[Stretched polyethylene (UHMWPE)--a new substance modification for minimizing wear in artificial knee joint replacement].
Polyethylene wear is a major cause of aseptic loosening of knee endoprostheses. With the aim of minimizing this mechanical wear, we stretch-modified the structure of polyethylene. From plates of UHMWPE, stretched PE samples were produced under defined conditions, and subsequently submitted to friction tests in a fluid environment (cycles 5 x 10(5), frequency 1.5 Hz, load 500 N, contact stress 10 MPa). After load testing, the stretched samples revealed a 70% reduced wear rate in comparison with non-stretched samples. Microscopic examination (light microscopy, scanning electron microscopy) showed abrasive scratches in all test samples, but only in the non-stretched specimens were signs of pitting found. Translating these results to unidirectional tractive rolling on the tibial plateau in the knee joint suggests that a significant reduction in polyethylene wear can be expected. However, further experimental investigations need to be carried out to confirm this highly promising possibility.
Wirtz
D C
DC
Orthopädische Universitätsklinik der RWTH Aachen. dcwirtz@post.klinikum.rwth-aachen.de
Schopphoff
E
E
Weichert
D
D
Niethard
F U
FU
D004548:Elasticity; D019544:Equipment Failure Analysis / Q000295:instrumentation*; D006801:Humans; D007720:Knee Prosthesis; D011095:Polyethylenes; D011474:Prosthesis Design; D011475:Prosthesis Failure
D011095:Polyethylenes; C111601:ultra-high molecular weight polyethylene