Review Question - QID 7146

In a total hip prosthesis, using a larger diameter ball (for example, 36 mm instead of 28 mm) can improve stability. All other factors being equal, the volumetric rate of wear of the bearing surfaces would be expected to be greater with a larger diameter, due to the longer sliding distance per step. However, in laboratory tests of metal-metal bearings, larger diameter metal-metal hips, such as surface replacements, have shown wear rates comparable to conventional, smaller diameter metal-metal hips. What is the most likely explanation for this?