Frontline Angels starters Garrett Richards and Andrew Heaney have combined to make only seven starts this season. Both have been presumed to be out for the season due to a torn ulnar collateral ligament in their respective throwing elbows. That injury is typically what leads to Tommy John surgery and a 12-14 month recovery period thereafter.

In the cases of Richards and Heaney, however, each could be back this season if a procedure works as intended.

Despite a torn UCL, Garrett Richards could be back this season. USATSI

Via, here's the most pertinent portion on stem-cell shots from Dr. Steve Yoon at the Kerlan-Jobe Clinic in L.A.:

So, on May 16, Yoon extracted bone marrow from Richards, concentrated it and injected the mixture back into the UCL in his elbow, aiming to repair the injured ligament.

Yoon, among others, said he believes this same-day procedure carries promise for healing ligament damage. Bone marrow, along with fat tissue, contains mesenchymal stem cells that can regenerate into a range of tissue types that keep a ligament intact.

This type of regenerative therapy, referred to as stem-cell treatment, is seeing wider use in professional sports leagues in the U.S., including major league baseball, emerging as an alternative to surgery for pitchers such as the Angels' 28-year-old right-hander.

Heaney got the shot a few weeks before Richards, too.

This is going to be a very interesting case to follow, because it's obviously a lot quicker timetable than returning from Tommy John surgery -- the story notes that recovery could be around 12 weeks from the stem-cell shot. Twelve weeks instead of 12 months? That's a revolution. Again, if it works as intended. Dr. Yoon himself isn't 100 percent sure it'll work.

"The gist of it is we don't fully understand how all of it works on a cellular level and how it works when you inject this material into an injured area," Yoon said. "But anecdotally, meaning through experience over the years, we've seen good things happen with these type of ejections, with this type of material."

Throwing arms are a lot different than other body parts -- arms aren't meant to heave objects over and over at 90-plus miles per hour, after all -- so there's always a chance this won't fully do the job.

Still, keep an eye on Heaney and Richards. This could be the start of something that sweeps over baseball over the course of the next decade. Let's say they come back firing darts and don't re-injure their arms, we'll surely see more pitchers elect this route instead of Tommy John surgery.