Hi Gail W
Welcome to Hip Talk.
Glad you are interested in hip resurfacing. I know of several people that have both a THR and a resurfacing. Several decided like you, that after their THR, they wanted their other hip done as a resurfacing since it is bone conserving.
Hopefully, your THR is also a MOM or metal on metal THR which is actually the same size cup and thr cap as a resurfacing. The acetabuar cups and size of the femur devices are the same size. It is just that the resurfacing femur cap does not require the bone be cut off and a long rod be pounded into the femur bone.
I have heard several surgeons including Dr. Mont discuss the fact that a resurfacing gives a person a more natural gait since it is much more like your orignal hip than a THR. I have one gait study here
http://www.surfacehippy.info/gaitstudy.phpIt makes sense to me as a non medical person that very little of the femur bone is removed and it is only capped almost like a crown on a tooth. So the surgeon is not changing the structural design of the hip. It does take a very experinced surgeon to place the acetabular cup in the proper position with the proper angle. That is one of the differences in Resurfacing. It is critical that the components are placed properly. The resurfacing surgery is much more techincal and difficult than a THR. So I always suggest using the most expeirenced surgeons available.
I hope that helps some. I look forward to learning what decision you make and how your new hip is when you decide what to do. Good Luck.
Pat