How do PRP Injections Work?
Welcome back to part 2 of our injection series. Today we will be looking at Platelet Rich Plasma (PRP) injections, which are arguably the most popular type of injections that people turn to when they do not want to receive a cortisone or similar injection. Today we’ll be looking at what it is, how it works, and a brief overview of the research on how effective it is.
What are PRP injections?
To understand PRP, we need to understand the composition of blood. Blood is composed of three primary components: red and white blood cells (RBCs/WBCs), platelets, and plasma. Red and white blood cells account for a little under half of the total volume of blood and are responsible for transporting oxygen throughout the body (performed by RBCs) and protecting the body from infection (performed by WBCs). Plasma is the liquid portion of blood and is responsible for creating the fluidity necessary for all the solid components of blood (RBCs, WBCs, and platelets) to circulate throughout the body. Platelets are cells that are most well known for allowing blood to clot but are also involved in growth and healing processes throughout the body.
PRP is plasma that contains a platelet concentration that is approximately 4-5 times higher than what is found in normal blood. This is done by using a centrifuge to isolate the platelets from blood and then returning the platelets to a certain portion of the plasma to create the desired concentration. In addition, the platelets are subjected to a process called degranulation, which causes the platelets to release growth factors over a period of several days. Once this process is complete, the PRP can then be injected into specific areas of the body.
PRP Mechanisms of Action
The specially-treated platelets in PRP deliver a broad spectrum of growth factors to the injected area. These growth factors facilitate 1) the creation of cells that are the precursors to cartilage (chondrogenesis), 2) the creation of new blood vessels (angiogenesis) 3) decreased inflammation, and 4) the ability of cells to change into other, more needed cells (cell differentiation). When looking specifically at the effects of PRP on the cartilage in joints, PRP decreases the rate of death of the cells that produce cartilage and increases the concentration of the molecules (proteoglycans) that are responsible for the majority of a joint’s ability to absorb force.
Research on PRP Injections
The most common use for PRP injections for musculoskeletal problems is for treating knee osteoarthritis (OA), and the results are promising. One study found that patients with knee OA that received a PRP injection had improvements in knee pain, function, and quality of life compared to a control group. This group also experienced a lower degree of cartilage degeneration in the knee compared to the control group at the 2-year mark.
In a similar study that also looked at the knee, participants that were still having knee pain 4 months after surgery to repair their meniscus received 6 PRP injections over the course of 6 months. This group experienced greater improvements in pain and function compared to a control group, as well as a decreased rate of cartilage degeneration over several of the joint surfaces within the knee.
One last study I will mention examined the effect of PRP injections for individuals with chronic Achilles tendinopathy. This study found there was a decrease in tendon thickness (a good sign for this condition) and decreased pain 12 weeks after the injection when compared to a control group.
Summary
PRP injections cause an increase in growth factors in the area of injection, resulting in improved blood flow, an increased number of cells responsible for making cartilage, and decreased inflammation. While the research examining the effectiveness of PRP injections is relatively small, PRP appears to be effective for treating tendon injuries and arthritis, among others that I did not cover in this post.
I hope this provides a helpful overview for you on the how PRP injections work. If you are considering trying injections before some type of surgery and want to learn more, or if you are thinking about giving physical therapy a shot (no pun intended), click the link below to schedule a free consultation!
Western Slope Rehab and Performance is Here to Help
If you are struggling with injuries or have recently been in a motor vehicle accident, we can help. We are a physical therapy company that provides home-based orthopedic services in the Grand Junction, CO, area, as well as telehealth appointments throughout Colorado. If you would like to schedule a free consultation, you can call us as 970-462-9177, or fill out our contact form here.
If you found this post valuable, please like and share on our Facebook page, which is updated regularly with new content.