Platelets are not just for clotting.

PLATELET-RICH PLASMA, EXPLAINED

Platelet-rich plasma [PRP, a concentrate made from your own blood] is autologous. It comes from you and goes back into you on the same visit. There is no donor material and no drug.

How is a PRP injection done?

• Blood draw. A standard draw from a vein. The volume depends on the target.
• Centrifugation. The sample is spun to separate red cells from plasma. This concentrates the platelet part.
• Preparation. The concentrate is drawn off. Platelet concentration, leukocyte content (white cells) and volume are chosen for the tissue being treated. A tendon and an arthritic joint do not want the same preparation.
• Image-guided placement. Ultrasound or fluoroscopic (live X-ray) guidance puts the injection where it is meant to go. This step separates a targeted injection from a hopeful one.
• Load management afterward. What you do in the next six weeks has a real effect on the result.

How does PRP work?

Platelets are not only clotting cells. Their alpha granules carry PDGF, TGF-β, VEGF, EGF and IGF-1. These are signals. They call in local progenitor cells (early cells that can mature into new tissue), drive angiogenesis (new blood vessel growth) and shape how collagen is laid down and organized. In a healthy acute injury, this chain of events runs on its own and finishes. In a chronic one, it has usually stalled.

Why a repair stalls in the first place

Three things commonly hold it there. Only one of them is mechanical.

• Metabolic inflammation. Chronic low-grade inflammatory signaling keeps tissue in a breaking-down state instead of a rebuilding one. It is NF-κB-driven and kept going by fat tissue and liver crosstalk.
• Insulin resistance and hyperinsulinemia. These impair delivery through the smallest blood vessels. They also degrade collagen quality directly. A tendon in an insulin-resistant patient is repairing with poorer raw material.
• Load, economics and sleep. The tissue is hurt again before it firms up. That is usually because the person cannot stop doing the thing that hurts it. Broken sleep makes it worse, because most tissue repair signaling happens at night.

This is why we look at your metabolic panel before treating a tendon. It is not upselling. It is the difference between calling up a repair process and asking one to run where it has already failed once.

How many treatments, and how long

Most tendon and joint protocols involve one to three injections spaced several weeks apart. Response is gradual. This is a biological process, not an anesthetic. People who expect same-day relief are usually disappointed at two weeks and satisfied at three months. Some people do not respond at all. We say so here, not after you have paid for a series.

What the visit and recovery look like →

Not all PRP is the same preparation

This is the least understood fact about the treatment. It explains much of the mixed results in the published literature. “PRP” names a category, not a product. Two clinics can deliver preparations that differ several-fold.

• Platelet concentration. Systems vary widely in how much they concentrate above baseline. More is not automatically better. There is evidence of a ceiling above which extra platelets add nothing.
• Leukocyte content. Leukocyte-rich preparations bring white cells and extra inflammatory signaling. In a tendon that may be useful. Inside a joint it is more debated, and leukocyte-poor preparations are generally preferred inside the joint.
• Red cell contamination. Leftover red cells release free hemoglobin and iron into the target. That is pro-oxidant (it promotes oxidation, a chemical stress on tissue) and works against the repair.
• Activation. Some protocols activate the platelets before injection. Others rely on collagen in the tissue itself to activate them. This changes how quickly the growth factors are released.
• Volume. What suits a knee joint is not what suits a plantar fascia.

The most important of those differences is the white cell concentration. It decides whether a preparation provokes inflammation or avoids it. So it decides whether it belongs in a joint or on a tendon. That decision is set out in full on leukocyte-rich and leukocyte-poor PRP.

A clinic using one protocol for every patient and every tissue has chosen convenience. If you read that trials of PRP are inconsistent, this is a large part of why: they were not testing the same treatment.

Should PRP be injected with image guidance?

A preparation placed next to the target, not in it, does nothing. Studies of blind injection accuracy are humbling across most sites. A knee without an effusion (fluid in the joint), a subacromial space, a hip joint, a specific degenerate segment of tendon: all are missed at rates that would surprise most patients.

Ultrasound also does something guidance is rarely credited for. It lets us see what we are treating before we treat it. A tendon that looks intact, a partial tear nobody suspected, a bursa doing more than the tendon: each changes the plan in the room, not three months later.

What we do at the same visit

An injection is the smallest part of the appointment. Around it is an examination that includes the joints above and below. We review imaging against that exam, not in place of it. And we look at the metabolic picture, which decides what raw material the repair will run on.

That last piece is the practice’s real position, not an add-on. Tendon and cartilage repair are anabolic (building) processes, and they run on the material available. Asking a tendon to rebuild in an insulin-resistant, chronically inflamed, sleep-deprived body is asking it to do what it already failed to do once.

What can’t PRP do?

• It does not regrow cartilage in an arthritic joint.
• It does not repair a large retracted tendon tear.
• It does not work quickly, and anyone who promises relief next week is describing a different mechanism.
• It does not work for everyone. The honest figure is that a meaningful minority get nothing.
• It does not remove the need for the loading program, which does much of the work.

Related reading

• Platelet lysate — when platelets are the problem
• Why the trials disagree
• What we treat
• Am I a candidate?
• Recovery timeline
• Risks and side effects

A short history, and why it matters to you

PRP was not invented for orthopedics. It came out of transfusion medicine. It was used in cardiac surgery and oral and maxillofacial surgery from the 1980s onward. Surgeons there wanted a way to improve graft and wound healing. Its move into musculoskeletal medicine came later. Professional athletes using it, and the coverage that followed, sped that up considerably.

That history explains two things. It explains the strong safety record: autologous blood products have been given to people for a long time. It also explains the marketing problem. A treatment made popular by athletes attracts claims that outrun the evidence. That is because the people it was publicized in are young, healthy, extremely well rehabilitated, and nothing like the average patient.

Reading a PRP study without being misled

If you are researching this yourself, four questions separate a useful study from a misleading one.

• What was the control? Against no treatment, almost anything looks good. Against an injected control, the comparison means something.
• How long was follow-up? Stopping at eight weeks favors corticosteroid. Running to a year usually reverses the result.
• Was the preparation characterized? Were platelet concentration and leukocyte content reported, or assumed? Most trials do not report them.
• Who was excluded? This is the one nobody checks. It is the reason trial results may not describe you at all.

That last question is the subject of why your insurer will not pay for this. It is the most useful thing on this website to understand before deciding anything.

What results can I realistically expect from PRP?

Not a cure, and not nothing. Take a well-selected patient with a degenerate tendon. A reasonable expectation is meaningful improvement in what the tissue tolerates. It arrives gradually between six weeks and three months and keeps firming up for months after that.

For an arthritic joint, a reasonable expectation is a period of less pain and better function, commonly six to twelve months. That happens in a joint whose imaging has not changed. Repeat treatment is normal, not a sign of failure.

And for a minority of people in both groups, nothing. That figure belongs in the conversation before treatment, not after.

What people ask before their first injection

Is PRP a stem cell treatment?

No. PRP contains concentrated platelets and the growth factors they carry. It has no stem cells at all. Any clinic calling it stem cell therapy is misdescribing what is in the syringe. What that phrase actually covers.

Does it hurt?

The draw is an ordinary blood draw, and local anesthetic is used at the skin. Discomfort varies sharply by site. A knee joint is straightforward. A plantar fascia is among the more uncomfortable injections in musculoskeletal medicine, and it is done under a regional block. What the visit involves.

Why do I have to stop anti-inflammatories?

Because they suppress the exact inflammatory signaling the injection was given to provoke. We agree on the window with you, rather than applying a blanket rule. Why the early phase matters.

How many injections will I need?

Commonly one to three, depending on the tissue and the response, spaced several weeks apart. Partial response at three months is the clearest reason for a second. The assessment points.

Will it regrow my cartilage?

No. Nothing available today reliably does, and a treatment sold on that promise is overselling. What PRP appears to do in a joint is change the environment, not the structure. What that means for an arthritic knee.

Is one clinic’s PRP the same as another’s?

No, and this is the least understood thing about it. Platelet concentration, leukocyte content and volume all vary. They should be chosen for the tissue being treated. Questions worth asking any clinic.

Is it covered by insurance?

Generally not. Medicare and the commercial payers decline to cover it. That is why this is a self-pay practice. What that classification is actually deciding.

How long do PRP injections last?

In an arthritic joint, a reasonable expectation is a stretch of less pain and better function, commonly six to twelve months, while the X-ray stays the same. Repeat treatment is normal, not a sign of failure. In a worn tendon, the improvement arrives gradually between six weeks and three months. It keeps firming up for months after that. A minority of people get nothing.

What is the downside of PRP injections?

It is slow, because it is a biological process, not an anesthetic. People who expect same-day relief are usually disappointed at two weeks. It does not regrow cartilage or repair a large retracted tendon tear. It does not work for everyone, and a meaningful minority get nothing. And it does not replace the loading program, which does much of the work.

Is PRP worth the money?

For a well-selected patient, a realistic result is not a cure and not nothing. It is meaningful improvement in what a tendon tolerates, or six to twelve months of less pain in an arthritic joint. The deciding factors are the tissue, the preparation, accurate image-guided placement and the metabolic state of the body doing the repair. That is why we look at your metabolic panel before we treat.

What the injection is actually competing with

A repair is an anabolic (building) process, and building runs on what the body can supply. So the useful question is not “does PRP work” but “what is it working against.”

In a metabolically healthy person, it is working with the tissue. In someone carrying metainflammation, it is working against a standing headwind. Insulin resistance degrades delivery through tiny blood vessels to an enthesis (where tendon meets bone). That spot was already the part of the limb with the worst blood supply. Glycation (sugar bonding to protein) cross-links the new collagen into something stiffer and more brittle than what it replaced. And a circulating inflammatory signal holds the whole area in a demolition posture, not a construction one.

You can deliver a perfect growth-factor signal into that and get very little. Not because the treatment failed. It is because it was asked to build without materials.

Which is why we ask about things that sound unrelated

Your fasting glucose. Your sleep. Whether the job lets you offload the limb. Whether you live alone.

None of that is a lead-in to selling you something, and none of it is wellness advice. Each one is an input to the same equation. A clinic that treats the tendon while ignoring them is doing precise work on a small part of the problem. That is the definition of a symptom-based silo. It is the reason so many people arrive here after competent care that did not help.

Where this actually sits with the FDA

Patients ask whether this is experimental, usually because of the wording in a denial letter. It is not. Whether a plan pays for something, and what that something is, are two separate questions.

• It is approved by the FDA for use in humans. The preparation systems are regulated medical devices with FDA clearance. Platelet-rich plasma is given under that framework. This is established medical practice, not a trial and not an experiment.
• The material is your own blood. It is drawn from you, concentrated, and returned to you in the same visit. There is no donor material and no drug.
• You are not enrolled in anything. No study, no placebo arm, no protocol. A physician assesses you and treats you.

So why will my plan not pay for it?

Because the language in that letter is coverage language, not regulatory language. It means the plan has decided it will not carry the cost of this across its whole membership. It is a budget decision about what a plan buys.

It is not a statement that the procedure is unlawful, unproven for you, or experimental in the regulatory sense. Plans decline to cover plenty of lawful, well-established care. They also cover some things with weaker evidence than this.

The practical result for you is simple: this is a self-pay practice. We do not bill insurance. You will know the cost before anything is drawn. What that means for you, including pre-tax accounts.