Computer‐assisted surgery for placing toggle constructs across the coxofemoral joints of small equids using a minimally invasive approach–A proof‐of‐concept cadaveric study

Objective:To develop a minimally invasive technique for placing a toggle construct across the coxofemoral joint of small equids using computer‐assisted surgery.Study designExperimental cadaveric study.Sample populationThree pilot specimens: One donkey, one Shetland pony and one Warmblood foal. Six main study specimens: Three Shetland ponies, one American Miniature Horse, one Warmblood foal and one donkey.MethodsExperimental surgeries were performed on both coxofemoral joints of each cadaver. Using a minimally invasive surgical approach, 5.5 mm bone canals were drilled through the femur and acetabulum, traversing the coxofemoral joint. Intraoperative guidance was provided by a cone‐beam computed tomography (CBCT)‐coupled surgical navigation system. A toggle construct was introduced through the bone canals. Surgical accuracy aberrations (SAA) were measured at the femoral entry and exit points and at the acetabular entry point on merged pre‐ and postoperative CBCT scans. The coxofemoral joint was assessed for articular cartilage damage by gross dissection.ResultsA toggle construct was placed across all 18 coxofemoral joints. The overall median SAA in the main study was 2.8 mm (range: 0.4–8.0 mm). No cartilage damage was found in the cadaveric specimens of the main study.ConclusionThe described technique allowed for the placement of a toggle construct across the coxofemoral joint of small equid cadaveric specimens without prior coxofemoral luxation.Clinical relevanceThis technique may serve as an option for surgical stabilization of coxofemoral joints in small equids. Further biomechanical investigations are required to assess optimal implant positioning and toggle constructs

Computer-assisted surgery for placing toggle constructs across the coxofemoral joints of small equids using a minimally invasive approach-A proof-of-concept cadaveric study.

OBJECTIVE To develop a minimally invasive technique for placing a toggle construct across the coxofemoral joint of small equids using computer-assisted surgery. STUDY DESIGN Experimental cadaveric study. SAMPLE POPULATION Three pilot specimens: One donkey, one Shetland pony and one Warmblood foal. Six main study specimens: Three Shetland ponies, one American Miniature Horse, one Warmblood foal and one donkey. METHODS Experimental surgeries were performed on both coxofemoral joints of each cadaver. Using a minimally invasive surgical approach, 5.5 mm bone canals were drilled through the femur and acetabulum, traversing the coxofemoral joint. Intraoperative guidance was provided by a cone-beam computed tomography (CBCT)-coupled surgical navigation system. A toggle construct was introduced through the bone canals. Surgical accuracy aberrations (SAA) were measured at the femoral entry and exit points and at the acetabular entry point on merged pre- and postoperative CBCT scans. The coxofemoral joint was assessed for articular cartilage damage by gross dissection. RESULTS A toggle construct was placed across all 18 coxofemoral joints. The overall median SAA in the main study was 2.8 mm (range: 0.4-8.0 mm). No cartilage damage was found in the cadaveric specimens of the main study. CONCLUSION The described technique allowed for the placement of a toggle construct across the coxofemoral joint of small equid cadaveric specimens without prior coxofemoral luxation. CLINICAL RELEVANCE This technique may serve as an option for surgical stabilization of coxofemoral joints in small equids. Further biomechanical investigations are required to assess optimal implant positioning and toggle constructs

Improvement of liquid crystal tunable lenses with weakly conductive layers using multifrequency driving

A common technique to realize the gradient electric field profile that is required in liquid crystal tunable lenses is the use of a weakly conductive layer. Thanks to this layer, an applied voltage with a certain frequency allows us to obtain a refractive index profile that is required for the lens operation. Due to the limited degrees of freedom, however, it is not possible to avoid aberrations in a weakly conductive layer-based tunable lens for a continuously tunable focal length. In this work, we discuss the use of additional higher frequency components in the voltage signal to reduce the lens aberrations drastically. (C) 2020 Optical Society of Americ

A Solve-RD ClinVar-based reanalysis of 1522 index cases from ERN-ITHACA reveals common pitfalls and misinterpretations in exome sequencing

Purpose Within the Solve-RD project (https://solve-rd.eu/), the European Reference Network for Intellectual disability, TeleHealth, Autism and Congenital Anomalies aimed to investigate whether a reanalysis of exomes from unsolved cases based on ClinVar annotations could establish additional diagnoses. We present the results of the “ClinVar low-hanging fruit” reanalysis, reasons for the failure of previous analyses, and lessons learned. Methods Data from the first 3576 exomes (1522 probands and 2054 relatives) collected from European Reference Network for Intellectual disability, TeleHealth, Autism and Congenital Anomalies was reanalyzed by the Solve-RD consortium by evaluating for the presence of single-nucleotide variant, and small insertions and deletions already reported as (likely) pathogenic in ClinVar. Variants were filtered according to frequency, genotype, and mode of inheritance and reinterpreted. Results We identified causal variants in 59 cases (3.9%), 50 of them also raised by other approaches and 9 leading to new diagnoses, highlighting interpretation challenges: variants in genes not known to be involved in human disease at the time of the first analysis, misleading genotypes, or variants undetected by local pipelines (variants in off-target regions, low quality filters, low allelic balance, or high frequency). Conclusion The “ClinVar low-hanging fruit” analysis represents an effective, fast, and easy approach to recover causal variants from exome sequencing data, herewith contributing to the reduction of the diagnostic deadlock

Twist exome capture allows for lower average sequence coverage in clinical exome sequencing

Background Exome and genome sequencing are the predominant techniques in the diagnosis and research of genetic disorders. Sufficient, uniform and reproducible/consistent sequence coverage is a main determinant for the sensitivity to detect single-nucleotide (SNVs) and copy number variants (CNVs). Here we compared the ability to obtain comprehensive exome coverage for recent exome capture kits and genome sequencing techniques. Results We compared three different widely used enrichment kits (Agilent SureSelect Human All Exon V5, Agilent SureSelect Human All Exon V7 and Twist Bioscience) as well as short-read and long-read WGS. We show that the Twist exome capture significantly improves complete coverage and coverage uniformity across coding regions compared to other exome capture kits. Twist performance is comparable to that of both short- and long-read whole genome sequencing. Additionally, we show that even at a reduced average coverage of 70× there is only minimal loss in sensitivity for SNV and CNV detection. Conclusion We conclude that exome sequencing with Twist represents a significant improvement and could be performed at lower sequence coverage compared to other exome capture techniques

A Wave Based Unit Cell Method to predict absorption and transmission coefficients of poroelastic materials containing periodic inclusions

his paper presents an efficient Wave Based modelling procedure to predict the absorption and transmission coefficient of infinite poroelastic materials containing a periodic grid of inclusions. As compared to standard numerical prediction schemes it offers the following advantages: (1) contrarily to Transfer Matrix Methods the layers do not need to be homogeneous, (2) contrarily to multipole methods, the inclusions do not need to be circular, (3) as compared to element based prediction techniques, unbounded domains can easily be accounted for and the procedure allows more easily for optimisation routines since it is a meshless and computationally more efficient technique. The Wave Based Method is an indirect Trefftz approach; it approximates the dynamic fields using a weighted sum of exact solutions of the governing differential equations. The Multi-Level Wave Based Method, which allows to describe the dynamic field of a cavity containing an inclusion, is extended in two ways: (1) Bloch-Floquet conditions are imposed on the boundaries to take into account the periodicity of the complete structure and (2) novel unbounded acoustic wave functions are presented that fulfil the acoustic Helmholtz equation, the Sommerfeld radiation condition and the Bloch-Floquet conditions. The implementation of the method is validated with the multipole method.status: accepte

Second-kind boundary integral equations for electromagnetic scattering at composite objects

International audienc

A Second-Kind Galerkin Boundary Element Method for Scattering at Composite Objects

International audienceWe consider the scattering of time-harmonic acoustic waves at objects composed of several homogeneous parts with different material properties. In [X. Claeys, A single trace integral formulation of the second kind for acoustic scattering, Report 2011-14, SAM, ETH Zürich] a novel second-kind boundary integral formulation for this scattering problem was proposed. We recast it into a variational problem set in L2 and investigate its Galerkin boundary element discretization from a theoretical and algorithmic point of view. Empiric studies demonstrate the competitive accuracy and superior conditioning of the new approach compared to a widely used Galerkin boundary element approach based on a first-kind boundary integral formulation

Control of edge modes in finite vibro-acoustic resonant metamaterials

Metamaterials have shown great potential as lightweight and performant vibro-acoustic solutions. Made from conventional materials, metamaterials exhibit stop band behavior resulting from the dynamic interaction between a host structure and its resonant additions on a subwavelength scale. In these stop bands, metamaterials outperform common vibro-acoustic solutions, beating the mass law. Stop band behavior can be predicted in the design stage with unit cell modeling, assuming the metamaterial to be an infinite periodic structure. In any practical application, structures have a finite size and their dynamic behavior is influenced by the boundary conditions. This paper analyzes numerically and experimentally the interaction of a 1D finite sized metamaterial with different boundary conditions. The effect of the edge modes on the predicted stop band behavior is investigated. Two methods are proposed to reduce the influence of edge modes and to achieve the designed stop band behavior performance also in the finite metamaterial system.status: accepte

Second-Kind Boundary Integral Equations for Scattering at Composite Partly Impenetrable Objects

We consider acoustic scattering of time-harmonic waves at objects composed of several homogeneous parts. Some of those may be impenetrable, giving rise to Dirichlet boundary conditions on their surfaces. We start from the second-kind boundary integral approach of [X. Claeys, and R. Hiptmair, and E. Spindler. A second-kind Galerkin boundary element method for scattering at composite objects. BIT Numerical Mathematics, 55(1):33-57, 2015] and extend it to this setting. Based on so-called global multi-potentials, we derive variational second-kind boundary integral equations posed in $L^2(\Sigma)$, where $\Sigma$ denotes the union of material interfaces. To suppress spurious resonances, we introduce a combined-field version (CFIE) of our new method. Thorough numerical tests highlight the low and mesh-independent condition numbers of Galerkin matrices obtained with discontinuous piecewise polynomial boundary element spaces. They also confirm competitive accuracy of the numerical solution in comparison with the widely used first-kind single-trace approach