Take a Pause on Platelet-Rich Plasma

Volume 10, Issue 1

In this week's issue of Talking Therapeutics, we're taking a slightly different approach to our usual column. Rather than look at a drug therapy, we're going to look at a treatment modality known as platelet-rich plasma (PRP). We're making this diversion in light of the 3 randomized clinical trials that were recently published in the Journal of the American Medical Association exploring the effects of this agent for a variety of musculoskeletal conditions.

Point 1: PRP Makes Sense (In Theory)

Symptomatic, radiographically documented knee osteoarthritis (OA) affects more than 14 million adults in the United States and approximately 240 million worldwide. Symptomatic, radiographically documented ankle OA has been estimated to affect 3.4% of people older than 50 years of age (approximately 3 to 4 million adults in the United States). Achilles tendinitis has an estimated incidence of approximately 2 per 1000 people in the Netherlands and is associated with Achilles tendon rupture, an extremely disabling condition.

These 3 conditions: knee OA, ankle OA, and Achilles tendinopathy, are costly and disabling, yet few effective therapies are available that relieve pain and also reverse underlying tissue damage.

Platelets are rich in growth factors such as platelet-derived growth factor, epidermal growth factor, insulin-like growth factor, transforming growth factor β1, vascular endothelial growth factor, and basic fibroblast growth factor. These substances have protean anabolic properties including the capacity to remodel bone and blood vessels and promote angiogenesis, chondrogenesis, and collagen synthesis. These processes are collectively involved in healing following musculoskeletal injury.

PRP is a particularly appealing therapy because it is derived from a patient’s own cells, averting the risk of immune-mediated rejection, and because it can be delivered at the point of care.

Point 2: Evidence Doesn’t Support the Theory

As someone who has battled with Achilles tendonitis before, I know the allure of PRP. I consistently turned it away given the high cost and questionable data. Considering the first of these new randomized trials, I’m very glad that I did.

One trial involved 240 participants with pain at the midportion of the Achilles tendon. Treatment with a single injection of intratendinous PRP vs a placebo injection resulted in a mean Victorian Institute of Sport Assessment-Achilles score of 54.4 vs 53.4 at 6 months, respectively (range, 0 [worst symptoms] to 100 [no symptoms]). This difference was not statistically significant.

Likewise, in the trial of 288 adults aged 50 years or older with knee OA, participants who were randomized to receive 3 PRP injections improved by 2.1 points on a 1- to 10-point pain scale over 12 months, whereas participants randomized to placebo improved by 1.8 points, a difference that was neither clinically meaningful nor statistically significant.

Finally, in a trial of 100 patients treated with 2 intra-articular PRP injections vs placebo injections with saline, the resulted mean change in the American Orthopedic Foot and Ankle Society score was 10 vs 11 points over 26 weeks; a between-group difference that was not statistically significant.

Taken together, these three trials consistently show that currently available PRP modalities offer little benefit to justify the high out-of-pocket costs that most patients accrue. Until future data demonstrates a meaningful benefit, it’s time to hit pause on PRP for OA and Achilles tendonitis.