September 2, 2026; By rarebluemoon
Someone comes in with a knee that has hurt for two years. They have read about platelet-rich plasma. They want to know one thing: does it work?
I understand the question. I also think it is the wrong one, and that the wrongness of it explains a great deal about why patients spend thousands of dollars on injections that do nothing for them.
Here is what the evidence actually looks like when you sit down with it.
A quick definition, because the marketing language obscures it.
Platelet-rich plasma starts with your own blood. A small volume is drawn and spun in a centrifuge, which separates it into layers and allows the platelet-dense fraction to be collected. That concentrate is then injected at the site under evaluation. Platelets carry growth factors, and the working hypothesis is that delivering them in concentration influences the local healing environment.
Prolotherapy works differently. It uses an irritant solution, usually dextrose, injected where ligaments and tendons attach to bone, on the theory that a controlled local response prompts tissue remodeling.
Neither involves donor material. Neither is a stem cell therapy, a distinction that matters both clinically and legally in Florida, and one that clinics blur more often than they should.
In 2021, the RESTORE trial was published in JAMA. It was a well-designed piece of work: 288 participants aged 50 and older with symptomatic knee osteoarthritis, randomized to three PRP injections or three saline injections, with participants, injectors, and assessors all blinded. At twelve months, PRP produced no significant improvement in knee pain or in medial tibial cartilage volume compared with saline.
That is about as clean a negative result as this field produces.
Then in 2025, a meta-analysis in the American Journal of Sports Medicine pooled randomized trials of PRP against placebo and reached a different conclusion. PRP delivered clinically relevant functional improvement out to twelve months, exceeding the threshold for a difference patients actually notice.
Two credible sources. Opposite conclusions. This is the point where most clinics pick whichever paper suits their business and stop reading.
The meta-analysis went further, and this is the part I wish every patient knew.
The authors separated trials by platelet concentration, using a cutoff around one million platelets per microliter. Both higher and lower concentration preparations produced meaningful improvement at three and six months. But the benefit was still there at twelve months only in the high-concentration group.
In other words, PRP is not one product. It is a category of products that differ substantially from one another, and those differences appear to change the result.
The American College of Rheumatology reached the same underlying observation from the opposite direction. Its guideline with the Arthritis Foundation strongly recommends against PRP for knee and hip osteoarthritis, and among the stated reasons is concern about the heterogeneity and lack of standardization across available preparations.
Read those two documents together and a coherent picture emerges. A guideline body says the evidence is too inconsistent to recommend. A meta-analysis suggests part of that inconsistency traces to what is actually in the syringe. Both can be right at once.
Suppose the preparation is excellent. There is still a question underneath it that determines everything: are we injecting the structure that is actually causing the pain?
In 2008, researchers examined knee MRIs from a community sample in Framingham, selected without regard to whether anyone had knee complaints. Meniscal tears turned up frequently in people with no symptoms at all. Roughly six in ten subjects with a meniscal tear on imaging reported no knee pain, aching, or stiffness in the previous month.
Sit with the implication. If a patient with knee pain gets an MRI, a tear is found, and everyone concludes the tear is the problem, there is a substantial chance everyone has just made an assumption rather than a diagnosis. The finding may be real and irrelevant at the same time.
Now stack the two variables. A patient receives an injection of a preparation whose platelet concentration nobody measured, aimed at a structure that may not be generating their symptoms. When it fails, the conclusion drawn is usually “PRP does not work.”
That conclusion is not supported. What failed might have been the product, the target, or both.
My approach is unglamorous, and it disappoints people who arrive wanting a procedure scheduled this week.
Before an injection is discussed, we establish what is actually wrong. Imaging is part of that, with its limitations acknowledged. When symptoms and imaging disagree, looking is more informative than guessing.
We also establish a baseline. Pain scores, function, and range of motion are recorded before anything happens. Without that, neither of us can honestly say afterward whether it helped.
If you are considering regenerative injections in West Palm Beach or anywhere else, these questions will tell you more about a clinic than any brochure:
I offer these therapies. I also think the field has been oversold, and the overselling has come at the direct expense of patients who could have been helped by a more careful diagnosis and were sold a syringe instead.
The useful question is not whether regenerative injections work. It is whether this preparation, delivered to this structure, in this patient, with a baseline recorded and a plan for reassessment, is a reasonable thing to try.
That question takes longer to answer. It also happens to be the only version worth asking, and it is the difference between a therapy and a transaction.
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