Ein neuer, der ISO/FDIS 14242-1 entsprechender Hüftsimulator: E-SIM

The continuing development of new, highly sophisticated materials for the articulating surfaces of total hip endoprostheses involves the need for testing, not only of biocompatibility and dynamic loadability, but also of tribological properties (friction, wear, lubrication). For decades, the wear resistance of these materials has been tested in wear simulators. In consequence of the currently often widely differing test methods, the technical committee (TC 150) of the ISO (International Organization for Standardization) has been concerned to develop an International Standard (ISO/FDIS 14242 1 and 2: Implants for Surgery - wear of total hip joint prostheses - on the basis of kinetic and kinematic data from gait analysis. This new standard will be the basis for ensuring the comparability of scientific data obtained from tribological. testing of total hip endoprotheses. The new hip simulator, E-SIM, presented in this paper, complies with the currently published FDIS (Final Draft International Standard), and enables testing in accordance with these specifications

Strain measurement at the knee ligament insertion sites

We describe the modification of an existing method of ligament strain measurement at the knee joint in detail. At ten fresh joint specimens we used that technique where strain gauges are attached to the ligamentous insertions and origins. We both improved the preparation of the attachment site and the application of the strain gauges. In a special apparatus the specimens were moved from 0degrees extension to 100degrees flexion while simulating muscle strength and axial force. Testing was performed at the posterior cruciate ligament with both intact and transsected anterior cruciate ligament. In contrast to other existing techniques it does not affect the motion of the joint or the integrity and the function of the ligaments. Unlike the original description of that method we could register a loading behaviour of the posterior cruciate ligament that is similar to those reported in the literature

Banddehnungsmessung am Kniegelenk - Der Dehnungsmeßstreifen und seine Alternativen

Those techniques for measuring ligament tension at the knee joint that are most commonly cited and easiest to carry out are discussed, These include four techniques based on the use of strain gauges. Apart from the Omega transducer and the buckle transducer, there is also the tendon force transducer, and the application of strain gauges to the bony ligament insertion sites, Other indirect measuring methods considered are the mercury strain transducer and the Hall effect transducer. The parameter measured with all of these methods is fluctuating current or voltage, which is then correlated with ligament tension. Three direct measurements are also discussed: the separation distances of marked fibres of the ligaments, replacement of fibres by threads, and a load cell/bone plug construction. The measured value is equated with the effective change in ligament length