Dylan Hartley will miss the remainder of the season and England's summer tour of South Africa as he continues to recover from concussion.
The hooker has not played for Saints since the Champions Cup defeat at Saracens on January 20.
He went on Six Nations duty after that game at Allianz Park and suffered concussion in the loss to Ireland on March 17, being replaced after 57 minutes of that match.
And he has been unable to play any part for his club since, with Mike Haywood, Reece Marshall and Charlie Clare continuing to deputise.
Following specialist medical advice, Hartley will take an extended period of rest over the summer with a view to starting Saints’ pre-season training.
He will be sidelined for Saints' final two matches of the current campaign, at Wasps on Sunday and at home to Worcester Warriors on May 5.
Hartley said: “I’m very disappointed that I will not be available for selection for Saints’ remaining Premiership games, as well England’s tour to South Africa.
“It has been recommended by specialists that I take a break this summer and while I find that decision hard to accept, it’s important I listen to that advice.
“I intend to use this time to recover fully from my injury, so I can be ready to hit the ground running when pre-season training starts later this summer."