We have posted journals in the past that support the use of platelet rich plasma (PRP) injections to help heal many orthopedic injuries, but we have not discussed how PRP injections work. Platelets circulate in the blood and play an important role in hemostasis (controlling bleeding) and wound healing. When there is injury, platelets flock to the injured tissue. When they adhere to this tissue, it triggers release of many bioactive factors including: growth factors, chemokines and cytokines (signaling proteins that recruit other cells), and pro-inflammatory mediators. Some of the cells that are recruited are white blood cells that help debride the wound and regulate inflammation. Since platelets, and the many bioactive factors they secrete, are so important for wound healing, it is thought that purposefully adding extra platelets to an injured area will help to expedite healing. PRP has also been found to exert anti-inflammatory properties by blocking enzymes involved in the inflammatory pathway. Therefore, PRP can exert both pro-inflammatory and anti-inflammatory effects.
Since the platelets used for PRP injections are derived from the patient’s own blood, it is a very safe injection with low risk of side effects. PRP injections are made by drawing blood and then spinning it down in a centrifuge to separate the platelet rich plasma from the rest of the blood. This concentrated platelet rich plasma is then reinjected into the site of injury. It is important to keep in mind that it may take four to eight weeks to begin to see some benefit from the injection.