I'm not entirely sure what we're talking about here.
Are we talking about wearing out the BHR prosthetic bearing?
Or, are we talking about the longevity of the hip surface replacement as a whole?
It's an important distinction, because each has a different answer. It would be impossible for a human to "wear out" a BHR prosthetic bearing. We would have to live for hundreds of years for that to happen. The laws of metallurgy and physics dictate this.
Answering the other question is near impossible, because so many factors dictate the life of a hip surface replacement. Surgical technique, recovery, activity level, bone density, weight, health, diet, flexibility, metal allergies, accidents, cell turnover, vascularity, bone resorption, bone cement longevity... and probably a lot of things no one has figured out just yet.
I just had my six month with Dr. Pritchett yesterday. He says the best any doctor can tell anyone at this point, is what he told me: "This hip should last you a long time." Vague, but realistic.
I have an uncle who had a heart transplant at Stanford in 1990. Doctors gave him another 10 years at the most. He's still alive today and still one of the most cantankerous bastards I know.
If my hip gives me as long as his heart... I'll be happy.