Platelet-rich plasma (PRP) (also known as blood injection therapy) is a medical treatment being used for a wide range of musculoskeletal problems. Platelet-rich plasma refers to a sample of serum (blood) plasma that has as much as four times more than the normal amount of platelets. This treatment enhances the body’s natural ability to heal itself and is used to improve healing and shorten recovery time from acute and chronic soft tissue injuries.
Platelets are part of the blood that circulate around the body ready to help with blood clotting should you have a cut, broken bone, injury that bleeds internally, or any other type of injury. Besides containing clotting factors, the platelets release growth factors that help start the healing sequence. With a concentrated amount of platelets, larger quantities of these growth factors are released to stimulate a natural healing response. Plasma is the clear portion of the blood in which all the other blood particles such as platelets, red blood cells, and white blood cells travel.
Blood injection therapy of this type has been used for knee osteoarthritis, degenerative cartilage, spinal fusion, bone fractures that don’t heal, and poor wound healing. This treatment technique is fairly new in the sports medicine treatment of musculoskeletal problems, but gaining popularity quickly.
In theory, blood injection therapy could be used in any area where a rapid healing response is desired such as the tendon-muscle junction, muscle injuries, torn ligaments, damaged joints, or inflamed tissue (e.g., plantar fasciitis).
Torn tendons and ligaments don’t always heal well because they have a poor blood supply. Connective tissues such as ligaments and tendons heal by filling in with scar tissue that doesn’t bear the brunt of large loads well. This increases the risk of re-injury. Other available treatments for chronic tendon problems do not necessarily improve the tendon’s ability to heal in the same way that PRP does. And injections of PRP don’t have the side effects that can occur with steroid injections or long-term use of non-steroidal anti-inflammatory drugs (NSAIDs).
The platelet-rich plasma therapy has been around long enough now to start studying it more carefully. Researchers have found that the platelet-rich plasma preparation varies significantly from sample to sample. That means patients aren’t always getting the same amount of platelets and growth factors. This has been shown to be true from one treatment to the next and even from one patient to the next. The question comes up: why the differences?
To find out, researchers from the University of Connecticut sampled blood from eight people on three separate occasions (baseline or first blood draw, fourteen days later, one month later). Each sample was analyzed for each patient at each of those time periods.
They used three different lab techniques to harvest the platelets: 1) a single-spin technique (referred to as LP), 2) an alternative single-spin method (the HP method, and 3) a double-spin (DS) technique. Each technique is carefully described for the reader including the number of minutes spun and the revolutions per minute.
In all cases, the HP (alternative single-spin separation method) gave the best results with the highest percentage of white blood cells and platelets. The one-step LP method far outperformed the other two methods.
There were clear differences in outcomes not only with the differing techniques used but also for the different times the samples were taken for each individual. The question naturally arises: why would platelet levels and white blood cell levels vary over time for the same person? The authors suggest age could make a difference. Or there could be a physiologic reason why these variations exist that we just don’t know about yet.
What the study does show is that the method of separation when obtaining platelet-rich plasma makes a difference in the number of white blood cells and platelets collected. Physicians may want to take this fact into consideration when selecting the method used.
For example, it might be helpful to choose the method that matches the intended use of the plasma. One thing to keep in mind is the fact that too many white blood cells can actually cause an overreaction in the tissues. And too much inflammation at certain points in the healing process may not be a good idea.
Perhaps the double spin method (yields lower levels of platelets and white blood cells) would work best when a mild healing response is needed. Likewise, there may be times and situations where increased antibacterial and an increased immune response would be helpful. In those cases, the single-spin method might be the most useful.