Source: Carl Crawford out 3 months

The Boston Red Sox announced Thursday night that Carl Crawford has a sprained ulnar collateral ligament in his left (throwing) elbow, the injury that often results in Tommy John elbow reconstruction surgery.

But rather than opt for surgery, the team said the outfielder will follow a protocol of more conservative treatment.

"It is what it is what it is," Red Sox manager Bobby Valentine said Thursday night after Boston's 10-3 over the White Sox in Chicago. "We'll just let Mother Nature take the time to heal him up and get him back. I don't know how to explain it or put it into my thought. I wish he was 100 percent. Not playing for awhile is going to kill him more than it's killing me."

A major league source told ESPN's Pedro Gomez that Crawford is expected to miss three months, a timetable that Crawford challenged in a text message to John Tomase of the Boston Herald.

"I don't know where they got three months from," Crawford texted, adding he doesn't expect to be out that long.

"I'm good," he texted. "It's just one of those things you can't control. I'm still looking forward to coming back strong."

The Red Sox said in their statement that Dr. James Andrews, who examined Crawford Thursday, confirmed the diagnosis made by the team's medical staff.

"Carl Crawford was examined by the Red Sox medical staff," the statement read. "He was diagnosed as having a left elbow ulnar collateral ligament sprain. A conservative treatment protocol was recommended. Carl was also examined by Dr. James Andrews who was in agreement with the assessment and plan. Carl received a Platelet Rich Plasma (PRP) injection and will be shut down from baseball activity during the initial phase of his treatment."

PRP therapy for tissue injuries is a fairly recent development for professional athletes, and its effectiveness is still debated. Golfer Tiger Woods and pro football players Hines Ward and Troy Polamalu are among the athletes who have undergone the treatment.

"Some physicians are finding better success with PRP injections on partial UCL tears, depending on the location of the tear within the ligament,'' said ESPN.com sports medicine expert Stephania Bell.

As a member of the Los Angeles Dodgers in 2008, pitcher Takashi Saito, who had a torn UCL in his throwing elbow, underwent PRP treatment instead of undergoing Tommy John surgery. After missing two months (53 games), he returned to pitch at the end of the season and in the playoffs.

The process, as described by Scientific American: "For the treatment, doctors take a small vial of a patient's blood, about 30 milliliters, and spin it in a centrifuge to separate the platelet-rich plasma from the other components. Then they inject the concentrated platelets at the site of the patient's injury. In theory, the growth factors that platelets secrete (not including human growth hormone) spur tissue recovery."

The ulnar collateral ligament is located on the inside of the elbow, where it attaches the humerus bone to the head of the ulna bone, and stabilizes the elbow. A sprained UCL is a common injury for pitchers, a consequence of overuse.

Three Red Sox pitchers -- Junichi Tazawa, Daisuke Matsuzaka and John Lackey -- have undergone Tommy John surgery in the past two years. Tazawa has resumed pitching, Matsuzaka on Saturday is making his second rehab start, and Lackey is expected to miss the season.

In an eerie coincidence, Crawford's former teammate with the Tampa Bay Rays, Rocco Baldelli, sprained his UCL under very similar circumstances to Crawford. Like Crawford, Baldelli was rehabilitating from another injury -- in Baldelli's case, torn knee ligaments -- when he tore his UCL while throwing in the outfield.

Crawford, of course, has been in Florida rehabbing from a left wrist surgery when he hurt his elbow, an injury he said he first became aware of while the team was still in spring training. Crawford returned to Boston for an MRI on April 10, and after a follow-up exam in Boston on Tuesday, sought out Andrews for a second opinion.

Baldelli ultimately underwent Tommy John surgery and missed the 2005 season.

The Red Sox statement did not indicate the severity of the sprain, which is measured by a grading system. As outlined by livestrong.com, a Grade 1 sprain typically refers to an overstretched ligament, a Grade 2 sprain is a partial tear with mild instability of the joint, and a Grade 3 is a severe or complete tear with significant instability of the joint.

Another notable position player, Albert Pujols, had a sprained UCL in April 2003, and not only did not have surgery, but played some outfield, with instructions from manager Tony La Russa to flip the ball lightly either to the shortstop or center fielder.

"If it doesn't work, if something goes wrong, I'll quit," La Russa said at the time. "You won't have to fire me."

Pujols played the entire season, batting .359 with 43 home runs. He later had surgery on the elbow in both 2008 and 2009.

Crawford had been limited to serving as DH in extended spring training games, hitting a home run earlier this week. But the Sox statement indicated that will cease as well.

Crawford, who signed a seven-year, $142 million contract with the Red Sox after the 2010 season, struggled mightily in his first season in Boston, batting a career-low .255, with a .289 on-base percentage that was the lowest of any Red Sox left fielder ever (minimum 300 plate appearances).

He underwent surgery on his wrist early in January, then came to camp expressing hopes of being ready for the season opener, though the Red Sox thought May 1 was more realistic. But Crawford suffered a setback after engaging in bunting drills, and both the player and team refrained from making any further projections.

On Thursday, Red Sox third baseman Kevin Youkilis said, "It stinks. We hope he gets healthy as quick as possible because he's a great player. We hope he can be here to help us out."

With Jacoby Ellsbury incurring a partially dislocated shoulder in the home opener on April 13, the Red Sox had hoped that Crawford's return would come in the near future.

Now it's possible that Ellsbury, who is expected to miss at least six weeks, could return before Crawford.