"Barry has gone today (Monday) for his operation," Smith told Rangers World.
"It is an unusual operation in the sense that footballers don't normally have this type of injury but the specialist says that it is not too difficult.
"Tendons normally tear or become detached but his is split down the middle.
"When he was moving his ankle the tendon was secured at the ends but it was opening in the middle and that was what was causing the pain.
"So the operation is straight forward enough but to ensure the pliability there needs to be a period of the recuperation which looks like three to four months."