If you suffer from knee pain, you may be a candidate for a PRP (platelet rich plasma) injection. To perform PRP, a sample of your blood is harvested either in the office or in surgery just as if you were giving blood. The blood sample is then spun in a centrifuge device to isolate the platelet cells which are felt to be the first invaders after an injury. The cells are then injected after a local anesthetic has been given into the damaged area. It is believed that the cells can jump start the healing process to accelerate healing or to initiate healing in chronic degenerative tissue. The injection is usually performed for tendon or muscle damage such as a partial tear or degeneration. It is commonly used for patellar tendon and quadriceps tendon injuries. Furthermore, it can be used for arthritis of the knee to treat symptoms of pain and swelling. The injection often takes 4-8 weeks to work. It may be repeated if you have incomplete resolution of your symptoms. It is considered experimental by insurance companies and is therefore not covered by insurance. Cost usually ranges from $500-$1000.