Overview

What is an Achilles tendon?

The Achilles (uh-KILL-ease) tendon is a band of tissue in the back of your leg. This tendon links your heel bone (calcaneus, pronounced cal-KAY-nee-us) to your calf muscles. It’s also called the calcaneal tendon.

You have two Achilles tendons, one in each leg. The Achilles tendons are the strongest and biggest tendons in your body. The Achilles averages about 15 centimeters (6 inches) in length, but it’s up to 26 centimeters (10 inches) long in some people.

Achilles tendons can handle about four times a person’s body weight. But people commonly experience Achilles tendon injuries because of the stress put on this tendon. Almost 1 in 4 athletes have an Achilles tendon injury during their lifetime.

Function

What does an Achilles tendon do?

The Achilles tendon, also called the heel cord, helps lift your heel off the ground. You use this tendon when you:

Climb stairs.
Jump.
Run.
Stand on your tiptoes.
Walk.

Anatomy

Where is your Achilles tendon?

The Achilles tendon starts in the middle of your calf and extends down to your heel. It connects your calf muscles (gastrocnemius and soleus muscles) in the back of your lower leg to the heel bone in your foot.

The gastrocnemius muscle has two heads that crisscross the knee joint. This muscle flexes your knee and ankle. The soleus muscle flexes your foot to point your toes downward.

What are the parts of the Achilles tendon?

Strong collagen fibers make up the Achilles tendon. As with other tendons, a layer of paratenon cells surround each layer of the Achilles. The paratenon layer provides blood flow to the tendon and lubricates its movement.

Healthcare providers often classify parts of the Achilles as the:

Noninsertional Achilles tendon: The parts of the Achilles that are higher up the calf, including the midtendon and preinsertional tendon.
Midtendon: The part of the Achilles at the narrowest part of the ankle, visible as a cordlike structure at the back of the lower calf or upper ankle.
Preinsertional Achilles tendon: The part of the tendon just above the heel.
Insertional Achilles tendon: The point where the Achilles tendon attaches to the heel bone.

Bursae, small sacs of fluid, cushion your Achilles tendon at its insertion point into your heel. The bursae aren’t part of the Achilles itself, but injuries to the tendon often affect them.

Conditions and Disorders

What conditions and disorders can affect the Achilles tendon?

Problems involving the Achilles tendon are called Achilles tendinopathy. Achilles tendon disorders include:

Anterior Achilles tendon bursitis: Walking, often in high-heeled shoes, inflames the bursa at the back of your heel.
Achilles paratenonitis: Overuse, repeated movements or poorly fitted shoes inflame the paratenon.
Achilles tendinitis (tendonitis): Too much activity, like running, walking or sports, causes your Achilles tendon to swell and become painful.
Achilles tendinosis: Overuse or aging gradually causes your tendon to degenerate, resulting in thickening due to scar tissue.
Achilles tendon rupture: Running uphill, jumping or quickly changing speed or direction can tear the Achilles tendon completely or partially.
Posterior Achilles tendon bursitis: Extra strain on the Achilles tendon (from injuries to the heel or diseases such as rheumatoid arthritis or gout) inflames the bursa.

What are common tests to check the health of your Achilles tendon?

Your healthcare provider first does a physical exam to check for Achilles tendinopathy. Your provider looks for Achilles tendon pain when they move or press your tendon.

They examine the area around your heel and lower leg for:

A knot on the back of the leg or bruising over the tendon (signs of a tendon rupture).
Swelling, tenderness, redness or warmth (signs of tendinitis, tendon bursitis or Achilles paratenonitis).
Thickening or small bumps (signs of tendinosis).

Your healthcare provider may also use tests including:

Thompson test (calf squeeze test): If your foot doesn’t flex downward when your provider presses your calf, you may have an Achilles tendon rupture.
Matles test (knee function test): If the toe end of your foot doesn’t point away from your leg when your provider bends your knee at a right angle, you may have an Achilles tendon rupture.
Magnetic resonance imaging (MRI): Your provider can see detailed images of your leg and ankle. These images can help diagnose an Achilles tendon rupture and other Achilles problems.
Ultrasound (sonography): Your provider can scan images of your Achilles tendon to look for a tendon rupture.
X-rays: Your provider may take X-rays of your foot to check for problems related to tendinopathy, such as degeneration or bone spurs. They can also use X-rays to find hardening of the lower part of the Achilles tendon, a sign of tendinitis.

How are Achilles (calcaneal) tendon problems treated?

Healthcare providers usually treat calcaneal tendon problems with nonsurgical treatments, including:

Immobilization: A boot or leg cast may help treat moderate to severe Achilles tendon problems, including partial tendon ruptures.
Nonsteroidal anti-inflammatory drugs (NSAIDs): Over-the-counter medicines can help manage Achilles tendon pain.
Orthotics: Custom-made shoe orthotics or heel-lift orthotics can ease pain, especially if you have Achilles tendinitis or tendinosis.
Physical therapy: Stretches and exercises can strengthen your calf muscle.
RICE therapy: Rest, ice, compression (with a sports bandage or tape) and elevation can help your tendon heal.

If you completely rupture your Achilles tendon, you may need surgery as soon as possible. Your health provider makes a recommendation based on your overall health, age, medical history and seriousness of the tear. Health providers often treat partial Achilles tendon ruptures with nonsurgical treatments.

Care

How can I keep my Achilles tendons healthy?

To help reduce your risk of Achilles tendon problems:

Alternate high-impact with low-impact activities.
Avoid activities that place stress on your Achilles tendons, such as running up hills.
Do daily exercises to stretch and strengthen your calf muscles.
Increase the duration and intensity of your activity at a gradual pace.
Take time for a warmup before you exercise.
Wear well-fitting shoes designed for the activity you’re doing.

Frequently Asked Questions

When should I call a healthcare provider about my Achilles tendons?

If you still experience pain and symptoms three to six months after you start treatment, you should talk to a healthcare provider. In some cases, severe Achilles tendonitis can lead to an Achilles tendon rupture, which requires surgery.

A note from Cleveland Clinic

Your Achilles tendon connects your calf muscles to your heel bone. Though the Achilles tendon is strong, people frequently experience Achilles tendon injuries. Conditions that impact the Achilles tendon include bursitis, tendinitis, tendinosis and tendon rupture. Providers treat most Achilles tendon issues nonsurgically, though tendon rupture often requires surgery. With proper rest and activity, many Achilles tendon injuries heal within three to six months.

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Achilles Tendon