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Medical Engineering & Physics

Elizabeth Anne Gallagher, Steven Lamorinière, Patrick McGarry
Carbon fibre reinforced PEEK (CF/PEEK) laminates provide mechanical advantages over homogenous metal osteo-synthesis implants, e.g. radiolucency, fatigue strength and strength to weight ratio. Implants can be designed with custom anisotropic material properties, thus enabling the engineer to tailor the overall stiffness of the implant to the specific loading conditions it will experience in vivo. In the current study a multi-scale computational investigation of idealised distal radius fracture fixation plate (DRP) is conducted...
March 15, 2019: Medical Engineering & Physics
Ming Xu, James Yang, Isador H Lieberman, Ram Haddas
Finite element (FE) method has been widely used to study the screw-bone connections. Screw threads are often excluded from the FE spine model to reduce computational cost. However, no study has been conducted to compare the effect of such simplification in the screw models on the predicting accuracy of the model. The effects of different screw-bone connection types on the overall spine biomechanics are also unknown. In this study, three different types of screw-bone connections were compared using FE simulations in this study: (1) screw and bone are not fully bonded (contact connection); (2) screw is rigidly bonded with the bone (bonded connection); and (3) simplified-geometry-rigid (SGR) connection...
March 14, 2019: Medical Engineering & Physics
Fabio Bianchi, Julian H George, Majid Malboubi, Antoine Jerusalem, Mark S Thompson, Hua Ye
Peripheral nerves are continuously subjected to mechanical strain during everyday movements, but excessive stretch can lead to damage and neuronal cell functionality can also be impaired. To better understand cellular processes triggered by stretch, it is necessary to develop in vitro experimental methods that allow multiple concurrent measurements and replicate in vivo mechanical conditions. Current commercially available cell stretching devices do not allow flexible experimental design, restricting the range of possible multi-physics measurements...
March 13, 2019: Medical Engineering & Physics
Murtadha D Hssayeni, Michelle A Burack, Joohi Jimenez-Shahed, Behnaz Ghoraani
BACKGROUND AND OBJECTIVE: Motor fluctuations between akinetic (medication OFF) and mobile phases (medication ON) states are one of the most prevalent complications of patients with Parkinson's disease (PD). There is a need for a technology-based system to provide reliable information about the duration in different medication phases that can be used by the treating physician to successfully adjust therapy. METHODS: Two KinetiSense motion sensors were mounted on the most affected wrist and ankle of 19 PD subjects (age: 42-77, 14 males) and collected movement signals as the participants performed seven daily living activities in their medication OFF and ON phases...
March 12, 2019: Medical Engineering & Physics
Mohammad Taghi Karimi, Lanie Gutierrez-Farewik, Anthony McGarry
The head of femoral bone is deformed in the subjects with Leg Calve Perthes disease (LCPD). This may be due to the excessive loads applied on it. There are no studies that report the hip joint contact force in subjects with LCPD. Therefore, the aim of this study was to evaluate the hip joint contact force in subjects with Perthes disease. Ten typically-developing (TD) children and 10 children with LCPD were recruited in this study. The kinematics and kinetics of the subjects were evaluated in 3D motion analysis...
March 12, 2019: Medical Engineering & Physics
Brad W R Roberts, Jeremy C Hall, Andrew D Williams, Hossein Rouhani, Albert H Vette
Kinetic data acquired from force plates embedded in moving platforms naturally contain artifacts due to platform acceleration, called force plate inertial components. While they can be estimated and removed from the measured signals, the system's inertial properties need to be known. Our objective was to: (1) develop a method for estimating the inertial properties and force plate inertial components for any instrumented platform; (2) estimate the inertial properties specifically for the Computer-Assisted Rehabilitation Environment (CAREN); and (3) validate the estimates with new experimental data...
March 11, 2019: Medical Engineering & Physics
Xiao-Hong Wang, Xiang Dong, Bao-Zhang Zhu, Lei Jiang, Zhong-Min Jin, Toru Suguro, Cheng-Kung Cheng
The primary intent of anatomical knee implants is to replicate the motions of a normal knee joint. In developing such designs, a preclinical evaluation of kinematic behavior is needed. This study introduces an in vitro testing method for recording movements of the knee joint. A novel testing jig was developed and incorporated into a knee simulator setup alongside a motion capture system to directly track the medial and lateral movements of a knee prosthesis. The test system developed in this study required a number of factors to be validated; (i) gait inputs to the knee simulator (result: 0...
March 11, 2019: Medical Engineering & Physics
Alessandro Garofolini, Simon Taylor, Patrick McLaughlin, Robert Stokes, Michael Kusel, Karen J Mickle
Toe flexor strength is a pivotal biomechanical contributor for effecting balance and gait. However, there are limited reports that evaluate measurement accuracy and repeatability of this important attribute. Dynamometers are designed to measure force which can be used to derive joint torque if the perpendicular distance to the joint axis is known. However, an accurate and reliable measurement method to assess the ability of the toe flexor muscles to produce torque, is lacking. Here we describe a new device and method, designed to quantify the toe flexor torque developed at the metatarsal phalangeal joint...
March 9, 2019: Medical Engineering & Physics
Zahraa M Abdulhasan, John G Buckley
To terminate gait, the mechanical work-done by the lower-limbs is likely to be predominantly negative but how such work is produced/completed has not previously been investigated. The aim of this study was to determine the amount of negative mechanical (external) work-done by the lower-limbs, along with the associated joints (muscle) work, to terminate gait and how these work contributions were affected by a change in surface angle. Eight males completed terminations on the level floor and a declined ramp. Negative mechanical limb-work (limbW( - ve) ) was computed (each orthogonal direction) as the dot-product of the ground-reaction-force and centre-of-mass (CoM) velocity...
March 8, 2019: Medical Engineering & Physics
Mehdi Saeidi, Maziar Ramezani, Piaras Kelly, Thomas Neitzert, Pranesh Kumar
The purpose of this research was to study the efficacy of a novel implant for osteoarthritic knees. This implant is designed to eliminate excessive loads through the knee and to provide suitable conditions for possible tibiofemoral cartilage repair. The implant was designed for the medial side of the knee joint. Finite Element Analysis (FEA) was performed for an extended knee position of the knee joint. Von Mises stress and contact pressure distributions on the medial and lateral compartments were investigated as well as stress distributions throughout the implant's plates...
March 7, 2019: Medical Engineering & Physics
Arne Feldmann, Marcel Schweizer, Simon Stucki, Lutz Nolte
Surgeons, scientists and development engineers of surgical devices require phantoms and materials for testing and training purposes. Human or animal bones are the gold standard, but difficult to obtain, prepare and handle. While polyurethane foams can be used as a substitute for trabecular bone, cortical bone substitutes have not been evaluated. In this study, a standard surgical drill bit (⌀ 3.2 mm) with clinical process parameters was used to compare 5 different materials with bovine cortical bone: polyurethane with three different densities, short-fiber-filled epoxy and an artificial bone material...
March 5, 2019: Medical Engineering & Physics
Allison L Clouthier, Colin R Smith, Michael F Vignos, Darryl G Thelen, Kevin J Deluzio, Michael J Rainbow
Articular geometry in the knee varies widely among people which has implications for risk of injury and pathology. The goals of this work were to develop a framework to systematically vary geometry in a multibody knee model and to use this framework to investigate the effect of morphological features on dynamic knee kinematics and contact mechanics. A statistical shape model of the tibiofemoral and patellofemoral joints was created from magnetic resonance images of 14 asymptomatic knees. The shape model was then used to generate 37 unique multibody knee models based on -3 to +3 standard deviations of the scores for the first six principal components identified...
March 5, 2019: Medical Engineering & Physics
Rahul R Rajendran, Arindam Banerjee
Mucus clearance from the airways is vital to reduce the risk of infection and to improve pulmonary function. The removal of mucus is propelled either by a rhythmic ciliary motion or shear-induced by turbulent expiratory airflow. However, in chronic airway diseases, the mucociliary motion is impaired due to mucus hypersecretion and altered biophysical properties. As a result, the ciliary motion is insufficient to remove mucus from the airways and expiratory airflow plays the more dominant role. In this work, the role of expiratory airflow in pathologic mucus clearance was investigated in a three-dimensional idealized bifurcating lung geometry...
March 5, 2019: Medical Engineering & Physics
Sílvio Leão Vieira, Lucas Nonato de Oliveira, Antonio Adilton O Carneiro
Commonly dose-responses of conventional dosimetric methods are affected by a saturation dose and are known to be limited when the delivered dose is relatively high. In contrast, elastic properties of polymer-gel dosimeter phantoms play major roles in a new dosimetry technique using magnetic resonance elastography (MRE). A single volume of polymer-gel dosimeter solution containing methacrylic and ascorbic acid in gelatin initiated by copper was prepared. The material was subsequently stored in cylindrical containers for future use as a biological tissue-mimicking phantom material...
March 4, 2019: Medical Engineering & Physics
D Rittel, A Dorogoy, G Haïat, K Shemtov-Yona
Dental implant stability influences the decision on the determination of the duration between implant insertion and loading. This work investigates the resonant frequency analysis by means of a numerical model. The investigation is done numerically through the determination of the eigenfrequencies and performing steady state response analyses using a commercial finite element package. A peri-implant interface, of simultaneously varying stiffness, density and layer thickness is introduced in the numerical 3D model in order to probe the sensitivity of the eigenfrequencies and steady state response to an evolving weakened layer, in an attempt to identify the bone reconstruction around the implant...
March 2, 2019: Medical Engineering & Physics
Nikolas K Knowles, G Daniel G Langohr, Mohammadreza Faieghi, Andrew J Nelson, Louis M Ferreira
Subject- and site-specific modeling techniques greatly improve the accuracy of computational models derived from clinical-resolution quantitative computed tomography (QCT) data. The majority of shoulder finite element (FE) studies use density-modulus relationships developed for alternative anatomical locations. As such, the objectives of this study were to compare the six most commonly used density-modulus relationships in shoulder finite element (FE) studies. To achieve this, ninety-eight (98) virtual trabecular bone cores were extracted from uCT scans of scapulae from 14 cadaveric specimens (7 male; 7 female)...
March 1, 2019: Medical Engineering & Physics
S C Mitchell, G Grangard, W Kahouli, C Dalldorf, A Crain, E Lee, A Hamlin, L Feeney, H Johnstone, G P Luke, S G Diamond, D F Bauer
Cerebral spinal fluid (CSF) shunts are the main treatment for hydrocephalus. They divert excess CSF from the ventricular system to the abdominal, pleural, or intravascular space where it is absorbed. The shunt valve regulates flow based on intracranial pressure (ICP) to maintain a physiologically stable and safe ICP. Shunt malfunction is difficult to detect, life-threatening and common. The present study demonstrates that snap-though buckling (STB) shells can be transformed into pressure-relief valves that act in the normal physiological range of ICP...
March 1, 2019: Medical Engineering & Physics
Frank Hübner, Roland Schreiner, Carolin Reimann, Babak Bazrafshan, Benjamin Kaltenbach, Martin Schüßler, Rolf Jakoby, Thomas Josef Vogl
The purpose of the study was to validate the simulation model for a microwave thermal ablation in ex vivo liver tissue. The study aims to show that heat transfer due to the flow of tissue water during ablation in ex vivo tissue is not negligible. Ablation experiments were performed in ex vivo porcine liver with microwave powers of 60 W to 100 W. During the procedure, the temperature was recorded in the liver sample at different distances to the applicator using a fiber-optic thermometer. The position of the probes was identified by CT imaging and transferred to the simulation...
February 27, 2019: Medical Engineering & Physics
Ryo Tanaka, Yoshiki Ishii, Takahiro Yamasaki, Hiromichi Kawanishi
PURPOSE: In order to evaluate the movement strategy in sit-to-stand (STS) motion, it is necessary to measure the center of gravity (COG). However, there is no established method for enabling this using convenience device in the clinical setting. The purpose of this study was to validate the measurement of the COG during the STS motion using an inexpensive, portable and markerless motion capture system (MLS). METHOD: Eighteen healthy adults participated in our study...
February 20, 2019: Medical Engineering & Physics
Fateme Badie, Hamid Reza Katouzian, Mostafa Rostami
Varus misalignment of the hip-knee-ankle angle causes greater loads on the medial compartment of the knee and increases the risk of developing knee osteoarthritis. High tibial osteotomy is a surgical method where the load-bearing axis is shifted laterally. The purpose of this study is to define a subject-specific three-dimensional multibody model of the knee to investigate the effect of osteotomy on cartilages and menisci during the stance phase of gait. It is assumed that osteotomy transfers load-bearing to the lateral parts of the knee...
February 14, 2019: Medical Engineering & Physics
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