The Northern Ireland international was injured at Doncaster in midweek in only his second game back following over two months on the sidelines.
Scans have confirmed the club's worst fears and boss Eddie Howe said: "Unfortunately Martin has had a recurrence of his thigh injury, which is a huge blow to us.
"He is going to be out for about eight weeks with a slight tear, but the likelihood is he is going to struggle to play again this season.
"We would like to think we could get him back, but there is clearly a problem in there and we need to make sure we address it and get it right for the lad's sake.
"He did all his rehab spot on and we gave him time to get right, but it is just one of those things that you can't give a reason for and it's just unfortunate for him."
Source: PA
