Labadie was the club captain when he was forced off during a win against Port Vale in April with an anterior cruciate ligament injury.
It came only weeks after Conor Wilkinson suffered a similar issue.
Riley signed in the summer, but is yet to feature for the Saddlers – he underwent an exploratory operation last month from which he is recovering.
Labadie and Riley are back in light training, but boss Michael Flynn said it was unlikely they would feature before the new year.
He said: “They are getting there very slowly but I can’t see them coming back this side of Christmas if I’m honest.”
Wilkinson is also a long term absentee but Flynn said he is ‘getting closer’ and they would know more in a week’s time.