The Scotland midfielder had an operation that will keep him out for up to three months of the new campaign after suffering discomfort in pre-season.
The 30-year-old - who underwent surgery to repair ligaments in his right ankle in 2006 - admitted he feared the worst when going down to London for the operation.
"I was upset and down about what happened, but I will be back stronger and better than before," Ferguson told the Scottish Sun.
"I came through worse when I shattered my kneecap at Blackburn and was scared I might never play again. This injury is not at that level.
"We all hoped that rest would cure it, but then in pre-season training I was in pain again. I just couldn't turn and I knew it was time to bow out.
"I had felt rotten in pre-season. Then we found that one of the ligaments had split and the other was hanging off the bone.
"Now I know that it is fixed, that I can come back pain-free."