Achilles Tendonitis

Achilles tendonitis is a common cause of pain at the back of the heel and lower leg. The Achilles tendon connects the calf muscles to the heel bone, and irritation or overuse can cause pain, tightness, and swelling. Most cases improve with conservative care, and early treatment helps protect the tendon from more serious damage.

Runner on a trail holding the back of her ankle from Achilles tendonitis
Medical illustration of Achilles tendonitis and the tendon fibers

What Is Achilles Tendonitis?

The Achilles tendon is the largest tendon in the body. It lets you point your foot, push off when walking, and rise onto your toes. Repeated stress can irritate the tendon and cause small tears in its fibers, leading to pain, stiffness, and thickening.
 
Achilles tendonitis can develop in the middle of the tendon or where it attaches to the heel bone. Left untreated, a weakened tendon is more likely to tear. If the tendon does tear, Achilles tendon repair restores its strength.

Treatments For Achilles Tendonitis

Most people improve with conservative treatment that calms the tendon and then rebuilds its strength.

Conservative care

  • Activity changes. Reducing running and jumping while the tendon calms down.
  • Physical therapy. Calf stretching and progressive strengthening.
  • Heel lifts and footwear. Reduce strain on the tendon.
  • Bracing or a walking boot. Rests the tendon when pain is severe.
  • Anti-inflammatory medication. Eases pain when appropriate.

When pain persists

  • Custom orthotics. Correct foot mechanics that add stress to the tendon.
  • Image-guided injections. Considered selectively, around but not into the tendon.
  • Achilles tendon repair. Repairs a torn or badly damaged tendon.
  • Debridement. Removes damaged tissue or a bone spur at the heel.

Surgery is rarely needed for tendonitis. It is reserved for a torn tendon or symptoms that do not improve after months of conservative care.

How Achilles Tendonitis Is Diagnosed

Diagnosis begins with your symptoms and activity history and an examination of the tendon for tenderness, thickening, and strength. X-rays can show bone spurs or calcium where the tendon attaches to the heel. Ultrasound or MRI shows the tendon itself and can reveal degeneration or a tear.
 
If heel or calf pain has lasted more than a few weeks, or you felt a pop, have it evaluated.
Illustration of the Achilles tendon and heel

What Causes Achilles Tendonitis?

Achilles tendonitis usually builds up from repeated stress rather than a single injury. Common causes and risk factors include:

Overuse

Running, jumping, and court sports, especially with a sudden increase in training.

Tight calf muscles

Add strain to the tendon with every step.

Foot mechanics

Flat feet or rolling in can stress the tendon.

Footwear

Worn-out or unsupportive shoes.

Heel bone spurs

Can rub and irritate the tendon at its attachment.

Age

Tendons lose flexibility and blood supply over time.

Two Types Of Achilles Tendonitis

Where the pain is felt helps guide treatment.

Middle of the tendon

Noninsertional tendonitis

Pain a few inches above the heel.

  • More common in younger, active people
  • The tendon may thicken or swell
  • Often responds well to calf strengthening

At the heel bone

Insertional tendonitis

Pain where the tendon attaches to the heel.

  • Can occur in anyone, active or not
  • Often linked to bone spurs at the heel
  • Heel lifts and footwear changes often help

Both types usually improve with conservative care. A sudden pop, snap, or weakness in the back of the ankle may mean a tear and needs prompt evaluation.

Frequently Asked Questions

What is Achilles tendonitis?

Achilles tendonitis (also spelled tendinitis) is irritation and inflammation of the Achilles tendon, the large tendon that connects the calf muscles to the heel bone. It is usually caused by overuse.

What is the difference between tendonitis and tendinosis?

Tendonitis describes active irritation and inflammation. Tendinosis describes longer-term wear and breakdown of the tendon fibers. Both cause pain and stiffness and are treated in similar ways.

Where does Achilles tendonitis hurt?

Pain is felt along the back of the leg just above the heel (midportion tendonitis) or where the tendon attaches to the heel bone (insertional tendonitis).

Why is my Achilles stiff in the morning?

Morning stiffness is a hallmark of Achilles tendonitis. The tendon tightens overnight, and pain often eases as it warms up, then returns after activity.

Can I keep running with Achilles tendonitis?

Running through the pain can make it worse and raise the risk of a tear. Reducing or changing activity while the tendon calms down, then returning gradually, is safer.

How long does Achilles tendonitis take to heal?

Mild cases often improve in several weeks. Longer-standing tendonitis can take several months of consistent stretching, strengthening, and activity changes.

Can Achilles tendonitis lead to a rupture?

A weakened, degenerated tendon is more likely to tear. A sudden pop or snap in the back of the ankle, followed by weakness, needs prompt evaluation.

When is surgery needed for Achilles tendonitis?

Rarely. Surgery is considered when months of conservative care have not helped, when the tendon is badly degenerated, or when it has torn.

Symptoms Of Achilles Tendonitis

Symptoms often start mildly and worsen with continued activity. They may include:

  • Pain along the back of the leg or heel, often worse after activity.
  • Stiffness especially first thing in the morning.
  • Swelling or thickening of the tendon.
  • Tenderness when the tendon is squeezed.
  • A pop or sudden weakness which may mean the tendon has torn and needs prompt care.
Illustration of an inflamed Achilles tendon at the back of the heel

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