Cementing techniques for hip resurfacing arthroplasty: development of a laboratory model.

BACKGROUND Hip resurfacing is extremely technique-sensitive, yet scientific investigations into cementing techniques are lacking. In this study, we tested open-cell, reticulated, carbon-foam materials in comparison with paired human femoral heads to validate a laboratory cementing model for resurfacing arthroplasty. METHODS Paired human femoral heads prepared for resurfacing were compared with thirty and sixty-pore-per-inch fat-filled foam specimens. Two different cementing techniques were analyzed: manual application of high-viscosity cement, and half component-filling with low-viscosity cement. Real-time measurements were made of cement pressure and temperature. Cement penetration areas and depths were quantified. RESULTS We found no significant differences between the human femoral heads and the fat-filled thirty-pore-per-inch foam models in all measured variables (pressures at the top, chamfer and outer wall, temperature at the 5-mm and 15-mm subsurface). There was no significant difference in the cement penetration of the human femoral heads and the fat-filled thirty-pore-per-inch foam models. There were a number of significant differences between the human femoral heads and the sixty-pore-per-inch foam models with use of the low-viscosity cement technique. The differences between the cementing techniques were greater than those between the three materials for most of the measurements. CONCLUSIONS Fat-filling (to emulate bone marrow) of lower-density carbon foam more closely simulates the cement penetration resistance and thermal properties of human femoral heads than does the denser (unfilled) material. This model is sensitive to differences in cementing technique.