Nothing beyond some inflammation was found, according to manager Ned Yost.
"Nothing, he's fine," Yost said. "They just did it as a precaution."
That confirmed the initial diagnosis by head athletic trainer Nick Kenney after Perez felt a "pinch" in his knee while running the bases on Monday night at Minnesota. Perez played Tuesday night at Colorado, then sat out Wednesday night with "discomfort."
So, to be on the safe side, the Royals scheduled an exam for Thursday's off-day.
"It was right dead on with what Nick said: A little irritation for that patella tendon, a little swelling in the back where he kind of hyperextended it but nothing -- all the ACL, MCL, meniscus is all in great shape," Yost said.
"It was exactly what we thought it was. Nick did it as a precaution and so Salvy would have peace of mind."
Perez did sound very happy over the phone.
"I'm going to play [Friday night]," he said. "I'm good."
Of course, that's what Perez always says, but it'll be up to Yost and Kenney to evaluate him before the series opener at Texas.
"We'll see how he feels. It's a pain tolerance thing. He's pretty tolerant, but again I'll talk to Nick and see what his recommendation is," Yost said. "If he doesn't play [Friday], he'll be playing the next day for sure."
The current problem is with the right knee, not the left knee which Perez injured in Spring Training 2012, prompting surgery to repair a torn meniscus that kept him out about half the season.
"Salvy feels a lot better now, knowing what he went through with that meniscus deal two years ago," Yost said. "It scared him a little bit, so this gives him a little peace of mind."