Jordan Houghton will undergo surgery on the injury he sustained at Barnet last weekend.
The midfielder was forced off early at The Hive following a late and reckless tackle and now looks set to spend the next eight weeks on the sidelines.
“I'm gutted for him and it’s bad news for us,” Martin said in his pre-match press conference ahead of Saturday’s Sky Bet League One clash with Accrington Stanley.
“Jordan is a really big part of what we're doing and he’s been a really important player for us since he took over.
“He's upset but it won't be the end of his season - it looks like it will be eight weeks plus. It's only a small operation that he’ll need.
“He'll get it fixed early next week and then it's about getting him fit and ready. Mentally, these things can be tough but Jordan is a resilient character and it will help him come back quicker.”
Houghton joins fellow midfielder Louis Thompson on the Dons’ list of long-term absentees although the latter is expected to be back in action quicker than first thought.
“His recovery is going well,” Martin said. “He's back with Norwich and is spending time with his family because he's just had a baby - congratulations to him and Verity!
“We'll look forward to having him back. He saw a specialist and got some positive news so it won't be as long as we feared, which is great.”
MK Dons will be looking to secure a fourth straight away win on Saturday when they travel to the Wham Stadium to take on Accrington Stanley.
Supporters can watch the game LIVE on iFollow MK Dons, courtesy of a Video Match Pass.
With an iFollow MK Dons Video Match pass, you will be able to watch Russell Martin's side in action on your laptop, computer, tablet or mobile device! Want to watch on your tablet or mobile device? Download the new EFL iFollow App and watch on the go, wherever you are!
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