The goalkeeper, who has had knee problems before in his Wednesday career, damaged the cruciate ligaments of his right knee - just after returning to the team following a similar injury to his left knee.
The former Preston star went down twice against Millwall at the weekend and was replaced by skipper Lee Bullen between the sticks.
Paul Sturrock will now go into the transfer market as he looks for an experienced stopper who will be under pressure to keep Wednesday in the championship.
With the transfer deadline now passed, Sturrock can only sign a loan player although Manchester City's Nicky Weaver will not be coming back to Hillsborough.
Chris Adamson will now be on standby and could be plunged straight into first-team action against Crystal Palace on Saturday if a new goalkeeper is not found.
Meanwhile Steve MacLean plays in the reserves tonight against Nottingham Forest in Burton and will hopefully make his first appearance of the season at some point against The Eagles.