Onions suffered the injury on England's tour of Bangladesh
England and Durham seam bowler Graham Onions has been ruled out of all cricket for up to three months because of a back problem and knee surgery.
A scan by a specialist earlier this week revealed a bone stress reaction in his back and he was told rehabilitation will take up to 12 weeks.
"I am naturally incredibly disappointed to miss the bulk of the domestic season," said the 27-year-old.
"I hope with rest I can be back on the field nearer the end of the summer."
Onions made his England Test debut last summer with a remarkable five-wicket haul against the West Indies.
He reinforced his reputation with impressive displays in the Ashes and on England's tour of South Africa before Christmas, and so far he has taken 28 wickets in eight Tests, averaging 31.03.
But he was forced home from the tour of Bangladesh earlier this year after injuring his back in a nets session, and the problem has not cleared up as hoped.
He also underwent surgery on cartilage in his left knee on Wednesday, a procedure which requires the same amount of recovery time as his back problem.
"The England and Wales Cricket Board medical team has been very supportive and all I can do is be patient, work hard on my rehabilitation programme and focus on my number one goal which is to be fully fit and available for selection for the Ashes tour to Australia," he said.
His injury-enforced absence is set to keep him out of the Test series against Bangladesh and part of the series against Pakistan, as well as the one-day internationals against Australia and Scotland
Onions' Durham coach Geoff Cook, who is hoping to lead the team to a third consecutive county championship title, called the injury a "minor tragedy" for the player and England.
"This time last year he was picking up wickets every time ball he got the ball in his hand," he said.
"He deservedly earned a call-up to the England team on the back of that and then he played a key role in the Ashes win last summer.
"It's a minor tragedy for him. It is for England cricket generally."