GLENDALE, Ariz. -- Details are sketchy on Zack Greinke's right elbow injury, but manager Don Mattingly said it's not serious and the pitcher could resume playing catch on Friday.
Greinke rejoined the Dodgers Tuesday, a day after receiving an injection in the back of his elbow in an effort to reduce inflammation. What caused the inflammation hasn't been explained and might not be known, but it puts Greinke's availability for the Opening Day roster in jeopardy.
The Dodgers announced Monday that Greinke received an injection of platelet-rich plasma and anti-inflammatory medication from Dr. Neal ElAttrache in Los Angeles. He was prescribed two or three days of rest before resuming a progressive throwing program.
Upon entering the Dodgers' clubhouse, Greinke was greeted by a flurry of reporters' questions about his injury, but he responded with few details.
Greinke said he didn't know if he would be ready for his first regular-season start on April 2 and cautioned that anything written "is premature." He was asked how his elbow felt after the injection and said he didn't know how he was supposed to feel.
Mattingly repeated that he thinks Greinke will be ready to start the season because the injury isn't serious and Greinke isn't that far behind.
However, Greinke has made only two starts this spring for a total of five innings, while Opening Day starter Clayton Kershaw made his fourth start on Sunday and has pitched 13 innings. Greinke missed Monday's start because of the injured elbow and the previous start because of the flu. He hasn't pitched in a game since March 1.
"We won't put him out there unless he's ready," said Mattingly. "We won't force a square peg in a round hole just because I said he'd be ready. If he's not ready, he's not pitching. Same as Carl [Crawford]. He wants to be ready for Opening Day, and so do I. If he's not ready, he won't play."
Pitching coach Rick Honeycutt said he wouldn't speculate whether Greinke would be ready to pitch on April 2.
"To me, it's still too early to make that determination," said Honeycutt. "I'd rather get to where he's able to throw. You want me to speculate. Why go there until we know?"
Greinke said the diagnosis of "inflammation" was something he and the team knew for a while, having had an MRI exam last week that ruled out structural damage to ligaments or tendons.
"I think we did [know the diagnosis]," he said. "But we just have to figure out what to do with what it is."
Asked if he was concerned about flying to Los Angeles for an exam, he said: "Not really. I didn't know exactly what the problem is. I guess I still don't. Maybe they do. I'm not a doctor."
Greinke said he wasn't sure if the discomfort he felt the past two weeks is the same discomfort he's felt in previous seasons "or a little different."
Honeycutt said Greinke was "at the point where he felt he could throw, but it didn't feel quite right. Our approach is to get it right first."
Greinke said he had never heard of platelet-rich plasma injections until new teammate Chad Billingsley chose that treatment over Tommy John reconstruction for the partially torn ligament he sustained last year. Greinke said he talked to Billingsley about the procedure.
"It sounds like it makes a lot of sense, the thought process," he said. "I don't know what it's supposed to do. I didn't know I was getting it until yesterday. Bills said earlier this spring what his injury was and what happens and why he decided to do that instead of surgery. I thought it was interesting."
The PRP therapy involves drawing the patient's blood and, with a centrifuge, separating the platelets, then re-injecting the concentrated platelets into the involved area to speed healing.
Billingsley said he chose PRP because of timing more than anything else. Had he chosen Tommy John surgery immediately, he would have missed the 2013 season anyway. If PRP worked (as it has so far), he would be available to pitch this year. If not, he would have had Tommy John surgery and still missed this season.
"I had nothing to lose by trying it," he said. "It gave me a chance to be here today."
Billingsley said he "absolutely" credits the PRP for healing the ligament, "along with our great medical staff." Matt Guerrier also has avoided flexor tendon surgery after received three PRP injections last year.
Greinke was signed to a $147 million contract in December (the richest in history for a right-hander at the time) after exceeding 200 innings in four of the last five seasons. He missed reaching the 200-innings mark in 2011 because of a broken rib sustained during the spring in a pickup basketball game that left him on the disabled list throughout April.
Ken Gurnick is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.