摘要:

Reconstruction of the rheumatoid metacarpophalangeal (MCP) joint is generally achieved by means of implantation of a hinged silastic prosthesis. These implants reduce the pain in joint and restore some degree of mobility. However, they are prone to failure after a relatively short life-span. In this study, two popular designs of MCP implant, the Swanson and the Sutter, were compared by means of three-dimensional finite element analysis. The aim was to examine how the differing geometry effected their relative stiffness as replacement joints, and whether they were inherently prone to high stress concentrations during flexion. Although the Swanson design implant exhibited relatively greater resistance to flexion, both designs showed regions of high stress concentration and it was noted that neither was without its limitations. The use of the finite element technique was found to be an excellent way to provide preliminary design evaluation information, allowing further evolution before clinical trials.

ISSN:0309-1902    

DOI:10.3109/03091909609008394

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

There is a growing demand that severely disabled children should be offered a normal-looking, comfortable alternative to highly supportive wheelchair seating to facilitate relaxation and social integration. An evaluation of five chairs, funded by Medical Devices Agency, an executive agency of the Department of Health, was undertaken with potential and actual users of these chairs to investigate the chairs'function with respect to the child's posture, and what features were effective. Twenty-nine children tried five chairs for up to 30 min in each; and a postal survey received 100 responses. The chairs seem to meet many users’postural needs (78% of postal survey; 31 -72% of short-term evaluation depending on chair); the chairs’adjustability and availability of special features are important in meeting the needs of this user group; evidence of poor design and its implications are discussed.

ISSN:0309-1902    

DOI:10.3109/03091909609008395

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

This study quantified the orthotropic elastic changes in cortical bone due to aging as well as determined any elastic changes after acute treatments of growth hormone (GH). Three groups of twenty rats represented three age groups of young adult (9 months), middle age (20 months), and old (31 months) rats. During a ten day period, half of the rats in each age group were given twice-daily doses of recombinant human GH while the remaining half were injected with a vehicle control (saline). The effects of aging and GH on the elastic characteristics of cortical bone were quantified via ultrasonic wave propagation. Propagation velocities of longitudinal and shear waves were measured through cubic cortical specimens from the posterior femoral diaphysis. Density was measured by Archimedes’technique. The normalized, orthotropic elastic properties of Young's moduli (Eii), shear moduli (Gii), and Poisson's ratios (vii) were calculated and used to compare the groups (where i and j = 1, 2, or 3 reference the radial, circumferential, and longitudinal axes, respectively). Cortical elastic moduli consistently increased with age with the strongest effects demonstrated in radial dependent properties such as E11(+25-3% from 9 to 31 months, p = 00004) and G12(+12-6%from20to31 months, p = 0-0419). The ratio of transverse to axial displacement (Poisson's ratio) typically decreased with age (9 to 31 months) as seen in V31(-24-95%, p = 0-0134) and V32(-20-7%, p = 00015). Overall, a ten day treatment with GH produced no global statistical change in elastic properties (p>0-05). However, GH did minimize the age related differences that were measured for E22, E33, and V32between the 9 and 31 month old groups essentially returning old bone to its youthful elastic state. These finding add orthotropic detail to the current understanding of changing cortical elastic properties during aging as well as providing a reference for further studies of GH.

ISSN:0309-1902    

DOI:10.3109/03091909609008396

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

A transcutaneous blood gas monitor is a non-invasive tool that is used clinically. Magnetic resonance imaging (MRI) of the rat has been performed for basic research of pathology and brain science. Non-invasive monitoring of blood gas is expected for such small animal experiments because of the need to minimize blood loss. We applied a commercially available transcutaneous blood gas monitor to rat experiments with MRI. The monitoring responses to rat arterial tension of carbon dioxide (paCO2) appeared to change exponentially with the time constant 1820±40 s, which was five times slower than that of man. The jump in paCO2, however, can be translated only by a differential slope of values monitored by tras cutaneous measurement of carbon dioxide (tcpCO2) at the timing of paCO2change without waiting for the saturated value of tcpCO2. The magnetic field of MRI did not affect blood gas monitoring and magnetic material in the blood gas sensor did not jeopardize the magnetic homogeneity of imaging. The transcutaneous blood gas monitor can be applied to MRI measurements with paCO2jumps.

ISSN:0309-1902    

DOI:10.3109/03091909609008397

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

ISSN:0309-1902    

DOI:10.3109/03091909609008398

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

ISSN:0309-1902    

DOI:10.3109/03091909609008399

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Encyclopedic Handbook of Biomaterials and Bioengineering, Part A–Materials, Vol. 1 and 2and Part B–Applications, Vol. 1 and 2 Edited by D. L. Wise, D.J. Trantolo, D. E. Altobelli, M.J. Yaszemski, J. D. Gresser and E. R. Schwartz. Marcel Dekker Inc. (New York, 1995). Price $995.00.Design of cardiac pacemakersEdited bv J. G. Webster (IEEE Press, New York, USA. 1995) pp. 496. Price $6995, ISBN 0-7803-1 134-5.A Guide to Commissioning and Quality Control of Treatment Planning Systems: Institution of Physics and Engineering in Medicine and Biology Report Number 68Edited by H. M. Morgan, A. M. Morgan and R. A. Lake. IPEMB Publications (York, UK), pp. 50. Price£17, ISBN 0904 181 839.Medical Imaging–The Assessment of Image Quality ICRU Report 54International Commission on Radiation Units and Measurements (Bethesda, MD, USA, April 1996), pp. 88. ISBN 0-913394-53-X.Implantation Biology. The Host Response and Biomedical DevicesEdited by R. S. Greco (CRC Press (USA)), 1995, pp. 418. Price£111.50. ISBN 0-8493-4432-8.Structure and dynamics of membranes (Parts A&B)Bv R. Lipowskv and E. Sackmann. Elsevier (Amsterdam). 1995, pp. 1028. Price Dfl 545.00/US£320.50, ISBN 0444 81975 4.

ISSN:0309-1902    

DOI:10.3109/03091909609008400

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

ISSN:0309-1902    

DOI:10.3109/03091909609008401

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

ISSN:0309-1902    

DOI:10.3109/03091909609008402

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor