Hi Patty
AVN is one of the most common reasons people have resurfacing. If a person waits too long with very advanced AVN, then they could lose the window of opportunity to have a resurfacing. A doctor will be able to tell you if you are a candidate and how advanced your AVN is.
Also many of us had cysts. They are very common with hip problems. The surgeons can normally fill them when they do a resurfacing.
You will be in good hands with Dr. Gross. He and Lee Webb will explain it all to you.
A MOM metal on metal THR uses the same type of acetabular cup as a hip resurfacing, but the cap of the device is attached to a long, larger femor device. If you have a resurfacing and at some point needed a revision, it is possible to keep the acetabulur cup and only replace the femur device. I have a large website about THRs which you might want to look at. It explains all the different devices. Many people have had MOM thrs and are as active as people with hip resurfacings. They just had to have a larger amount of their femur bone cut off.
http://www.hipsforyou.com There are even more mid head type of devices inbetween the resurfacing and THRS being developed. The medical field of hip replacement is changing every day.
Good Luck.
Pat