Platelet-rich plasma (PRP), a therapy used to help heal surgical wounds and tendon injuries, may also relieve symptoms of early knee osteoarthritis (OA), according to a new study out of the Hospital for Special Surgery (HSS) in New York. Researchers there say patients with knee OA reported significantly improved pain and function for 12 months after a single PRP injection. The findings, published online in Clinical Journal of Sports Medicine, also suggest that PRP may slow joint damage if administered early in the course of the disease.

"The results are very exciting," says Brian Halpern, MD, chief of the Primary Care Sports Medicine Service at HSS and lead author of the study. "This suggests that PRP may have the potential not only to relieve symptoms but also to delay progression of OA, although we don't know if that will continue year after year." Dr. Halpern is also a clinical associate professor at Weill Cornell Medical College in New York.

PRP is a preparation of platelets derived from a person's own blood. It's obtained by spinning a small amount of blood in a centrifuge to separate the platelets from red and white blood cells. The concentrated platelets are then injected into problem areas where they are thought to release growth factors and stimulate the healing process.

In the HSS study, researchers injected 22 patients with 6 milliliters of PRP and followed them for one year. All participants had diagnosed knee OA and had arthritis-related pain for an average of 14 months. The patients were clinically evaluated at baseline and periodically throughout the year for knee pain, function, stiffness and the ability to perform tasks of daily living, such as climbing stairs. Study participants also underwent magnetic resonance imaging (MRI) to evaluate joint cartilage at baseline and at one year – something not done in previous PRP studies.

Although questionnaires used in the study – the visual analog scale (VAS) and Western Ontario and McMaster Universities Arthritis Index (WOMAC) – are validated tools routinely used to assess pain and function in people with OA, they are subjective. An MRI, on the other hand provides an objective picture of changes in the joint.

Seventeen patients completed the study and full MRI data was available for 15. For the majority of patients, clinical outcomes were encouraging. On the VAS pain scale, pain was reduced 56.2 percent at 6 months and nearly 60 percent at one year. WOMAC scores showed similar reductions in pain and stiffness. Activities of daily living (ADL) scores also improved significantly: 46.8 percent at 6 months and 55.7 percent at one year.