The Achilles tendon is the largest tendon in the body. It connects the two main calf muscles – the gastrocnemius and soleus – to the heel bone (the calcaneus). Common injuries of the Achilles tendon include tendonitis (inflammation), tendinosis (degeneration), and rupture.
Achilles tendinitis most often results from overuse during work or athletic activities. The sheath surrounding the tendon (the paratenon) may become swollen. Symptoms include a burning pain and tenderness during or after activity. The condition may become chronic without treatment and rest.
Tendinosis also comes from overuse, but unlike tendinitis, it is chronic and degenerative. Continuous stress produces microtears and a breakdown of the collagen tissue within the Achilles tendon. The condition is often painful and may reduce tendon strength and mobility.
An Achilles tendon may rupture because of overuse or an injury such as a direct blow to the lower leg or ankle. Most commonly, it tears when the calf is contracting while an external force is stretching it. Symptoms include severe pain and a popping sound at the time of injury, followed by swelling and the inability to stand or point the toes.
For tendinitis and tendinosis, treatment includes rest, ice, over-the-counter pain relievers and physical therapy. Heel lifts, which elevate the heel and diminish stress on the Achilles tendon, are often very helpful. Occasionally immobilization in a walking boot or cast is recommended. Ruptures are treated either with surgery, a cast or both.