In vitro wear simulation on the RandomPOD wear testing system as a screening method for bearing materials intended for total knee arthroplasty.
The 16-station RandomPOD wear test system, previously validated for prosthetic hip wear, was used in the simulation of knee wear mechanisms with a ball-on-flat test configuration. This consisted of a CoCr pin with a ground and polished spherical bearing surface (radius 28 mm) against a conventional, gamma-sterilized UHMWPE disk in serum lubrication. The biaxial motion, consisting of x and y translations, and the load was non-cyclic. Relative to the disk, the center of contact wandered within a circle of 10mm diameter, and the average sliding velocity was 15.5mm/s (ranging from 0 to 31 mm/s). The load varied non-cyclically between 0 and 142 N (average 73 N). In the 60-day test with 16 similar wear couples, moderate adhesive wear, the principal wear mechanism of a well-functioning prosthetic knee, dominated. This showed as a burnished, circular wear mark (diameter 13.2mm, area 137 mm(2)). The wear factor was 2.04 ± 0.03 × 10(-6)mm(3)/Nm (mean ± 95 percent confidence limit). For the first time a truly multidirectional, realistic and uniform, large capacity pin-on-disk simulation of knee wear mechanisms was implemented.
Aalto University School of Engineering, Department of Engineering Design and Production, PO Box 14300, FI-00076 Aalto, Finland. Electronic address: vesa.saikko@aalto.fi.
Vesa
V
Saikko
D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D003198:Computer Simulation; D006801:Humans; D008153:Lubrication; D008422:Materials Testing / Q000295:instrumentation; D009038:Motion; D011095:Polyethylenes / Q000737:chemistry*; D019736:Prostheses and Implants; D011474:Prosthesis Design
D011095:Polyethylenes; C111601:ultra-high molecular weight polyethylene
Contact mechanics; Non-cyclic; Polyethylene; Total knee replacement; Wear simulation