Bartolo Colon, NYA (Stem cell therapy)
Despite the potentially life-altering benefits of stem cell research and its potential real-life applications, negative attention and fierce debate have surrounded its ethics, cost, and effectiveness. The majority of the controversy arises from the use of fetal or embryonic stem cells for research and/or transplantation into another human.

This story on Bartolo Colon and the use of stem cells raised as many eyebrows throughout baseball as it did questions about the effectiveness of Colon's procedure and the obligation of a player to accept that his career has come to an end. Because Dr. Joseph Purita—the orthopedic surgeon who treated Colon—admitted to using HGH in procedures on the general public, MLB was forced to launch an investigation into both him and his practices. He claims not to have used HGH on professional baseball players—since it's illegal, and all—and for now we'll just have to take him at his word.

Even though a large part of the focus of Colon's story elsewhere will be on the HGH part of the procedure, the real news should be the use of stem cells in sports medicine. In the world of sports medicine, embryonic and fetal stem cells are not used; instead, mesenchymal stem cells (MSCs), found in the patient's bone marrow, adipose tissue, synovium, and muscle tissues, are used.

Among the many properties of MSCs, sports medicine physicians focus on the ability of these cells to transform themselves into many different tissue types and their effectiveness in doing so. Sometimes they can transform themselves into cell types that aren't quite what the doctor ordered, but in general they tend to transform into what is needed at that particular location. Colon's injury to his rotator cuff represented a perfect scenario to use these MSCs.

Colon had a partial rotator cuff tear and ligament damage in his elbow when he met with Dr. Purita. He agreed to perform these injections, and in April of 2010, Colon began the process of returning to a major-league mound. Colon had been fighting injuries the last several years and was essentially out of baseball prior to the procedure.

One of the key reasons for Colon's near-exit from baseball was his partial rotator cuff tear. The rotator cuff tendons can't regenerate their normal tensile strength, but instead lay down scar tissue—it's better than nothing, but still mechanically weaker than the normal tendon. Tearing often happens close to the bony attachment itself in a zone where there is relatively little blood supply, and also where several different types of tissue transition to bony tissue. Rotator cuff repairs, even if the repair is done perfectly, still leave the zone of different tissues and low blood supply with scar tissue (making it mechanically weaker than the normal shoulder). This is one of the reasons why rotator cuff repairs have a higher failure rate than ACL or Tommy John surgeries.

Dr. Purita essentially inserted the MSCs into the area, allowing them to turn into all of the different types of tissue needed at that weak spot. When MSCs first began to be used for tendon healing in sports medicine, doctors would just inject the MSCs into the area. Now the MSCs are often modified with genes–one of them being MT1-MMP–or supplemented with PRP injections that act as catalysts and greatly enhance tissue regeneration versus scar tissue formation, ultimately leading to higher tensile strengths.

The population size of these treatments in elite pitchers is relatively small, but the results are highly encouraging. MSCs have been used successfully for years with AIDS and cancer patients, so at the very least we know that the treatments are safe. Ultimately, Dr. Purita may have gotten lucky with the players he has performed this on, but so far Colon looks to be a changed man.

After averaging 89.6 mph on his fastball in the previous years for which we have PITCHf/x data, Colon is averaging 92.3 mph with his four-seamer this season. His slider has more movement and a more pronounced spin, and he—well, his pitches, anyway—look closer to the Colon of old than anyone would have thought possible. It's possible that this procedure transformed Colon from the butt of many a spring training joke about the Yankees rotation into an above-average hurler—those 8.9 strikeouts per nine and a command of his pitches that he hasn't had since a season four teams and six years ago are better than any advertisement Dr. Purita could buy.

The only thing more surprising than Colon's resurgence is that fellow Yankee and even more oft-injured pitcher Mark Prior hasn't asked for a referral yet.

Kendrys Morales, LAA (Left ankle surgery)
When the Angels changed the original diagnosis from a fracture to a fracture/dislocation it certainly helped explain why Morales has been having so much difficulty in his rehabilitation. Fracture/dislocations are nasty injuries—a lot of the time, the foot is pointed the wrong way, and there ends up being severe damage to the bone and a lot of the ligaments and connective tissue in the area. A typical fracture of the ankle that requires surgery takes about three to four months to heal up, but Morales is now closing in on a year since his original surgery.

After Morales experienced continued difficulties while running, new imaging revealed the damage in his ankle: bone cysts, degenerative changes in the ankle, and extensive scar tissue. Until the surgeons go into the ankle, they won't know the full extent of the damage. Morales will have to undergo surgery on his left lower leg and ankle to remove scar tissue in hopes of salvaging as much cartilage as possible. If the damage is severe enough, he could have an even longer rehabilitation than the planned six months—and there is a chance that he'll never makes it back.

Dallas Braden, OAK (Left shoulder surgery–capsule)
Chris Young, NYN (Right shoulder surgery–capsule)
News of Chris Young's decision to undergo surgery for his re-tear of the capsule barely qualified as news, but the announcement concerning Braden came as more of a surprise. Braden will have surgery performed by Dr. David Altchek on Monday, a procedure that should end his 2011 season. This is why when an MRI is said to reveal no structural damage, you have to take the news with a grain of salt.

Johan Santana had a similar injury, and his recovery timeline called for a 10-12-month absence—you can expect the same for Braden and Young. The comps for isolated capsule tears aren't too numerous, but Chien-Ming Wang and Kelvim Escobar both underwent surgeries on their capsules within the last several years. You can see how well that went for both of them.

Flesh Wounds: Hong-Chih Kuo was placed on the 15-day disabled list with anxiety disorder, which can be truly debilitating at times… Peter Moylan will have surgery after all for his bulging/herniated disc. After going under the knife of Dr. Robert Watkins, he will be out for 12 weeks, assuming everything goes smoothly… Brian Schneider strained his left hamstring and was placed on the disabled list, just in time for Carlos Ruiz to come off of it today (if all goes according to plan)… Blake Hawksworth suffered another groin strain and was also diagnosed with right hip impingement. He is considered day-to-day and will change his workouts to avoid any painful activities from the impingement… Geovany Soto strained his left groin.