Blood injections: Are they effective?
Many of my athlete patients are asking me about PRP injections and whether they work. Platelet rich plasma (PRP) has been used to treat dermatologic and maxillofacial conditions since the 1950’s, but only recently has it been used to treat orthopedic conditions.
What is PRP?
PRP is a sample of ones own blood where the concentration of platelets is above baseline amounts. Platelets are cells found in our blood which work with coagulation factors to stop bleeding. When a sample of ones blood is placed in a test tube and then centrifuged, the liquid and solid components of blood separate. The plasma and platelets are separated from the heavier red blood cells and white blood cells. The platelet and plasma portion is then isolated. This mixture contains higher concentrations of growth factors such as platelet derived growth factor, endothelial cell growth factor, and other growth factors. Investigators have postulated that by concentrating and injecting these growth factors into injured tissue, that the healing potential of that tissue will be improved.
There are dozens of commercial systems available to physicians to prepare PRP. However, the final platelet concentration depends on many factors, including the commercial system used, the initial volume of whole blood used, and patient age to name a few. Moreover, a higher number of platelets does not necessarily lead to improved tissue healing. The phase of healing and the timing of PRP administration are also important predictors of success. Because no two samples of PRP are exactly the same, it is difficult to study PRP and compare results in one study to results in another study on PRP. This muddies the water a bit when trying to draw conclusions about the effectiveness of PRP on tissue healing.
Is it effective?
In the office, I commonly see patients with various degrees of knee or shoulder arthritis. Some patients ask me if PRP injections will help reverse their arthritis or at least reduce their pain levels. Most studies show no additional benefit of injecting PRP over giving hyaluronic acid injections for the treatment of knee arthritis. Furthermore, it is important to remember that most insurance plans cover hyaluronate injections whereas they do not cover PRP injections in an office setting. Thus, patients are often stuck paying thousands of dollars for PRP injections when the data would suggest that there may be no added benefit over HA injections. Furthermore, the American Academy of Orthopedic Surgeons recently came out with a position statement which states that they are “unable to recommend for or against growth factor injections and/or platelet rich plasma for patients with symptomatic osteoarthritis of the knee.”
In the lab, PRP has been shown to promote bone healing and bone growth. However, the results of PRP in treating patients where bone growth is desired have been less successful. For example, spine surgeons have tried to use PRP to help increase their spinal fusion rates, but PRP does not seem to confer any benefit in spine fusion rates.
PRP does seem to have a role in the treatment of some patients with chronic tendonitis. Studies comparing PRP to steroid injections for tennis elbow have shown that patients injected with PRP have more sustained and added benefit. Studies looking at injecting PRP for achilles tendonitis did not show the same added benefit.
PRP has been studied in patients undergoing rotator cuff repair in the shoulder. The thought is that PRP may improve healing rates of the rotator cuff tendon back to bone. The results of studies are mixed, but most studies have shown no difference in healing rates when PRP is added. The same findings have been shown in patients undergoing Achilles tendon repair, with no significant improvement in healing seen in patients injected with PRP after undergoing an Achilles tendon repair.
Enhancing tissue healing with PRP and concentrated growth factors is an exciting area of clinical research. However, the current indications for PRP injections are limited with questions remaining about its efficacy and also concerns for cost to the patient.