ANAHEIM -- On May 2, Steve H. Yoon, a physician at the Kerlan-Jobe Orthopaedic Clinic in Southern California, extracted stem cells from Andrew Heaney's bone marrow and injected them into the damaged ulnar collateral ligament in his elbow. Fourteen days later, Yoon did the same with Garrett Richards.
Now the Angels' two best, most promising starting pitchers are left to wait, and hope.
If the stem-cell therapy works, Heaney and Richards will be lined up to pitch for a full season in 2017 and may even be able to contribute toward the end of this very summer. If it doesn't, they will undergo Tommy John surgery that, at this point, is certain to knock them out until the start of 2018.
It is a franchise-altering set of circumstances, especially for an Angels organization that carries a depleted farm system and a maxed-out budget.
The consensus from within seems to be that this is at least worth a shot.
"There are examples of pitchers that have opted to go the conservative-care route and it has worked for them," Angels general manager Billy Eppler said. "I think the last thing that we want to do as an organization is push a guy towards surgery. One of the unanimous pieces of advice that these guys get from the doctors is to not go to the operating table unless you are at a point of being 100 percent convinced that it is your only option to heal your arm, and that you feel you've exhausted every other option."
PRP vs. stem cells
Six years ago, Yoon began treating partial UCL tears with platelet-rich plasma injections, wherein a patient's blood is spun in a centrifuge to concentrate the platelets, which contain healing elements that are then injected into the affected area.
Yoon found that PRP worked for about 50 percent of patients. But in that time he also experimented with the use of stem cells from concentrated bone marrow and "noticed that the success rates, anecdotally, were much higher with regards to pitchers going back to throwing, and not having to undergo surgery."
Yoon estimates that he has performed stem-cell procedures on 15 to 20 Major League pitchers and that "less than 50 percent" ultimately needed Tommy John surgery, though he is not allowed to reveal the names of his patients. The results can be misleading, in both directions, because success is contingent on the type of tear and the amount of time allotted for healing.
Dr. David Crane, who specializes in regenerative therapy for Blue Tail Medical Group in the Midwest, said he has done about 50 of these stem-cell procedures since 2004, the vast majority of them for pitchers in high school and college. About five were Major Leaguers, and Crane said only one wound up needing Tommy John surgery. He claims to have a 90-percent success rate overall, but he is also picky with the patients he chooses.
Said Crane: "If it's a partial tear, and they still have the healing potential, and the stem cells from bone marrow are good, it's a useful tool."
Major League players have used PRP to treat a variety of ailments over the last 10-plus years. And ever since Bartolo Colon used stem cells from his own bone marrow and fat to treat an injured shoulder and elbow in 2010, the practice of stem-cell therapy has slowly gained acceptance.
Crane felt ostracized from his orthopedic colleagues when he began stem-cell procedures about 12 years ago. But now, he said, "A lot of physicians who were initially argumentative with me are more friendly, because they see it work."
Hard evidence is difficult to come by, however.
The Food and Drug Administration and the International Society for Stem Cell Research say studies have not definitively proven that stem-cell therapy safely and effectively repairs damaged connective tissue. Yoon's encouragement, he admits, is "anecdotal," gained mostly from conversations with colleagues.
"I think that it's a viable alternative for the partial tears," Crane said. "I can't say for certain that we have long-term-outcome data that says it is the way to go, but I can tell you that if I had a partial tear and I was a thrower, I'd try this before having Tommy John surgery."
Dr. Alan Beyer, who works out of the Newport Orthopaedic Institute in Southern California, is a little more cynical about the practice.
He considers it "conjecture" to assert that stem cells can effectively repair damaged UCLs.
"People think it's going to work and help, but there's no validated studies that prove that it does," said Beyer, speaking in generalities because he is not privy to the medicals for Richards and Heaney. "A lot of this is really just taking a flier and hoping that it does the job."
The three doctors interviewed agree that the procedure, used only on pitchers with partial tears, carries minimal risk. But Beyer believes it's "very possible" that a ligament that has had a partial tear heal "is not going to be as robust as a surgically repaired ligament."
"Then you're just kicking the can down the road," Beyer said, "and in six or eight months, we're right back to where we are. That's certainly possible."
Such a scenario would be a nightmare for the Angels. Yoon has seen it happen before, but, he added, "that can happen with somebody who undergoes Tommy John, as well."
The risk, Yoon believes, is no different.
Due to patient confidentiality and HIPAA laws, Yoon did not go into specifics about the circumstances surrounding Richards and Heaney. The team initially diagnosed Richards with a "high-grade tear" of his UCL. With Heaney, doctors' findings ranged from "normal wear and tear consistent with age and usage" to "some degree of tear," according to Eppler.
Both will be re-evaluated within six weeks, which for Heaney means June 13 and for Richards means June 27. Yoon has found that pitchers can normally start throwing off a mound within 12 weeks, putting Heaney on a progression around late July and Richards around the middle of August. Crane said pitchers return to game action after anywhere from three and six months, depending on the thrower.
Richards' recovery could be more difficult because he throws so hard, putting more stress on his elbow. He was initially considered likely to undergo Tommy John surgery, but consulted with a variety of doctors, teammates and friends over a two-week period and ultimately decided to take the non-surgical route.
"This is just something that was an option, and I decided to take it," Richards said. "Why not, right?"
Different styles, similar approaches
Richards throws right-handed, with a fastball that sits in the mid to high-90s, and he has a lot of moving parts in his delivery. Heaney throws left-handed, with a smoother motion and a fastball clocked mostly at 90 mph. Their styles are different, as is the nature of their tears -- but their reasoning is similar.
Both feel more comfortable with a 16- to 18-month recovery from Tommy John surgery, and even if they would've immediately opted for surgery, both believe there was a strong likelihood that they wouldn't have had enough time to pitch in a Major League game before the end of the 2017 season.
In other words, they don't necessarily believe they are wasting much time.
They also didn't experience noticeable pain that prompted abrupt exits from their last outings, making them more open-minded about a non-surgical route.
Heaney completed six innings in his April 5 start, though his velocity dropped as the game went on. The 24-year-old was initially diagnosed with a flexor muscle strain and resumed throwing less than two weeks later, before being shut down again. Richards exited his sixth start of the season -- on May 1 in Arlington -- after 79 pitches because of what the Angels initially deemed dehydration and fatigue. He then played catch in the days that followed, until an MRI exam revealed the tear.
"I wasn't in pain before I got hurt, before I started having these symptoms," said Richards, who turns 28 on Friday. "It's hard for me to just have surgery when I don't feel like something is surgically required."
Heaney had similar thoughts.
"I want to give myself that chance," he said. "If I just rushed into surgery, I'd never know if it would've worked or not. Obviously it's a [bad] situation anyway. But if it ends up taking ..."
That's the hope Heaney and Richards cling to, though their chances of success are difficult to predict at this point. Beyer considers the practice "a long shot" in general. Eppler, on the other hand, is "hopeful."
"You want what's best for these guys," Eppler said. "They have a very long career ahead of them. They're thoughtful, they've considered all of the opinions, and made the decision that they're comfortable with. We fully support them."
Alden Gonzalez has covered the Angels for MLB.com since 2012. Follow him on Twitter @Alden_Gonzalez and Facebook , and listen to his podcast.