Radiology glossary

Achilles Tendinopathy — What It Means on Your Report

Part of: General orthopedic findings, explained

Full explainer: Achilles Tendinopathy — What It Means on Your Report

The Achilles tendon — the great cord connecting the calf muscles to the heel — is worn, thickened, and irritated. As the body's largest and strongest tendon, it absorbs enormous loads with every step and push-off, and when training load outpaces the tendon's slow repair — the classic story in runners — its fibers become disorganized, the tendon thickens, and abnormal vessels grow in. Radiologists distinguish two patterns: mid-portion tendinopathy, a thickened sore zone a few centimeters above the heel, and insertional tendinopathy at the heel attachment itself, which often travels with a bony prominence (Haglund's deformity) and bursitis — and the two are managed differently. The typical symptom is aching and stiffness in the tendon, worst with the first steps in the morning or at the start of a run, easing as it warms up. A painful, thickened Achilles is also a weakened one, which is why sudden rupture is the complication doctors watch for — though most tendinopathy never ruptures. The finding describes the tendon's worn state; recovery is a slow rebuilding of its capacity.

What it means on CT

CT is not the test for Achilles tendinopathy — the tendon's internal wear is invisible on it. CT may show the bony prominence of Haglund's deformity or calcification within a chronic tendon, but the tendinopathy itself cannot be assessed. Tendon evaluation belongs to ultrasound and MRI. CT occasionally enters the picture for related reasons — mapping bone in detail after a trauma, evaluating a bony prominence associated with the tendon, or searching for an alternative diagnosis when the presentation is unclear. But the tendon’s internal condition, which is the heart of this diagnosis, is invisible to it. If a CT appears in your records, it was addressing a neighboring question your doctor can identify.

What radiologists look at next

For Achilles tendinopathy, the radiologist measures the tendon's maximum thickness and compares it with the normal side, noting whether the disease is mid-portion or insertional — the critical distinction. They assess fiber disorganization, neovascularity on Doppler, and any partial tears or calcific deposits within the tendon. The surroundings are surveyed: the retrocalcaneal bursa for bursitis, the paratenon for inflammation, and the calcaneus for Haglund's prominence or edema. The report separates pure tendinopathy from partial tearing, since the two follow different paths.

Where it commonly shows up

• Achilles tendon
• heel
• ankle
• posterior ankle
• calcaneus

Questions to ask your doctor

• Is this mid-portion or insertional tendinopathy?
• Is there any partial tear within the tendon?
• Is there associated bursitis or a Haglund's prominence?
• What training or footwear factors are overloading it?
• How long does recovery usually take?

Common questions

What does Achilles tendinopathy feel like?

Typically aching and stiffness in the tendon above the heel, worst with the first steps in the morning or when starting exercise, easing as it warms up — then aching again afterward. The tendon may feel thickened or tender to squeeze. A sudden sharp “kick” sensation with immediate weakness is different and needs urgent evaluation for rupture.

Can it rupture?

A degenerated tendon is weaker than a healthy one, so the risk is higher than normal — but most tendinopathy never ruptures, especially with sensible load management. Warning signs of rupture include a sudden pop, immediate sharp pain, and inability to push off the foot. Your doctor will explain what to watch for and how to protect the tendon during recovery.

What is the difference between mid-portion and insertional tendinopathy?

Mid-portion affects the tendon's middle zone, a few centimeters above the heel, and usually responds well to progressive loading programs. Insertional affects the attachment at the heel bone itself, often with bursitis and a bony prominence, and it is more irritable — certain stretches that help the mid-portion kind can aggravate it. The distinction shapes the plan, which is why the report specifies it.

Related conditions

• Tendinopathy — What It Means on Your Report
• Bursitis — What It Means on Your Report
• Plantar Fasciitis — What It Means on Your Report