Many people have heard the term “platelet-rich plasma” in news stories in connection with athletic injuries, however, not all may realize that when platelet-rich plasma (PRP) is injected into and around a joint, it is actually a type of prolotherapy. In fact, PRP has been used as a formula in prolotherapy since around 2005. The approach has been shown to be effective not only for older injuries but also for recent ones, making it ideal for athletic injuries. It has also successfully been used in the treatment of osteoarthritis (OA) and helpful for cartilage repair.
Not All Platelet-Rich Plasma Is Equal
As the use of PRP has grown, so has the demand for, and availability of, PRP–concentrating machines and methods; several manufacturers now make these systems. There are also doctors who “do it themselves” using a regular type of centrifuge rather than one of the systems developed for this purpose. The basic differences among these various methods are: 1) the amount of concentration of platelets (how many times a person’s normal levels (called “baseline” levels); and 2) the presence and number of red or white blood cells.1
Platelet Concentration
There is debate in the medical community about what is the best platelet concentration or cell type for different conditions; however, most data supports a platelet concentration of four to six times a patient’s normal level (baseline) for most musculoskeletal problems.2 More specifically, since the average normal patient’s platelet count is 250,0000 platelets per microliter, this means that the magic number is 1.0 million to 1.5 million platelets per microliter (four to six times normal baseline). This concentration has shown better tissue regeneration when compared to lower platelet concentrations. It also seems that much higher concentrations could have an inhibitory effect,3 which may decrease effectiveness.4 Therefore, four to six times baseline has become the most commonly used concentration for PRP, and this concentration range is known as “high-density.” Remember that platelets work by sending out biochemical messages so that nearby available stem cells will come and help repair injured areas. It has been found that when high-density PRP is used, there is a stronger stem-cell response when compared to whole blood or PRP with lower platelet concentrations.
Red and White Blood Cells
The other difference between PRP is the number of red and white cells. Keep in mind that most of the red cells are already removed in the making of PRP: whole blood is 94% red cells as compared to only 5% red cells in PRP. However, even though the remaining red cells are greatly diminished, it is believed that any red cells may still cause unnecessary aggravation after treatment. One issue has been that removing too many red cells may greatly reduce platelet levels since some platelets are within the red cell layer. Fortunately, recent developments in technology now permit the ability to remove most of the red cells while still maintaining high platelet counts. Another issue is that with prolotherapy, clinicians may prefer this additional red blood cell irritation to “wake up” certain tissue types that are not healing. Therefore, both formulas are used in prolotherapy—the low red cell (“yellow”) and the regular red cell (“red”)—depending on the area treated, intended result, physician and/or patient choice, and treatment plan.
Regarding white blood cells, some physicians argue that white cells may cause too much pain and should be reduced, especially in joints.5 However, typically, white cells constitute only 1% of both whole blood and PRP, and therefore a very small percentage of the treatment formula. Also, white cells are very difficult to remove without seriously sacrificing platelet numbers.6 Most physicians also agree that white cells are important and improve wound healing; furthermore, white cells have antibacterial properties that are thought to potentially help reduce infection risk from, or after, the procedure (as long as done under appropriate sterile conditions of course).7 Therefore, it is generally agreed in the medical community that white cells are desirable and should remain in platelet-rich plasma formulas.8
Cortisone versus Platelet-Rich Plasma
Cortisone injections are commonly recommended for the treatment of joint pain. However, the use of cortisone is controversial because it tends to break down, rather than repair, joints and connective tissue, especially if done repeatedly. Current evidence now supports platelet-rich plasma to be more effective than cortisone for treatment of joint and connective tissue issues,9 especially long term. A well-designed, two-year, randomized, controlled, blind trial, with a significant test group of 100 patients investigated cortisone versus PRP injections for elbow tendon problems. The researchers concluded that PRP reduced pain and increased function significantly, exceeding the effect of corticosteroid injection even after two years.10 A similar study in 2017 agreed.11 These two treatments were also compared for use in chronic, severe plantar fasciitis and concluded: “PRP was more effective and longer lasting than cortisone injection.”12 Platelet-rich plasma has also been found to be a “superior treatment option” versus cortisone for lumbar facet (low back joint) injections, with longer lasting effectiveness.13
PRP versus Dextrose Prolotherapy
Both PRP and dextrose prolotherapy have been shown to stimulate natural healing.14 Both can be effective, and both should be considered in the treatment plan for connective tissue repair. PRP prolotherapy, however, may be deemed more appropriate in cases where the tissue or joint has become degenerated, there is osteoarthritis present or the problem is older and more chronic. When platelet-rich plasma is the formula used in prolotherapy, it provides not only needed irritation (concentrated platelets are aggravating) but also growth factors that provide a jump-start on healing. Using PRP is like adding fertilizer to newly planted seeds versus just planting the seeds; the condition of the “soil” can help to determine which formula is the best choice. Platelet-rich plasma may also be preferred over dextrose in cases of a tendon sheath or muscle injury; these areas are occasionally, but not typically, treated with dextrose.
Updated: 08/18/2018
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