Chronic ankle pain and instability (ankle gives way underneath you when standing or walking) are the most common reasons for corrective surgery when an old injury leads to arthritis. Swelling, loss of motion, and loss of function can really disturb a person’ quality of life until surgery seems like a great idea.
Arthrodesis is a medical term that means fusion. Fusion stops motion and thereby reduces stress on the painful joint. In the case of the ankle, in order to fuse the joint and stop motion, several bones must be fused together. The effect is to off-load the ankle joint but force is then transferred to the midfoot and hindfoot. Those areas can take quite a beating over time and develop degenerative problems of their own.
Starting out with an ankle fusion is often advised before taking the bones out and replacing them with an implant (ankle joint replacement). The fused site can always be converted to a replacement later. Joint replacements are not usually done if there are serious alignment issues in the hindfoot. If the foot doesn’t line up properly, the implant will just wear unevenly and possibly fail.
Before doing a joint replacement, ankle alignment may have to be corrected. This may require soft-tissue releases, ligament reconstruction, and/or bone cuts called osteotomy. For an osteotomy, the surgeon uses a wedge of bone to correct the alignment problem (deformity) first before putting the implant in place.
You may need to make another appointment with your surgeon to discuss these choices a bit more. It’s likely that the recommendation came as enough of a surprise that you may not have heard all of the explanation the surgeon gave about your situation. Having a second conversation about the indications, benefits, pros, and cons of each approach for you specifically would be a good idea.