Abstract
The science of tribology concerning hip arthroplasty has mainly dealt with total endoprostheses, whereas measurement values of hemiendoprosthetic implants are rare. The small amount of experimental tribologic data concerning hemiendoprosthetic implants in the form of pendulum trials, animal experiments, in-vivo measurements on human hip joints and pin on disc studies will be reviewed in the following work. The reported frictional coefficients in these studies were between 0,014-0,07. In order to test the friction coefficients of different femur head hemiendoprostheses (ceramic-cobalt chrome – and titanium heads and bipolar endoprostheses) against fresh cadaveric acetabula, the HEPFlEx-hip simulator (Hemi-EndoProsthesis Flexion Extension) was developed. In the simulator, the various hemiendoprosthetic heads are placed on a special cone and tested against a human cadaver acetabulum cast in MCP 47 woodmetal. The plane of movement of the apparatus is uniaxial with a rotating movement of +/− 35 degrees. The force is produced pneumatically dynamic with amounts of up to 5 kN. Newborn calf serum served as a lubricant. Preliminary results showed that the mean friction coefficient at 3 kN loading was μ=0.032–0.07 for ceramic against cartilage and μ=0.024–0.153 for metal against cartilage.
The abstracts were prepared by Nico Verdonschot. Correspondence should be addressed to him at Orthopaedic Research Laboratory, University Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
