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Platelet-Rich Plasma (PRP) Injections: What are they?

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What are PRP Injections

PRP Injections (platelet-rich plasma injections) are a form of prolotherapy (proliferation therapy). Prolotherapy is when a substance is injected into a target tissue to promote tissue growth. In a physiotherapy setting prolotherapy is often recommended to treat tendon and ligament injuries. “Joint injections” are also common but it is usually the ligamentous structures surrounding the joint that are being targeted.

PRP injections differ from inflammatory prolotherapy (the other form of prolotherapy discussed on Physio Roots) in the type of substance which is being injected. During a PRP injection, platelets from a patient’s own blood are injected into a specific tissue. Prior to injection, platelets are concentrated using a centrifuge to a much higher concentration than what is found in our bloodstream.

Why would you want to inject a high concentration of platelets into your injury?

Without making things too complicated (because it can get quite complicated), platelets secrete growth factors and essentially signal to other nearby cells to “come and start the repair process.” This would happen naturally after an injury. For example. if you were to damage any tissue, nearby platelets are “activated” releasing biochemical modulators that begin a cascade of cellular events. PRP injections are thought to “jump start” the same process.

Our tendons and ligaments are common targets for PRP injections. These tissues have a relatively poor blood supply compared to other tissues and heal much slower. Damaged ligaments and tendons are weaker and more susceptible to further injury. When they’re constantly being loaded beyond their capacity they may produce pain. Ligaments in particular are very important for stability at joints and a damaged ligament will allow for extra (sometimes unwanted) movement. It is believed that the PRP injection will help the target tissue to rebuild tissue at a faster rate or in higher quantities. This would effectively increase the strength of the structure being injected and possibly improve its capacity to stabilize and withstand load.

Like inflammatory prolotherapy, PRP injections are usually not the first line treatment. There are other options that can accomplish the same goal. If you are interested in PRP injections then it is best to speak to your healthcare providers or physiotherapist for more information about the indications, risks and benefits.

Please note

This article is not intended to be a literature review.  While some literature may be cited in some cases, this article should not be used as scientific-evidence of a treatment or service.  Please contact your physiotherapist or other appropriate health care provider to better understand the scientific literature supporting or refuting the use of a particular treatment.

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