This may be a little like comparing apples to oranges. Both are round. Both are fruit. Beyond that the similarities end. Ankle fusion puts your ankle in one position and keeps it there. Joint motion is very limited. An ankle replacement allows continued joint
Sometimes the fusion fails and the ankle forms a "false" joint. The result is ankle motion where no motion is wanted. Walking and going up and down stairs is not normal or smooth with an ankle fusion. The loss of motion and the stability provided reduce or get
rid of pain.
Studies show total ankle replacement (TAR) reduces painful symptoms but doesn't always increase motion. The patient with limited motion before the TAR will likely have reduced
motion after the ankle is replaced. Most patients report improved function anyway.
With less pain after TAR, even a small increase in motion makes it possible to manage walking, stairs, and most daily activities.