Non-invasive vibrometry-based diagnostic detection of acetabular cup loosening in total hip replacement (THR)
Total hip replacement (THR) is aimed at relieving pain and restoring function. The procedure has come a long way since it was introduced by Charnley in the early 1960 s, and was nominated as the operation of the century [1]. The high success rate of THR has contributed to the rapid increase in its use, with well over one million operations performed annually worldwide [2]. However, approximately about 4%–10% of all the involved implants are expected to fail in their first decade [3,4], mostly due to aseptic loosening, which has been identified as the primary THR failure factor since 1979 [5]. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 11, 2017 Category: Biomedical Engineering Authors: Abdullah A. Alshuhri, Timothy P. Holsgrove, Anthony W. Miles, James L. Cunningham Source Type: research
Multi-objective optimization of nitinol stent design
Nowadays, self-expanding nitinol stents are widely used as part of percutaneous minimally-invasive techniques aimed at treating occluded vessels. Unfortunately, several mechanical failures of such a class of devices have been observed [1]; this drawback often results in loss of scaffolding capabilities of the stent, thrombus formation, and restenosis [2,3]. In particular, partial or total stent fractures have been found in aortic [4], renal [5], and pulmonary [6] implants, as well as in lower limb arteries, i.e., superficial femoral artery (SFA) and popliteal artery [7 –10]. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 10, 2017 Category: Biomedical Engineering Authors: G. Alaimo, F. Auricchio, M. Conti, M. Zingales Source Type: research
Patient-specific biomechanical model of hypoplastic left heart to predict post-operative cardio-circulatory behaviour
The improvements in the diagnostic techniques, together with the progress in computational analyses, create new possibilities for the understanding of pathological conditions and their treatments. Indeed, the use of computational models built up from patient-specific information enables performing virtual surgery, predicting the post-operative behaviour and evaluating the treatment outcomes. In this context, an interesting application of computational approach is the surgical planning in patients affected by congenital heart disease such as the hypoplastic left (or right) heart syndrome (HLHS or HRHS) [1,2]. (Source: Medic...
Source: Medical Engineering and Physics - July 8, 2017 Category: Biomedical Engineering Authors: Elena Cutr ì, Alessio Meoli, Gabriele Dubini, Francesco Migliavacca, Tain-Yen Hsia, Giancarlo Pennati Source Type: research
Increased blood pressure variability upon standing up improves reproducibility of cerebral autoregulation indices
Cerebral autoregulation (CA) refers to the brain ’s control mechanisms responsible for maintaining cerebral blood flow at an appropriate, approximately constant, level despite changes in arterial blood pressure (ABP) [1]. Lassen [2] was the first to show this phenomenon, by plotting the so-called autoregulation curve combining the measurements f rom different human studies [3]. Other authors have obtained similar results both in animals [4–7] and more recently in humans [8,9]. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 7, 2017 Category: Biomedical Engineering Authors: Adam Mahdi, Dragana Nikolic, Anthony A. Birch, Mette S. Olufsen, Ronney B. Panerai, David M. Simpson, Stephen J. Payne Source Type: research
Effects of non-physiological blood pressure artefacts on cerebral autoregulation
Cerebral autoregulation (CA) encompasses all the cerebral blood flow regulation mechanisms that maintain cerebral blood flow at an approximately constant level despite changes in arterial blood pressure (ABP). The importance of CA is highlighted by a connection between CA impairment and clinical disorders such as stroke [1], subarachnoid haemorrhage [2] and head injury [3]. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 7, 2017 Category: Biomedical Engineering Authors: Adam Mahdi, Erica M Rutter, Stephen J Payne Tags: Communication Source Type: research
Neural and non-neural related properties in the spastic wrist flexors: An optimization study
Spasticity is a motor disorder that is commonly seen in many neurological disorders. It is clinically defined as a velocity-dependent increase in tonic stretch reflex with exaggerated tendon jerks, resulting from hyper-excitability of the stretch reflex [1]. In current practice, spasticity is commonly measured subjectively by rotating a joint and estimating the resistance according to an ordinal scale, such as the Modified Ashworth Score (MAS) [2]. Previous reports indicate that the intrinsic mechanical properties of the muscle and tendon may also be altered secondary to spasticity, and may thereby also contribute to the i...
Source: Medical Engineering and Physics - July 7, 2017 Category: Biomedical Engineering Authors: R. Wang, P. Herman, Ö. Ekeberg, J. Gäverth, A. Fagergren, H. Forssberg Source Type: research
Mathematical modelling of the maternal cardiovascular system in the three stages of pregnancy
Pregnancy is associated with physiologically significant but reversible changes in maternal hemodynamics and cardiac function in response to both foetal and maternal demands. Namely, maternal circulation needs to accommodate for an increase in blood volume to provide the nutrients and oxygen supply necessary for an optimal growth of the foetus through the placental circulatory system. In most female these demands are met without compromising the mother but they may prove to be a threat in mother with cardiovascular diseases. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 7, 2017 Category: Biomedical Engineering Authors: Chiara Corsini, Elena Cervi, Francesco Migliavacca, Silvia Schievano, Tain-Yen Hsia, Giancarlo Pennati Source Type: research
Evaluating and improving the performance of thin film force sensors within body and device interfaces
Sensors that measure force and pressure within biomechanical systems are important tools used by designers and researchers to gain insights into these typically complex systems. Compactness and ease of installation of pressure sensors are important considerations so that the biomechanical system is altered and disturbed as little as possible [1]. While there are multiple thin film sensors in the market, such as the Force Sensitive Resistor (FSR) sensor (Interlink Electronics, Camarillo, CA, USA) and the Quantum Tunneling Composite (QTC) sensor (Peratech Ltd, Richmond, North Yorkshire, UK), the advantages of FlexiForce (Tek...
Source: Medical Engineering and Physics - July 6, 2017 Category: Biomedical Engineering Authors: Jirapat Likitlersuang, Matthew J. Leineweber, Jan Andrysek Tags: Technical note Source Type: research
Kinematic behavior of a customized surface-guided knee implant during simulated knee-bending
The surface-guided total knee replacement (TKR) aims to provide patients with patterns of motion that are close to the normal knee joint. In a normal healthy knee, a combination of rollback of the femur over the tibial plateau and internal rotation of the tibia around a medial axis occurs during the joint flexion. The guidance of motion in a healthy knee is provided by the contact forces due to the femoral and tibial surface geometries, while the ligaments control the stability of the motion [1,2]. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 6, 2017 Category: Biomedical Engineering Authors: Shabnam Pejhan, Eric Bohm, Jan-Mels Brandt, Trevor Gascoyne, Urs Wyss Source Type: research
The impact of subchondral bone cysts on local bone stresses in the medial femoral condyle of the equine stifle joint
In humans, subchondral lucencies (SCLs) occur in the knee of youths and adolescents [1] due to mechanical factors (commonly related to athletics) and in skeletally mature individuals secondary to osteoarthritis (OA) [2]. SCL also occurs in young horses, most commonly in the medial femoral condyle (MFC) of the stifle joint, and causes lameness [3 –6] (Fig. 1). SCL is most common in horses ≤2years of age, but can occur in older horses. The occurrence in human youths and young horses are similar, and thus the equine stifle joint is a relevant and useful animal model. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 6, 2017 Category: Biomedical Engineering Authors: Lance L. Frazer, Elizabeth M. Santschi, Kenneth J. Fischer Source Type: research
Geometry of an inflated membrane in elliptic bulge tests: Evaluation of an ellipsoidal shape approximation by stereoscopic digital image correlation measurements
Experimental protocols coupling microstructural observations to mechanical loading often require taking strong assumptions about the global geometry of the samples during the tests. It comes from the very local nature of the measurements, since it is often very complicated to combine simultaneous macroscopic and microscopic observations. However, in order to use the structural data obtained on a representative volume element (RVE), the local behavior identified has to be homogenized, and to do so, knowledge about the global behavior of the considered material is needed. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 6, 2017 Category: Biomedical Engineering Authors: C. Jayyosi, K. Bruy ère-Garnier, M. Coret Source Type: research
A new mathematical model of wrist pulse waveforms characterizes patients with cardiovascular disease – A pilot study
The purpose of this study was to analyze and compare a series of measured radial pulse waves as a function of contact pressure for young and old healthy volunteers, and old patients with cardiovascular disease. The radial pulse waves were detected with a pressure sensor and the contact pressure of the sensor was incremented by 20gf during the signal acquisition. A mathematical model of radial pulse waveform was developed by using two Gaussian functions modulated by radical functions and used to fit the pulse waveforms. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 6, 2017 Category: Biomedical Engineering Authors: Dianning He, Lu Wang, Xiaobing Fan, Yang Yao, Ning Geng, Yingxian Sun, Lisheng Xu, Wei Qian Source Type: research
A FSI computational framework for vascular physiopathology: A novel flow-tissue multiscale strategy
Vascular pathologies are triggered by hemodynamical [1,2] and biochemical factors [3,4]. As a matter of fact, in the context of Abdominal Aortic Aneurysm (AAA), irregular hemodynamics have been shown to accelerate the progression of such a disease [5,6] with a common basis provided by diabetes, male gender, smoke and hypertension [7]. Moreover, t he imbalance of tissue biochemical pathways drives the onset of pathological remodeling, and thereby of histological alterations affecting vascular mechanics [8]. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 6, 2017 Category: Biomedical Engineering Authors: Daniele Bianchi, Elisabetta Monaldo, Alessio Gizzi, Michele Marino, Simonetta Filippi, Giuseppe Vairo Source Type: research
Mechanical behavior of rf-treated thrombus in mechanical thrombectomy
Stroke is the second leading cause of death with 6.7 million deaths per year [1]. Among all stroke cases, ischemic stroke accounts for 87% [2]. Ischemic stroke occurs when a thrombus or an embolus occludes a cerebral vessel, interrupting the blood flow. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 5, 2017 Category: Biomedical Engineering Authors: Chi Hang Chon, Zhen Qin, John CK Kwok, David CC Lam Source Type: research
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(Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 4, 2017 Category: Biomedical Engineering Source Type: research
