Many news outlets have reported Tiger Woods was treated with Platelet Rich Plasma (PRP) after his anterior crucitate ligament surgery. There have been no reported details but it may be reasonable to use PRP if he developed patellar tendonitis post operatively. It must be mentioned that PRP has never been associated with any specific performance enhancement. The use of PRP to treat tendonitis now has significant basic science and clinical support.
The stories center around a physician who treated Woods. The physician is being investigated for a variety of illegal activites. See the links below for details.
New York Times Article
Associated Press Story