All About Achilles Tendonitis

Achilles tendon problems cause pain in the back of the ankle. Jeannot Olivet / Getty Images

Achilles tendonitis is a condition of irritation and inflammation of the large tendon in the back of the ankle. Achilles tendonitis is a common injury that tends to occur in recreational athletes. Overuse of the Achilles tendon can cause inflammation that can lead to pain and swelling. It is differentiated from another common Achilles tendon condition called Achilles tendinosis. Patients with Achilles tendinosis have chronic Achilles swelling and pain as a result of degenerative, microscopic tears within the tendon.

The Achilles tendon is the largest tendon in the body. One of the critical factors that is implicated in Achilles problems is the limited blood supply to the tendon. Because of the limited blood supply, injury healing can be slow and difficult. Most blood flow to the tendon comes from the muscle above the tendon (the gastrocnemius and soleus muscles) and the bone below the tendon (the calcaneus). In between these is the Achilles and a typical watershed zone of blood flow where only a limited amount of oxygen and nutrients can be delivered to the tendon.

Causes of Achilles Tendonitis

Two important factors that can be related to the development of Achilles tendonitis are:

  • Lack of flexibility
  • Overpronation

Other factors associated with Achilles tendonitis are recent changes in footwear, and changes in exercise training schedules. Often long distance runners will have symptoms of Achilles tendonitis after increasing their mileage or increasing the amount of hill training they are doing.

As people age, tendons, like other tissues in the body, become less flexible, more rigid, and more susceptible to injury. Therefore, middle-age recreational athletes are most susceptible to Achilles tendonitis.

Symptoms of Achilles Tendonitis

The main complaint associated with Achilles tendonitis is pain behind the heel.

The pain is often most prominent in an area about 2-4 centimeters above where the tendon attaches to the heel. In this location, called the watershed zone of the tendon, the blood supply to the tendon makes this area particularly susceptible. The typical signs of tendonitis include:

  • Swelling of the Achilles tendon
  • Tenderness to touch of the tendon
  • Limited range-of-motion of the Achilles
  • Crepitus of the tendon

Patients with Achilles tendonitis usually experience the most significant pain after periods of inactivity. Therefore patients tend to experience pain after first walking in the morning and when getting up after sitting for long periods of time. Patients will also experience pain while participating in activities, such as when running or jumping. Achilles tendonitis pain associated with exercise is most significant when pushing off or jumping.

X-rays are usually normal in patients with Achilles ‚Äčtendonitis, but are performed to evaluate for other possible conditions. Occasionally, an MRI is needed to evaluate a patient for tears within the tendon.

If there is a thought of surgical treatment an MRI may be helpful for further evaluation and planning. MRIs can help determine the location and extent of tendon damage. Ultrasound has been used increasingly as this is a quick and easy test to perform that allows your provider to see the condition of the tendon and assess for tears of the Achilles.

Treatment of Achilles Tendonitis

Treatment of Achilles tendonitis begins with resting the tendon to allow the inflammation to settle down. In more serious situations, adequate rest may require crutches or immobilization of the ankle. Learn more about different treatments for Achilles tendonitis, including ice, medications, injections, and surgery.


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Schepsis, AA, et al. "Achilles Tendon Disorders in Athletes" Am. J. Sports Med., March 1, 2002; 30(2): 287 - 305.

van der Linden PD, et al. "Fluoroquinolones and risk of Achilles tendon disorders: case-control study" BMJ 2002;324:1306.

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