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Fatigue test under high flexion ASTM F2777

Normative References  



ASTM F2777: Standard Test Method for Evaluating Knee Bearing (Tibial Insert) Endurance and Deformation Under High Flexion

This test method describes a mechanical evaluation of the endurance and deformation properties of artificial aged UHMWPE tibial inserts used in total knee replacement implants. For this mechanical test, a maximum flexion angle and a tibial insert rotation around the superior-inferior axis (20° internal rotation) have to be selected. The worst case creep performance is determined after dynamic loading at 2,275 N for 220,000 cycles.

To evaluate the creep performance, the gap alternation between the tibial baseplate and insert is measured before and after the high flexion fatigue test. Additionally, an “A-P Draw Test” and a “Rotary Laxity Test” (according ASTM F1223) are performed before and after fatigue testing and compared with each other.

Subsequently the post-fatigue deformation is determined by means of 3D-scans.