Will PRP injections help my orthopaedic condition?
Platelet-rich plasma (PRP) injections have been all the rage in the public from sports media and now news media. Initially touted by the industry as a regenerative medicine, the way PRP injections work, it isn’t as straight forward as “regenerating [insert goal anatomical body part or tissue]”.
Q: How do they work?
A: It depends your pathology. Lets use an example of knee osteoarthritis. It’s easy to say that joint destruction occurs via “wear and tear.” However, it is much more complicated than that, as is with life. The homeostasis of joint metabolism, catabolic (breakdown) and anabolic (build up) processes are disrupted and more catabolic processes and molecular pathways are activated, resulted in joint degeneration.
Below you can see an example of the mechanisms that lead to a disruption in homeostasis and may result in actual manifestation of symptoms, such as pain, inflammation, swelling, or dysfunction.
Toll like receptors (TLRs) and damage-associated molecular patterns (DAMPs) activate molecular pathways downstream which activates nuclear factor-kappa beta (NF kB) the pro-inflammatory pathway. This activates inflammatory cytokines such as interleukin (IL) 2, IL 10, and others. This pro-inflammatory cascade can result in clinical manifestations.
Q: Ok, so how does PRP specifically work now?
A: It works differently in tendon and muscle versus joint. In the joint, it will attempt to halt the pro-inflammatory pathways and improve the overall homeostasis of the joint via the mechanisms described below.
In the tendon, pathology occurs by interstitial gapping (microtears), abnormal collagen organization and collagen degeneration. As a tendon is hypovascular, the concept is to improve the healing response by again, decreasing pro-inflammatory pathways and improve anabolic pathways.
Most importantly with all of these pathways, the clinical response is less pain.
Image from Sanchez et al, Mechanism of PRP, Regenerative Medicine, 2019, Choudhery
Below, the multiple pathways of how PRP is hypothesized to work.
Everts et al Int J Mol Sci 2020