth substrates. Due to the nested nature of equations modeling this phenomenon, the inter-relation between instrument alignment and parameter estimation accuracy is somewhat opaque. In this study, we intentionally shift incident angle information from a high-quality XRR data set and refine a series of shifted data sets using an identical structural model to assess the effect this angle misalignment has on parameter estimation. We develop a series of calibration curves relating angle misalignment to variation in layer thickness and density for a multilayer GaAs/AlAs Certified Reference Material on a GaAs substrate. We then test the validity and robustness of several approaches of using known thickness and density parameters from this structure to calibrate instrument alignment. We find the highest sensitivity to and linearity with, measurement misalignment from buried AlAs and GaAs layers, in contrast to the surface layers, which show the most variability. This is a fortuitous result, as buried AlAs and GaAs exhibit the highest long-term stability in thickness. Therefore, it is indeed possible to use reference thickness estimates to validate XRR angle alignment accuracy. Buried layer mass density information also shows promise as a robust calibration approach. This is surprising, as electron density of buried layers is both a highly-correlated phenomenon and a subtle component within the XRR model.

Improving Beamtime Efficiency for Residual Stress Neutron Experiments

Starting during the shut-down of the HZB research reactor BER-II in 2011/2012 the E3 residual stress and texture diffractometer in Berlin underwent a comprehensive upgrade. The investments were broken down into different criteria, such as enhancing the instrument performance and accuracy as well as extending the range of applications for the user community. Here, we report about the gains achieved after integrating and commissioning the individual hardware and software tools included in the upgrade project, namely a motorized primary slit to accurately adjust the gauge volume, a secondary optics radial collimator and a laser scanner to precisely and quickly align the sample. The integration of the presented devices is further supported by software developments to shorten the instrument alignment procedure and measurement time. The upgrade has improved the efficiency of the available neutron beamtime.

Nurse–surgeon object transfer: Video analysis of communication and situation awareness in the operating theatre

BackgroundOne of the most central collaborative tasks during surgical operations is the passing of objects, including instruments. Little is known about how nurses and surgeons achieve this. The aim of the present study was to explore what factors affect this routine-like task, resulting in fast or slow transfer of objects. MethodsA qualitative video study, informed by an observational ethnographic approach, was conducted in a major teaching hospital in the UK. A total of 20 general surgical operations were observed. In total, approximately 68h of video data have been reviewed. A subsample of 225min has been analysed in detail using interactional video-analysis developed within the social sciences. ResultsTwo factors affecting object transfer were observed: (1) relative instrument trolley position and (2) alignment. The scrub nurse's instrument trolley position (close to vs. further back from the surgeon) and alignment (gaze direction) impacts on the communication with the surgeon, and consequently, on the speed of object transfer. When the scrub nurse was standing close to the surgeon, and “converged” to follow the surgeon's movements, the transfer occurred more seamlessly and faster (<1.0s) than when the scrub nurse was standing further back from the surgeon and did not follow the surgeon's movements (>1.0s). ConclusionsThe smoothness of object transfer can be improved by adjusting the scrub nurse's instrument trolley position, enabling a better monitoring of surgeon's bodily conduct and affording early orientation (awareness) to an upcoming request (changing situation). Object transfer is facilitated by the surgeon's embodied practices, which can elicit the nurse's attention to the request and, as a response, maximise a faster object transfer. A simple intervention to highlight the significance of these factors could improve communication in the operating theatre.

Inefficient Vibrational Cooling of C60 in a Supersonic Expansion

High-resolution gas-phase infrared spectroscopy of buckminsterfullerene (C60) was attempted near 8.5 μm using cavity ring-down spectroscopy. Solid C60 was heated in a high-temperature (~950 K) oven and cooled using an argon supersonic expansion generated from a 12.7 mm × 150 μm slit. The expected S/N ratio is ~140 for vibrationally cold C60, but no absorption signal has been observed, presumably due to a lack of vibrational cooling of C60 in the expansion. Measurements of D2O at 875 K are presented as a test of instrument alignment at high temperature and show that efficient rotational cooling of D2O occurs in the hot oven (Trot = 20 K in the expansion), though vibrational cooling does not occur. The attempted C60 spectroscopy is compared to previous work which showed efficient vibrational cooling of polycyclic aromatic hydrocarbons (PAHs). Possible alternative experiments for observing a cold, gas-phase spectrum of C60 are also considered.

Patient-Specific Instrumentation Does Not Shorten Surgical Time: A Prospective, Randomized Trial

The primary purpose of this prospective, randomized study was to determine if patient-specific instrumentation (PSI) for total knee arthroplasty (TKA) shortened surgical time. Secondarily the number of instrument trays and alignment were also compared to cases performed with traditional instrumentation (TI). Fifty-two cases (26 per group) were randomized and videotaped to measure the length of surgery, as well as each individual surgical step. Component alignment and mechanical axis was measured radiographically for each patient. Total surgical time was over 4 minutes shorter for patients in the TI group (57.4 minutes vs. 61.8 minutes; P<0.01). More instrument trays were used in the TI group (7.3 vs. 2.5; P<0.001). There was no significant difference in mechanical alignment between groups on postoperative long alignment radiographs (P=0.77). In conclusion, PSI did not shorten surgical time or improve alignment compared with TI in this prospective, randomized trial, but did reduce the required number of trays.

Comparison of custom to standard TKA instrumentation with computed tomography

There is conflicting evidence whether custom instrumentation for total knee arthroplasty (TKA) improves component position compared to standard instrumentation. Studies have relied on long-limb radiographs limited to two-dimensional (2D) analysis and subjected to rotational inaccuracy. We used postoperative computed tomography (CT) to evaluate preoperative three-dimensional templating and CI to facilitate accurate and efficient implantation of TKA femoral and tibial components. We prospectively evaluated a single-surgeon cohort of 78 TKA patients (51 custom, 27 standard) with postoperative CT scans using 3D reconstruction and contour-matching technology to preoperative imaging. Component alignment was measured in coronal, sagittal and axial planes. Preoperative templating for custom instrumentation was 87 and 79 % accurate for femoral and tibial component size. All custom components were within 1 size except for the tibial component in one patient (2 sizes). Tourniquet time was 5 min longer for custom (30 min) than standard (25 min). In no case was custom instrumentation aborted in favour of standard instrumentation nor was original alignment of custom instrumentation required to be adjusted intraoperatively. There were more outliers greater than 2° from intended alignment with standard instrumentation than custom for both components in all three planes. Custom instrumentation was more accurate in component position for tibial coronal alignment (custom: 1.5° ± 1.2°; standard: 3° ± 1.9°; p = 0.0001) and both tibial (custom: 1.4° ± 1.1°; standard: 16.9° ± 6.8°; p < 0.0001) and femoral (custom: 1.2° ± 0.9°; standard: 3.1° ± 2.1°; p < 0.0001) rotational alignment, and was similar to standard instrumentation in other measurements. When evaluated with CT, custom instrumentation performs similar or better to standard instrumentation in component alignment and accurately templates component size. Tourniquet time was mildly increased for custom compared to standard.

Opto-Mechanical Structure Design of the Image Stabilization Collimator

The collimator has an extensive application as an experiment equipment that can provide an infinity goal in the instrument alignment and testing.This paper provides a new type of collimator with image stabilization function in consideration of human disturbance factors, including environment micro-vibration and so on. Liquid surface which appears natural level under gravity imaging optical path of collimator can emerge through liquid refraction and reflex later. And we should make use of this phenomenon. Mathematical modeling and analysis on the principle of dynamic imaging of the liquid wedge have been made to design several optical principle charts of the collimator with image stabilization function.One of the image stabilization optical principle structure styles has been designed based on its mechanical structure.An experiment prototype is produced and is made more practical.

Effects of tibial torsion on distal alignment of extramedullary instrumentation in total knee arthroplasty

Background and purpose Whether tibial torsion affects the positioning of extramedullary instrumentation and is a possible factor in malalignment of the tibial component in total knee arthroplasty (TKA) is unknown. We assessed the influence of tibial torsion on distal alignment of extramedullary systems for TKA, using the center of the intermalleolar distance as anatomical reference at the ankle joint.Patients and methods We analyzed CT scans of knee and ankle joints of 50 patients with knee osteoarthritis (mean age 73 years, 52 legs). The tibial mechanical axis was identified and translated anteriorly at the level of the medial one-third (proximal AP axis 1), at the medial border of the tibial tuberosity (proximal AP axis 2), and at the level of the talar dome (distal AP axis). The center of the intermalleolar distance and the width of the medial and lateral malleolus were calculated. The proximal AP axes 1 and 2 were translated at the level of the ankle joint and any difference between their alignment and the distal AP axis was calculated as angular and linear values.Results The center of the ankle joint was located, on average 2 mm medial to that of the intermalleolar distance. The distal AP axis was externally rotated by 18° and 27° compared to the proximal AP axes 1 and 2, respectively. Overall, the center of the ankle joint was shifted laterally by 9–11 mm with respect to the proximal AP tibial axes.Interpretation To avoid a varus tibial cut in TKA, extramedullary alignment systems should be aligned more medially at the ankle joint than previously thought, due to the effect of tibial torsion and—to a lesser extent—to the different malleolar width.

Plasmonic interferometers for label-free multiplexed sensing

We report a plasmonic interferometric biosensor based on a simple slit-groove metallic nanostructure that monitors the phase changes of surface plasmon polaritons resulting from biomolecular adsorptions. The proposed sensing scheme integrates the strengths of miniaturized plasmonic architectures with sensitive optical interferometry techniques. Sensing peak linewidths as narrow as 7 nm and refractive index resolutions of 1 × 10(-5) RIU were experimentally measured from a miniaturized sensing area of 10 × 30 µm(2) using a collinear transmission setup and a low-cost compact spectrometer. A high-density array of such interferometric sensors was also fabricated to demonstrate its potential for real-time multiplexed sensing using a CCD camera for intensity interrogation. A self-referencing method was introduced to increase the sensitivity and reduce sensor noise for multiplexing measurements. The enhanced sensing performance, small sensor footprint, and simple instrumentation and optical alignment suggest promise to integrate this platform into low-cost label-free biosensing devices with high multiplexing capabilities.

Broadband wide-angle dispersion measurements: Instrumental setup, alignment, and pitfalls

The construction, alignment, and performance of a setup for broadband wide-angle dispersion measurements, with emphasis on surface plasmon resonance (SPR) measurements, are presented in comprehensive detail. In contrast with most SPR instruments working with a monochromatic source, this setup takes advantage of a broadband∕white light source and has full capability for automated angle vs. wavelength dispersion measurements for any arbitrary nanostructure array. A cylindrical prism is used rather than a triangular one in order to mitigate refraction induced effects and allow for such measurements. Although seemingly simple, this instrument requires use of many non-trivial methods in order to achieve proper alignment over all angles of incidence. Here we describe the alignment procedure for such a setup, the pitfalls introduced from the finite beam width incident onto the cylindrical prism, and deviations in the reflected∕transmitted beam resulting from the finite thickness of the sample substrate. We address every one of these issues and provide experimental evidences on the success of this instrument and the alignment procedure used.

Development of a Nanoprecision 3-DOF Vertical Positioning System With a Flexure Hinge

This paper describes the conceptual design of an ultraprecision 3-DOF (Z, Ox, Oy) vertical positioning system with nanometer precision. The vertical out-of-plane positioning system can be used for various nanoalignment applications, such as optical instrument alignment. The proposed vertical positioning system is driven by three piezoelectric (PZT) actuators and is guided by three rotationally symmetric hinges. Because the displacement generated by a PZT actuator is very small, the proposed system also includes an amplification hinge mechanism. Because the relationships between the variables of the hinge parameters and system performance levels are complicated, an optimization procedure to obtain optimal design parameters, which maximize the system bandwidth, is developed. Based on the solution to the optimization problem, the design of a vertical positioning system and finite-element-method simulation results are presented. Finally, the stage is manufactured and tested for verification. The stroke of the translational movement is 190 mm, and the stroke of the rotational movement is 0.5 mrad, whereas their in-position stability levels are ±2 nm and ±20 nrad and resolutions are 5 nm and 80 nrad, respectively. The settling time is less than 45 ms.

Some Comments on Mapping from Disease-Specific to Generic Health-Related Quality-of-Life Scales

An article by Lu et al. in this issue of Value in Health addresses the mapping of treatment or group differences in disease-specific measures (DSMs) of health-related quality of life onto differences in generic health-related quality-of-life scores, with special emphasis on how the mapping is affected by the reliability of the DSM. In the proposed mapping, a factor analytic model defines a conversion factor between the scores as the ratio of factor loadings. Hence, the mapping applies to convert true underlying scales and has desirable properties facilitating the alignment of instruments and understanding their relationship in a coherent manner. It is important to note, however, that when DSM means or differences in mean DSMs are estimated, their mapping is still of a measurement error–prone predictor, and the correct conversion coefficient is the true mapping multiplied by the reliability of the DSM in the relevant sample. In addition, the proposed strategy for estimating the factor analytic mapping in practice requires assumptions that may not hold. We discuss these assumptions and how they may be the reason we obtain disparate estimates of the mapping factor in an application of the proposed methods to groups of patients.

Patient-specific Total Knee Arthroplasty Required Frequent Surgeon-directed Changes

Patient-specific instrumentation potentially improves surgical precision and decreases operative time in total knee arthroplasty (TKA) but there is little supporting data to confirm this presumption. We asked whether patient-specific instrumentation would require infrequent intraoperative changes to replicate a single surgeon's preferences during TKA and whether patient-specific instrumentation guides would fit securely. We prospectively evaluated the plan and surgery in 60 patients treated with 66 TKAs performed with patient-specific instrumentation and recorded any changes. A subset of six postoperative radiographic changes to the femoral and tibial components (implant size, coronal and sagittal alignment) was analyzed to determine if surgeon intervention was beneficial. Each guide was evaluated to determine fit. We compared patient demographics and implant sizing in the patient-specific instrumentation group with a control group in which traditional instrumentation was used. We recorded 161 intraoperative changes in 66 knee arthroplasties (2.4 changes/knee) performed with patient-specific instrumentation. The predetermined implant size was changed intraoperatively in 77% of femurs and 53% of tibias. We identified a subset of 95 intraoperative changes that could be radiographically evaluated to determine if our changes were an improvement or detriment to reaching goal alignment. Eighty-two of the 95 changes (86%) made by the surgeon were an improvement to the recommended alignment or size of patient-specific instrumentation. The guide did not fit securely on eight femurs (12%) and three tibias (5%). Tourniquet time and blood loss were not improved with patient-specific instrumentation. We caution surgeons against blind acceptance of patient-specific instrumentation technology without supportive data.

Improved parametric empirical determination of module short circuit current for modelling and optimization of solar photovoltaic systems

Correct modelling of solar photovoltaic (PV) system yields is necessary to optimize system design, improve reliability of projected outputs to ensure favourable project financing and to facilitate proper operations and maintenance. An improved methodology for fine resolution modelling of PV systems is presented using module short-circuit current (Isc) at 5-min time-scales, and clearly identifies pertinent error mechanisms that arise when working at this high resolution. This work used a modified version of the Sandia array performance model, and introduces new factors to the calculation of Isc to account for identified error mechanisms, including instrumentation alignment, spectral, and module power tolerance errors. A simple methodology was introduced and verified where specific module parameters can be derived solely from properly filtered performance time series data. In particular, this paper focused on methodologies for determining the predicted Isc for a variety of solar PV module types. These methods of regressive analysis significantly reduced the error of the predicted model, and demonstrate the need for this form of modelling when evaluating long term PV array performance. This methodology has applications for current systems operators, which will enable the extraction of useful module parameters from existing data in addition to more precise continuous monitoring of existing systems, and can also be used to more accurately model and optimize new systems.