Definition of Achilles tendinitis:

Achilles tendinitis is when the Achilles tendon becomes swollen, inflamed, and painful at the heel.

The Achilles tendon connects your calf muscles to your heel bone. It is used for walking, running, and jumping.

Causes, incidence, and risk factors:

There are two large muscles in the calf: the gastrocnemius and the soleus. These muscles create the power needed to push off with the foot or go up on the toes. The large Achilles tendon connects these muscles to the heel.

These are important muscles for walking. This tendon can become inflamed, most commonly as a result of overuse or arthritis. Inflammation can also occur with injury and infection.

Tendinitis due to overuse is most common in younger people. It can occur in walkers, runners, or other athletes. Sports like basketball that involve jumping put a large amount of stress on the Achilles tendon. Repeated jumping can lead to Achilles tendinitis.

Achilles tendinitis may be more likely to occur:

• After a sudden increase in the amount or intensity of an activity
• When the calf muscles are very tight (not stretched out)

Tendinitis from arthritis is more common in middle-aged and elderly people. A bone spur or growth may form in the back of the heel bone. This may irritate the Achilles tendon and cause pain and swelling.