[Abrasion reducing polyethylene ceramic-metal compound hip prosthesis head].
There are two specific problems in using metallic or ceramic heads for hip prostheses: (1) the amount of polyethylene abrasions in the cup caused by the heads (especially a metal head). (2) the polyethylene abrasions caused by Al2O3 ceramic heads is far less than metal heads, but its ability to adapt geometrically is limited due to its being less strong. The abrasions appear because of geometric differences in the prosthetic joint, local problems in the surface architecture and physical/chemical interactions between the different materials. In this study we compare the new "Titan-Niob Ceramic Multilayer Sandwich Head" (built three layers of microsegregation phases and three in-between layers of ultrathin metal, 8-10 microns thick, and a surface with integrated grease holes) with the common CoCrMo heads and Al2O3 ceramic heads. Testing 2,000,000 cycles in a bodylike liquid under permanent loads of 90 kPa, periodically increasing up to 250 kPa, simulating normal stress situations (i.e., walking), the "Titan-Niob Ceramic Multilayer Sandwich Head" showed major advantages over the metal heads and also over the ceramic heads even though the ceramic head has been accepted so far to have the best friction coefficient. Furthermore, there has been no problem in surface fracture with the "Titan-Niob Ceramic Multilayer Sandwich Head".
Hennig
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Abteilung für Unfallchirurgie, Universität Erlangen-Nürnberg.
Repenning
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D001696:Biomechanical Phenomena; D002516:Ceramics; D004867:Equipment Design; D004868:Equipment Failure; D006622:Hip Prosthesis; D006801:Humans; D011095:Polyethylenes; D013499:Surface Properties; D016474:Weight-Bearing
D011095:Polyethylenes