The ASMI says that curveballs do not cause arm injuries:
http://www.nytimes.com/2009/07...aseball/26score.html
“I don’t think throwing curveballs at any age is the factor that is going to lead to an injury,” said Glenn Fleisig, the chairman of research at the American Sports Medicine Institute in Birmingham, Ala."
The issue appears to be that curveballs lead to pitchers being more successful at young ages and then they get overused: http://usatoday30.usatoday.com...pitching-study_n.htm
"Part of the confusion is that the pitchers that throw curveballs tend to be the ones that throw a lot," ASMI research director Glenn Fleisig said Wednesday. "So it's hard to separate those factors. But when you do separate them statistically, the pitchers who pitch too much are the ones who got hurt, whether they throw a curveball or not."
It's far more likely that Dr Andrews does more operations today because the operations work better today. 40 years ago the number of operations would have been 0. Over the years, the success rate has gotten higher (90%?) so the risk/reward calculaton makes sense. It used to be if you were a 14 year old kid, and you injured your UCL, you just found another sport (parents aren't going to pay for an expensive operation that has a very low chance of success). Dr Jobe put Tommy John's chances of pitching again at 100-1: http://www.jhutriplehelix.com/...edicine-bryan-kohrs/ Now, you can get an operation that can more than likely fix the issue. That's likely the main reason why Andrews would be doing more operations. I would imagine that the number of open heart surgeries in the 1920s was pretty low, but it's a lot more common today (risk/reward due to increased success rate). It's a logicial fallacy to assume that just because there are more operations today the problem is getting worse.