What Is a Platelet-rich Plasma Injection?

Platelets are small cells in the blood that help form clots to stop bleeding. Platelet-rich plasma (PRP) is a patient’s own concentrated platelets. PRP contains a large number of growth factors, which are thought to stimulate healing.

When PRP is injected, it can aid the body’s natural healing of injuries. The goal is not only to relieve symptoms but also to create actual healing. In some cases, PRP injections may reduce the need for medication and/or surgery.

PRP injections have been used to treat tendon, ligament, cartilage and bone injuries, as well as arthritis. Around the foot and ankle, PRP is used for treatment of tendon and ligament injuries such as plantar fasciitis and Achilles tendinitis.

PRP injections are not recommended for the treatment of infections or cancer.


A small amount of a patient’s blood is drawn and then spun at high speed. The platelets are concentrated to contain 3-5 times the concentration of growth factors compared to normal human blood. Your foot and ankle orthopaedic surgeon will then inject this liquid around or near the area being treated. They may use ultrasound or an X-ray as a guide for placing the injection.

Your surgeon may recommend a single injection or a series of injections based on the injury being treated and your initial response to the therapy.


You may experience mild pain and irritation of the area for several days following the injection. Some doctors may ask patients to limit motion or weightbearing activity immediately following the injection. The use of a brace, boot, or cast may be recommended during the early post-injection course.

Three to seven days after the injection, you may gradually return to normal physical activities. The return to full activity is determined based on your response to the therapy and the recommendation of your surgeon.

Risks and Complications

As PRP is obtained from your own blood, the risk of reaction is low. As with any injection, there is a small risk of injury to any structures in the area as well as a very small risk of infection.


How many PRP injections can I have?
A treatment may require a series of injections, perhaps 3-5. However, multiple injections often are not recommended if there is no improvement in symptoms following the first or second treatment.


Original article by MaCalus Hogan, MD
Last reviewed by David Garras, MD

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