Mechanical and histological evaluations of cobalt-chromium alloy and hydroxyapatite plasma-sprayed coatings in bone

Chyun-Yu Yang, B. C. Wang, W. J. Chang, E. Chang, J. D. Wu

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29 Citations (Scopus)


This study evaluated the mechanical and histological behavior of cobalt- chromium (CoCr) alloy and hydroxyapatite (HA) plasma-sprayed coatings in canine cortical bone after 6 and 12 weeks of implantation, using CoCr alloy as the substrate. The substrate was bond-coated with microtextured CoCr alloy coating to ensure adherence between the substrate and top coats. A macrotextured CoCr alloy top coat with surface roughness R(a) = 34.25 ± 5.50 μm was produced to create suitable pores ranging from 25 μm to 200 μm for bone ingrowth. For HA top coat, a relatively smooth surface (R(a) = 15.14 ± 3.21 μm) was prepared for bone apposition. Shear testing of bone/implant interfaces showed that the CoCr alloy top coat exhibited significantly lower (p < 0.01) mean shear strength than the HA top coat at each time interval. The maximum shear strength was 10.88 ± 0.38 MPa for HA-coated implants 12 weeks post-implantation. After histological evaluations, substantial differences in the extent of new bone formation and the types of implant/bone contact were found between two kinds of implants. Direct bone-to-HA coating contact was consistently observed, while a layer of fibrous tissue intervening at the bone CoCr alloy coating interface was found. Occasionally, partial dissolution of HA coating was seen after 12 weeks of implantation. The results of this study suggested that plasma-sprayed macrotextured CoCr coatings may not be an effective alternative for biological fixation.

Original languageEnglish
Pages (from-to)167-174
Number of pages8
JournalJournal of Materials Science: Materials in Medicine
Issue number3
Publication statusPublished - 1996 Jul 1

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Bioengineering
  • Biomaterials
  • Biomedical Engineering


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