Effect of head surface roughness and sterilization method on wear of uhmwpe acetabular cups: Preliminary hip joint simulator results

Anneli Jedenmalm, Walther Leardini, Mara Zavalloni, Saverio Affatato

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

More than one million hip joint replacements are performed each year in the world. However, the implants do not last forever due to material limitations, even though the operation is successful. The most common material combination used today is a CoCr head articulating against an UHMWPE (Ultra High Molecular Weight Polyethylene) acetabular cup. Several investigations have shown that the metal head is roughened inside the body and thus accelerating wear of the polymer cup. The sterilization method is also known to have effect on the wear properties. In vitro wear tests are however usually performed with as new implants. This investigation aimed at study the impact of head surface roughness on wear of both sterilized and non-sterilized acetabular cups. A total of nine acetabular cup and head pairs were wear tested in a hip joint simulator for 2Million cycles (Me) with bovine calf serum as lubricant. Wear was determined by weighing of all cups. The heads were of CoCrMo and the average initial head surface roughness was 15nm (R a), measured with a white light interference profilometer. The roughening was produced with a SiC paper producing circular multidirectional wear tracks to a surface roughness of about 400nm (R a). The cups were of UHMWPE and the sterilized cups were 3Mrad gamma-radiated in nitrogen. The surface roughness after wear test was unchanged for the roughened heads, while the initially smooth heads were slightly roughened. Preliminary results show that the rough heads increase the wear of the cups 2-fold. The γ-irradiation affected both wear- and soak rate.

Original languageEnglish
Title of host publicationProceedings of 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006
Volume2006
Publication statusPublished - 2006
Event8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006 - Torino, Italy
Duration: Jul 4 2006Jul 7 2006

Other

Other8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006
CountryItaly
CityTorino
Period7/4/067/7/06

Keywords

  • Hip prostheses
  • Hip simulator
  • Roughened femoral heads
  • Surface roughness
  • UHMWPE
  • Wear

ASJC Scopus subject areas

  • Engineering(all)

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  • Cite this

    Jedenmalm, A., Leardini, W., Zavalloni, M., & Affatato, S. (2006). Effect of head surface roughness and sterilization method on wear of uhmwpe acetabular cups: Preliminary hip joint simulator results. In Proceedings of 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006 (Vol. 2006)