Achilles tendinopathy

What it means

Achilles tendinopathy describes changes within the Achilles tendon, the thick, strong cord connecting the calf muscles to the heel bone, that develop from repeated stress over time rather than a single injury. Instead of the classic picture of inflammation, imaging and tissue studies show the tendon fibres becoming disorganized, thickened, and less orderly than normal tendon structure, alongside small blood vessels growing into areas usually devoid of them. It can affect the middle portion of the tendon, several centimetres above the heel, or the lower portion where the tendon attaches to the heel bone, known as insertional Achilles tendinopathy, which behaves slightly differently and is often linked to a bony prominence at the back of the heel.

Why it appears on a CT or MRI report

MRI and ultrasound are the main tools for assessing the Achilles tendon, since they show soft tissue detail that X-ray and CT cannot. A report describing tendinopathy typically notes thickening of the tendon, changes in its normal signal or texture suggesting disorganized fibres, and sometimes fluid around the tendon. At the insertional form, imaging may also show a bone spur at the back of the heel or irritation of the nearby cushioning sac (bursa). Radiologists distinguish tendinopathy, which reflects degeneration and thickening, from a partial or complete tear, a more significant structural disruption, since the two are managed differently.

What it usually means

Achilles tendinopathy is extremely common, particularly in runners, in people who have recently increased their activity level or changed footwear, and in the general population from midlife onward as tendons naturally lose some resilience with age. It typically develops gradually, with aching or stiffness at the back of the ankle that is often worse first thing in the morning or at the start of exercise and may ease somewhat with movement, only to return afterward. Most cases improve without surgery. The best-studied treatment is a structured, progressive loading exercise programme, often involving slow heel-raise and heel-drop exercises, which encourages the tendon to remodel and strengthen over several months. Activity modification, supportive footwear, and gradual return to sport also play an important role. A smaller number of persistent cases, particularly ones that do not respond to several months of dedicated exercise therapy, may be considered for other treatments or, occasionally, surgery.

When to follow up

Mild, longstanding thickening seen incidentally on a scan, without significant symptoms, generally needs no urgent action. See a doctor or physical therapist if you have ongoing pain, stiffness, or swelling at the back of the ankle, especially if it is affecting your activity or not improving with rest, since early guided exercise therapy tends to work better than waiting. Seek prompt care for a sudden sharp pain with a snap or pop and difficulty pushing off, which raises concern for a tear rather than tendinopathy and needs urgent assessment.

A plain-language way to picture it

Picture a thick rope made of many tightly wound strands. Repeated heavy strain, without enough time to recover between uses, can gradually fray and loosen those strands so the rope becomes thicker but less orderly and slightly weaker, even though it is not cut through. Achilles tendinopathy is that gradual fraying process within the tendon, which is why patient, steady strengthening, giving the strands time to reorganize and rebuild, tends to work better than rest alone.