To understand the physiological principles behind the science of platelet rich plasma, one needs to have a basic understanding of the components of blood and their purpose. Blood is made up of four components including plasma, red blood cells (RBC), white blood cells (WBC), and platelets.
The plasma is known as the transporter and is the liquid component of the blood made up mostly of water. The role of red blood cells is to carry oxygen picked up from the lungs and to distribute the oxygen throughout the body delivering the oxygen to the body cells. Red blood cells are also responsible for removing carbon dioxide from the cells.
White blood cells are responsible for fighting off infections, killing germs, and removing dead blood cells. Last, and most important for PRP, are the platelets. Platelets play a significant role in the healing of tissue including:
• Increase tissue regeneration (tendon, ligament, soft tissue)
• Decrease inflammation
• Decrease pain
• Increase collagen (foundational component of all soft tissue)
• Increase bone density
• Increase angiogenesis (development of new blood cells)
A normal blood sample would be made up of 93% RBC, 6% platelets, and 1% WBC. Through the use of a centrifuge, the blood components are separated and the ratios are changed in PRP to 94% platelets and 5% RBC (Sampson, S., Gerhardt, M., & Mandelbaum, B., 2008).
Theoretically, reintroducing a high concentration of platelets directly into an injured area should enhance the healing process. This is the theory behind PRP.
One of the greatest benefits to this treatment is that the injured athlete uses his/her own blood for the procedures. This eliminates all kinds of potential problems including disease transmission and tissue rejection.
Blood is drawn from the patient (about 30-60ml) and then centrifuged for approximately 15 minutes. The blood is then separated into platelet poor plasma (PPP), RBC, and PRP. The platelet-poor plasma is then extracted and discarded. After one more shaking procedure, the platelet rich plasma is withdrawn.
The procedure is done on an outpatient basis. To be able to find the exact location of the injury site, a dynamic musculoskeletal ultrasound is used. The ultrasound provides a picture of the deep tissues within the body.
Once the exact location is determined, the patient is prepared with a local anesthetic (lidocaine) if desired. One source recommended that the PRP be spread using a “peppering” technique injecting the PRP in a clock-like manner to better cover the injured area (Sampson, S., Gerhardt, M., & Mandelbaum, B., 2008). The patient is then observed for 15-20 minutes and then discharged.
Because there may be discomfort experienced by the patient at the site of the injection for up to one week, patients are encouraged to ice the injection site, elevate the limb, modify activity, and take acetaminophen for pain control (Sampson, S., Gerhardt, M., & Mandelbaum, B., 2008).
Although the procedure is considered safe, there are possible side-effects that the patient should be aware of including:
• Allergic reaction
• Scar tissue formation
• Neurovascular injury
• Calcification at the injection site
As with any procedure, there are contraindications that the patient should also be aware of. Contraindications are specific conditions of the patient in which the treatment should not be used because it may exacerbate an existing condition. Contraindications for PRP include the following preexisting conditions:
• Presence of a tumor
• Metastatic disease
• Active Infections
• Pregnancy and/or active breastfeeding
What is PRP currently used to treat in sports medicine?
Although the research samples are small, the current research supports the use of PRP for the treatment of chronic non-healing tendon injuries in the elbow, patella, and achilles for treating tendinitis, tendinosis, or tendinopathy (overuse injuries to tendons causing microtears in the collagen fibers of the tendon).
It is well known in the sports medicine field that treating tendinitis is difficult because tendons tend to heal very slowly and athletes tend to want to push and play through pain and discomfort. Unfortunately, tendinitis heals best with rest. Very few athletes want to rest.
Traditional treatment for tendinitis usually includes rest, anti-inflammatory medication, hot and cold therapies, and strength exercises. Some physicians will also treat tendinopathies with corticosteroid injections, but these have the possible side effects of atrophy and permanent structural changes in the tendon that may weaken the tendon and eventually lead to a rupture.
More Information: Read about sports injury treatment using the P.R.I.C.E. principle - Protection, Rest, Icing, Compression, Elevation.
In a recent study published in the American Journal of Sports Medicine (2006), twenty patients were evaluated with chronic epicondylar elbow pain (epicondylitis is an overuse injury also known as “tennis elbow”
or “golfer’s elbow” depending on which side of the elbow the pain is on). Fifteen patients were treated with PRP and five were designated as part of a control group and treated with a local anesthetic.
The treatment group had a 60% improvement of pain at eight weeks, 81% at six months, and 93% at the final follow-up at 12-38 months. Of note, there was a 94% return to sporting activities and a 99% return to activities of daily living. There were no side effects or complications reported.
Although the results of this study support the use of PRP, the subject sample was extremely small. This means that the results may or may not be duplicated in a larger study.
Also supporting the treatment of PRP for epicondylitis was a recent study published in the American Journal of Sports Medicine (February 2010). The study compared PRP treatment with corticosteroid injection in 100 patients with chronic lateral epicondylitis (tennis elbow).
Their results showed a significant difference between the two treatments with the PRP patients demonstrating improved reduction in pain and improved function as compared to the patients injected with corticosteroids. Also noteworthy was the report that the corticosteroid group was that their pain was “better initially and declined, whereas the PRP group progressively improved” (Peerbooms, J.C, et.al, 2010).
Although PRP is a hot topic now in the field of sports medicine, the large controlled, double-blind scientific studies to validate its effectiveness are needed. Unfortunately, to date, the literature is full of pilot studies with very small sample sizes or individual case studies (single person stories). In the science community, these types of studies are not sufficient to validate a new scientific methodology.
However, even with the lack of scientific evidence, the use of PRP seems to be exploding into all kinds of areas in sports medicine. Good medical practice is that the specific uses of a new treatment follow scientific evidence.
However, in this case, the number of proposed treatment uses for PRP has escalated ahead of the research. What are needed now are quality studies that research the effectiveness of PRP on all possible tissues and injuries that might be effectively treated by PRP.
If you suspect that you have a sports injury, it is critical to seek the urgent consultation of a local sports injuries doctor for appropriate care. To locate a top doctor or physical therapist in your area, please visit our Find a Sports Medicine Doctor or Physical Therapist Near You section.
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Foster, T.E., Puskas, B.L. Mandelbaum, B.R., Gerhardt, M.B. & Rodeo, S.A. (November, 2009). Platelet-Rich Plasma: From Basic Science to Clinical Application. American Journal of Sports Medicine.
Hammond, J.W., Hinton, R.Y., Curl, L.A., Muriel, J.M. & Lovering, R.M. (June, 2009). Use of Autologous Platelet-Rich Plasma to Treat Muscle Strain Injuries. American Journal of Sports Medicine. 37(11):1135-1142.
Pearbooms, J.C., Sluimer, J., Bruihn, D.J., & Gosens, T. (February, 2010). Positive Effect of an Autologous Platelet Concentrate in Lateral Epicondylitis in a Double-Blind Randomized Controlled Trial: Platelet-Rich Plasma Versus Corticosteroid Injection With a 1-Year Follow-up. American Journal of Sports Medicine. 38:255-262.
Reider, B. (June 2009). Proceed with Caution. Americal Journal of Sports Medicine. 37(11): 2100-2111.
Sampson, S., Gerhardt, M., & Mandelbaum, B. (December, 2008). Platelet Rich Plasma Injection Grafts for Musculoskeletal Injuries: A Review. Current Reviews in Musculoskeletal Medicine. 1(3-4):165-174.