Written by Ada’s Medical Knowledge Team
What is Achilles tendonitis?
Achilles tendonitis, also known as Achilles tendinopathy or Achilles tendinitis, is a condition affecting the Achilles tendon. The Achilles tendon is a large tendon which attaches the calf muscles to the bony heel of the foot. When the tendon becomes inflamed or damaged, usually through overuse, a person has developed Achilles tendonitis and will experience pain.
This condition mostly affects athletic and active people, especially mature adults between the ages of 30 and 50. The incidence rate is around five to 10 people in 100,000. 1
Treatment is usually simple and mainly involves resting from the specific exercises that cause the pain. This will often be supplemented by regenerative/rehabilitative stretching exercises, most often tailored to the person and taught by a physical therapist. Most people recover from Achilles tendonitis without any lasting effects.
Symptoms of Achilles tendonitis
The most common symptom of Achilles tendonitis is pain in the back of the foot and heel. The onset of pain may be sudden or gradual. 2
- Pain at the back of the foot and heel when moving the ankle
- Pain when pointing the toes, or pushing off from the toes
- Pain which becomes worse after exercising
- Stiffness along the back of the foot and heel, especially with the first steps in the morning
- Swelling and tenderness in the back of the foot and heel
- Thickening of the tendon
- Bone spurs in cases of insertional tendonitis (see insertional Achilles tendonitis)
People experiencing possible symptoms of Achilles tendonitis should consult a doctor. In addition, the free Ada app can be used to carry out a symptom assessment.
Causes of Achilles tendonitis
The Achilles tendon is a large, thick tendon that attaches the calf muscles to the bony heel of the foot. This tendon bears the weight of the body when pushing off from the toes in the act of walking or running.
- Suddenly increasing the amount or intensity of exercise
- Not stretching out the calf muscles properly after exercise
- Running or exercising to excess
- Running on hard surfaces
- Jumping repeatedly during exercise or sports
- Manual labour which puts stress on ankles and feet
- Having bone spurs (osteophytes) which rub against the Achilles tendon
- Not wearing sufficiently supportive shoes for exercise
- Having flattened arches in the foot
Although Achilles tendonitis is commonly referred to as tendonitis, the condition does not always involve inflammation of the tendon. Over time, tendons ‒ including the Achilles tendon ‒ degenerate. When this happens, they become damaged and lose elasticity. Pain which is caused by this progressive degeneration is called Achilles tendinosis, or sometimes Achilles tendinopathy; however tendinopathy is technically an umbrella term for tendonitis and tendinosis. 5
Noninsertional Achilles tendonitis
55 to 65 percent of Achilles tendonitis cases are classified as noninsertional Achilles tendonitis: the fibers in the center of the Achilles tendon begin to degenerate or become inflamed, swell and become thicker. 4 6
Insertional Achilles tendonitis
Insertional Achilles tendonitis occurs when the Achilles tendon degenerates or gets inflamed at the point where the tendon attaches, or inserts, to the heel bone. Bone spurs, projections that develop along bone edges, also known as osteophytes may form in cases of insertional Achilles tendonitis. 4 7
Achilles tendon rupture
A complication of Achilles tendonitis can be an Achilles tendon rupture. A rupture occurs when a tendon tears, partially or completely, after being stretched beyond its capacity. Achilles tendonitis can increase the chances of a rupture occurring. 8 9
Around 80 percent of Achilles tendon ruptures occur during exercise and while playing sports. People most commonly develop the condition between the ages of 30 and 50. 1
The antibiotic class fluoroquinolones which, among many others, includes ciprofloxacin and moxifloxacin, may cause Achilles tendon rupture, even after a short course. Corticosteroid injections into the heel can also increase a person’s risk of developing Achilles tendon rupture. 10 11 7
Diagnosis of Achilles tendonitis
Achilles tendonitis can usually be diagnosed based on the symptoms, following a physical examination of the ankle and tendon. Other tests may be needed in more serious cases of Achilles tendonitis to establish the extent of the problem. These may include: 3 4
- X-ray, which does not produce images of tendons but can reveal hardening (calcification) of tendons, as well as bone spurs
- Magnetic resonance imaging (MRI) scan, which uses magnets and radio waves to look inside the body to produce detailed images of tendons, muscles and other soft tissue and may be of use when planning surgery
Treatment of Achilles tendonitis
Most people with Achilles tendonitis will be treated with non-surgical options.
Rest is vital to allow the Achilles tendon to heal. Any exercise or activity that causes pain should be stopped until the pain subsides. Depending on the severity of the tendonitis, this could take six months or longer. In severe cases, an immobilization boot may be necessary for a few weeks to reduce stress on the foot. An immobilization boot, also known as a walking boot or walking cast, is a removable alternative to a plaster cast, often used to aid healing after fracturing a bone or bone surgery. A splint worn at night has also been shown to temporarily reduce pain. 4 5 12
Physical therapy and exercises are recommended to help strengthen the calf muscles, which reduces stress on the Achilles tendon. Training programmes that focus on a particular type of muscle exercise, known as eccentric training, have been shown to help particularly well in cases of tendonitis. A common exercise is standing on a step and slowly lowering the heel, though a physical therapist can advise on the most appropriate exercises and demonstrate how to perform them. 60 to 90 percent of people who use eccentric exercises to strengthen their Achilles tendon report pain relief. 4 12 13 14
Ice, in the form of ice in a bag or an ice pack, can be applied to the affected area which may help reduce swelling. However, recent studies suggest ice may be more effective at treating inflammatory conditions such as paratenonitis, a condition where the tendon sheath around a tendon becomes inflamed, than tendonitis itself. 3 5 14
Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, can also help provide pain relief. If the tendon is not inflamed, painkillers such as paracetamol may be effective at relieving pain, too. NSAIDs should not be taken for long periods of time, as this can result in the development of side effects, such as stomach upsets and damage to the tissue of the gastrointestinal system. If needed, doctors can recommend appropriate painkillers for long-term use. 4 15
Studies have shown that glycerol trinitrate ointment, applied daily as a patch for six months, reduces pain and can help improve outcomes for people with Achilles tendonitis. 12
Shock-wave therapy is a procedure that increases blood flow to an injured area, speeding up the healing process by using a device to pass low-energy sound waves into the body. Studies have shown the treatment to be promising for treating Achilles tendonitis. 14 16
If Achilles tendonitis injuries take a long time to heal, a treatment where the person’s blood is taken from the arm vein and separated to extract platelet-rich plasma, which is then injected back into the tendon site, may be an option. However, while the evidence suggests few harmful side effects, there is still discussion around the treatment’s effectiveness. 13
Good to know: Corticosteroid injections may help to reduce inflammation and pain on a short term basis, but are not generally recommended for Achilles tendonitis, because they make the tendon more likely to rupture, especially if multiple, recurrent injections are given. 7
Surgical treatments for Achilles tendonitis
Where Achilles tendonitis fails to respond to non-surgical methods after six months, surgery may be necessary. There are a number of surgical procedures available, depending on the nature and location of the injury. A surgeon will recommend the best option. Possible procedures include: 4 17
- Debridement and repair, which removes damaged parts of the tendon. This may be performed if less than 50 percent of the tendon is damaged
- Debridement with tendon transfer may be performed when more than 50 percent of the tendon is damaged. The remaining tendon is supported with other tendon tissue, often taken from the long tendon of the big toe
- Gastrocnemius recession, which lengthens the calf muscle to place less stress on the Achilles tendon
- Bone spur removal, in cases of insertional tendonitis. Artificial anchors may be implanted to attach the tendon to the bone
Prevention of Achilles tendonitis
There are a number of ways to help prevent Achilles tendonitis: 5
- Taking care to warm up the body gently but properly, with light exercise before running or sprinting, such as brisk walking for a few minutes
- Gradually increase the duration and intensity of exercise
- Cool down after exercise, such as by changing to (brisk) walking for a few minutes after running or sprinting
- Stretching fully after exercising
- Strengthen calf muscles to reduce stress on the Achilles tendon
- Use supportive footwear while exercising or playing sports
If pain does occur, it is wise to rest the foot until receiving a definitive diagnosis and treatment plan to prevent a more severe injury developing. If a person experiences Achilles pain for the first time or it persists, they should seek medical treatment.
Other ways to refer to Achilles tendonitis
- Achilles tendinitis
- Achilles tendinopathy
FAQs for Achilles tendonitis
Q: Can Achilles tendonitis cause foot pain?
A: Yes. Achilles tendonitis causes pain in the back of the foot and the heel. See the section on Symptoms of Achilles tendonitis.