"He had been a regular in the squad to the turn of the year but the injury just happened and then the examination revealed the extent of it and what was required," gaffer Mark Robins told the Star.
"It's dreadful luck for the lad and the club because a fit Richie Barker is a real asset."
Meanwhile the pitch conditions at Underhill for this weekend's game at Barnet will be monitored closely over the next 48 hours.
New signing Jamie Clarke is set for his debut if the game goes ahead.
