Nova, 31, was diagnosed with the sprain after reporting discomfort following Thursday's 5-4 loss to the Reds. He said the injury first occurred while fielding a ground ball late in his start against the Tigers at PNC Park on April 25.
He hasn't thrown since Thursday, but could resume flat-ground work in the coming days. Pirates director of sports medicine Todd Tomczyk said he believes 10 days will be enough time for Nova's injury to heal.
"It's a minor irritation to his ring finger, the ligament," Tomczyk said. "To put him in the best position, short term and long term, as a group we felt it was best for him to take the 10 days."
Both Nova and Tomczyk have made it clear that Nova is not using the finger injury as an excuse for his struggles in May. He's allowed 25 runs, 20 earned, over five starts this month for a May ERA of 7.61.
"Ivan wasn't really Ivan," Tomczyk said. "There is a medical condition in that ring finger that has been causing impairment. So he was spraying more than he's used to. His velocity was the same. But there's something there that he needs to take a little time off and build himself back up."
Kingham, Pittsburgh's No. 12 prospect as ranked by MLB Pipeline, was pulled after pitching one inning in his Triple-A start on Friday so he would be available to start in Nova's place if needed.
"Nick is ready to pitch," Pirates manager Clint Hurdle said. "He was explained the situation, the possibility of why he came out after the one inning and what very well could happen here. He was one of the options."
The 26-year-old arrived in Pittsburgh on Sunday night and is eager for the opportunity to contribute to the club.
"I'm glad I can come here and help the guys," Kingham said. "Anything can happen. You can't look too forward in the future, just take it as it goes, take it one step at a time, one day at a time."
Kingham has made three starts in the Majors this season. He took a perfect game into the seventh inning in his big league debut on April 29 against the Cardinals, beat the Brewers on May 4 and surrendered three runs over six innings in a losing effort to the Padres on May 19.
In six starts for Indianapolis, he's registered 30 strikeouts while surrendering eight runs, seven earned, over 29 2/3 innings.
"I'm here to do what I can with the opportunities that I can," Kingham said. "We'll see what happens."