PRP is plasma with many more platelets than what is typically found in blood. The concentration of platelets and, thereby, the concentration of growth factors — can be 5 to 10 times greater (or richer) than usual.
To develop a PRP preparation, blood must first be drawn from a patient. The platelets are separated from other blood cells and their concentration is increased during a process called centrifugation. Then the increased concentration of platelets is combined with the remaining blood.
Platelets have a vital role in the healing of injured tissues. The alpha granules of platelets contain growth factors which result in various biological effects. However, variations in individuals and differences in preparation methods can affects the absolute and relative concentrations of these different factors in PRP, which could account for differences in clinical outcome.
The release of these factors can be rapidly triggered by platelet activators thrombin and calcium. This results in the formation of a gel which can be used in open surgery but is impractical for injection. More gradual activation of platelets is also possible through exposure to damaged collagen, which attracts platelets through cytokine for PRP to be administered without pre-activation into damaged tissues.
How Does PRP Work?
To speed healing, the injury site is treated with the PRP preparation. This can be done in one of two ways:
• PRP can be carefully injected into the injured area. For example, in Achilles tendonitis, a condition commonly seen in runners and tennis players, the heel cord can become swollen, inflamed, and painful. A mixture of PRP and local anesthetic can be injected directly into this inflamed tissue. Afterwards, the pain at the area of injection may actually increase for the first week or two, and it may be several weeks before the patient feels a beneficial effect.
• PRP may also be used to improve healing after surgery for some injuries. For example, an athlete with a completely torn heel cord may require surgery to repair the tendon. Healing of the torn tendon can possibly be improved by treating the injured area with PRP during surgery. This is done by preparing the PRP in a special way that allows it to actually be stitched into torn tissues.
What Conditions are Treated with PRP? Is It Effective?
Research studies are currently being conducted to evaluate the effectiveness of PRP treatment. At this time, the results of these studies are inconclusive because the effectiveness of PRP therapy can vary. Factors that can influence the effectiveness of PRP treatment include:
• The area of the body being treated
• The overall health of the patient
• Whether the injury is acute (such as from a fall) or chronic (an injury developing over time)
Chronic Tendon Injuries
According to the research studies currently reported, PRP is most effective in the treatment of chronic tendon injuries, especially tennis elbow, a very common injury of the tendons on the outside of the elbow.
An injection of PRP is used to treat tennis elbow.
The use of PRP for other chronic tendon injuries — such as chronic Achilles tendonitis or inflammation of the patellar tendon at the knee (jumper’s knee) is promising. However, it is difficult to say at this time that PRP therapy is any more effective than traditional treatment of these problems.
Acute Ligament and Muscle Injuries
Much of the publicity PRP therapy has received has been about the treatment of acute sports injuries, such as ligament and muscle injuries. PRP has been used to treat professional athletes with common sports injuries like pulled hamstring muscles in the thigh and knee sprains. There is no definitive scientific evidence, however, that PRP therapy actually improves the healing process in these types of injuries.
More recently, PRP has been used during certain types of surgery to help tissues heal. It was first thought to be beneficial in shoulder surgery to repair torn rotator cuff tendons. However, the results so far show little or no benefit when PRP is used in these types of surgical procedures.
Surgery to repair torn knee ligaments, especially the anterior cruciate ligament (ACL) is another area where PRP has been applied. At this time, there appears to be little or no benefit from using PRP in this instance.
Some initial research is being done to evaluate the effectiveness of PRP in the treatment of the arthritic knee. It is still too soon to determine if this form of treatment will be any more effective than current treatment methods.
PRP has been used in a very limited way to speed the healing of broken bones. So far, it has shown no significant benefit.
How long does it take?
The procedure takes approximately one to two hours, including preparation and recovery time. Performed safely in a medical office, PRP therapy relieves pain without the risks of surgery, general anesthesia, or hospital stays and without a prolonged recovery. In fact, most people return to their jobs or usual activities right after the procedure.
How often should this procedure be done?
Up to three injections may be given within a six-month time frame, usually performed two to three weeks apart. You may, however, gain considerable to complete relief after the first or second injection.
What are the expected results?
Because the goal of PRP therapy is to resolve pain through healing, it could prove to have lasting results. Initial improvement may be seen within a few weeks, gradually increasing as the healing progresses. Research studies and clinical practice have shown PRP therapy to be very effective at relieving pain and returning patients to their normal lives. Both ultrasound and MRI images have shown definitive tissue repair after PRP therapy, confirming the healing process. The need for surgery can also be greatly reduced by treating injured tissues before the damage progresses and the condition is irreversible.