I know a lady in her very late 70s who recently had hip replacement surgery, and she just returned to her tap dance class. The tap dance group she is in competes (average age of the group is about 80).
Also, just a tip about working with your physical therapist: TELL your PT what your goal is - show him/her some dance photos and TELL the PT THAT is what you need to get back to. Some people taking physical therapy want to do only enough to get in and out of their recliner chair and click through channels on the TV. TELL your PT that you want to do more than that - the PT may be delighted that you've got some plans to do things!