|Synonyms||Achilles tendonitis, Achilles tenosynovitis, Achilles tendinopathy|
|Anatomic image of Achilles tendonitis: affected tendon shown in red|
Achilles tendinitis (Achilles tenosynovitis, Achilles tendinopathy, calcaneal tendinitis) is disruption of the Achilles tendon by degeneration, trauma, or inflammation. This tendon is the extension of the gastrocnemius and soleus muscles onto the calcaneus (heel bone): it causes the foot to extend (plantar flexion) when those muscles contract.
The most common signs and symptoms are pain and tenderness of the affected tendon; swelling may also occur. The pain may be continuous, or only occur with use of the tendon. These symptoms may extend into the surrounding tissue. The tendonitis may cause limitation of motion in the ankle joint. A common cause is overuse and/or improper use of the gastrocnemius and soleus muscles among those participating in physical activity involving the legs. Excessive pronation of the foot while walking or running can contribute to the disruption of the tendon.
Diagnosis is made by obtaining the relevant history, and physical examination of the tendon; X-ray and MRI may help confirm the diagnosis. Preventive measures include proper stretching of the gastrocnemius and soleus muscles prior to physical activity involving the legs, exercises to strengthen these muscles, and wearing shoes for proper cushioning and to prevent excessive pronation.
Treatment should be supervised by a podiatrist or orthopedist and often includes rest, ice, non-steroidal antiinflammatory agents, a boot to keep the tendon from being stretched while walking, and physical therapy. Failure to protect the disrupted tendon until recovery can result in a rupture of the tendon.
Signs and symptoms
Symptoms can vary from an ache or pain and swelling to the local area of the ankles, or a burning that surrounds the whole joint. With this condition, the pain is usually worse during and after activity, and the tendon and joint area can become stiffer the following day as swelling impinges on the movement of the tendon. Many patients report stressful situations in their lives in correlation with the beginnings of pain which may contribute to the symptoms.
Achilles tendinitis is a common injury, particularly in sports that involve lunging and jumping. It is also a known side effect of fluoroquinolone antibiotics such as ciprofloxacin, as are other types of tendinitis.
Swelling in a region of micro-damage or partial tear can be detected visually or by touch. Increased water content and disorganized collagen matrix in tendon lesions may be detected by ultrasonography or magnetic resonance imaging.
Achilles tendinitis is thought to have physiological, mechanical, or extrinsic (i.e. footwear or training) causes. Physiologically, the Achilles tendon is subject to poor blood supply through the synovial sheaths that surround it. This lack of blood supply can lead to the degradation of collagen fibers and inflammation. Tightness in the calf muscles has also been known to be involved in the onset of Achilles tendinitis.
During the loading phase of the running and walking cycle, the ankle and foot naturally pronate and supinate by approximately 5 degrees. Excessive pronation of the foot (over 5 degrees) in the subtalar joint is a type of mechanical mechanism that can lead to tendinitis.
An overuse injury refers to repeated stress and strain, which is likely the case in endurance runners. Overuse can simply mean an increase in running, jumping or plyometric exercise intensity too soon. Another consideration would be the use of improper or worn-down footwear, which lack the necessary support to maintain the foot in the natural/normal pronation.
The Achilles tendon does not have good blood supply or cell activity, so this injury can be slow to heal. The tendon receives nutrients from the tendon sheath or paratendon. When an injury occurs to the tendon, cells from surrounding structures migrate into the tendon to assist in repair. Some of these cells come from blood vessels that enter the tendon to provide direct blood flow to increase healing. With the blood vessels come nerve fibers. Researchers including Alfredson and his team in Sweden  believe these nerve fibers to be the cause of the pain - they injected local anaesthetic around the vessels and this decreased significantly the pain from the Achilles tendon.
Achilles tendinitis is usually diagnosed from a medical history, and physical examination of the tendon. Projectional radiography shows calcification deposits within the tendon at its calcaneal insertion in approximately 60 percent of cases. Magnetic resonance imaging (MRI) can determine the extent of tendon degeneration, and may show differential diagnoses such as bursitis.
Deteriorating changes start to appear with age, but attempting to slow down these changes is key in the prevention of Achilles tendinitis. Performing consistent physical activity will improve the elasticity and strength of the tendon, which will assist in resisting the forces that are applied.
It is essential to stretch and warm-up before beginning an exercise session in order to prepare and protect the tendon for work. Warm-ups enhance the tendon's capability of being stretched, further aiding in protection from injury. Prevention of recurrence includes following appropriate exercise habits and wearing low-heeled shoes. In the case of incorrect foot alignment, orthotics can be used as a preventative way to properly position the feet. Footwear that is specialized to provide shock-absorption can be utilized to defend the longevity of the tendon. Achilles tendon injuries can be the result of exceeding the tendon's capabilities for loading, therefore it is important to gradually adapt to exercise if someone is inexperienced, sedentary, or is an athlete who is not progressing at a steady rate.
Eccentric strengthening exercises of the gastrocnemius and soleus muscles are utilized to improve the tensile strength of the tendon and lengthen the muscle-tendon junction, decreasing the amount of strain experienced with ankle joint movements.  This eccentric training method is especially important for individuals with chronic Achilles tendinosis which is classified as the degeneration of collagen fibers.  These involve repetitions of slowly raising and lowering the body while standing on the affected leg, using the opposite arm to assist balance and support if necessary, and starting with the heel in a hyperextended position. (Hyperextension is typically achieved by balancing the forefoot on the edge of a step, a thick book, or a barbell weight. so that the point of the heel is a couple of inches below the forefoot.)
Seeing a podiatrist or orthopedist for treatment as soon as possible after the diagnosis is recommended, because this injury can lead to an Achilles tendon rupture with continued overuse. Possible treatments include:
- Ice and cold compression therapy.
- Use of a heel pad - may reduce strain on the tendon.
- An eccentric exercise routine designed to strengthen the tendon.
- Applying light to medium compression around the ankle and lower calf by wearing elastic bandages throughout the day. (Using these elastic bandages while sleeping can reduce morning stiffness but care must be taken to apply very light compression during sleep.) Inappropriate compression can inhibit healing by hindering circulation.
- Non-steroidal anti-inflammatory drugs.
- Ultrasound therapy.
- Manual therapy.
- Physical therapy.
- Application of a boot or cast.
- Corticosteroid injection - although it can increase the risk of tendon rupture.
- Autologous blood injections - results have not been highly encouraging and there is little evidence for their use.
- Prolotherapy (sclerosant injection into the neovascularity) and extracorporeal shockwave therapy. 
The prevalence of Achilles tendinitis varies among different ages and groups of people. Achilles tendinitis is most commonly found in individuals aged 30–40 Runners are susceptible, as well as anyone participating in sports, and men aged 30–39.
Risk factors include participating in a sport or activity that involves running, jumping, bounding, and change of speed. Although Achilles tendinitis is mostly likely to occur in runners, it also is more likely in participants in basketball, volleyball, dancing, gymnastics and other athletic activities. Other risk factors include gender, age, improper stretching, and overuse.  Another risk factor is any congenital condition in which an individual’s legs rotate abnormally, which in turn causes the lower extremities to overstretch and contract; this puts stress on the Achilles tendon and will eventually cause Achilles tendinitis.
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