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Knee News

One PRP Injection May Be All That is Needed for Painful Knee Arthritis

Platelet-rich plasma (PRP), also known as blood injection therapy, continues to be investigated by researchers. They are looking for a way to control painful symptoms from knee osteoarthritis. Efforts to regenerate lost joint cartilage using this type of treatment may also help slow down the disease process.

Scientists still aren't quite sure how these therapeutic proteins aid in cartilage repair. The basic idea is to remove platelets from the patient's own blood and inject it into the joint. The blood plasma is prepared in such a way as to include three to four times more than the normal amount of platelets.

Platelets have growth factors that may speed up the body's natural healing process. This treatment may shorten recovery time from acute soft tissue injuries. In the case of chronic joint degeneration, it may stimulate a healing process in the joint cartilage (called chondrogenesis).

But as you will see from this study, the benefits reported by patients (decreased pain and stiffness and increased motion and function) came after only slightly more than two weeks. And that might be too quick to really be caused by true joint regeneration. The authors suggest perhaps the platelet-rich plasma improves overall joint environment making it possible for the joint to "feel better" even when cartilage tissue isn't changed directly.

We may not know for a while just how PRP therapy works. But studies like this one will help determine the best way to administer the treatment for optimal results. There were a total of 78 patients (156 knees) who received either one PRP injection, two PRP injections (spaced three weeks apart), or a placebo (injection containing just a saline solution).

Results were compared among the three groups using patient report of pain levels, stiffness, physical fitness, and complications. They used the Western Ontario and McMaster Universities Arthritis Index (WOMAC) questionnaire. This survey was given to the patients both before and after treatment to assess changes in these measures. They also asked about patient satisfaction with treatment.

They found that patients started noticing a difference in their symptoms anywhere between 13 and 19 days after the first injection. There was a significant improvement in patients who actually received the platelet-rich plasma compared with the placebo injection. But the benefits reported weren't any better or greater with two injections compared with one.

There were some adverse effects of treatment (e.g., dizziness, headache, nausea, increased heart rate) in the injection groups only. Patients who received the most number of platelets were more likely to experience these complications. So for example, 22 per cent of the single-injection group reported problems but 44 per cent of the group who received two injections experienced side effects. In other words, twice as many people in the two-injection group had complications compared with the single injection group. These effects were considered mild and only lasted a short time.

Everyone was followed for up to six months to see the long-term effects of platelet-rich plasma (PRP) injection therapy. Two-thirds of the two groups who received PRP injections were satisfied with the results. That compared with almost 90 per cent of the placebo group who were NOT happy with the results. Patients with milder osteoarthritis seemed to get the most benefit from the PRP treatment.

It was apparent from analysis of the data collected between the six weeks period to six months that the positive results started to decline over time. The trend was for a gradual worsening of symptoms as time went by. But the pain, stiffness, and function were still much better than before the injection therapy.

The authors concluded that platelet-rich plasma (PRP) injections may not be the "wonder drug" some say they are but they do provide significant symptom relief. A single injection may be all that is needed every six months to aid in managing the pain and stiffness.

This type of "staged" treatment approach may provide enough improvement in patient function to make it worth the expense. Until more is understood about how PRP works, it may be enough to use the treatment as a temporary management tool against the early effects of osteoarthritis.


Sandeep Patel, MS, et al. Treatment With Platelet-Rich Plasma is More Effective Than Placebo for Knee Osteoarthritis. In The American Journal of Sports Medicine. February 2013. Vol. 41. No. 2. Pp. 356-364.

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*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.
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