Plasma is the liquid portion of whole blood. It is composed largely of water and proteins, and it provides a medium for red blood cells, white blood cells and platelets to circulate through the body. Platelets, also called thrombocytes, are blood cells that cause blood clots, as well as other necessary growth and healing functions.

Platelet-rich plasma (PRP) is produced from a person’s own blood. It is a concentration of one type of blood cell (platelets), which is critical for blood clotting. This concentration is injected to an injured or diseased part of a person’s body to accelerate the healing of damaged tendons, ligaments, muscles, bones and joints. A key advantage of PRP injections is that they can reduce the need for opioids, or even over-the-counter anti-inflammatory medications. In fact, use of anti-inflammatories should usually be ceased at the time of PRP treatment, because the platelet-rich plasma optimizes the initial inflammatory response involved with healing.

PRP injections are prepared by taking anywhere from one to a few tubes of your own blood. It is then run (“spun down”) in a centrifuge to separates the blood into its various components: red and white blood cells, plasma, platelets, etc. The platelets are collected and concentrated to anywhere from 2 to 8 times their normal number. The platelets are then mixed into a blood plasma liquid base and injected directly into the area of injury. Ultrasound imaging is sometimes used to guide the injection. The images below show a PRP injection into a patient’s torn tendon. The ultrasound guidance is shown at left and the injection is shown at right.

PRPs injections are used primarily for soft tissue injuries, such as minor rotator cuff and Achilles tendon tears. Its use in other soft-tissue injuries is becoming more common. It has been demonstrated to improve function and reduce pain in people who have tendonitis or chronic tendinosis conditions such as tennis elbow or golfer’s elbow.

It can also be used to treat injuries to ligaments and muscles. For example, improved muscle regeneration has been shown in gastrocnemius (calf) muscle injuries. In a small study involving knee osteoarthritis, PRP treatment was shown to be more effective than hyaluronic acidtreatment.

The side effects of PRP injections are very limited because, since the injections are created from your own blood, your body will not reject or react negatively to them.

Competitive athletes should be aware that platelet-rich plasma does contain endogenous growth factors, and so some sports regulatory agencies consider it to be a performance-enhancing substance. For instance, the World Anti-Doping Agency and the United States Anti-Doping Agency forbid the injection of PRP within muscles because of the possibility that the growth factors could enhance a person’s performance. However, there are currently no data to suggest that PRP is actually a performance-enhancing substance.