Normally, the top experienced hip resurfacing surgeons will tell you the percentage chance that you will get a hip resurfacing. They are able to read the x-rays and should know going in what they are going to do. Dr. De Smet would tell you that he will give you a hip resurfacing, but he did have a problem or 2 after doing 3000, so even he now tells you there is a very, very small chance of a THR.
Things can happen during surgery, but for the top experienced surgeons, they seldom do. They know what they are going to do. It should not be a decision made in surgery. The less experienced surgeons will not be as sure about the results since they are "not very experienced." You want to use the surgeons that have done a thousand or better yet, several thousands.
Use the top experienced surgeons and you have a pretty good idea of exactly what is going to be done. If your career depends on a hip resurfacing - don't take chances. Only use one of the surgeons that have done thousands.
Also you should know
what THR would be used if this surgeon is not sure what he is going to do. I would not be happy approaching surgery without a decision about what is going to be done, but that is me after reading thousands of hip resurfacing stories. You don't want surprises. Unless you get a large ball THR, you will have restrictions.
Get several opinons before accepting only one surgeons guess that he is not sure what he is going to do.
Dr. Gross of SC, Dr. Brooks of OH, Dr. Rogerson of WI, Dr. Bose of India or Dr. De Smet of Belgium are a few that will give you a free email consultation. Dr. Gross will actually call you after a few weeks. Get several opinions and find out what the top doctors think so you can make an educated decision about what surgeon you want to use and what you will receive as far as hip resurfacing or THR.
http://www.surfacehippy.info/listofdoctors.phpPat