The flanker will need specialist assessment before a definite timescale for a return to training can be determined. He will, however, be out for the foreseeable future.
Tony McGahan and the Munster management are without 11 players for the trip to Milton Keynes, including Denis Leamy, who undergoes hip surgery today, and long-term absentees David Wallace, Doug Howlett and Jerry Flannery.
Mike Sherry (ankle) is due to play for either Munster 'A' in their British & Irish Cup quarter-final this weekend or his club Garryowen in the Ulster Bank Bateman Cup.
Troy Smith (foot), Felix Jones (foot) and Tommy O'Donnell (knee) have all been pencilled in for February returns, while Wallace and Tom Gleeson (shoulder) are both on course to resume training in March.
With his side chasing a home draw in the quarter-finals, head coach McGahan said: "I don't know the exact stats but I think there is an exceptionally high percentage of home sides going through. Nevertheless, Munster have won a couple of quarter-finals away from home and progressed through there as well.
"We recognise the benefits of a home game though, not only to our supporters but commercially and to the province and to the city as well.
"We understand those, we've had two quarter-finals in the last three years. We know the benefit and the buzz it gives and the familiarity of preparing in your own home town, getting all those things.
"That is certainly on the table for us this weekend. This season, our primary goal was to get to the quarter-finals; we will see how we go from there."
MUNSTER Squad (v Northampton Saints) - Backs (12): Conor Murray, Tomas O'Leary, Duncan Williams, Ronan O'Gara, Ian Keatley, Danny Barnes, Simon Zebo, Will Chambers, Lifeimi Mafi, Keith Earls, Johne Murphy, Denis Hurley.
Forwards (16): Marcus Horan, Wian du Preez, John Ryan, Stephen Archer, BJ Botha, Damien Varley, Denis Fogarty, Donnacha Ryan, Paul O'Connell, Donncha O'Callaghan, Ian Nagle, Mick O'Driscoll, Peter O'Mahony, James Coughlan, Billy Holland, David O'Callaghan.