In this episode of The Shoulder Physio Podcast, I am giving a monologue, not a rant, a calm, rational, and reasonable solo exploration into the world of platelet-rich plasma for shoulder pain. Well, that's the intent. Anyway. I may get excited at some points. I do have a tendency of doing that, and I apologize in advance. I find platelet rich plasma or PRP to be one of these sexy and appealing treatments in musculoskeletal medicine that look good on the surface. But when you peep behind the facade, there is often very little substantive evidence supporting its widespread use. The aim of this episode is to provide an honest and balanced account of the merits, all lack thereof of PRP for shoulder pain. I hope you find this episode helpful in clearing up or even refuting some of the sensational claims. You may have heard about PRP before we start the podcast.
Without further delay, I bring to you my monologue on platelet-rich plasma for shoulder pain. Recently, for some inexplicable reason, I have experienced a significant uptake in patients asking me about PRP for their shoulder pain. Perhaps this is a case of selection bias because I tend to see patients with more persistent shoulder complaints, and they're often willing to try absolutely anything that could in principle reduce their pain. And this is completely understandable. There is also evidence that suggests that PRP is still a hot area of research, and perhaps this is translating integrator awareness from the general public. I'm sure Joe Rogan has done a podcast on PRP before, or at least mentioned it in passing in one of his episodes. Okay, so, so with all that taken into account, perhaps it is somewhat explicable that patients are asking me about PRP.
So what's the story with PRP in relation to shoulder pain? What is the proposed mechanism of action? It's all about that healing. PRP is part of this new wave of regenerative medicine. PRP apparently houses a veritable who's who of chemical agents involved in the healing process and can even cure male pattern baldness. It doesn't, but we're led to believe it does. Trust me, if it did, I would be the first person to go out and get some PRP. All the growth factors seem to be found in PRP from insulin-like growth factor to transforming growth factor to vascular endothelial growth factor, all the growth factors. For more information on the active ingredients of PRP, see the paper by Foster et al 2009 that I have listed in the show notes. So with all the goodness purportedly housed in a, in a single vile of PRP, who wouldn't want a jab of this stuff into their sore spot?
To be honest, as a lay person, I probably would. So the basic science and method of PRP is as follows. Step one, draw blood from the patient. Step two, spinning it around in the little spiny thing, which is called centrifugation to isolate the platelet-rich plasma. Step three, inject this goodness into the site where the miracle is to take place for the shoulder. This magic spot is typically the subacromial space rather than than the tendon itself. Step four, watch the magic happen. Pretty simple. Four steps. Get the blood, spin it around, inject it into the source bot, watch the person get better. But is it really so simple? Actually, no. Some people believe that the true effect of PRP comes from its anti-inflammatory mechanism and has nothing to do with its proposed anabolic or healing effect. There is also active discussion about the best method and dose of PRP administration and I will talk about this very point in a late in a later part of this podcast.
Like anything in health science, PRP is plagued by controversies, paradoxes, and limited research. Remember, evidence-based medicine is very, very young. This should not be surprising. Evidence-based medicine has been around for 30 or 40 years at most. We are still trying to figure out the science behind many of these, uh, appealing treatments. So is the proposed healing mechanism that I've just outlined above, biologically plausible, possibly it's intuitive to want to bathe damaged tissue in a sea of growth factors and hope this will translate into improved tissue health and thus less pain. But is pain really as simple as enhancing tissue structure? Hopefully you know that this is a rhetorical question. Does P I P do what it claims? Does it actually enhance tissue structure? Let's have a look at the evidence. So the evidence base for this is quite small and unsurprisingly inconclusive. There is no definitive evidence that suggests PRP improves the healing of rotator cuff tissue relative to another injection type or even exercise in human subjects.
A well conducted study by Schwitzguebel et al 2019 in the American Journal of Sports Medicine compared PRP to saline in its ability to positively influence rotator cuff tear healing, shoulder pain, and function, then people with rotator cuff tears. The results of this study don't make happy reading for PRP proponents, there were no differences in rotator cuff tear size, pain, and function between PRP and saline injections, but there were more adverse offense events in the PRP group. There are some laboratory studies in rats mostly that show it might be effective for stimulating healing, but nothing much in humans. So the healing propaganda of the PRP marketing companies has probably been a touch ambitious, given the current evidence. Disclaimer, I don't hate big pharma. So this is not a personal vendetta against big pharma.
The evidence doesn't really suggest that PRP substantially improves the healing of human tissue compared to other injections. So what about good old-fashioned efficacy and effectiveness? Let's start with efficacy. How does PRP compare to placebo for managing shoulder complaints? PRP might just might be slightly better than a placebo injection in the medium term only for managing rotator cuff related shoulder pain. According to very flimsy evidence from a few clinical trials in these same studies, there were no differences at short-term, which is less than eight weeks and long-term, which is greater than one year follow-ups. So PRP might be better than a placebo injection at the medium term only, but there is no difference between PRP and placebo at short term. At short term and long-term follow ups. For me, this means the efficacy is still uncertain.
What about effectiveness compared to a corticosteroid injection? PRP is worse at short-term follow ups and then similar, uh, long-term follow ups. Given this, I would probably rather people receive a PRP injection instead of a corticosteroid injection because of the uncertain and possible toxic effects of corticosteroids. Remember, a corticosteroid injection will almost always outperform comparative interventions in the short term, but tends to worsen over time. We've seen this numerous times with tennis elbow research. See the Coombes et al 2013 paper in the show notes below. Typically a dramatic short term improvement is seen in the corticosteroid injection group, followed by steady regression from six to eight weeks onwards, culminating in an often negative long-term effect against comparator interventions and injections. What about exercise compared to PRP? I could really only find one rigorous clinical trial investigating this and then is by, it is by Nejati et al 2017.
Again, see the show notes for this paper. This trial compared a PRP alone group versus an exercise alone group and followed up participants at one three and six months. The results were that exercise was superior to PRP up to three months for pain and function and there were no major differences in range of motion and rotator cuff structure at six months. There were no differences between the two groups. So it appears that exercise is better up to three months compared to a PRP injection. This does tickle my biases, but this trial should be replicated before we get to carried away. I will practice what I preach here and not overclaim the benefits of exercise versus PRP for cuff pain based on one solitary study are there method methodological issues in PRP research? Some PRP advocates quite rightly proclaim the evidence base is flawed due to differing PRP administration techniques and methods in clinical research.
And this is a valid criticism of the research that's out there. They claim that this renders reinterpretation of PRP research challenging and suggests there is far more work to be conducted in this area. We see similar problems with exercise research, where exercise programs in clinical trials are often poorly reported, making it hard to interpret and replicate this research. And this is something broadly across the spectrum in health science research that we should improve. Then this is the, the open science push towards, uh, making our research as transparent as possible, which will help with fu future research endeavors and then also publishing the particulars of your protocols up on some open science plat platform, such as open science framework. I would like to see another five to 10 really good clinical trials with open and transparent methods comparing PRP with placebo, like a saline injection, a corticosteroid injection, and simple progressive exercise and see who comes out on top.
My hypothesis is that PRP will be fairly comparable with simple progressive exercise over time. It might be worse than a corticosteroid injection in the short term, but in the longer term, at like six to 12 months and beyond, I reckon A PRP will be just as comparable to a corticosteroid injection and maybe even better given that we see these, uh, regression and negative effects of a corticosteroid injection at longer term follow-ups. But whether PRP will outperform exercise is still dubious for me. So my concluding thoughts, PRP is not a panacea for rotator cuff related shoulder pain. As the, uh, as the evidence currently stands, it might not outperform a simple saline injection or a placebo injection based on a very narrow evidence base of one trial, and it is probably worse or at best, equivocal to exercise alone.
Again, this is based on one solitary trial and this is the Nejati et al 2017 trial. It could be an option for those who have tried gallantly with exercise based rehab for a significant amount of time, three to six months, and are failing to progress after this time period. It's perfectly reasonable to want to try some other intervention if you are getting nowhere with a particular type of rehabilitation. The risks of PRP are probably low, but not zero, and the benefits are probably negligible versus simple exercise. So what I say to my patients who ask about PRP is the following, you can certainly try PRP and you are within your rights to do so. There is no strong scientific, scientific evidence, consensus or basis for me to recommend this for you based on the evidence at the time of speaking.
I'm happy to provide you some resources for you to read and you can come to your own decision or you are more than welcome to consult a sports physician or an orthopedic surgeon who might specialize in this area. So, so that's a, that's a snapshot of the kind of rhetoric that I use for patients who ask about PRP. I am honest, but I'm, but I am also careful not to demand that they choose a particular treatment that might satisfy my bias in particular. And then this is the key of shared decision making. You present the evidence and you leave that person's space to come to their own decision in their own time. So p i P seems to be just another thing in musculoskeletal medicine that is pretty similar to all the other things that we have available. It doesn't deserve the media hype, but I think continued research is warranted in light of the aforementioned limitations of current evidence. As it stands, there is no strong scientific evidence to support the routine use or recommendation of PRP in clinical practice for the management of rotator cuff related shoulder pain. Until this changes, I remain skeptical. I cover the role of injection therapy in detail in my online shoulder course. There is a one hour module dedicated to this topic. Having up-to-date knowledge in this area can help conversations that you have with your patients and colleagues and lead to more informed clinical decision making. Check out the course at www.shoulderphysio.com.