ASTM F2777 Dynamic fatigue test under deep flexion
We offer a characterization of the strength and deformation of inlays made of UHMW-PE according to ASTM F2777. Thereby, the tested inlays are subjected to artificial aging before testing.
For the dynamic test, the tibial component is aligned according to the maximum permissible posterior inclination and the femoral component according to the maximum flexion angle. The femoral component is placed close to the posterior edge of the UHMW-PE bearing and an initial internal rotation of 20° is applied. A cyclic load with a maximum of 2,275 N and a minimum of 227.5 N (R = 10) is then applied via the femoral component. The frequency is 0.5 to 2 Hz with a cycle number of 220,000.
For the evaluation, the contact surfaces of the inlay are measured with a coordinate measuring machine and the extent to which the inlay can be raised and tilted apart from the tibial component is determined. In addition, the "anterior-posterior tensile test" and the "rotational stability test" are performed according to ASTM F1223. The results of these investigations are determined and compared before and after the cyclic loading.