Preclinical Testing of Femoral Hip Components: An Experimental Investigation With Four Prostheses

2005 ◽  
Vol 127 (5) ◽  
pp. 872-880 ◽  
Author(s):  
John R. Britton ◽  
Patrick J. Prendergast
Keyword(s):  
Steady State ◽  
Femoral Component ◽  
Clinical Performance ◽  
Relative Displacement ◽  
In Vitro Tests ◽  
Preclinical Testing ◽  
Early Migration ◽  
Component Type ◽  
Comparable Performance

Existing standards for the preclinical testing of femoral hip implants have been successful in the objective of guaranteeing the implant’s fatigue strength. There is a need for an experimental test which could ensure prostheses were not susceptible to aseptic loosening. In this study we measure the relative movement between the prosthesis and the bone of four different cemented femoral component designs in in vitro tests. The aim is to determine if differences can be distinguished and whether the differences correlate with clinical performance. The four designs are the Charnley (DePuy International Ltd., UK), the Exeter (Stryker Osteonics Howmedica Corp., USA), the Lubinus SPII (Waldemar-Link GmbH, Germany), and the Müller Curved (JRI Ltd, UK). Five tests were carried out for each femoral component type, giving a total of 20 tests, and their permanent relative displacement (termed migration) and recoverable (i.e., elastic) relative displacement (termed inducible displacement) monitored over one million loading cycles. Considerable variation occurred in the tests. Nonetheless, most femoral components migrated medially, posteriorly, and distally. Most also rotated into varus. Translations of the Charnley (64microns) and Lubinus (67microns) implants were less than the Müller (72microns) and Exeter (94microns) implants, but this difference is not statistically significant. Most of the femoral components had rapid early migration followed by slower steady-state migration. With regard to the steady state inducible displacements of the prostheses, those of the Charnley, Exeter, and Lubinus decreased or were stable with respect to time, whilst those of the Müller typically increased with respect to time. It is concluded that migration is not a suitable basis for in vitro comparison of prosthesis designs. However, inducible displacement trends provide a clinically comparable performance ranking.

Research On Dental Amalgam: 1982-1986

1988 ◽  
Vol 2 (1) ◽  
pp. 71-82 ◽  
Author(s):  
D.B. Mahler
Keyword(s):  
Clinical Performance ◽  
High Sensitivity ◽  
Dental Amalgam ◽  
Performance Criterion ◽  
Dental Restoration ◽  
In Vitro Tests ◽  
Significant Finding ◽  
Amalgam Restorations

This paper is a five-year review of selected research papers on dental amalgam which were published during the years 1982 through 1986. Papers presented at scientific dental meetings are also included. During the past five years, clarification of amalgam metallurgy has been made, and a few innovative modifications have been recommended. The addition of palladium, indium, and selenium to dental amalgam has been suggested, but commercial applications have yet to be made. The mechanical property of creep has been studied more extensively, while the applicability of fracture toughness tests has been examined. More work has been done on the microleakage of amalgam restorations, with certain alloy factors showing an influence on this problem. Most in vitro investigations on the use of cavity varnish or resin films beneath amalgam restorations show reduced microleakage. Additionally, many electrochemical investigations were conducted. A most significant finding was that amalgam does not appear to break down in vivo as much as in vitro tests would indicate, the buffering action of saliva being protective in this regard. The marginal fracture evaluation of clinical amalgam restorations is still being used as a major clinical performance criterion, and measuring techniques for this failure mode have been improved. Measurements of metallic ion loss from amalgam were made with instruments of high sensitivity, but no evidence has been found to associate this loss with any disease entity. The rare presence of an allergy to mercury appears to be the only contra-indication for the use of amalgam as a dental restoration. Further research on dental amalgam can lead to improved clinical performance of this most useful restorative material.

scholarly journals In Vitro Models for the Development of Peripheral Nerve Conduits, Part I: Design of a Fibrin Gel-Based Non-Contact Test

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3573
Author(s):  
Paola De Stefano ◽  
Angelica Silvia Federici ◽  
Lorenza Draghi
Keyword(s):  
Peripheral Nerve ◽  
Clinical Performance ◽  
In Vitro Models ◽  
In Vitro Tests ◽  
Neural Cells ◽  
Animal Testing ◽  
Fibrin Gel ◽  
Specific Implementation

Current clinical strategies to repair peripheral nerve injuries draw on different approaches depending on the extent of lost tissue. Nerve guidance conduits (NGCs) are considered to be a promising, off-the-shelf alternative to autografts when modest gaps need to be repaired. Unfortunately, to date, the implantation of an NGC prevents the sacrifice of a healthy nerve at the price of suboptimal clinical performance. Despite the significant number of materials and fabrication strategies proposed, an ideal combination has not been yet identified. Validation and comparison of NGCs ultimately requires in vivo animal testing due to the lack of alternative models, but in the spirit of the 3R principles, a reliable in vitro model for preliminary screening is highly desirable. Nevertheless, more traditional in vitro tests, and direct cell seeding on the material in particular, are not representative of the actual regeneration scenario. Thus, we have designed a very simple set-up in the attempt to appreciate the relevant features of NGCs through in vitro testing, and we have verified its applicability using electrospun NGCs. To this aim, neural cells were encapsulated in a loose fibrin gel and enclosed within the NGC membrane. Different thicknesses and porosity values of two popular polymers (namely gelatin and polycaprolactone) were compared. Results indicate that, with specific implementation, the system might represent a useful tool to characterize crucial NGC design aspects.

Anti-Diabetic Activity of a Mineraloid Isolate, in vitro and in Genetically Diabetic Mice

2011 ◽  
Vol 81 (1) ◽  
pp. 34-42 ◽  
Author(s):  
Joel Deneau ◽  
Taufeeq Ahmed ◽  
Roger Blotsky ◽  
Krzysztof Bojanowski
Keyword(s):  
Dna Microarrays ◽  
Human Fibroblasts ◽  
Diabetic Animal ◽  
In Vitro Tests ◽  
Diabetic Mice ◽  
Fossil Material ◽  
Expression Of Genes ◽  
Enhanced Expression ◽  
Genetically Diabetic Mice

Type II diabetes is a metabolic disease mediated through multiple molecular pathways. Here, we report anti-diabetic effect of a standardized isolate from a fossil material - a mineraloid leonardite - in in vitro tests and in genetically diabetic mice. The mineraloid isolate stimulated mitochondrial metabolism in human fibroblasts and this stimulation correlated with enhanced expression of genes coding for mitochondrial proteins such as ATP synthases and ribosomal protein precursors, as measured by DNA microarrays. In the diabetic animal model, consumption of the Totala isolate resulted in decreased weight gain, blood glucose, and glycated hemoglobin. To our best knowledge, this is the first description ever of a fossil material having anti-diabetic activity in pre-clinical models.

Comparison of High Purity Factor IX Concentrates and a Prothrombin Complex Concentrate in a Canine Model of Thrombogenicity

1991 ◽  
Vol 66 (05) ◽  
pp. 609-613 ◽  
Author(s):  
I R MacGregor ◽  
J M Ferguson ◽  
L F McLaughlin ◽  
T Burnouf ◽  
C V Prowse
Keyword(s):  
High Purity ◽  
Time Course ◽  
Prothrombin Complex Concentrate ◽  
Degradation Products ◽  
Canine Model ◽  
Factor Ix ◽  
In Vitro Tests ◽  
Albumin Infusion

SummaryA non-stasis canine model of thrombogenicity has been used to evaluate batches of high purity factor IX concentrates from 4 manufacturers and a conventional prothrombin complex concentrate (PCC). Platelets, activated partial thromboplastin time (APTT), fibrinogen, fibrin(ogen) degradation products and fibrinopeptide A (FPA) were monitored before and after infusion of concentrate. Changes in FPA were found to be the most sensitive and reproducible indicator of thrombogenicity after infusion of batches of the PCC at doses of between 60 and 180 IU/kg, with a dose related delayed increase in FPA occurring. Total FPA generated after 100-120 IU/kg of 3 batches of PCC over the 3 h time course was 9-12 times that generated after albumin infusion. In contrast the amounts of FPA generated after 200 IU/kg of the 4 high purity factor IX products were in all cases similar to albumin infusion. It was noted that some batches of high purity concentrates had short NAPTTs indicating that current in vitro tests for potential thrombogenicity may be misleading in predicting the effects of these concentrates in vivo.

A Comparison of the in Vitro and in Vivo Thrombogenic Activity of Factor IX Concentrates Using Stasis (Wessler) and Non-Stasis Rabbit Models

1980 ◽  
Vol 44 (02) ◽  
pp. 081-086 ◽  
Author(s):  
C V Prowse ◽  
A E Williams
Keyword(s):  
Platelet Rich Plasma ◽  
Thrombus Formation ◽  
Factor Ix ◽  
Coagulation System ◽  
In Vitro Tests ◽  
Clinical Use ◽  
Low Activity

SummaryThe thrombogenic effects of selected factor IX concentrates were evaluated in two rabbit models; the Wessler stasis model and a novel non-stasis model. Concentrates active in either the NAPTT or TGt50 in vitro tests of potential thrombogenicity, or both, caused thrombus formation in the Wessler technique and activation of the coagulation system in the non-stasis model. A concentrate with low activity in both in vitro tests did not have thrombogenic effects in vivo, at the chosen dose. Results in the non-stasis model suggested that the thrombogenic effects of factor IX concentrates may occur by at least two mechanisms. A concentrate prepared from platelet-rich plasma and a pyrogenic concentrate were also tested and found to have no thrombogenic effect in vivo.These studies justify the use of the NAPTT and TGt50 in vitro tests for the screening of factor IX concentrates prior to clinical use.

In Vitro Thrombogenicity Tests of Factor IX Concentrates

1979 ◽  
Vol 42 (05) ◽  
pp. 1355-1367 ◽  
Author(s):  
C V Prowse ◽  
A Chirnside ◽  
R A Elton
Keyword(s):  
Factor Viii ◽  
Partial Thromboplastin Time ◽  
Generation Time ◽  
Activated Partial Thromboplastin Time ◽  
Factor Ix ◽  
In Vitro Tests ◽  
Factor Viii Inhibitor ◽  
Factor Ixa ◽  
Viii Inhibitor

SummaryVarious factor IX concentrates have been examined in a number of in vitro tests of thrombogenicity. The results suggest that some tests are superfluous as in concentrates with activity in any of these tests activation is revealed by a combination of the non-activated partial thromboplastin time, the thrombin (or Xa) generation time and factor VIII inhibitor bypassing activity tests. Assay of individual coagulant enzymes revealed that most concentrates contained more factor IXa than Xa. However only a small number of concentrates, chiefly those that had been purposefully activated, contained appreciable amounts of either enzyme.

Inhibition of Fibrinolysis and Fibrinogenolysis in Man: Comparison of ε-Aminocaproic Acid and Kallikrein Inhibitor

1963 ◽  
Vol 10 (01) ◽  
pp. 106-119 ◽  
Author(s):  
E Beck ◽  
R Schmutzler ◽  
F Duckert ◽  
Keyword(s):  
Aminocaproic Acid ◽  
Side Reactions ◽  
In Vitro Tests ◽  
Factor V ◽  
Clinical Use ◽  
Strong Inhibitor ◽  
Kallikrein Inhibitor ◽  
Therapeutic Possibilities

SummaryInhibitor of kallikrein and trypsin (KI) extracted from bovine parotis was compared with ε-aminocaproic acid (EACA): both substances inhibit fibrinolysis induced with streptokinase. EACA is a strong inhibitor of fibrinolysis in concentrations higher than 0, 1 mg per ml plasma. The same amount and higher concentrations are not able to inhibit completely the proteolytic-side reactions of fibrinolysis (fibrinogenolysis, diminution of factor V, rise of fibrin-polymerization-inhibitors). KI inhibits well proteolysis of plasma components in concentrations higher than 2,5 units per ml plasma. Much higher amounts of KI are needed to inhibit fibrinolysis as demonstrated by our in vivo and in vitro tests.Combination of the two substances for clinical use is suggested. Therapeutic possibilities are discussed.

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