Northampton Town manager Gary Johnson says he is considering bringing in a defender on loan.
Seth Nana Ofori-Twumasi suffered serious knee ligament damage against AFC Wimbledon.
The Cobblers boss told BBC Radio Northampton: "It's disappointing for him and leaves us a bit short, with Byron Webster also out long-term.
"We might look at a loan. We've just about got enough cover but we don't want to get caught out."
Nana has made six appearances since signing a permanent deal with Northampton in the summer, following a loan deal while at Peterborough in 2010/11.
He will now undergo surgery.
"I feel sorry for him, he's such an enthusiastic lad and he's going to be a top player," said Johnson.
"I would say [he's going to be out for] months. But hopefully he'll recover quickly and he'll be more experienced for the experience."