A platelet-rich plasma (PRP) injection is an therapy that uses a patient's platelets to accelerate the healing of damaged joints, ligaments, tendons, or muscles.Ultrasound imaging is sometimes used to guide the injection. PRP injections use each individual patient's own healing system to improve musculoskeletal problems. A PRP injection is a low-risk procedure and does not usually cause major side effects. 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. The idea is that injecting PRP into damaged tissues will stimulate your body to grow new, healthy cells and promote healing.Plasma is a component of your blood that contains special “factors,” or proteins, that help your blood to clot.