Pierre is set to miss the majority of the rest of the season after an operation on Monday.
The 24-year-old picked up the injury against Blackburn Rovers in their 1-1 draw on December 23, in which he scored his first goal for the club.
Northampton’s manager Jimmy Floyd Hasslebaink said: “It’s a huge blow because he was playing ever so well. He was grasping what we wanted and we are going to miss his physicality.”
The boss has said his defender has the same injury as Aaron Phillips but expects his team to cope with the loss of Pierre, with other members of the squad expected to fill in.
He said: “You have to be flexible in this business and we have to adjust.”
Rangers manager Steven Gerrard is weighing up a move for Liverpool full-back Jon Flanagan, reports claim.
Scottish champions Celtic are reportedly ready to offer full-back Calvin Miller a new deal before sending him out on loan.
Everton target Jack Wilshere has sparked a scramble for his signature after confirming he is leaving Arsenal this summer.
Tottenham's hopes of landing Wilfried Zaha have been hit by the news Crystal Palace have offered him a bumper new deal to stay.
Ryan Giggs says Gareth Bale would be the perfect fit for Manchester United but has doubts over whether he will leave Real Madrid.
Manchester City's attempts to sign Riyad Mahrez could be in doubt again as reports claim Leicester only want a straight cash deal.