|Achilles tendonitis is a painful and often debilitating inflammation of the Achilles tendon, also called the heel cord. The Achilles tendon is the largest and strongest tendon in the body. It is located in the back of the lower leg, attaches to the heel bone (calcaneus), and connects the leg muscles to the foot. The Achilles tendon gives us the ability to rise up on our toes, facilitating the act of walking, and Achilles tendonitis can make walking almost impossible.
There are three stages of tendon inflammation:
Peritenonitis with tendinosis
Peritenonitis is characterized by localized pain during or following activity. As this condition progresses, pain often develops earlier on during activity, with decreased activity, or while at rest.
Tendinosis is a degenerative condition that usually does not produce symptoms (i.e., is asymptomatic). It may cause swelling or a hard knot of tissue (nodule) on the back of the leg.
Peritenonitis with tendinosis results in pain and swelling with activity. As this condition progresses, partial or complete tendon rupture may occur.
Incidence and Prevalence
Achilles tendonitis is more common in athletes and overall incidence of the condition is unknown. It occurs in approximately 6-18% of runners.
Risk Factors and Causes
Poorly conditioned athletes are at the highest risk for developing Achilles tendonitis. Participating in activities that involve sudden stops and starts and repetitive jumping (e.g., baseball, basketball, football, tennis, running, dancing) increases the risk for the condition. It often develops following sudden changes in activity level, training on poor surfaces, or wearing inappropriate footwear.
Achilles tendonitis may be caused by a single incident of overstressing the tendon, or it may result from a series of stresses that produce small tears over time.
The condition also develops in people who exercise infrequently and those who are just beginning an exercise program, because inactive muscles and tendons have little flexibility because of inactivity. It is important for people who are just starting to exercise to stretch properly, start slowly, and increase gradually.
In some cases, a congenital (i.e., present at birth) condition causes Achilles tendonitis. Typically, this is due to abnormal rotation of the foot and leg (pronation), which causes the arch of the foot to flatten and the leg to twist more than normal.
This condition causes the lower leg muscles (e.g., gastrocnemius, soleus) to stretch more than normal. Like a rubber band, the further the muscles stretch, the tighter they become. The force on the Achilles tendon and the heel bone increases, resulting in Achilles tendonitis. Because the arch of the foot naturally flattens over time, especially in athletes, Achilles tendonitis often develops later in life.
Women who wear high-heeled shoes often and switch to sneakers for exercise also can develop Achilles tendonitis. The Achilles tendon and lower leg muscles gradually adapt to a shortened position because the shoes prevent the heel from stretching all the way to the ground. When this occurs, wearing sneakers or flat shoes forces the Achilles tendon to stretch further than it is accustomed to, causing inflammation. If high heels are worn everyday, stretching should be done every morning and night to keep the Achilles tendon lengthened.
Signs and Symptoms
In most cases, symptoms of Achilles tendonitis develop gradually. Pain may be mild at first and worsen with continued activity. Repeated or continued stress on the Achilles tendon increases inflammation and may cause it to rupture. Partial or complete rupture results in traumatic damage and severe pain, making walking virtually impossible and requiring a long recovery period. Patients with tendinosis may experience a sensation of fullness in the back of the lower leg or develop a hard knot of tissue (nodule).