You were told tendonitis. The tendon is not inflamed.

PRP FOR TENDONITIS

PRP for tendonitis aims to restart a repair process that stalled. It does not aim to suppress inflammation, because a chronically painful tendon is not inflamed. It shows messy collagen and new vessels carrying nerve fibers. Concentrated platelets release growth factors into a zone with poor delivery. They are injected under ultrasound guidance, alongside a loading program.

The word is wrong, and the word is why the treatment keeps failing. Anti-inflammatories, rest and a steroid injection all aim at inflammation that stopped being there months ago.

Is chronic tendonitis actually inflammation?

When a chronically painful tendon is biopsied, what everybody expects to find is not there. There are no real numbers of inflammatory cells. Instead there is collagen disarray — fibers that should run side by side lying in messy bundles. There is more ground substance (the gel between the fibers). And there is neovascularization: new small vessels growing into the tendon from outside, each one with nerve fibers alongside.

That last detail explains the pain. Nerves arrive with the vessels. So a tendon can hurt a great deal while looking only a little abnormal on a scan. How bad the picture looks and how bad the pain is routinely fail to match.

The correct term for this is tendinopathy. Tendinosis is used when the focus is on the degeneration itself. “Tendonitis” describes an inflammatory condition, and a chronic tendon mostly is not one. The ending is not fussiness. -itis points every treatment choice that follows toward suppressing inflammation, and that is the wrong target.

Why do anti-inflammatories, rest and steroid shots keep failing?

Follow the logic the word sets up. If the problem is inflammation, a non-steroidal anti-inflammatory should fix it. Rest should let it settle. A corticosteroid injection should fix it for good. Each of those follows reasonably from a false starting point.

Anti-inflammatories ease pain for a while and do nothing to the messy collagen. Rest is worse than neutral. A tendon that is not loaded gets weaker, and the thing that lines collagen up along the line of force is force. A corticosteroid injection matters most of the three, because it works — briefly and convincingly. Yet the twelve-month data in lateral elbow tendinopathy has it doing worse than doing very little at all. It is a loan against the tendon, and the repayment is real.

So people arrive here having done three sensible things. None of them addressed the problem, and they have concluded that nothing works. What actually happened is that nothing they tried was aimed at the right thing.

Why doesn’t tendonitis heal on its own?

Two brakes hold a degenerate tendon in that state. The first is mechanical and local. Tendons at the classic sites — the Achilles midportion, the common extensor origin at the elbow, the gluteal insertion — have poor blood supply exactly where they fail. There is little margin for repair to begin with.

The second is body-wide, and it gets missed almost everywhere. Insulin resistance and raised blood sugar glycate collagen, cross-linking it so it gets stiffer and fails at lower strain. A tendon under that metabolic load lays down worse tissue than the tissue it is replacing. Chronic metabolic inflammation — the low-grade kind that has nothing to do with the acute inflammation the name implies — holds the tissue in a breakdown state, not a rebuilding one. This is set out at length on metabolic health and tissue repair. It is the most common reason a technically correct treatment falls short.

The systemic number behind every tendon on this site

Tendinopathy is treated almost everywhere as a loading problem, and load truly is half of it. The other half shows up when you compare groups of people instead of activities.

A systematic review with meta-analysis pooled 31 studies on tendinopathy and diabetes. Tendinopathy was substantially more common in people with diabetes — odds ratio 3.67 (95% CI 2.71 to 4.97) across 17 of those studies. The link also ran the other way. Diabetes was more common among people with tendinopathy. Some people had both. They had carried diabetes about 5.26 years longer than people with diabetes and no tendinopathy. Their tendons were also measurably thicker than controls on imaging.

How long people were exposed mattered. That is what you would expect if the mechanism is glycation slowly cross-linking collagen. It stiffens the tendon, lowers the strain it can take before it fails, and slows the repair once it has. It is not what you would expect if the answer were just that some people do more with their arms.

This is the general finding. Each tendon then has its own evidence on top of it, and that evidence differs by site. The Achilles has the fluoroquinolone link and the loading data. The rotator cuff has a blood sugar control finding that changed retear rates after repair. The gluteal tendons have a hormone trial whose effect was gated by body mass. We put the numbers on the page they belong to, instead of repeating one number everywhere. What we measure is on the metabolic health page.

How does PRP work for tendonitis?

The reasoning is specific, not general. Concentrated platelets release growth factors into a zone that has poor delivery and has stopped remodeling. The goal is to restart a repair process that stalled, not to suppress anything. That is the opposite goal to a steroid. That is why the two are not interchangeable, and why choosing between them is a real decision, not a preference. That comparison is laid out on PRP compared with cortisone.

The evidence is truly mixed, and it is worth saying so in the same breath. Systematic reviews of PRP across tendon and ligament healing report benefit that varies substantially. It varies by site, by preparation, and by whether a loading program went with it. Ultrasound-guided delivery performs better than blind injection. That is why nothing here is injected by landmark. Against corticosteroid, PRP tends to come out ahead at twelve months, and steroid tends to come out ahead at six weeks. That is exactly what you would expect from a treatment aimed at rebuilding, not at silencing.

The loading program is not the aftercare

This is the part most people get wrong, and it is worth being blunt about. The injection supplies biology. Load supplies direction. Collagen laid down in a tendon that is not being loaded lines up badly. It makes tissue no stronger than what it replaced.

Heavy slow resistance work, stepped up over roughly twelve weeks, is the treatment. The injection is what makes that work possible in a tendon that had stopped responding to it. Some programs are done in name only — a sheet of exercises, done sometimes, at a weight that never goes up. That is the single most common reason a correctly placed injection produces nothing.

Which tendon, and what that changes

“Tendonitis” is not one condition, and the site changes the answer more than anything else does.

• Lateral elbow — the site where the twelve-month evidence most clearly favors PRP over a steroid injection.
• Medial elbow — where the ulnar nerve complicates the picture and has to be ruled in or out before anything is injected.
• Achilles — where the best-known trial is negative. Midportion and insertional cases behave differently here, and we say so instead of burying it.
• Patellar — where the calendar matters as much as the tendon, because the rehab cannot be done mid-season.
• Gluteal — called bursitis for decades, mostly is not. It is driven by squeezing that the usual stretching advice makes worse.
• Rotator cuff — where what is torn decides everything and symptoms will not tell you which.

When it is not the tendon at all

A real share of people sent here for a tendon injection do not have a tendon problem. Pain referred from the neck can show up as a shoulder or elbow that hurts with use; that is covered on shoulder or neck. Lateral (outer) hip pain is often blamed on the tendon when the lower spine is driving it. A trapped nerve can mimic tendon pain closely enough to fool a scan reading. And an inflammatory arthropathy — several tendons in a younger person, with morning stiffness — needs a rheumatologist’s opinion, not a needle.

The assessment exists to answer that before anything is drawn. If the honest answer is that your problem is somewhere else, that is what you will be told.

For a tendon that has stalled, your physician may pair the injection with shockwave therapy for tendon pain.

Frequently asked questions

If it is not tendonitis, why does everyone call it that?

Because the name is older than the histology (the tissue studies). The studies that showed the degenerative picture came after the term was already in every chart, every discharge note and every search box. Clinicians mostly moved to tendinopathy. The world did not follow. There is no harm in the word, as long as it is not steering the treatment.

Should I stop taking anti-inflammatories?

Not always, and not on our say-so if they are being used for something else. They are reasonable for short-term pain control. What they are not is a treatment for the tissue underneath. Taking them for months on the belief that they are working on the tendon is the mistake to avoid.

I have already had a steroid injection. Does that rule me out?

It does the opposite. A steroid injection that helped and then wore off is useful information — it tells us the pain is coming from where we thought. What we do next is change course rather than repeat it, because the twelve-month picture for repeated steroid in tendon is not good.

The tennis elbow page goes through it in detail.

How long before I know whether it worked?

Longer than people expect. Week two often feels like nothing, and that is normal, not a failure — the recovery timeline sets out why. Real change is judged at around three months, alongside the loading program, not before it.

Is PRP better than cortisone for tendonitis?

They aim at opposite things. A steroid shot quiets the area and often works fast. PRP aims to restart repair. Head to head, the steroid tends to look better at six weeks, and PRP tends to look better at twelve months. In tennis elbow, the twelve-month data has a steroid shot doing worse than doing very little. That is why we will not repeat it endlessly.

Is PRP worth it for a tendon that will not heal?

It depends on the tendon, and the evidence is honestly mixed. Results vary by site, by how the PRP is prepared, and by whether a loading program goes with it. Tennis elbow is where the twelve-month evidence most clearly favors PRP. The best-known Achilles trial was negative. Injection under ultrasound does better than a blind injection, so nothing here is placed by feel.

Does diabetes make tendonitis more likely?

Yes. A review pooling 31 studies found tendon problems were substantially more common in people with diabetes, at more than three and a half times the odds. People with both had carried diabetes about five years longer. That fits sugar slowly stiffening the collagen in the tendon. That is why we check your metabolic picture before deciding whether an injection is worth doing.

Do I still need to do exercises after a PRP injection?

Yes, and they matter as much as the injection. PRP supplies the biology; load tells the new collagen which way to line up. Heavy, slow strength work, stepped up over about twelve weeks, is the treatment. The injection makes it possible in a tendon that had stopped responding. An exercise sheet done now and then, at a weight that never goes up, is the most common reason PRP fails.

Related reading

• Injured at work
• PRP compared with cortisone
• Recovery timeline
• Metabolic health and tissue repair
• What we treat
• Am I a candidate?
• Risks and side effects
• The ankle sprain that never came right

In a tendon the question of duration partly dissolves.