That's according to a tweet from Avery. PRP involves placing a small amount of a patient's blood into a centrifuge. The blood is spun at a high speed until red blood cells separate from the platelets. The concentrated platelets, with protein and other substances said to aid healing, are injected into the injured ligaments or tendons to promote tissue growth and repairs.
Both Callahan and Avery sustained knee injuries, and PRP has become increasingly popular in treating with pro athletes.
Didn't the Stones' Keith Richards simply replace his blood?