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The effectiveness of multiple PRP injection treatment for knee osteoarthritis: 2021 2-year study

Updated: Feb 27

Multiple platelet-rich plasma (PRP) injections are superior to single PRP injections or saline in osteoarthritis of the knee: the 2-year results of a randomised, double-blind, placebo-controlled clinical trial 2021.

The effectiveness of multiple PRP injection treatment for knee osteoarthritis: 2021 2-year study

Journal of Orthoscopy and Sports Medicine

What is osteoarthritis?

Osteoarthritis of most joints, particularly of the knee is a major cause of chronic pain and musculoskeletal disability worldwide, alongside having huge impacts on society. Although there are many treatments options for osteoarthritis, there is no definitive treatment that can prevent or stop the progression of this joint disease.

Osteoarthritis causes loss of joint cartilage resulting in a narrowing of the joint space. The treatment of cartilage disease is very difficult as cartilage tissue is isolated from a good vascular supply. Newly developed treatment methods have focused on stimulating the cartilage healing process, improving the damage that has already occurred and slow in the progression of further degenerative changes. A popular treatment method is platelet-rich plasma (PRP), a liquid rich in autologous growth factors and healing cells used to facilitate repair and reduce inflammation. PRP is obtained by centrifuging the patient's own blood, and the platelet rate in the obtained liquid is 4–5 times higher than in the blood. Growth factors which are released from platelets play an important role in the angiogenesis (new blood vessel formation) and proliferation of chondrogenic (cartilage) cells, tissue remodeling and healing.

The main focuses on the treatment of osteoarthritis are to reduce joint pain and stiffness, increase functional capacity, reduce joint damage and increase quality of life. PRP treatment has been used by many clinicians practising within musculoskeletal medicine worldwide for the last three decades.

In this new 2021 double blinded study, the primary purposes were to prove the efficacy of PRP injection treatments on knee pain and functions by comparing patients with mild to moderate OA with a placebo control group. But also to further understand and appreciate the effectiveness and safety of multiple doses compared to a single dose.

The main report from this study, again, showed that PRP improved the pain and improved joint function. The effectiveness of PRP treatment according to the initial reports was seen to continue for 6 months with a single dose and for beyond 12 months with three doses, thus being consistent with other reports. Therefore, it can be recommended that PRP injections are repeated at 3-6 month intervals, depending on compliance with rehabilitation and degree of severity. Furthermore, in this study, it was observed that patient satisfaction was higher and lasted longer in PRP and multiple-dose groups. In a recent study, it has been shown by magnetic resonance imaging (MRI) that PRP treatment has a significant positive effect on the cartilage volume of the knee joint.


The results of this study showed that PRP has a positive effect on pain and improving functional capacity in the treatment of osteoarthritis, with an increased benefit of multiple treatments over one single dose.

Further information and full details on this study can be found here.


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