Fatigue fracture of knee tibial trays has been one of the most commonly reported failure mechanisms of Total Knee Replacements (TKR). It is caused by loss of underlying bone support resulting from biological reactions, such as wear-induced osteolysis. Under these conditions, the tibial tray becomes mechanically unstable, and cyclic loading imparted by normal walking causes fatigue cracks, ultimately leading to catastrophic failure.
The ISO 14879-1 standard 'Determination of Endurance Properties of Knee Tibial Trays' provides a common set of test parameters for determining and validating the fatigue properties of different tibial tray designs. Our
8870 servohydraulic and
ElectroPuls™ Electrodynamic test systems will assist designers, manufacturers and researchers through the product life-cycle process, from deriving fundamental material properties, such as resistance to fatigue crack propagation, to testing the entire tibial tray and beyond.
We use a clamping fixture to secure one half of the tibial tray, simulating a fully supported condyle. The other unsupported condyle is then subjected to physiologically representative loading. By using our unique
Dynacell™ load cell, dynamic inertial errors (such as those caused by the fixturing and from hydro-dynamics that result when testing in an environmental bath) can be removed, allowing for a more accurate measurement of load being applied to the specimen.
We recommend that you review ISO 14879-1 to fully understand its requirements.