In this video, we are going to talk about osteoarthritis and a treatment for osteoarthritis that has been used by many orthopedic surgeons and other healthcare professionals called platelet-rich plasma, or PRP. We will discuss what PRP is and how it might work. Then we will dive into the current research on the effectiveness of PRP for osteoarthritis of the hip and knee.

Please understand, in this video, I am not giving you medical advice. This is meant for general information and educational purposes only.

Osteoarthritis is the most common form of arthritis, affecting more than 30 million adults in the USA, or approximately 23% of the adult population. It’s the second most expensive condition treated in US hospitals, accounting for more than $16.5 billion in hospital costs.

What is osteoarthritis?

It has become increasingly clear that OA is the result of a long chain of events rather than just being “wear and tear” of the joint, despite most orthopedic surgeons telling patients it is simply a wearing out of the bone and cartilage in their hips and knees from injuries, and repetitive stress on the joints, like running three or six miles per day or doing a physically demanding job. While loss and breakdown of articular cartilage is the endpoint of this disease process, the actual disease involves an imbalance of the inflammatory mediators of the joint, resulting in cartilage degeneration, degeneration of the extracellular matrix, systemic inflammation throughout the body, chondrocyte cell death, osteophyte – or bone spur – formation, and bone remodeling.

As of today, there are no treatments that definitively cure osteoarthritis. Treatment by most orthopedic surgeons and doctors focuses on trying to decrease the patient’s symptoms. They focus on trying to modify patient activities, relieve pain and stiffness, improve joint function, improving quality of life, and delay or avoid the need for joint replacement.

Nonoperative treatments most orthopedic surgeons use today include nonsteroidal anti-inflammatory drugs, weight loss, dietary supplements such as glucosamine and chondroitin sulfate, topical agents and topical anti-inflammatory medications, and intra-articular injections of corticosteroids (cortisone shots) or hyaluronic acid.

Drawing blood to make platelet-rich plasma

Let’s talk quickly about cortisone shots and their pros and cons.

A recent Cochrane review concluded that corticosteroids provided a small benefit compared with placebo 4 to 6 weeks after injection, a small effect 13 weeks after injection, and no difference was noted at 26 weeks after the injection. That’s why you hear people who have had a cortisone shot say that it wore off and that they needed another one, and another one.

But also understand that post-injection flare-ups can occur in up to 25 percent of patients receiving cortisone shots, which can last several days. Occasionally patients have skin depigmentation or skin and fat necrosis at the injection site.

More importantly, there is evidence that the increased usage of cortisone shots can lead to cartilage breakdown. A recent randomized clinical trial compared corticosteroid injections to saline injections in patients with knee arthritis. The authors found that the cortisone shots resulted in greater cartilage volume loss seen on MRI compared with saline. And there was no significant difference in knee pain severity between the patients who had received a cortisone shot and those who had gotten a placebo injection.

Now let’s turn our attention to platelet-rich plasma.

What is platelet-rich plasma?

Platelet rich plasma, or PRP, is being widely used by orthopedic surgeons for a number of injuries and conditions owing to the healing potential contained within the platelets.

PRP is an autologous blood product that is created by first obtaining a small amount of blood through a blood draw, concentrating that blood sample use a centrifuge, and then administering the concentrated plasma product back into the patient by an injection into the joint. The concentrated plasma product contains a high concentration of platelets – at least two times greater than what’s in your whole blood.

How might PRP help in osteoarthritis?

In the lab, at least, PRP seems like it would be very helpful to patients dealing with osteoarthritis. The platelets’ alpha granules constitute a reservoir of critical growth factors, as well as cytokines and many other proteins. The dense granules of the platelets store ADP, ATP, calcium ions, histamine, serotonin, and dopamine.

PRP is thought to improve the environment within the joint rather than create a long-lasting regenerative effect. Research in the lab shows that PRP can alter the imbalance between pro- and anti-inflammatory cytokines that leads to those inflammatory pathways, which could be a key way PRP affects disease progression.

In addition to down regulating the joint inflammation, PRP might positively influence chondrocyte apoptosis, or cartilage cell death. PRP might not lead to hyaline cartilage regeneration, but it still might offer a clinical benefit with symptomatic and functional improvement and possibly a slowdown of the degenerative processes.

When platelets are activated, growth factors contained in their α-granules respond in a localized manner. This process is quick. Almost 70 percent of the growth factors contained within the α-granule are secreted in the first 10 minutes. These growth factors, along with coagulation factors, cytokines, chemokines, and other proteins stored within the platelet, have been shown to stimulate chondrocyte and chondrogenic stem cell proliferation, promote chondrocyte cartilaginous matrix secretion, and diminish the catabolic effects of pro-inflammatory cytokines.

PRP also appears to increase production of type II collagen, stimulate endogenous hyaluronic acid production, and assist with stem cell survival and proliferation.

Let’s look at the scientific research over the last few years to see how well PRP has done for osteoarthritis.

Scientific studies looking at PRP for osteoarthritis

A 2021 meta-analysis of 30 randomized controlled trials looking at different intra-articular injections for knee osteoarthritis found that intra-articular injections of PRP demonstrated the best overall outcome compared to steroids, hyaluronic acid and placebo for patients with knee osteoarthritis at 3, 6 and 12-months follow-up.

A 2021 meta-analysis of 26 randomized controlled trials looking at PRP vs. hyaluronic acid for knee osteoarthritis. The analysis included over 2400 patients with knee arthritis. The WOMAC total scores, WOMAC physical function scores, and VAS scores of the PRP group were better than the those of the hyaluronic acid group at 3, 6, and 12 months. The PRP group had better WOMAC pain, WOMAC stiffness, EuroQol VAS, and International Knee Documentation Committee scores than the hyaluronic acid group at 6 and 12 months. There was no significant difference in adverse events between the 2 groups. The researchers concluded that for the nonsurgical treatment of knee osteoarthritis, compared with hyaluronic acid, intra-articular injection of PRP could significantly reduce patients’ early pain and improve function. PRP was more effective than hyaluronic acid in the treatment of knee osteoarthritis, and the safety of these 2 treatment options was comparable.

A 2020 meta-analysis of 34 randomized controlled trials, including 1403 knees in PRP groups and 1426 in control groups, showed similar results. PRP injections provided better results than other injectable options. This benefit increases over time, being not significant at earlier follow-ups but becoming clinically significant after 6 to 12 months.

Are these results just a reflection of the placebo effect?

Important placebo effects have been observed in almost every knee injection study and are even greater in biologic trials where patients perceive they are getting a “regenerative medicine.” However, while placebo plays an important role in PRP results, as demonstrated by the similar outcome compared to saline up to 6 months, the PRP benefit exceeds the mere placebo effect.

How much PRP should be injected into your joint?

Various commercial PRP kits usually focus on taking minimal patient blood, ranging from 20 ml to 30 ml. The final product is usually 3–4 ml. Some experts believe, and I agree with this idea, for adequate treatment of osteoarthritic knees, volumes of at least 8 ml of PRP should be injected. The goal is to ensure that platelets as well as plasma in the final PRP product can diffuse and reach all areas within the joint. When PRP is activated, the plasma forms a clot which traps the platelets thereby creating a biologic scaffold. With larger volumes of PRP injected, the absolute number of platelets is greater, providing more growth factors. Producing 8 ml PRP would mean drawing more blood, and using more than one kit, at least with most of the ones currently commercially available.

Surgeon injecting PRP for knee arthritis

Caution about the research

There are many different methods of preparation, and different final products: PRP, leukocyte-rich PRP, platelet-rich fibrin, platelet gel, and more. All these platelet products have varying concentrations of blood cells, plasma, or fibrinogen. Therefore, they have different concentrations of growth factors and bioactive molecules, meaning they could have different efficacy for knee osteoarthritis.

The exact composition of PRP is not reported in many of the available studies. There are differences between leukocyte-rich and leukocyte-poor PRP and much more. Plus, humans have different numbers of platelets in our blood, so studies comparing PRP will lead to different results.

Plus, other than the leukocyte content, research studies differ in terms of volume of blood harvested, use of anticoagulant, number and speed of centrifugations, the final volume of PRP obtained, the overall number of platelets, their integrity and activation method, and more. All of these factors that could influence the properties of the final PRP product and how well it helps patients with osteoarthritis.

Is PRP covered by insurance?

Most insurance companies still consider PRP experimental and will not cover these treatments. And again, I’m not giving you medical advice. This information about platelet-rich plasma is intended for informational and educational purposes only.


Based on these recent studies, platelet-rich plasma offers a benefit that, although not significant at the early follow-ups (1 to 2 months), greatly exceeds the benefits over time, both versus the placebo effect and the improvement offered by other intra-articular injections at 12 months, without an increased risk of adverse events.

Scales focused on function, pain, or other osteoarthritis symptoms show a common trend. While no difference between PRP and cortisone shots or hyaluronic acid injections is observed in the first months after the injection, PRP benefits become noticeable starting from 6 months and increased up to the 12-month follow-up being statistically and clinically significant.

Now it could be that PRP doesn’t offer better results than other types of injections – steroids, hyaluronic acid – but instead offers longer lasting benefits. The differences between PRP and other injections become apparent over time when the effects of placebo or other intra-articular treatments wear out.

While it is substantial, the improvement in patients who undergo PRP injections for osteoarthritis is still partial improvement. We still need more research to confirm benefits and to identify the best formulation and indications for PRP injections in knee osteoarthritis.

Links to studies in the comments

If you would like to read the studies I mentioned in the video, here are links to them:

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I’m Dr. David Geier. Thank you for watching, and I look forward to helping you feel and perform Better Than Ever.