[Study on the strength and microcleanliness of the stem of the total hip prostheses]

Using 8 types of total hip prosthetic stems that are presently the most commonly used in clinical applications, we conducted a mechanical and metallurgical study based on measurements of strength and microcleanliness. The Müller, Kyocera Bioceram 4M type and the Thackray Charnley proved to be excellent in terms of strength, whereas the Müller and Kyocera Bioceram 4M type yielded superior results for microcleanliness. The strength and microcleanliness of the casts were of a lower grades, allowing the wroughts to be superior to the former. Vacuum-melted stems gave particularly favorable results. Even those stems which had been made with the same mold or of the same metallic material varied in terms of strength and microcleanliness depending upon the manufacturing processes. There were notable correlations among microcleanliness, O2 content and strength, and improvements in metallic materials and manufacturing processes will enable us to minimize nonmetallic inclusions and O2 contents and thus increase the strength and microcleanliness as well.