I know "osteo" means bone and "necrosis" means death...

My mom's supposed to go to Greece on this magical history tour at the end of September, but the "arthritis" in her hip's been really bad lately, so she went to the doctor.  He wanted an X-ray, and apparently she has decreased blood flow to her left hip, which causes "Osteonecrosis". 

Basically, bones, like muscles and skin and everything, require blood to grow and produce cells and stuff.  When the blood flow to a bone is reduced, the bone tissue stops growing, and it starts to die.

What causes this?  Apparently, alcoholism (not likely in my mom's case), overuse of steroids like prednisone (very likely since she grew up in the 60's with really bad allergies to everything), and injury (she's not a football player, so also not likely).  My bet is on the steroids.

What fixes it?  Well, the bone continues to deteriorate over time, and can spread to other bones (pelvis, femur), so they want to do a hip replacement.  I'm all for doing hip replacements on older...old...elderly...geriatric (that's the word I was looking for) patients, but my mom's really young (okay, a spritely 54).  If the doctor says she needs one, I'll support him/her, but I will definitely be researching other options in the mean time.  A hip replacement at a younger age apparently shortens your life expectancy, and that's not cool because my mom has to live forever.