This tendon usually fails for reasons that are not in the tendon.

ACHILLES TENDINOPATHY

Achilles tendinopathy is degeneration of the tendon, not inflammation. The cause is rarely limited to the tendon. Diabetes, fluoroquinolone antibiotics and a tendon you stand on all day all drive it. Loading is the treatment. A biologic such as PRP is added, under ultrasound guidance, only after a correct twelve-week program has plateaued.

The Achilles is the strongest tendon in the body. When it breaks down, the reason is almost never limited to the tendon. And this is the structure where that stops being a theory and becomes a list of things we can measure.

What is the difference between midportion and insertional Achilles tendinopathy?

Midportion tendinopathy sits two to six centimeters above the heel bone. That is a watershed zone, where blood supply is poorest. Insertional tendinopathy sits where the tendon attaches to the calcaneus (heel bone). It often comes with a bone spur, with the retrocalcaneal bursa (a fluid sac behind the tendon) involved. Sometimes there is calcium inside the tendon itself.

They respond differently to everything. Midportion responds well to eccentric loading (lowering the heel slowly). Insertional often gets worse with the same exercise done off a step. That is because dorsiflexion (pulling the foot up) presses the insertion against the bone. Getting this wrong is one of the most common reasons an Achilles rehab program fails. It is the first thing we establish here.

Is Achilles tendinopathy inflammation or degeneration?

Chronic Achilles pain is degenerative, not inflammatory. The tendon shows disordered collagen, more ground substance (the gel between fibers), and neovascularization. That means new vessels growing in from the fat pad in front, with nerve fibers alongside them. Those nerves are a plausible source of the pain. That is why the tendon can hurt a lot while looking only moderately abnormal on imaging. The same mismatch, and why the word tendonitis keeps leading to the wrong treatment, is on the tendinopathy page.

What causes Achilles tendinopathy besides overuse?

Here is the number that reshapes this whole page. A systematic review and meta-analysis pooled 31 studies. It found tendinopathy substantially more common in people with diabetes. The odds ratio was 3.67 (95% CI 2.71 to 4.97) across 17 studies. The link ran both ways: diabetes was also more common in people with tendinopathy. People with both had had diabetes about 5.26 years longer than people with diabetes and no tendinopathy. Their tendons were also measurably thicker than controls.

That is a dose relationship with how long the exposure lasted, in a structure most people think of as purely mechanical. Glycation (sugar bonding to protein) cross-links collagen. That stiffens the tendon and lowers how much strain it can absorb before it fails. Chronic metabolic inflammation keeps the tissue breaking down instead of rebuilding. And the Achilles has the poorest blood flow of any tendon we treat. So it has the least margin to absorb either.

Then there is the exposure patients are rarely warned about. A systematic review found fluoroquinolone antibiotics associated with tendon injury and rupture. The link is strongest at the Achilles. Did this start within months of a course of one? Then that belongs in the history. It changes how carefully we load you.

And there is the plain human driver, which is not in any paper. You cannot rest a leg. An elbow can be left alone. A tendon you stand on all day never gets the settling period the tissue is asking for.

So the first work here is not the injection. It is finding out what the tendon is being asked to repair in. That means the metabolic panel, the medication history, the sleep and the nicotine exposure. What gets measured, and why it comes before anything else, is on the metabolic health page.

What is the best treatment for Achilles tendinopathy?

A level-1 network meta-analysis looked at nonsurgical treatment for midportion Achilles tendinopathy. It pooled 22 randomized trials and 978 patients. Over the longer term, the wait-and-see approach performed markedly worse than eccentric exercise (standardized mean difference −1.51, 95% CI −2.02 to −1.01). The same analysis found that the extra treatments worth considering were ones added to a loading program, not used in place of it.

That is the shape of the evidence. It is why loading is not something we suggest while you wait for the real treatment. It is the real treatment. A catalyst is a step inside it.

One caveat we will state, not bury. That analysis ranked a high-volume injection containing corticosteroid among the useful add-ons. We do not make that trade at this tendon. The reason is in the caution section below. Shockwave therapy is a reasonable further option with its own evidence base.

When is PRP used for Achilles tendinopathy?

The logic is the same as for any stalled tendon. Send a strong repair signal into a degenerated zone with poor blood supply. Then shape the result with load. The multispecialty regenerative-medicine guidelines review tendon targets among their questions. The order they lay out is the one used here: diagnostic work-up first, rehab alongside, biologic after.

In practice, a candidate has a degenerated tendon. They have finished a correct twelve-week program at the correct location and truly plateaued. Insertional disease responds less well to loading alone. That is where the case for adding something is strongest.

Here is how we do it. Injection here is peritendinous (around the tendon) and ultrasound-guided, with a small volume, not a large one inside the tendon itself. That is because a small target next to a load-bearing structure is not a place to aim a needle by feel. The terrain work starts before the catalyst goes in. A partial tear gets its own plan rather than a referral: a protected start in a heel lift or boot, ultrasound-guided PRP beside the tendon, then loading that builds more slowly and closer ultrasound follow-up.

Ruling out what it is not

• Partial tear — a clear event, a gap you can feel, or a sudden change in a long-sore tendon. This changes the pace of the plan, not the goal: we treat it without surgery, with protected loading and closer follow-up.
• Retrocalcaneal bursitis — pain in front of the tendon, not inside it.
• Posterior ankle impingement — pain when the foot is forced to point down, common in dancers.
• Inflammatory enthesitis — a seronegative spondyloarthropathy (an inflammatory arthritis) can show up as Achilles pain. It needs rheumatology, not an injection.

How it is treated here

• Weeks 0 to 2. Protected weight-bearing, sometimes a heel lift to take load off. Isometric calf holds for pain relief.
• Weeks 2 to 6. Eccentric or heavy slow resistance calf work. Do it off a step for midportion disease, and flat-footed only for insertional.
• Weeks 6 to 12. Building load toward the demand you actually have, including speed if you run.
• Months 3 to 9. Continued loading. Achilles remodeling is slower than any other tendon on this site. Going back to impact early is how people relapse.

Why this tendon deserves more caution than most

The Achilles carries several times body weight with every step, and it has no backup. No second structure quietly takes over if it fails. That single fact governs how we treat it here. No corticosteroid in or around it without a compelling reason. No large volumes inside the tendon. And no rushing back to impact because someone feels better at six weeks.

Feeling better is not the same as being ready. Tendon pain improves well before tendon capacity does. That gap, comfortable but not yet strong, is exactly where re-injury happens. It is why we keep people loading for months after the symptoms have quieted. A program that stops when the pain stops tends to produce a second episode inside the year.

The two questions that decide this

Everything above comes down to two questions, asked in this order.

• Which Achilles problem is it? Midportion and insertional are not versions of one condition. Midportion responds well to loading. That is why an injection there is a second move, not a first. Insertional responds less well. That is where the case for adding something is stronger. We will tell you which one you have before we tell you what we use.
• Has the loading program actually been done, and was it the right one? Not attempted. Not described in a leaflet. Done, for twelve weeks, at the correct location for the correct problem. People sent here for an injection who never had a correct loading program: that is the single most common finding in this clinic.

Answer both, and the decision usually makes itself. A degenerated midportion tendon in someone who truly finished a proper program and plateaued is a reasonable candidate. An insertional problem with the same history is a stronger one. A partial tear is a candidate too, on a slower and more protected plan. Even a complete rupture does about as well without an operation: in a Norwegian trial of 554 adults, surgery “was not associated with better outcomes than nonoperative treatment at 12 months” (Myhrvold and colleagues, 2022). A partial tear still has tendon in continuity, so it starts from a better place. The one exception to rush is a sudden gap with loss of push-off, which can mean a complete rupture and gets same-week imaging.

When it still does not settle

Check the diagnosis first. Look hard for a missed partial tear or an inflammatory cause. Then check whether the loading was right for the location, because a midportion program used on an insertional problem fails reliably. Then check what has changed in the terrain since the first visit. Only after those three does a second injection or a surgical opinion belong in the talk.

What people ask about an Achilles that will not settle

Is an injection the answer for Achilles tendinopathy?

Not as a first move for midportion disease. That is because loading is the treatment with the strongest support here. And a catalyst works on a repair that has stalled, not one that has never been properly loaded. Where a biologic does fit in the order is set out on the timing page.

Should I have a cortisone injection instead?

Around the Achilles, generally no. The link with rupture makes it a poor trade in a structure with no backup, whatever the short-term relief. The full comparison is on the cortisone page.

I have diabetes. Does that change my chances?

It changes the odds of having this at all. Tendinopathy was roughly three and a half times as common in people with diabetes in the pooled data. A longer duration of diabetes carried more of it. It is also the thing on your list you can change most. That is why we start with the bloodwork.

I took an antibiotic and this started. Is that related?

Possibly, if it was a fluoroquinolone. It is worth telling us, because it changes how carefully we load you. It also changes how long we expect remodeling to take. How that feeds into the decision is on the candidacy page.

How long before I can run?

Months, not weeks. The gate is how much load you tolerate, not the calendar, because capacity returns well after comfort does. The honest version of the schedule is on the recovery timeline.

Does PRP work for insertional Achilles tendinopathy?

Insertional disease is where the case for adding PRP is strongest. That is because it responds less well to loading alone than midportion disease does. It still starts with the right program: flat-footed calf work, not exercises off a step. That is because dorsiflexion presses the insertion against the heel bone. PRP comes in when that correct program has been done for twelve weeks and has plateaued.

Will Achilles tendinopathy heal with rest?

Rest alone rarely fixes it. In a pooled analysis of 22 trials and 978 patients, the wait-and-see approach did markedly worse over the longer term than eccentric exercise. There is also a practical problem: you cannot rest a leg you stand on all day. The tendon needs the right load, in the right amount, for months.

Can PRP treat a partial Achilles tear?

Yes, as part of a protected plan. We confirm the tear on ultrasound, settle it in a heel lift or boot, place PRP beside the tendon under ultrasound, and then rebuild load more slowly than we would for tendinopathy. Most partial tears heal this way without surgery. Inflammatory enthesitis is worked up with a rheumatologist first, and a tendon that has not yet had a correct twelve-week loading program and the metabolic work starts there.

How is PRP injected into the Achilles tendon?

Around the tendon, not into it in bulk. The injection is peritendinous and ultrasound-guided, because a small target against a load-bearing structure is no place to aim a needle by feel. We do not put a large volume inside the tendon itself. The loading program follows the injection, and that is what organizes the repair.

Related reading

• Why the word tendonitis produces the wrong treatment
• Why we ask for your bloodwork
• Plantar fasciitis
• The ankle sprain that never came right
• What recovery here looks like
• Risks and side effects