Heat Generation and Dissipation Behavior of Various Orthopaedic Bearing Materials
It has been shown that with high interfacial temperatures in hip bearings, it is possible to precipitate proteins, greatly reduce the compressive creep properties of ultrahigh molecular weight polyethylene (UHMWPE), and change the phase content of monolithic tetragonal zirconia. These induced features may alter the wear rate of UHMWPE. It was the objective of this study to examine the interfacial temperatures of oxidized zirconium (OxZr) heads as compared with metallic and ceramic heads coupled with polyethylene in a hip simulator. The interface temperatures were measured by placing thermocouples within 0.5 mm of the interface surface of both femoral heads and acetabular liners, and then articulating the surfaces using a 12-station AMTI anatomic hip simulator. The alumina femoral heads had the lowest average interfacial temperature, followed in increasing order by OxZr, CoCr, and zirconia. The ranking corresponds to the thermal conductivity of each material. A statistically significant difference (p<0.05) was found between all four materials for the femoral head temperature. No difference was seen in liner temperature between the alumina and OxZr groups, but statistical differences were found between all other combinations. Additionally, increasing head diameter, peak load, cyclic frequency, and serum concentration all resulted in statistically significant increases in both femoral head and liner temperatures.
Takashi Nakamura, Kimihiro Yamashita and Masashi Neo
S. Tsai et al., "Heat Generation and Dissipation Behavior of Various Orthopaedic Bearing Materials ", Key Engineering Materials, Vols. 309-311, pp. 1281-1284, 2006