Biomedical Engineering / Biomedizinische Technik

Published by De Gruyter

Volume 55 Issue 5

Issue of Biomedical Engineering / Biomedizinische Technik

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Contents
Journal Overview

Review

October 20, 2010

Zementfreie Hüftendoprothetik: eine aktuelle Übersicht / Cementless total hip arthroplasty: a review

Peter Diehl, Maximilian Haenle, Philipp Bergschmidt, Hans Gollwitzer, Johannes Schauwecker, Rainer Bader, Wolfram Mittelmeier

Page range: 251-264

Abstract

The purpose of total hip replacement (THR) is the restoration of a painless functioning hip joint with the main focus on the biomechanical properties. Advances in surgical techniques and biomaterial properties currently allow predictable surgical results in most patients. Despite the overwhelming success of this surgical procedure, the debate continues surrounding the optimal choice of implants and fixation. Femoral and acetabular implants with varying geometries and fixation methods are currently available. Problems inherent with acrylic bone cement, however, have encouraged surgeons to use alternative surfaces to allow biologic fixation. Optimal primary and secondary fixation of cementless hip stems is a precondition for long-term stability. Important criteria to achieve primary stability are good rotational and axial stability by press-fit fixation. The objective of the cementless secondary fixation is the biological integration of the implant by bony ingrowth. Nevertheless, current investigations show excellent results of cementless fixation even in older patients with reduced osseous quality. The main advantages of cementless fixation include biological integration, reduced duration of surgery, no tissue damage by cement polymerization and reduction of intraoperative embolisms. In comparison to cemented THR both, cementless sockets and stems provide good long-term results.

Research articles

September 15, 2010

Relative contributions of plantar fascia and ligaments on the arch static stability: a finite element study

Kai Tao, Wen-Ting Ji, Dong-Mei Wang, Cheng-Tao Wang, Xu Wang

Page range: 265-271

Abstract

The plantar fascia (PF) and major ligaments play important roles in keeping the static foot arch structure. Their functions and relative contributions to the arch stability have not been well studied. A three-dimensional finite element foot model was created based on the reconstruction of magnetic resonance images. During balanced standing, four cases after individual releases of the PF, spring ligament (SL), and long and short plantar ligaments (LPL and SPL) were simulated, to compare their biomechanical consequences with the normal predictions under the intact structure. Although the predictions showed the arch did not collapse obviously after each structure sectioning, the internal mechanical behaviors changed considerably. The PF release resulted in the maximal increases of approximately 91%, 65% and 47% in the tensions of the LPF, SPL and SL, produced the largest changes in all bone rotations, and brought an obvious shift of high stress from the medial metatarsals to the lateral metatarsals. The SL release mainly enhanced bone rotation angles and weakened the joint stability of the arch structure. The LPL and the SPL performed the roles of mutual compensation as either one was released. The influence of the LPL on the load distribution among metatarsals was greater than for the SPL and the SL.

September 15, 2010

Development of a device to simulate tooth mobility

Kurt-Jürgen Erdelt, Timea Lamper

Page range: 273-278

Abstract

Objectives : The testing of new materials under simulation of oral conditions is essential in medicine. For simulation of fracture strength different simulation devices are used for test set-up. The results of these in vitro tests differ because there is no standardization of tooth mobility in simulation devices. The aim of this study is to develop a simulation device that depicts the tooth mobility curve as accurately as possible and creates reproducible and scalable mobility curves. Materials and methods : With the aid of published literature and with the help of dentists, average forms of tooth classes were generated. Based on these tooth data, different abutment tooth shapes and different simulation devices were designed with a CAD system and were generated with a Rapid Prototyping system. Then, for all simulation devices the displacement curves were created with a universal testing machine and compared with the tooth mobility curve. With this new information, an improved adapted simulation device was constructed. Results : A simulations device that is able to simulate the mobility curve of natural teeth with high accuracy and where mobility is reproducible and scalable was developed.

September 15, 2010

Cardiac troponin T detection using polymers coated quartz crystal microbalance as a cost-effective immunosensor

Krongkamol Wong-ek, Orawon Chailapakul, Noppadon Nuntawong, Kata Jaruwongrungsee, Adisorn Tuantranont

Page range: 279-284

Abstract

Cardiac troponin T (cTnT) detection has been the focus of increased interest due to its role in myocardial infarction diagnosis. In this study, we report a relatively low coat technique to detect cTnT using a quartz crystal microbalance (QCM) sensor. A sensitive detection is achieved by introducing a QCM surface with a carboxylic polyvinyl chloride immobilization layer. The surface morphologies of this polymer film under varied deposition thickness have been investigated by field emission scanning electron microscopy and atomic force microscopy. A cTnT detection result from a modified QCM surface can be obtained within a short response time by a direct detection of the immunoreaction and a direct conversion of mass accumulation into a frequency shift, representing a measurable electrical signal. The relationship between the cTnT concentration and the response current from a QCM sensor shows detectability at the concentration of cTnT as low as 5 ng/ml.

August 23, 2010

Super-selective electrical stimulation of the left ventricle via a miniaturized magnetized stimulation wire: proof of concept study

Christian Knackstedt, Thomas Schimpf, Andreas Napp, Boerge Wessling, Christine Rothe, Karl Mischke, Uwe Schnakenberg, Patrick Schauerte

Page range: 285-290

Abstract

Cardiac resynchronization therapy provides a treatment option for patients with congestive heart failure. Electrodes are usually advanced via the cardiac venous system (CVS). Placement is often hampered by small vessel diameter or tortuosity. The aim of this study was to develop and test a magnetized stimulation wire (MSW) capable of being navigated into small and tortuous CVS branches. Therefore, a conventional guide wire with a permanent magnet and a single stimulation electrode at its tip was coated with iridium oxide at the distal end and insulated except for the very tip (coating thickness: 500 nm, active uncoated area: 10 mm 2 ). The MSW was designed to allow for a remote magnetic steering using a magnetic navigation system (MN) (Stereotaxis™). After in vitro testing of the electrical properties, the MSW was tested in an animal model (n=6 sheep): the MSW was placed in a CVS side branch and navigation characteristics of the MSW were determined. The effective (unipolar) pacing threshold was 4.9±2.4 V (at 2 ms pulse width). The rheobase was 1.89±0.44 V and the chronaxie time was 0.75±0.7 ms. The MSW could be navigated into small CVS branches with reasonable MN properties. This could allow stimulation at CVS sites currently not accessible for conventional stimulation catheters or electrodes.

September 15, 2010

Clinical proof of practicability for an ECG device without any conductive contact

Michael Czaplik, Benjamin Eilebrecht, Alexandre Ntouba, Marian Walter, Patrick Schauerte, Steffen Leonhardt, Rolf Rossaint

Page range: 291-300

Abstract

Heart rhythm disturbances are common symptoms of several heart disorders. One of the most effective screening methods is the traditional electrode-based ECG. However, this examination can be both time- and resource-consuming. Capacitive-coupling ECG (cECG) screening – working without any conductive electrical contact with the patient – might help to shorten the time required for diagnosis. In this study, we examine the practicability of employing a non-contact capacitive ECG in a clinical setting. A total of 30 volunteer patients aged over 50 years without pacemakers were included in our trial, after obtaining their written informed consent and their medical history. A cECG as well as a conventional, conductive ECG were recorded simultaneously. In addition to mathematical analysis, ECG data were manually evaluated by two clinicians blinded to the recording method and patient conditions. Data from 30 patients were collected during our study, seven of whom had experienced myocardial infarction. The obtained cECG signals showed a high correlation with the simultaneously recorded Einthoven lead II of the conventional ECG. The values for heart rate, PQ and QT time periods correlated particularly well. Significant differences were observed with regard to QRS duration. Data recorded in the supine position contained less motion artefacts and, in particular, there were fewer breathing artefacts compared to data collected from those in a sitting position. Owing to the easy and quick application of the cECG system, the feedback from the examined patients was consistently positive. In conclusion, recording cECG data in a sitting position provided sufficient quality for screening purposes. Further studies will be needed for the evaluation of cECG appropriateness in diagnosing heart disease.

September 15, 2010

Hybrid independent component analysis and twin support vector machine learning scheme for subtle gesture recognition

Ganesh R. Naik, Dinesh K. Kumar, Jayadeva

Page range: 301-307

Abstract

Myoelectric signal classification is one of the most difficult pattern recognition problems because large variations in surface electromyogram features usually exist. In the literature, attempts have been made to apply various pattern recognition methods to classify surface electromyography into components corresponding to the activities of different muscles, but this has not been very successful, as some muscles are bigger and more active than others. This results in dataset discrepancy during classification. Multicategory classification problems are usually solved by solving many, one-versus-rest binary classification tasks. These subtasks unsurprisingly involve unbalanced datasets. Consequently, we need a learning methodology that can take into account unbalanced datasets in addition to large variations in the distributions of patterns corresponding to different classes. Here, we attempt to address the above issues using hybrid features extracted from independent component analysis and twin support vector machine techniques.

About this journal

Objective
Biomedical Engineering / Biomedizinische Technik (BMT) is a high-quality forum for the exchange of knowledge in the fields of biomedical engineering, medical information technology and biotechnology/bioengineering. As an established journal with a tradition of more than 60 years, BMT addresses engineers, natural scientists, and clinicians working in research, industry, or clinical practice. All articles are peer-reviewed. All manuscripts must be submitted in English.

Topics

diagnostic imaging
image processing
biosignal processing
modelling and simulation
biomechanics
information and communication in medicine
telemedicine and e-health
surgery
minimum invasive interventions
endoscopy and image-guided therapy
diagnostic and therapeutic instrumentation
clinical engineering
micro- and nanosystems in medicine
active implants
biosensors
neuro-engineering
neural systems
rehabilitation and prosthetics
biomaterials
cellular and tissue engineering
artificial organs
biomedical engineering for audiology, ophthalmology, emergency and dental medicine
general subjects (e.g., education and training, health technology assessment)
special topics (e.g., linking proteomics and genomics with biomedical engineering, emergency medicine)

Article formats
Reviews, Research Articles, Short Communications