This is a 3 year old Pit Bull with severe arthritis in both her hips.
She was exhibiting discomfort in her left hip and the owner elected to have a total hip replacement performed. In this procedure the arthritic joint is removed and replaced with a artificial cup made of metal and high density plastic and a metal femoral head and stem. You can see the screw threads in the cup and stem. This is what initially secures the implants. Eventually bone will grow into the implants to make them permanently secure. After her recovery she was able to return to full, pain free activity.