PRP injections (and to a lesser extent Thoracic outlet surgery) seem to be kind of voodoo science. I've heard of a few athletes trying the PRP stuff, but I can't recall it being successful for anyone.
Masahiro Tanaka pitched well for like 6 years after a partial UCL tear and getting PRP. Never needed TJ. For some guys, it puts off needing TJ for a year or two but they eventually need it (Garrett Richards and Aaron Nola fit into that camp). It only seems to work for slight tears/sprains.
