For about half a decade, it’s been something of an open secret in baseball that players—pitchers especially—regularly undergo stem-cell therapy to stave off surgeries and lost playing time. It’s a cutting-edge medical procedure, done by everyone from high-school standouts to major-league all-stars. It’s rarely discussed by players, or by their coaches, parents, doctors, or employers.
So when the Los Angeles Angels went public in 2016 with the news that first Andrew Heaney and then Garrett Richards were undergoing stem-cell therapy for torn ulnar collateral ligaments (UCLs), it was both anticlimactic and a revelation. For the first time, baseball pitchers and their employers were openly admitting trying this novel procedure that, while fairly well-proven anecdotally, has yet to be validated by any well-designed scientific study.
By now, that so-called Tommy John surgery for a torn or damaged UCL has become a rite of passage for the top-flight professional baseball pitcher is a cliche of sports punditry. Every young arm that can fold and then unfold itself into tortuous patterns that facilitate throwing baseballs at 95 miles per hour or faster is bound for the knife, once those upper body contortions inevitably tear the tissue on the inside of their elbows connecting their upper and lower arms, the UCL.
The first Tommy John surgery (or more properly, UCL reconstruction) was performed in 1974 by the orthopedic surgeon Frank Jobe, then the team physician for the Los Angeles Dodgers, on the eponymous pitcher. It was a great success; Tommy John came back to pitch 14 more years in the pros, racking up 164 wins with four different teams.
TJ surgery is fairly straightforward: the connective tissue that makes up the UCL is either replaced with a tendon taken from elsewhere in the patient’s own body or from the donated tissue of a cadaver.
Nevertheless through the mid-1970s and into the ‘80s, TJ was something of a rarity; just a handful of baseball players underwent that particular knife. In the 1990s the numbers started to tick up, and then in the 2000s, they exploded. From 1995 to 2005, there was an average of 28 TJ surgeries per year across all levels of pro baseball; from 2005 to 2015, there was an average of 84 TJ surgeries per year.
Then something strange happened. In 2016, the total number of TJ surgeries performed dropped to 90, from 127 the year before, a 30% decline. Only one other year in Tommy John history, 2008, saw such a precipitous drop from the previous year. By 2009, TJ numbers were back to 2007 levels; obviously it remains to be seen whether 2017 will look more like 2015 or more like last year. But the data suggest that if TJ surgery numbers are in fact starting to trend downward, it might have something to do with the rise of stem-cell therapy.