Difficult question Greedfly.........
The indications for ankle replacement (ankle arthroplasty) and ankle fusion ( ankle arthrodesis) are quite different and you have not given any particulars of your disease process or symptoms (although i would guess that pain would be at the top of the list.
Bur here are a few comments:
For the relief of pain........both operations are equal.
For mobility.........it depends upon arthritis in the joint below (subtalar joint)
How long will it last...........an arthrodesis will last longer than a replacement.
Sorry this has been a little "bitty" but i am not an Orthopod.
The only alternative to operation is analgesics (pain killers)



