I have a question about the new blood injection therapy available for sports injuries. I understand they take the patient’s own blood and spin it down to get just the platelets. Then they inject those platelets into the injured area. But don’t platelet just cause blood to clot? How does this help the sprained ankle for example?

Platelet-rich plasma (PRP) (also known as blood injection therapy) is a medical treatment being used for a wide range of musculoskeletal problems. Platelet-rich plasma refers to a sample of serum (blood) plasma that has as much as four times more than the normal amount of platelets. This treatment enhances the body’s natural ability to heal itself and is used to improve healing and shorten recovery time from acute and chronic soft tissue injuries.

It has been used for years after plastic surgery and surgery on the mouth, jaw, and neck. It seems to promote bone graft healing. Researchers have found a way to combine this substance with other chemicals to make it into a putty or gel that can be painted on a surgical site to speed up healing.

Blood injection therapy of this type has been used for knee osteoarthritis, degenerative cartilage, spinal fusion, bone fractures that don’t heal, and poor wound healing. This treatment technique is fairly new in the sports medicine treatment of musculoskeletal problems such as ankle sprains or torn tendons, but gaining popularity quickly.

Platelets do circulate in the bloodstream ready and available for any cuts or wounds where clotting the blood is needed. Once activated in response to an injury, platelets also release active proteins and growth factors that assist with wound healing.

In fact, the tiny biologically active substances released when platelets are broken down help with the formation of new blood vessels to the damaged area and even new tissue. In theory, anyway, injecting additional platelets should dramatically increase (four to 15 times) the number of growth factors at the site of the injury.

We say “in theory” because results of studies in this area are in conflict (don’t agree) or simply show no benefit of using platelet-rich plasma injection over a placebo. In a recent meta-analysis, researchers from the Center for Evidence-Based Orthopaedics at McMaster University in Canada report on the efficacy (benefits) of platelet-rich plasma use for a variety of orthopedic conditions.

A meta-analysis means a large number of studies with small-to-medium numbers of participants are combined or pooled together. This method increases the n (number of patients involved) and allows for more meaningful statistical results. Sometimes smaller studies are high-quality but without the necessary number of patients involved, the results are limited in providing evidence that a treatment (such as PRP) is beneficial.

They found 895 articles on the subject but only 33 studies that qualified to be included. There was a general lack of standardization among the studies reviewed. In terms of pain control and improved function as a result of decreased pain, only six studies showed a benefit of the platelet-rich plasma (PRP) injection. One study even showed the control group had the best results. The remaining studies could not show a benefit of PRP over placebo.

The inability to conclude that PRP is an effective treatment for bone and soft-tissue injuries may have more to do with the lack of standardization in study design and different way outcomes were measured. As a result, the authors summarized by saying the evidence is unclear that platelet-rich plasma is an effective treatment for orthopedic conditions.