Background: Material wear testing is an important technique in the development and\r\nevaluation of materials for use in implant for total knee arthroplasty. Since a knee joint\r\ninduces a complex rolling-gliding movement, standardised material wear testing devices\r\nsuch as Pin-on-Disc or Ring-on-Disc testers are suitable to only a limited extent because\r\nthey generate pure gliding motion only.\r\nMethods: A rolling-gliding wear simulator was thus designed, constructed and\r\nimplemented, which simulates and reproduces the rolling-gliding movement and loading\r\nof the knee joint on specimens of simplified geometry. The technical concept was to run a\r\nbase-plate, representing the tibia plateau, against a pivoted cylindrical counter-body,\r\nrepresenting one femur condyle under an axial load. A rolling movement occurs as a result\r\nof the friction and pure gliding is induced by limiting the rotation of the cylindrical\r\ncounter-body. The set up also enables simplified specimens handling and removal for\r\ngravimetrical wear measurements. Long-term wear tests and gravimetrical wear\r\nmeasurements were carried out on the well known material pairings: cobalt chromepolyethylene,\r\nceramic-polyethylene and ceramic-ceramic, over three million motion cycles\r\nto allow material comparisons to be made.\r\nResults: The observed differences in wear rates between cobalt-chrome on polyethylene\r\nand ceramic on polyethylene pairings were similar to the differences of published data for\r\nexisting material-pairings. Test results on ceramic-ceramic pairings of different frontalplane\r\ngeometry and surface roughness displayed low wear rates and no fracture failures.\r\nConclusions: The presented set up is able to simulate the rolling-gliding movement of the\r\nknee joint, is easy to use, and requires a minimum of user intervention or monitoring. It is\r\nsuitable for long-term testing, and therefore a useful tool for the investigation of new and\r\npromising materials which are of interest for application in knee joint replacement\r\nimplants.
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