Reduced wear of cross-linked UHMWPE using magnesia-stabilized zirconia femoral heads in a hip simulator

Clin Orthop Relat Res. 2011 Aug;469(8):2337-45. doi: 10.1007/s11999-011-1800-7. Epub 2011 Feb 11.


Background: To reduce wear, the ideal bearing surface in joint arthroplasty should be smooth and hydrophilic. Ceramics generally offer better wettability than metals and can be polished to a smoother finish. However, clinical studies have found no reduction in liner wear when using yttria-stabilized zirconia (Y-TZP) instead of cobalt chromium alloy (CoCr) femoral heads.

Question/purposes: We (1) determined whether a hard, diamond-like carbon (DLC) coating would enhance the wettability of CoCr and magnesia-stabilized zirconia (Mg-PSZ) femoral heads without increasing roughness, and (2) compared their wear performance.

Methods: In an observational study limited to CoCr and Mg-PSZ heads, we measured roughness and contact angle on as-received and DLC-coated heads. Eight heads then were subjected to 11 million cycles of wear in a hip simulator against cross-linked ultrahigh molecular weight polyethylene (XLPE) liners.

Results: Mg-PSZ femoral heads were smoother and more hydrophilic than CoCr heads. Although DLC coatings did not reduce roughness, they reduced the contact angle of CoCr and Mg-PSZ substrates, which may provide enhanced lubrication in vivo. In hip simulator tests, liners bearing against CoCr heads wore at a greater rate compared with Mg-PSZ heads. The DLC coating on Mg-PSZ heads did not reduce wear further.

Conclusions: The wear rate of XLPE versus Mg-PSZ was seven times less than CoCr heads, probably owing to lower roughness and greater wettability of Mg-PSZ heads.

Clinical relevance: The use of Mg-PSZ femoral heads should lead to reduced wear in vivo compared with CoCr heads, but the clinical benefit of DLC-coated Mg-PSZ is unclear.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbon
  • Chromium Alloys
  • Cross-Linking Reagents
  • Hardness
  • Hardness Tests
  • Hip Prosthesis*
  • Humans
  • Materials Testing
  • Polyethylenes*
  • Prosthesis Design
  • Prosthesis Failure
  • Stress, Mechanical
  • Wettability
  • Zirconium / chemistry


  • Chromium Alloys
  • Cross-Linking Reagents
  • Polyethylenes
  • ultra-high molecular weight polyethylene
  • Carbon
  • Zirconium
  • zirconium oxide