PG,
This information from recent 2015 study might help better localize the medical concern and focus, which is on TJ for the population aged 15-19. The study describes a "staggering" increase in the numbers for ages 15-19, and is also interesting in suggesting how misinformed so many are about the issue of overuse and TJ:
http://www.rushortho.com/pdf/E...n-UCLR-AJSM-2015.pdf
To address the issues which both you and Roothog have about TJ not being possible until recently, it appears the authors intend to do further analysis comparing TJ and ACL repairs in the involved age group of 15-19, since both are pretty new in the spectrum of successful surgeries amd sports injuries.
These authors conclude the rise in numbers for ages 15-19 needs to correlate with greater education and a better understanding of risk reduction, which hopefully some of these discussions will provide for those with son's ages 10-19.