Seriously, if you have a missed syndesmosis injury (which often happens in conjunction with fractured fibula), then there is a possibility to get a fusion (screw) between the tibia and fibula to stabilise the joint. This may help - too difficult to explain here and not sure whether it applies to you, but perhaps is an alternative.
I would avoid a fusion like the plague. It will just stuff up your other joints nearby. Wait until ankle replacement is a little better if the pain is that bad.
I know it sounds outrageous and callous, but you would be much better off with an amputated foot than an ankle fusion. Amputees in the Paralympics can run 100m in between 11 and 12 seconds in the men's races (which is a lot faster than me). If they had a race in the Paralympics for those people with an ankle fusion, the winner would limp in at about the 30 second mark. This is non-sensical to me, that surgeons could suggest an option that is functionally so terrible compared to the alternative of amputation. If your ankle pain is bad enough to warrant an amputation, then have it cut off and start training for the Paralympics (because at least you will be able to run again, and fast!). If you suddenly don't think the pain is that bad, then try glucosamine.