Been doing some research into hip surgeries and found a site that has some good explanations and pictures of various hip surgeries.

From the site:

A metal cup with a polyethylene liner that is inserted into the acetabulum during a total hip replacement.

Link: http://www.hopkinsmedicine.org/gec/series/fixing_hip_fractures

Related posts:

1. Total hip replacement animation
2. Before and after THR X-rays
3. One month after THR