The Leinster back row, who now faces four months on the sidelines, has been hampered by the injury this season but featured in all three Tests defeats to New Zealand this month after playing through the pain barrier.
But Ireland manager Mick Kearney has revealed O'Brien will undergo corrective surgery this week in a bid to solve the hip problem.
"He is going having some keyhole surgery on his hip to repair some cartilage damage," said Kearney.
"Surgery is imminent, it's going to happen within the next week or so and the recovery period for this type of operation is 13 to 15 weeks. It means it could be up to four months.
"Obviously it's going to make him doubtful for the November series. Full recovery is expected but I suppose, like any operation, there is always some risk attached to it.
"But certainly the medics would feel that he would make a full recovery and that he will certainly be back.
"The date I think [his recovery] is towards the end of October and he should be back playing Heineken Cup rounds three and four in December.
"It has been an ongoing problem and it has been managed over a period of time. The exact length of time, I can't be sure of at this stage."
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