As I understand it, it is never for the orthopaedic surgeon to tell YOU when you need a total hip, but for you to tell him or her as to its timing, even if the cartilage is worn down and the bone is without blood supply the hip should only be replaced when you can't function/ stand it any more, as hip replacements are not guaranteed to last one's entire life and may loosen and need to be replaced again. Total hip replacements wear out faster in younger people because they tend to be more active and stress them more.
Now if he/she is talking about hip resurfacing, that is a different story, but as I understand it that would not be done in cases where the bone has lost its blood supply. So I suppose the operation that has been recommended is total hip replacement.
The correct surgeon, the correct timing of the operation and the correct type of operation and prosthesis are truly important it would seem-- so a second opinion from someone who not only does these but teaches others to do so would seem prudent.
My two cents worth.
PS I looked up the faculty at University of Indiana Orthopaedic Surgery department and found this:
http://www.orthopaedics.iu.edu/faculty.htm