Biomechanical Performance of the Cemented Hip Stem with Different Surface Finish

The integrity of the cemented fixation interface is responsible for the long-term longevity of artificial hip prostheses. Metallic stems with roughened surfaces are considered to provide stronger adhesion with cement. However, clinical studies have reported that roughened stems show a lower survival rate than polished stems. These studies clearly reveal that the causes of artificial stem loosening are very complicated and multifaceted. Therefore, this study was conducted to investigate the mechanical effect of stem surface finish in cemented hip replacement. To accomplish this, a series of cement–metal specimens were tested configurations to assess the mechanical characteristics of the cement–metal interface specimens. A finite elemental model of cemented femoral prostheses was then created, in which the cement–stem interface was assumed to be in different bonding states according to the experimentally measured interface properties. The failure probabilities of the cement mantle and cemented interface under physiological loadings were evaluated. Experimental results indicate that the polished metal produced higher interfacial tensile and lower shearing strengths than the roughened metal. The polished stems were predicted to induce a lower failure probability of cement mantle and higher integrity of the cement–stem interface when compared to the roughened stem. Overall, current results provide significant evidence to support the clinical outcomes of cemented hip prostheses with different stem surface finishes.