PRP Therapy: What It Is, How It Works and What the Research Actually Shows

Exercise is the best thing you can do to stay healthy. But painful conditions such as osteoarthritis, muscle strains, ligament tears and tendonitis can keep you on the couch.  

PRP may help get you active again.  

Cedars-Sinai is a leader in PRP therapy and regenerative medicine research.  

Platelet-rich plasma is a noninvasive injection therapy usually used in orthopedics and sports medicine, and successful treatment can help delay or avoid surgery. It is also becoming more common in dermatology and wound healing. Its use quadrupled between 2010 and 2020.

How Does PRP Work?

At Cedars-Sinai, if your doctor recommends PRP therapy, technicians will draw a small amount of your blood and place it in a centrifuge to separate the plasma and platelets from red and white blood cells. The plasma (the liquid part of your blood) and platelets (the cells that cause clotting) are then injected into the target tissue in your body.

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“Platelets are rich in growth factors—proteins that help with healing,” said Bert Mandelbaum, MD, vice chair of the Department of Orthopaedic Surgery at Cedars-Sinai. “A PRP injection delivers a high concentration of these growth factors directly to the treatment site.”

By reducing pain and inflammation, PRP can help improve and restore function in the joint.

Most of the moving joints in the body—there are more than two hundred of them—are “synovial joints.” They sit inside closed capsules where there is no blood. PRP therapy injects platelets into these normally closed capsules to promote healing.

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“By reducing pain and inflammation, PRP can help improve and restore function in the joint,” said Mandelbaum. “The main goal of the treatment is to increase the time during which people can be active in their lives.”

A PRP treatment usually takes less than an hour to complete, and because it is autologous, meaning it’s made from your own tissue, there’s very little risk of an allergic or immune reaction.

What Conditions Can Be Treated With PRP?

Orthopedics and sports medicine

‍The most common use of PRP is in the treatment of musculoskeletal conditions that involve inflammation, which increases pain and functional limitations. These include:

• Osteoarthritis (when cartilage in joints wears down allowing bone-on-bone contact, particularly in knees)  

• Torn rotator cuff (tears in tendons in the shoulder)

• Tendonitis (inflammation in a tendon, such as tennis elbow)

• Muscle and ligament strains

• Post-surgery inflammation to encourage healing

Dermatology

• Aging skin

• Hair loss

• Scar tissue, such as acne scars

• Wound healing, such as in severe skin burns and chronic ulcers

Other less common medical applications include dental surgery, eye care, urology and gynecology.

What Does the Research Say?

The FDA requires that all drugs be tested for safety and efficacy in large-scale studies. But because PRP comes from your own body, the FDA does not regulate it as a medicine. It is not understood why PRP therapy sometimes works and sometimes doesn’t.  

We found that when certain proteins were present in the PRP, the patient responded.

Cedars-Sinai recently published a small-scale study in the Orthopedic Journal of Sports Medicine that attempts to identify the factors that make PRP successful or unsuccessful.

The study followed 30 active patients who were treated with PRP therapy for knee osteoarthritis. Six weeks after their treatment, 19 (63%) of them reported their pain had improved.

“We found that when certain proteins were present in the PRP, the patient responded,” said Dmitriy Sheyn, PhD, the study’s senior author who leads the Sheyn Laboratory at the Cedars-Sinai Board of Governors Regenerative Medicine Institute. “When we found certain specific leukocytes, or white blood cells, in the PRP, the patients were less likely to see an improvement.”

Cedars-Sinai is participating in the Biologic Association Registry and Biorepository (BARB), a multicenter collaboration that includes the Mayo Clinic, the Hospital for Special Surgery, Northwell Health, the University of Colorado Hospital, Stanford Health Care and the Cleveland Clinic. Through the BARB, Sheyn is preparing to analyze a larger study of as many as 1,200 knee osteoarthritis patients treated with PRP, which he hopes will better inform physicians about when and why the therapy is effective for that purpose.

In the future these studies may help providers predict which patients will see a benefit from the treatment, as well as inform personalized treatments.

Mandelbaum, co-author of the study and co-director of the Regenerative Orthobiologics Center, said PRP science is still evolving.

“It's tricky when you're dealing with biologics,” he said. “When you take a drug, like Motrin, you know you’re getting 200 milligrams in every pill. But the contents of a patient’s PRP is very individual and variable. One person’s PRP might only have 100,000 platelets, another might have 250,000.”  

Mandelbaum said multiple PRP treatments and PRP therapy combined with other treatment components, such as hyaluronic acid, can be more effective at reducing inflammation than PRP alone.

What to Expect After PRP Treatment

PRP is not guaranteed to work, and it generally takes a few weeks before patients experience a reduction in pain and inflammation. Healing and tissue repair can take longer and may require additional treatments.  

PRP tends to be more effective for people who combine the therapy with exercise, Mandlebaum said.

“When you exercise, there's crosstalk between the muscles, the heart and the rest of your body, and that interaction helps make the biology better,” said Mandlebaum. “You’re more likely to get results if you’re actively using the parts of your body that are being treated.”  

Is PRP Right for You?

Anyone experiencing joint pain or other conditions that might respond to PRP should seek an individual evaluation with a doctor who has experience with the treatment.  

“PRP is not a cure-all,” Mandelbaum said. “But a physician who has experience with it can evaluate your condition, your overall health and other factors to let you know whether it might be an appropriate, nonsurgical approach for you.”  

Fast Facts About PRP

PRP has not been shown to cure arthritis: PRP can reduce pain and inflammation for some patients and conditions, improving function and playspan.

PRP can be considered for any adult: While its early use was primarily in professional sports, it is now considered for any adult with chronic joint or tendon pain.

PRP is not the same as a cortisone injection: Cortisone is a fast-acting anti-inflammatory that reduces pain in two to seven days but can damage tissues with repeated use. When effective, PRP reduces inflammation in three to six weeks, its effects last longer and it can also promote healing and tissue repair.

PRP does not work the same for everyone: The ingredients of a PRP injection are highly variable and affected by many factors, including health, diet, exercise and genetics.

PRP is not dangerous, experimental or unproven: How PRP therapy works is not well understood, but studies have shown it to be safe to use and effective for some patients and conditions.

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