I'm 51, and just had a THR last July. I've been on the mat (carefully) quite a bit since then. I'm not taking much ukemi, but can still teach, and my personal training is pretty weapons-heavy these days.
If you go for the THR, talk to your docs about your expectations for what you can and cannot do after surgery.
If you want to read about my experiences with the surgery, recovery and subsequent training, look up my blog Arx Hereticus at http://arxhereticus.blogspot.com/
. Go back to July or so to read about the hip replacement and therapy.
If you want to talk hippy stuff, get in touch with me offline at email@example.com