3-Tribology of the Artificial Hip

• Wear of the bearing surface is a major factor in the service life of total hip and surface replacements. • The hip bearing constitutes a tribological system; thus, wear is a system property impacted by multiple variables, such as bearing dimensions, anatomic placement, bearing materials, loading conditions, joint motion, and lubricant. • Various bearing couples with different wear properties are available. A cobalt-chromium-molybdenum (Co-Cr-Mo) and ceramic femoral head articulating against a highly cross-linked ultra-high-molecular weight polyethylene (XLPE) acetabular component are the most common bearing surfaces used today. • Wear testing of hip bearings is necessary to assess materials and geometries preclinically following American Society for Testing and Materials (ASTM) and International Organization for Standardization (ISO) standards. • Although wear has significantly decreased with the use of XLPE liners, it is important to try to reduce wear and its effect on host tissues because total hip arthroplasty (THA) is often performed on young patients.