The biomechanics of wounds at physiologically relevant levels: Understanding skin's stress-shielding effect for the quantitative assessment of healing.

Wounds are responsible for the decrease in quality of life of billions of people around the world. Their assessment relies on subjective parameters which often delays optimal treatments and results in increased healthcare costs. In this work, we sought to understand and quantify how wounds at different healing stages (days 1, 3, 7 and 14 post wounding) change the mechanical properties of the tissues that contain them, and how these could be measured at clinically relevant strain levels, as a step towards quantitative wound tracking technologies.

Computational homogenization of histological microstructures in human prostate tissue: Heterogeneity, anisotropy and tension-compression asymmetry.

Human prostatic tissue exhibits complex mechanical behaviour due to its multiphasic, heterogeneous nature, with hierarchical microstructures involving epithelial compartments, acinar lumens and stromal tissue all interconnected in complex networks. This study aims to establish a computational homogenization framework for quantifying the mechanical behaviour of prostate tissue, considering its multiphasic heterogeneous microstructures and the mechanical characteristics of tissue constituents. Representative tissue microstructure models were reconstructed from high-resolution histology images.

Mechanical mapping of the prostate in vivo using Dynamic Instrumented Palpation; towards an in vivo strategy for cancer assessment.

A calibrated palpation sensor has been developed for making instrumented Digital Rectal Examinations (iDREs) with a view to assessing patients for prostate cancer. The instrument measures the dynamic stiffness of the palpable surface of the prostate, and has been trialled on 12 patients in vivo. The patients had been diagnosed with prostate cancer and were scheduled for radical prostatectomy.

Locating and sizing tumor nodules in human prostate using instrumented probing - computational framework and experimental validation.

Detection of tumor nodules is key to early cancer diagnosis. This study investigates the potential of using the mechanical data, acquired from probing the prostate for detecting the existence, and, more importantly, characterizing the size and depth, from the posterior surface, of the prostate cancer (PCa) nodules. A computational approach is developed to quantify the uncertainty of nodule detectability and is based on identifying stiffness anomalies in the profiles of point force measurements across transverse sections of the prostate.

Identification of tumor nodule in soft tissue: An inverse finite-element framework based on mechanical characterization.

Identification and characterization of nodules in soft tissue, including their size, shape, and location, provide a basis for tumor identification. This study proposes an inverse finite-element (FE) based computational framework, for characterizing the size of examined tissue sample and detecting the presence of embedded tumor nodules using instrumented palpation, without a priori anatomical knowledge. The inverse analysis was applied to a model system, the human prostate, and was based on the reaction forces which can be obtained by trans-rectal mechanical probing and those from an equivalent FE model, which was optimized iteratively, by minimizing an error function between the two cases, toward the target solution.

A novel palpation-based method for tumor nodule quantification in soft tissue-computational framework and experimental validation.

Variation in mechanical properties is a useful marker for cancer in soft tissue and has been used in clinical diagnosis for centuries. However, to develop such methods as instrumented palpation, there remain challenges in using the mechanical response during palpation to quantify tumor load. This study proposes a computational framework of identification and quantification of cancerous nodules in soft tissue without a priori knowledge of its geometry, size, and depth.

Quantitative mechanical assessment of the whole prostate gland ex vivo using dynamic instrumented palpation.

An instrumented palpation sensor, designed for measuring the dynamic modulus of tissue in vivo, has been developed and trialled on ex vivo whole prostate glands. The sensor consists of a flexible membrane sensor/actuator with an embedded strain gauge and is actuated using a dynamically varying airflow at frequencies of 1 and 5 Hz. The device was calibrated using an indentation stiffness measurement rig and gelatine samples with a range of static modulus similar to that reported in the literature for prostate tissue.

Dynamic instrumented palpation - a new method for soft tissue quality assessment: application to prostate disease diagnosis.

The objective is to establish the feasibility of using dynamic instrumented palpation, a novel technique of low-frequency mechanical testing, applied here to diagnose soft tissue condition. The technique is applied, in vitro, to samples of excised prostate gland affected by benign prostate hyperplasia and/or prostate cancer. Particular attention is paid to the relationship between the histological structure of the tissue and the dynamic mechanical properties in an attempt to separate patient-specific aspects from histopathological condition (i.

A novel method for rapid and quantitative mechanical assessment of soft tissue for diagnostic purposes: A computational study.

Biological tissues often experience drastic changes in their microstructure due to their pathophysiological conditions. Such microstructural changes could result in variations in mechanical properties, which can be used in diagnosing or monitoring a wide range of diseases, most notably cancer. This paves the avenue for non-invasive diagnosis by instrumented palpation although challenges remain in quantitatively assessing the amount of diseased tissue by means of mechanical characterization.

Histology-based homogenization analysis of soft tissue: application to prostate cancer.

It is well known that the changes in tissue microstructure associated with certain pathophysiological conditions can influence its mechanical properties. Quantitatively relating the tissue microstructure to the macroscopic mechanical properties could lead to significant improvements in clinical diagnosis, especially when the mechanical properties of the tissue are used as diagnostic indices such as in digital rectal examination and elastography. In this study, a novel method of imposing periodic boundary conditions in non-periodic finite-element meshes is presented.

Patient specific modeling of palpation-based prostate cancer diagnosis: effects of pelvic cavity anatomy and intrabladder pressure.

Computational modeling has become a successful tool for scientific advances including understanding the behavior of biological and biomedical systems as well as improving clinical practice. In most cases, only general models are used without taking into account patient-specific features. However, patient specificity has proven to be crucial in guiding clinical practice because of disastrous consequences that can arise should the model be inaccurate.

Quantitative diagnostics of soft tissue through viscoelastic characterization using time-based instrumented palpation.

Although palpation has been successfully employed for centuries to assess soft tissue quality, it is a subjective test, and is therefore qualitative and depends on the experience of the practitioner. To reproduce what the medical practitioner feels needs more than a simple quasi-static stiffness measurement. This paper assesses the capacity of dynamic mechanical palpation to measure the changes in viscoelastic properties that soft tissue can exhibit under certain pathological conditions.

Tissue quality assessment using a novel direct elasticity assessment device (the E-finger): a cadaveric study of prostatectomy dissection.

Introduction: Minimally invasive radical prostatectomy (RP) (robotic and laparoscopic), have brought improvements in the outcomes of RP due to improved views and increased degrees of freedom of surgical devices. Robotic and laparoscopic surgeries do not incorporate haptic feedback, which may result in complications secondary to inadequate tissue dissection (causing positive surgical margins, rhabdosphincter damage, etc). We developed a micro-engineered device (6 mm2 sized) [E-finger]) capable of quantitative elasticity assessment, with amplitude ratio, mean ratio and phase lag representing this.

Transmission of acoustic emission in bones, implants and dental materials.

There is considerable interest in using acoustic emission (AE) and ultrasound to assess the quality of implant-bone interfaces and to monitor for micro-damage leading to loosening. However, remarkably little work has been done on the transmission of ultrasonic waves though the physical and biological structures involved. The aim of this in vitro study is to assess any differences in transmission between various dental materials and bovine rib bones with various degrees of hydration.

Elasticity as a biomarker for prostate cancer: a systematic review.

To systematically review the range of methods available for assessing elasticity in the prostate and to examine its use as a biomarker for prostate cancer. A systematic review of the electronic database PubMed was performed up to December 2012. All relevant studies assessing the use of elasticity as a biomarker for prostate cancer were included except those not studying human prostates or reporting a sensitivity, specificity or quantitative elasticity value.

Nanotribology at high temperatures.

Recent molecular dynamics simulation results have increased conceptual understanding of the grazing and the ploughing friction at elevated temperatures, particularly near the substrate's melting point. In this commentary we address a major constraint concerning its experimental verification.

In vitro assessment of bone-implant interface using an acoustic emission transmission test.

The aim of this in vitro study was to determine the feasibility of monitoring the primary stability of dental implants using a simple transmission test with acoustic emission. Forty screw-shaped titanium dental implants were installed in the middle of 10 fresh bovine ribs obtained from different animals. The implants were divided into two size groups, 8.

The effect of coping/veneer thickness on the fracture toughness and residual stress of implant supported, cement retained zirconia and metal-ceramic crowns.

Objectives: The aim of the work was to assess the influence of coping and veneer thickness on the fracture resistance of porcelain-metal and porcelain-zirconia crowns in a clinically representative model.

Methods: A total of 30 zirconia and 30 precious metal copings were fabricated. There were 10 copings in each group of 0.

Atomistic aspects of ductile responses of cubic silicon carbide during nanometric cutting.

Cubic silicon carbide (SiC) is an extremely hard and brittle material having unique blend of material properties which makes it suitable candidate for microelectromechanical systems and nanoelectromechanical systems applications. Although, SiC can be machined in ductile regime at nanoscale through single-point diamond turning process, the root cause of the ductile response of SiC has not been understood yet which impedes significant exploitation of this ceramic material. In this paper, molecular dynamics simulation has been carried out to investigate the atomistic aspects of ductile response of SiC during nanometric cutting process.