Arsenal manager Arsene Wenger says it would be a gamble if the Gunners did not to bring in a new defender this month but that his side would cope.
The Gunners have frequently been left short of defensive cover this season with the likes of Laurent Koscielny, Kieran Gibbs, Nacho Monreal and Mathieu Debuchy all suffering injuries.
"It is risky [not to sign anyone] - too risky," said Wenger.
"If we have another injury or two we will struggle."
Debuchy is expected to be out for another three months after surgery on his right shoulder, leaving Wenger with only six fit senior defenders at the club.
"We can cope because we have [Calum] Chambers, [Per] Mertesacker, Koscielny," said the Frenchman, whose side face Manchester City on Sunday.
"But we have now lost Debuchy who can play centre-back, Monreal who can play centre-back and Gibbs has been out too.
The Gunners have been linked with a number of central defenders in the January transfer window, including West Ham's Winston Reid and Borussia Dortmund's Mats Hummels, but Wenger says it is difficult to sign quality players.
"Why have we not signed a defender? We haven't found one. We are not the only ones working on the case," he said.
"It is not a supermarket where you go in and buy a defender. It is a market that is very restricted. The players who can strengthen the best 10 teams in Europe, you don't find many and it is the same for everybody.
"We are a big attraction, of course we are. If it was easy we would do it.
"We have made enquiries but then you have the second handicap - who wants to sell their best player, especially a central defender, in the middle of the season? They say, 'come back in June or July'."