The standard “ISO 11491 Surgical implants - Determination of impact resistance of ceramic femoral heads for hip joint prostheses” developed by the International Organization for Standardization (ISO) describes two alternative test methods for determining the impact resistance of ceramic femoral heads for hip joint prostheses.
For the purposes of this standard, the terms and definitions given in ISO 7206-10 and the following apply:
This standard is used for material development, material comparison, quality assurance, implant system characterization, reliability analysis, and design data generation. Impact strength (cyclic strength) is determined by applying increasing energy impacts to the head/taper structure and determining the maximum energy that does not result in fracture. Alternatively, impact load (cyclic strength) is determined by quasi-static load release cycles, which define the maximum load that does not result in fracture.
These test methods are best suited to evaluate new types of ceramic ball head material with metal body tapers, as well as new taper design specifications, by comparing them to clinically established and proven ceramic ball head and metal body taper systems.
The testing machine used for impact testing has a rigid structure that can apply impact to the test specimen with a falling weight. The machine should be securely mounted on the floor or on a heavy, rigid bench, such as a granite or steel-topped measuring table. The machine houses an adjustable mass weight that will drop onto the specimen from an adjustable height to allow the application of various impact energies. The weight can be guided or free-standing. Any guiding mechanism will minimize friction. The guide mechanism should not be in contact with the striking assembly. The test specimen, consisting of a head and neck unit, should be supported on a holding block mounted on a load cell. The axis of the falling weight, the test specimen, the holding block and the load cell should be aligned vertically (plus/minus 1 degree) and laterally (plus/minus 1 mm).
The fixture used to position the test specimen should be of low mass but rigid and strong enough to withstand repeated impacts. An example of a testing machine is shown in the figure included in the standard.
To prevent the impact load from being applied to the specimen/neck unit assembly at an incorrect location, a linear bearing or low friction sleeve should be installed in the neck unit holder. This structure also prevents the specimen/neck unit assembly from unexpectedly moving after impact loading. The striking plate should have the appropriate hardness, diameter and thickness for the target of the drop weight.
Among the numerous tests, measurements, analyses and evaluation studies that our organization has carried out for businesses in various sectors, our organization also provides testing services defined in the standard “ISO 11491 Surgical implants - Determination of impact resistance of ceramic femoral heads for hip joint prostheses” with its trained and expert staff and advanced technological equipment.
To get an appointment, to get more detailed information or to request an evaluation, you can ask us to fill in our form and reach you.
