Oh, this should be loads of fun.

Just when you thought the mind-numbing decade-long discussion about baseball and performance-enhancing drugs was fizzling out, it's now being reported that Bartolo Colon's(notes) big comeback was aided by a controversial medical procedure involving stem cells.

Now Major League Baseball is looking into the surgery to see if any wrongdoing took place.

Wheee!

A New York Times reporting team led by Serge F. Kovaleski has all of the interesting and gory details — and I encourage all of you to go read it — but the gist is this: With Colon's career flagging due to a shredded rotator cuff and torn ligaments, a team of doctors extracted fat and bone marrow stem cells from Colon and injected them into his arm and shoulder to repair the damage done by a 13-season All-Star career.

The procedure was performed on Colon in April 2010 and now, just over a year later, the 37-year-old is thriving on a $900,000 contract with the New York Yankees. He's 2-1 with a 3.86 ERA and has helped bolster the rotation after the team lost Phil Hughes(notes) to injury.

But now all those "fountain of youth" stories have a source that's sure to be questioned and run through the morality machine. Though lead doctor Joseph R. Purita says no human growth hormones were used in Colon's procedure or similar treatments on athletes who played for the Baltimore Ravens, Miami Dolphins, Chicago White Sox and Texas Rangers, he has used them during other instances in the past. That would be the reason that MLB is looking into the process as the use of HGH has been banned by the sport. (Yankees GM Brian Cashman tells the Times that the club had no knowledge of this procedure when they signed Colon to a contract before the season.)

No matter what baseball finds in its investigation, you can be sure this is the starting point of another debate that has no clear answers — and could also possibly buy a little leeway of those already blackballed for steroid use. While stem cell treatments may not currently be banned by baseball, it would seem that their regenerative effects are similar in spirit to those offered by HGH, steroids and other PEDs. When you really get down to it, what's the difference between Colon staving off old age with this surgery and Barry Bonds doing the same with the cream and the clear? Both bring health risks, but only one has been stigmatized by those who follow the sport.

It's also pretty interesting to note that this is really just the first chapter of this issue. As medical treatment gets better and better and athletes can be built into bionic commandos, each sport is going to be faced with questions on which repairs or enhancements are permissible and which are not. You think this issue is difficult, wait until we're talking about watching a 50-year-old slugger head for career homer No. 1,000.