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Treatment With Platelet-Rich Plasma Shows Potential for Knee OA

Researchers report improvements in pain, function, and disease progression (Feb. 12)

A study by researchers at the Hospital for Special Surgery in New York, N.Y., has identified platelet-rich plasma (PRP) as a potential therapy for patients with osteoarthritis (OA) of the knee. The treatment improved pain and function and appeared to delay disease progression (in up to 73% of patients). The new findings were published online in the Clinical Journal of Sports Medicine.

Several treatments for OA exist, including exercise, weight control, bracing, nonsteroidal anti-inflammatory drugs (NSAIDs), cortisone shots, and viscosupplementation (a procedure that involves injecting a gel-like substance into the knee to supplement the natural lubricant in the joint). A new treatment that is being studied by a small number of doctors is PRP injections. PRP, which is produced from a patient’s own blood, delivers a high concentration of growth factors to arthritic cartilage that can potentially enhance healing.

“You take a person’s blood, you spin it down, you concentrate the platelets, and you inject a person’s knee with their own platelets in a concentrated form,” lead author Brian Halpern, MD, explained. “This then activates growth factors and stem cells to help repair the tissue, if possible; calm osteoarthritic symptoms; and decrease inflammation.”

In the new study, researchers enrolled 15 patients with early knee OA; gave each of them a 6-mL injection of PRP; and then monitored them for 1 year. The patients underwent clinical assessments at baseline, at 1 week, and at 1, 3, 6, and 12 months. At these time points, the researchers used validated tools to assess overall knee pain, stiffness, and function, as well as the patient's ability to perform various activities of daily living. At baseline and at 1 year after the PRP injection, the investigators also evaluated the knee cartilage with magnetic resonance imaging (MRI) — something that has not been done in other PRP studies. The radiologists reading the MRIs did not know whether the examination was performed before or after the PRP treatment.

While previous studies have shown that patients with OA can lose roughly 5% of knee cartilage per year, the researchers found that most of the patients in their study had no further cartilage loss. “The knee can be divided into three compartments: the medial compartment, the lateral compartment and the patellofemoral compartment,” Halpern said. “If we look at these compartments individually, which we did, in at least 73% of these cases, there was no progression of arthritis per compartment at 1 year. That is very significant, because longitudinal studies suggest a 4% to 6% progression of arthritis at 1 year.”

Treatment with PRP was also useful in improving pain, stiffness, and function. The investigators found that pain — measured by a standard test called the Western Ontario and McMaster Universities Arthritis Index — significantly improved, with reductions of 42% at 6 months and 56% at 1 year. On a visual analog scale, pain was reduced by 56% at 6 months and by 59% at 1 year. Functional scores improved by 24% at 1 year. Activity of Daily Living scores also showed a significant increase at both 6 months (47%) and 1 year (56%).

“We are entering into an era of biologic treatment, which is incredibly ideal, where you can use your own cells to try to help repair your other cells, rather than using a substance that is artificial,” Halpern said. “The downside is next to zero, and the upside is huge.”

Source: Hospital for Special Surgery; February 12, 2013.

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