Manager Ned Yost reported the surgery required about 2 hours, 45 minutes and was performed by Dr. Neal ElAttrache, head physician for the Dodgers.
"They had to repair three of the four muscles. Two of them were torn completely off the bone, the other one was torn to the point where they had to repair it," Yost said. "He got through it OK, the doctor felt good about it and it's month-to-month now, not day-to-day."
The range of time that Kendall might miss was expanded from eight to 12 months. Even so, Yost is optimistic that Kendall could be active during Spring Training and possibly resume playing in April.
But, he emphasized, the Royals won't rush him.
"It was an extensive repair," Yost said. "He's a tough guy, but this is something you can't rush."
Kendall, not prone to be patient, will have to be reminded daily to take his time.
"If he does it right, he can come back and reach his goal of playing another five or six years," Yost said. "He's got to be extremely patient and extremely smart about this situation. Hopefully, we won't have to employ a strait-jacket with him."