Pineda had the UCL injury in his right elbow examined by the Cincinnati Reds medical director, Dr. Timothy Kremchek, who agreed with the original recommendation of Tommy John surgery from the Yankees head team physician, Dr. Christopher Ahmad.
The 28-year-old Pineda is scheduled to undergo the surgery on Tuesday in Cincinnati, to be performed by Dr. Kremchek.
Pineda's last start was on July 5 when he gave up nine hits, including three homers, and five runs in just three innings against the Toronto Blue Jays.
Pineda is 8-4 with a 4.39 ERA and 92 strikeouts over 96 1/3 innings in 17 starts this season. He was 6-2 with a 3.32 ERA in the first two months of the season.
"It's pretty devastating," Yankees manager Joe Girardi told reporters Friday when the team first made the announcement. "It was devastating for him. He understands what it's like to work back from a serious injury, and now he's got to do it again."
Pineda missed all of 2012 while rehabbing from a right shoulder tear.