Exploring Biologics: Are Stem Cells and PRP Worth the Hype?
By Brian Feeley, MD
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I thought I’d take this opportunity to dive into a topic I often discuss with patients, at conferences, and even in the media: biologic treatments. These therapies are often offered as alternatives to traditional methods like anti-inflammatory medications, physical therapy, or surgery.
Take a common scenario: you go to a clinic with shoulder pain, rotator cuff tendonitis, or maybe a torn meniscus with some early arthritis. Your doctor runs through the usual options—rest, anti-inflammatories, physical therapy, maybe surgery. But what about stem cells or platelet-rich plasma (PRP)? These biologics sound cutting-edge and promising, and, in some clinics, they’re available. The catch? They come with a hefty price tag, ranging from $1,000 to over $10,000 out of pocket.
So, are these treatments worth it? Let’s break it down.
What Are Biologics?
The term “biologics” is broad, but the most common one people ask about is PRP (platelet-rich plasma). PRP is essentially a concentration of platelets that can promote healing, which makes sense since platelets drive the body’s natural healing response when you get a cut. Although it may seem new, PRP has been around for decades. It was first described by hematologists in the 1950s, used in oral surgery in the 1970s, and later in open-heart surgeries. It gained traction in orthopedic surgery in the early 2000s, particularly for treating tennis elbow.
What About Stem Cell Therapy?
Now, this is where things get complicated. The term “stem cell therapy” is often misleading. In reality, most of the time, the treatment marketed as “stem cell therapy” is actually a stromal cell therapy. Stromal cells can differentiate into other cell types but don’t meet the strict definition of true stem cells.
True stem cells must be undifferentiated, capable of self-renewal, and able to differentiate into multiple types of cells. They’re rare, and currently, no FDA-approved stem cell therapies exist in the U.S. for musculoskeletal conditions. So, when a clinic offers you stem cell therapy for a knee or shoulder injury, they’re likely talking about stromal cells, which are more limited in potential.
The Appeal of PRP and Stem Cell Treatments
PRP and other biologics are often used for conditions like knee arthritis, tennis elbow, and rotator cuff issues. They’re even marketed for muscle strains and various non-orthopedic treatments. The common rationale from physicians is that there’s a “treatment gap.” Patients
don’t want surgery, and traditional options aren’t always effective, so offering something like PRP gives them another choice.
But here’s the issue: PRP and stromal cell therapies often come with a hefty price tag and not a lot of solid evidence to back them up. While there are success stories and some studies showing benefits for specific conditions, the data isn’t overwhelmingly convincing. As a result, patients are left paying thousands of dollars for treatments that may not work.
Should We “Throw Some Biology In There”?
At conferences, I’ve heard people say, “Let’s throw some biology in there.” It sounds appealing, but it’s also risky. We don’t yet know if adding biologics like PRP to every treatment plan will really help the body heal, what some of the risks are, and we are passing the risk on to the patient, particularly the financial risk (without much rhyme or reason).
In my opinion, while biologics hold promise, especially as research progresses, they’re not yet the game-changers they’re often marketed as. And from a physician’s perspective, it’s tough to recommend treatments that come with high financial, patient directed costs and unclear benefits.
Looking Forward: Is the Future of Biologics Around the Corner? As someone who runs a lab studying stem cells and muscle repair, I’m still cautious about recommending these treatments for most musculoskeletal conditions. When patients ask if they should wait a few months or years for the technology to improve, I usually advise them to stay grounded in the available evidence.
Biologics may evolve into a more effective treatment option, but we’re not quite there yet. For now, careful consideration of the available data—and your wallet—is key.
Why I’m Still Skeptical of Biologics: Four Key Problems
As much as biologics like PRP and stem cell therapies sound promising, I remain skeptical for four key reasons, which I’ll unpack a bit more in this post.
1. Treating a Wide Range of Conditions with a Single Solution
The first red flag is that we’re trying to treat a huge variety of conditions—arthritis, rotator cuff injuries, muscle strains—with a single strategy. Think about it: PRP and stem cells are touted for everything from hair loss and sagging skin to early arthritis and muscle injuries. Even within just arthritis or tendinopathies, there’s an enormous spectrum of disease severity. So, how can one treatment work for all these conditions? It doesn’t make sense.
We’re dealing with complex biological processes, and we’re only beginning to understand them. So, the idea that a single treatment like PRP could fix everything seems overly simplistic and, frankly, unrealistic. Over time, I believe we’ll find that these biologics might work for certain specific conditions in certain types of patients, but not across the board.
2. Small Effect Sizes in Research
The second issue is that the effect sizes we see in studies on biologics are often small—and may not be clinically meaningful. You might hear that a study showed PRP or stem cell therapy was “statistically significant.” But what does that really mean? In technical terms, it means there’s less than a 5% chance that the difference observed in the study is due to random chance. However, this doesn’t necessarily translate into a clinical benefit—something that patients will actually feel.
What we care about in medicine is whether the treatment makes a meaningful difference in the patient’s life. There’s a concept called the minimally clinically important difference (MCID), which is the smallest change that patients actually notice and benefit from. If a study shows statistical significance but doesn’t meet the MCID threshold, then even though the treatment worked “on paper,” it may not provide real-world benefits.
3. Bias in the Research
Third, there’s bias—both conscious and unconscious—that creeps into the research. This is especially true for stem cell therapies, where there’s a lot of excitement and commercial interest. Whether intentional or not, bias can skew the results, and that’s something we need to be mindful of when evaluating studies.
4. High Costs Passed to Patients
Finally, and perhaps most importantly, is the cost to patients. These treatments are often marketed directly to consumers with misleading promises, and patients are left paying out of pocket—sometimes thousands of dollars—without a full understanding of the limited science behind them. This is very different from what we see with FDA-approved medications, where strict regulations control the marketing and ensure a higher standard of evidence.
Digging Deeper into Heterogeneity
Let’s return to the issue of heterogeneity. One of the biggest challenges is that we’re dealing with a wide range of conditions, and yet we’re suggesting that a stem cell or PRP treatment will work for all of them. Whether it’s knee arthritis, muscle strains, or even cosmetic concerns like hair loss, the treatment strategy is the same.
To me, this doesn’t make sense. These are highly complex processes, and we’re only starting to scratch the surface of understanding them. So, the idea that one biologic treatment can address all these conditions seems overly optimistic. It’s more likely that we’ll discover PRP or stem cells work well for specific types of tendinopathies or arthritis in select patients. But right now, it’s far too simplistic to think that these treatments are a one-size-fits-all solution.
Statistical Significance vs. Clinical Relevance Next, let’s talk about statistical significance. As we discussed in a previous podcast with Emily Oster, statistical significance is a very specific concept—it means the chance that the difference observed between groups is due to random chance is less than 5%. But just because a treatment is statistically significant doesn’t mean it will actually help a patient feel better.
What we really want to see is whether the treatment produces a clinically meaningful improvement. This is where the minimally clinically important difference (MCID) comes in. If a treatment doesn’t meet the MCID, then it might not be worth the cost—especially if it’s an expensive out-of-pocket treatment like PRP or stem cells.
A Case Study: PRP vs. Hyaluronic Acid for Knee Arthritis
Let’s look at an example of how these concepts play out in research. One well-known study by Brian Cole, a leading knee surgeon at Rush University, compared PRP with hyaluronic acid (a common gel injection used for knee arthritis). The study’s main goal was to assess pain reduction over one year using a scale called the WOMAC score. The researchers didn’t find a significant difference between the two treatments based on this primary outcome.
But here’s where things get tricky. When they did a subgroup analysis, they found that PRP performed better on a different scale—the IKDC score—from six to twelve months, especially in patients with mild arthritis and lower body mass indexes (BMI). This suggests that PRP might work better for certain groups of patients, particularly younger, thinner individuals with less severe arthritis.
However, if you only read the abstract or headlines, you’d walk away thinking “PRP works!” without understanding the nuances of the study or the specific patient groups who might benefit. This is why we need to be cautious when interpreting these results.
Systematic Reviews: The Bigger Picture
As more studies come out comparing PRP to other treatments, researchers can pool the data into systematic reviews to get a clearer picture. One of my favorite studies looked at 34 randomized controlled trials (RCTs) involving 1,400 patients with knee arthritis. This type of large-scale analysis is incredibly valuable because it helps us see trends across multiple studies and patient populations.
One of the most comprehensive studies in orthopedic surgery looked at the use of biologics—specifically PRP—across a wide range of conditions. It compared PRP to steroids, hyaluronic acid (gel injections), and placebos. The findings? While PRP often showed a statistical difference, there was frequently no clinically significant difference. This is a critical point when discussing treatments with patients. Even if a study shows statistical significance, it doesn’t necessarily mean that patients will experience an actual, meaningful improvement in their symptoms.
Diet and Exercise: The Real Treatment Gap Filler
When patients ask me, “Is there something that works better than PRP?” I have to answer, “Yes, but it’s not the quick, easy solution many hope for.” In fact, one of the most proven methods to improve knee arthritis is something we’ve known for decades: diet and exercise. There’s robust evidence, dating back to the early 2000s, that combining diet and exercise not only improves knee pain and function, but also meets the minimally clinically important difference (MCID)—the level of improvement patients actually feel. Moreover, weight loss has been shown to delay the need for joint replacement surgery and comes with additional health benefits, such as lowering the risks of heart disease and diabetes. Patients who lose even modest amounts of weight often rate their overall health as significantly better.
With the recent emergence of GLP-1 inhibitors, we’re likely to see a new wave of studies exploring their impact on weight loss and joint health, which could offer additional options for patients. But for now, I continue to emphasize that even a modest weight loss through reasonable exercise is likely the most reliable path forward for patients, especially those with mild to moderate arthritis. It may not be a quick fix, but it works.
Tendinopathy: Another Complex Challenge
Next, let’s move on to tendinopathy, a particularly tricky condition that affects tendons all over the body. We see it in cases like tennis elbow, golfer’s elbow, rotator cuff tendinitis, Achilles tendinitis, and patellar tendinitis. Chances are, most people have experienced at least one of these conditions at some point.
Tendinopathy doesn’t present the same way for everyone. It varies across age groups, physical activity levels, and the specific tendon involved. This variation makes treatment even more complicated, as it’s not always clear what we’re treating. The pathophysiology of tendinopathy involves multiple factors, including changes in blood supply to the tendon, increased pain sensitivity due to nerve changes, heightened inflammation, and disorganized collagen fibers. All of these factors make tendinopathy an extremely complex condition to treat effectively with a single therapy, such as PRP.
When you look at the data on PRP and tendinopathy, it’s clear that tennis elbow is the exception—PRP consistently shows positive results for this condition. However, for other tendinopathies, including rotator cuff issues, Achilles tendinitis, and patellar tendinitis, the evidence is less compelling. Some studies show a small statistical improvement, but the results often don’t meet the MCID, meaning patients don’t feel a noticeable difference, especially over time.
The Ongoing Challenge of Rotator Cuff Repair
Rotator cuff repair remains one of the most frustrating problems in orthopedic surgery. Despite advancements in surgical techniques, we still face high re-tear rates, especially in medically complex patients. In some studies, re-tear rates range from 20% to as high as 50%, depending on
the patient population. Even though many patients do well after a re-tear, not all do, and it’s a persistent challenge that we haven’t solved.
We’ve made significant strides in other areas of orthopedic surgery, such as ACL reconstruction, meniscus repair, and shoulder stabilization. But when it comes to rotator cuff healing, we still lag behind. This is where the question of using PRP or other biologic agents comes into play.
So, does PRP help with rotator cuff repairs? The answer is still unclear. Some studies show that it works, others show no effect, and some studies even suggest that PRP could be detrimental to the healing process. This inconsistency in the data makes it difficult to draw firm conclusions or confidently recommend PRP as a standard part of rotator cuff repair.
The Ethics of Biologics
There’s a common perception that biologic treatments, like stem cell therapy or PRP, seem more advanced, cutting-edge, or “natural” compared to conventional treatments such as steroids, physical therapy, or even surgery. This perception drives patients towards these therapies despite a lack of overwhelming evidence, especially when marketed directly to consumers. As our previous guest and medical ethics expert Zubin Master, PhD and others have explored, the direct-to-consumer marketing of biologic therapies often preys on patient hopes, particularly the desire to avoid more invasive procedures like joint replacement or tendon repair. Patients are often swayed by promises of pain relief, minimal invasiveness, and the allure of a more “modern” or “advanced” approach to treatment. The marketing messages can make biologics seem like a miracle cure, even though the evidence doesn’t always support these claims.
What’s even more concerning is that the cost of these treatments is largely passed on to the patient. Most of these biologic treatments aren’t covered by insurance, so patients are paying out-of-pocket for something that may not have clear, significant clinical benefits. That’s a huge financial burden, often with limited informed consent. Many patients aren’t fully aware of the nuances or the uncertainty behind the effectiveness of these therapies.
This is particularly troubling because direct-to-patient advertising for biologics is a whole different beast compared to the FDA-approved drug ads you see on TV. Those commercials have strict regulations, requiring clear communication about risks, side effects, and evidence-based benefits. In contrast, many stem cell and PRP clinics don’t face the same level of scrutiny, so the ads can be vague, promising hope without substantial data to back up the claims.
Ultimately, patients need to be cautious. There’s a place for biologics in certain cases, but the current science just doesn’t support them as the magic bullet they’re sometimes made out to be. It’s vital to have an honest discussion with your healthcare provider about the realistic benefits and risks before diving into these treatments. We need more rigorous studies, and until then, we must balance patient hopes with scientific reality.
So, as we think about biologics and their potential, we need to remember that this process will take time, just like how aspirin evolved over the centuries. We may not have all the answers right now, but with continued research, we’re starting to unlock the specific components within
therapies like PRP that could bring real, targeted benefits in the future. Whether it’s cartilage health, pain relief, or even something as surprising as improved cognition, these early findings give us hope that we’re on the right track.
It’s essential, however, to approach these therapies with a healthy dose of skepticism and scientific rigor. The story of biologics is still being written, and as clinicians and patients, we should demand the same standards we expect from any other medical treatment. We owe it to ourselves and our patients to be thoughtful in how we implement these new technologies.
Thank you for tuning into the Six to Eight Weeks podcast. I hope this episode gave you some clarity on the world of stem cells, biologics, and their applications in sports medicine. Don’t forget to subscribe on Apple Podcasts, Spotify, or wherever you get your podcasts, and stay tuned for more insightful discussions on sports medicine. Thank you!