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McIlroy, 28, suffered a recurrence of a rib injury at the Players Championship.
However, he said on Tuesday there would be "no limitations" on his swing when he opens up at Erin Hills on Thursday.
"I'm totally fine to play. It's just a matter of limiting my practice," said the world number two, who confirmed he will play in the Scottish Open in July.
The rib stress fracture, which McIlroy suffered in the close season, flared up as he lost a play-off to Graeme Storm at the South Africa Open in January.
McIlroy was ruled out for a number of tournaments in January and February but after returning to action, he felt the injury again at the Players Championship.
The Northern Irishman was forced to pull out of the PGA Championship at Wentworth and also missed the Memorial Tournament in America, which meant he has had no warm-up events in advance of the season's second major.
However, the 2011 US Open champion was upbeat on Tuesday as he spoke of his preparations for the event in Wisconsin.
"I don't feel like I need a run of events to get back into it," added McIlroy, who will play in the Scottish Open at Dundonald in order to fine tune his links preparation for the following week's Open Championship.
"Preparation-wise, instead of hitting five bags of balls I'll hit two. If you hit 100 drivers a day and you swing at 120mph, it's going to take its toll a little bit. So it's just a matter of managing that."
The long-hitting McIlroy added that he wasn't upset to see the rain falling heavily on Tuesday on the already lengthy 7,693-yard course.
"I wasn't crying when I saw that rain this morning. That's a long golf course that's only going to play longer," continued the four-time major winner, who is using a new putter this week.
Rory McIlroy has insisted he is "totally fine" to play in this week's US Open as he returns to action after a month out because of injury.