Platelet-rich plasma (PRP) is a platelet concentrate that may help to speed up tissue healing, without serious side effects, in some medical conditions. It has been tried as treatment for diabetic foot ulcers, muscle injury, tendon injury, and in a variety of cosmetic procedures. The only condition for which there are high-quality data and clear demonstration of effectiveness is arthritis of the knee. It is also apparent from the majority of published studies that PRP therapy has minimal risk of scar tissue formation or significant bad side effects.