Achilles Paratenonitis: How to Manage It

Achilles paratenonitis (also known as Achilles paratendinitis) is a common but often under-recognised cause of acute Achilles pain. Unlike Achilles tendinopathy, which involves swelling of the tendon itself, paratenonitis is inflammation of the paratenon — a thin, sheath-like structure that surrounds the tendon and helps it move. It occurs in runners, jumpers, and court-sport athletes, and is often misdiagnosed as Achilles tendonitis. So how do we diagnose Achilles paratenonitis, and what can we do about it?

What is Achilles paratenonitis?

The paratenon is a sheath that surrounds the Achilles tendon, allowing it to glide smoothly during ankle movement. In Achilles paratenonitis, repetitive friction inflames this sheath, causing pain and thickening around the tendon. The underlying tendon structure may still be normal, especially in the early stages, which is the key difference from Achilles tendinopathy.

Symptoms and clinical assessment

People with Achilles paratenonitis typically report:

Pain and swelling around the Achilles tendon, 2–6 cm above the heel bone
A creaking or squeaking sensation (crepitus) when moving the ankle — a hallmark feature, caused by the tight, inflamed sheath moving over the tendon
Swelling along the sides of the Achilles tendon
Pain during and after activity, particularly running or fast walking
Little or no morning stiffness — unlike Achilles tendonitis, where the first steps of the day are typically painful

On examination, we often find tenderness along the tendon, on its inner or outer surface. Usually, we feel creaking or crepitus as the ankle moves up and down. The Achilles tendon itself is typically of normal consistency, without focal thickening or nodularity.

Imaging in Achilles paratenonitis

Because it’s often difficult to tell Achilles paratendinitis from tendonitis, imaging helps confirm the diagnosis — and is important for ruling out other causes of Achilles or ankle pain.

Ultrasound

Ultrasound is the most practical test. In Achilles paratenonitis, the paratenon thickens, sometimes with fluid or increased blood flow around the tendon. The tendon itself usually looks normal, with no thickening or abnormal blood flow.

MRI

MRI is more sensitive than ultrasound to subtle inflammation. It shows oedema and thickening around the tendon (peritendinous change), while the Achilles tendon itself shows a normal signal — meaning its structure is intact. MRI can also diagnose other causes of ankle pain, such as posterior ankle impingement or a calcaneal stress fracture.

Differential diagnosis

It’s essential to distinguish Achilles paratenonitis from other causes of pain in the Achilles region:

Treatment of Achilles paratenonitis

Management focuses on reducing inflammation and load while preserving function.

Relative rest. Reduce or stop high-load activities, such as hill sprints and plyometrics.

Ice therapy. Applied locally to reduce swelling.

NSAIDs. A short course of oral ibuprofen or a prescription NSAID can reduce pain and inflammation, and frequent topical NSAID use, such as Voltarol cream, can also help.

Heel lifts. Reduce strain on the tendon during walking.

Gentle stretching and mobility. Avoid aggressive Achilles loading early on — we often limit loading to weighted isometric work rather than isotonic or eccentric exercise at first.

Cross-training. Low-impact activities such as cycling, the elliptical, and swimming maintain fitness while the paratenon inflammation settles.

Manual therapy or soft-tissue mobilisation. It may help reduce adhesions around the tendon.

In persistent cases, we sometimes consider an ultrasound-guided injection. Cortisone injections are rarely used, given the risk of tendon weakening and rupture. Instead, some doctors perform a hydrodissection using sterile water and local anaesthetic, which reduces inflammation without the same risk of weakening the tendon.

Surgery is rarely required, but debridement of the inflamed paratenon may be considered in chronic, non-responsive cases.

Frequently asked questions about Achilles paratenonitis

What causes creaking or crepitus in the Achilles tendon?

The classic cause is Achilles paratenonitis — the inflamed, thickened sheath (paratenon) creaks or squeaks as it moves over the tendon during ankle movement. It’s a hallmark sign that helps distinguish paratenonitis from Achilles tendinopathy, where crepitus is uncommon.

Do we treat Achilles paratenonitis and Achilles tendonitis differently?

Yes. Achilles paratenonitis responds quickly to relative rest and anti-inflammatory treatment. Achilles tendonitis, by contrast, is treated with heavy tendon loading, such as calf raises and progressive strengthening.

Can Achilles paratenonitis lead to Achilles tendonitis?

We think so. That’s why we treat paratenonitis promptly and thoroughly — to reduce the chance of it progressing to Achilles tendonitis, which is generally more difficult to manage.

How long does Achilles paratenonitis take to settle?

Because it responds well to relative rest and anti-inflammatory measures, paratenonitis often settles more quickly than Achilles tendinopathy — typically over a few weeks, provided the load is reduced early. Delaying treatment risks a longer recovery.

Can I keep running with Achilles paratenonitis?

Not at high load, while it’s painful. We reduce or stop running (especially hills and sprints) and switch to non-impact cross-training, with a graded return once the crepitus and pain settle.

Is a cortisone injection used for Achilles paratenonitis?

Rarely. Cortisone around the Achilles carries a risk of tendon weakening and rupture, so where an injection is needed, we prefer a hydrodissection with sterile water and local anaesthetic, under ultrasound.

Final word from Sport Doctor London about Achilles paratenonitis

Achilles paratenonitis (or paratendinitis) is a treatable cause of Achilles-region pain that involves inflammation of the tendon sheath rather than the tendon itself. Early diagnosis is critical to avoid progression into Achilles tendonitis, which responds less readily to rest and anti-inflammatory treatment. For athletes, prompt recognition can mean the difference between minimal time off running and a significant injury. If you have Achilles pain that doesn’t look like a typical tendon problem — especially with creaking or crepitus — see a sports medicine doctor for a timely diagnosis.

Dr Masci can assess Achilles pain in London, including an ultrasound in the clinic. Contact the team here or call +44 (0) 203 488 0350.