Are they thinking of fusing the bones in your foot so they don't move or fusing the ones in your ankle so your ankle won't flex and your foot will point forward in a fixed direction?
Not being able to move your foot could be problematic for scuba diving.
Are they doing this to speed recovery? Or are you having a lot of pain, and/or is there a lot of joint deterioration occurring?
Finally, who is paying the bill? Is an HMO involved or some one else's insurance company? Are there other treatment options? And have you gotten a second opinion?
Don't get in a hurry and never rush into a treatment of last resort until all the other less invasive and/or debilitaing options have been exhausted.
Always be willing to question your doctor and get details from him or her on various options. If he or she takes offense at you "challenging" his or her judgement, get a new doctor because it's your foot and your life - you want a doctor who is open to questions.
If the only limitations are caused by pain, and the pain is not due to new injury or damage occurring (in other words it hurts, but you are not getting hurt doing what ever causes the pain) then think twice about doing anything radical. In my professional experience clients who are only pain limited can still do anything they are motivated to do and the pain is not really a factor. They adjust to it or just ignore it and go on with life.
Also in my experience, heavy duty orthopedic procedures are not always effective and can leave a person just as bad off as before or worse and with less movement. So a second and even third opinion should be considered mandatory as is getting the facts on the percenages of success with that procedure, what constiutes "success" and the surgeon's own track record of success with that particular procedure. Skills and abilities vary and some docs are just plain better than others.