Total replacement of a diseased or traumatized hip joint is fast becoming one of the most common surgical procedures. The acetabular prosthetic shell is gaining widespread acceptance as a socket replacement for this procedure. Bio-materials research is providing a wealth of information regarding the life span, wear characteristics, and performance of these replacements, with a major clinical finding being the destruction of bone (osteolysis) at interfaces with the implants. Osteolysis is widely thought to be associated with the particulate wear debris released from articulation of the ball and socket. Formation and release of these particulates will depend not only on the relative motion occurring but also on the surface roughness of the replacement materials.