Achilles Tendon

The calf muscle in the leg tapers down and forms the Achilles’ tendon. This is the strongest tendon in the body and comes into use when we run, jump or balance our body weight on one leg. The main function of this tendon is to raise our heel when we are on our toes.

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What Is Achilles’ Tendon?

The Achilles’ tendon is the longest, thickest, and strongest tendon in the human body. It is ~12–15 cm long and arises close to the middle of the calf. Despite its size and strength, it is the most injured tendon. Achilles’ tendon rupture is a rupture in the lower body of an individual. This condition is characterized by a sharp pain, followed by an audible pop heard at the site of tendon rupture. Achilles’ tendon patients may suffer from disability. When the ankle is exposed to extreme movements, it causes stress on the tendon, leading to its rupture. This condition can be misdiagnosed as an ankle sprain in ~25% of individuals.
Achilles’ tendon rupture usually occurs in individuals between the age group of 21–50 years. This condition is more common in individuals with intermediate physical activity. Individuals playing sports such as tennis, basketball, volleyball, cycling, running, diving, gymnastics, or trekking can experience this tendon rupture. Right-handed patients mostly get Achilles’ tendon on the left leg and vice versa.
The incidence of Achilles’ tendon rupture is increasing. Note that ~18 per 100,000 individuals are affected by this tendon rupture. Moreover, ~16%–18% of footballers, 7%–18% of runners, 9% of dancers, 5% of gymnasts, and 2% of tennis players can lead to this tendon rupture. Note that ~1 million athletes suffer from Achilles’ tendon rupture every year. Males are more affected by this tendon rupture compared to females.


Because of the rupture of Achilles’ tendon, the following symptoms are seen in the individuals:

  • Pain in the ankle

  • Hearing a popping or crackling sound

  • Feeling of being kicked on the leg

  • Unable to stand with the affected leg

  • Difficulty in moving the foot

Few patients may not feel any pain during tendon rupture and can freely walk. In such patients, diagnosis becomes difficult.

Causes And Risk Factors


The site of Achilles’ tendon placed close to the calcaneal attachment receives most of the pressure. This pressure exerted injuries on the tendon or causes degenerative changes.

The causes for Achilles’ tendon rupture are listed below:

  • Any physical pressure exerted on the tendon.

  • Degeneration of tendon.

  • Injury because of trauma or crushing on the ankle.

  • Tear of the posterior ankle.

  • Amount of weight put on the injured area.

  • Sudden backward bending and contracting of the ankle.

  • Sudden backward bending and contracting of the feet.

The degenerative changes occur because of the following reasons:

  • Microtrauma

  • Medications

  • Chronic overloading

Risk Factors

Few risk factors associated with Achilles’ tendon rupture are listed below:

  • Degeneration of tendons collages (tendinosis)

  • Prolonged use of oral steroids or steroid injections

  • Inflammatory arthritis

  • Overexertion

  • The use of fluoroquinolone antibiotics

  • Patients with type O blood group

  • A family history of Achilles’ tendon

  • Obesity

  • Existing conditions such as

  • Inflammation

  • Chronic renal failure

  • Long-term dialysis

  • Deficiency of collagen

  • Diabetes mellitus

  • Gout

  • Thyroid or parathyroid disorders

  • Lupus

  • Rheumatic arthritis, autoimmune arthritis, and infectious arthritis

  • Microbial infections

  • High blood cholesterol

  • Inflammation of small intestine

  • Inflammation of tendon

  • Reduced fibril size

  • Foot problems such as cavus foot, lack of flexibility and strength, tibia vara, and improper alignment


Few patients do not experience any pain or difficulty in walking, which leads to delay in their hospital visit. This can lead to delay in the diagnosis or incorrect diagnosis. 

At first, the doctor examines the affected area. They observe for any swelling, bruising, and tenderness. However, this method does not clarify the exact medical condition. Patients with Achilles’ tendon can move their ankles up and down; hence, doctors will try moving the ankle. A patient with swelling and bruising in 24 h of injury helps in the early detection of tendon rupture. With time, the affected area gets filled with fluid, which makes it difficult to observe the rupture. For the tendon ruptures neglected and detected after four weeks, the affected area is filled with blood and appears as a swollen area because of the healing process. The trauma experienced in the lower body can verify via a radiograph to rule out any fractures. If Achilles’ tendon rupture is suspected, an ultrasound or magnetic resource imaging (MRI) is used to confirm the diagnosis. The following tests are performed to detect Achilles’ tendon rupture:

  • Physical examination

  • Thompson test: The Thompson test examines a suspected rupture to confirm Achilles’ tendon rupture. This is known as Simmonds’ calf squeeze test, which is the closest test for a perfect diagnosis for Achilles’ tendon rupture. In this test, the patient is kept kneeling on a chair or bench and the leg is squeezed over the calf muscle. If there is an Achilles’ tendon rupture, the affected leg will not move when the calf is squeezed. False-negative results may appear in tendon ruptures diagnosed after four weeks. This occurs because tendons are partially cured.

  • Knee flexion test: In this test, the patient is made to lie flat with the chest down. The knees are bent at 90°, and the ankle angle is measured for legs. A dorsiflexed or neutral ankle angle is observed in the Achilles’ tendon rupture.

Note that a combination of Thompson test and knee flexion test diagnose Achilles’ tendon rupture with a sensitivity of 100%. 

  • Imaging techniques: For a patient observing any symptoms of tendon rupture, diagnostic imaging is performed by radiography, ultrasound, or MRI. Diagnostic imaging provides an axial view of the ankle. An ultrasound is a cost-effective, non-invasive, and highly sensitive and accurate method. This test is preferred when the injured site is filled with fluid, blood, or tissue debris. When the clinical symptoms are not specific to the Achilles’ tendon rupture, MRI can be performed. However, physical tests such as the Thompson test and knee flexion test are more sensitive compared to MRI, which is helpful for detecting the severity of tendon rupture in neglected ruptures.


Patients with Achilles’ tendon rupture can undergo either surgical or non-surgical treatment. The type of treatment a patient wishes to undertake depends on the following conditions:

  • The outcomes of surgical versus non-surgical treatment.

  • Quicker resumption of work.

  • A chance of re-rupture in both treatments.

  • A treatment with lesser complications.

However, all patients require physical and orthotic therapy for healing, strengthening the muscles and increasing movement.

  • Non-surgical treatment 

Non-surgical treatment comprising rest, pain relief medications, elevation, and functional bracing is an initial treatment protocol for Achilles’ tendon rupture patients. Generally, patients with existing medical conditions or having a sedentary lifestyle are recommended non-surgical treatment. Moreover, doctors may suggest this treatment to reduce the complications associated with the surgical treatment.

  • Plaster cast

This non-surgical treatment is a traditional approach to treat Achilles’ tendon rupture. A plaster cast helps to control ankle movements because of immediate immobilization. Patients readily accept this treatment option. This treatment is an easier and cheaper option for patients. Disadvantages of this treatment include plaster sores, muscle stiffness, and poor skin hygiene of the plastered area.

  • Orthosis

Orthosis is a commonly used non-surgical treatment. The advantages of orthosis treatment include increased ankle flexibility, managing skin conditions, improvement in the total weight a patient puts on the injured area, and increased patient satisfaction.

  • Advantages of non-surgical treatment: No hospitalization, less hospitalization cost, no complications associated with wound healing, and no requirement for anaesthesia.

  • Disadvantage of non-surgical treatment: A higher risk for re-rupture (~40%).

  • Surgical treatment

Surgical treatment involves open surgery and percutaneous surgery. Before beginning any surgical treatment, the doctor usually suggests a plaster cast for the patient.

  • Open surgery

Open surgery is a procedure in which the doctor can dissect and open the ruptured tendon and remove any damaged or affected part. After the repair, the dissected part is stitched.

  • Percutaneous surgery

Percutaneous surgery reduces the impact of surgery on soft tissues. This surgery reduces any morbidity associated with the repair of Achilles’ tendon rupture. Nerve injury is a disadvantage of percutaneous surgery.

The healing rate in surgical and non-surgical treatments is similar. Functional bracing is generally recommended for 6–12 weeks. Both surgical and non-surgical treatment have a complication of re-rupture; however, surgical treatment has less incidence of re-rupture.


Achilles’ tendon rupture patients should perform daily exercises such as swimming, walking, jogging, and cycling. Exercise should be a part of their daily routine irrespective of treatment. Patients must do proper warming and stretching before beginning any exercise. Daily physical activity helps to build muscle strength and improve body movements. Weight-bearing activity is helpful for achieving good outcomes for motion, strength and return to daily activities. It reduces the total duration of healing and risk for re-rupture.

Prognosis And Complications


Many patients with Achilles’ tendon rupture recover well. Athletes can resume their physical activity as before. Few non-athlete patients may experience reduced movement. Patients treated with surgery have a re-rupture rate of 0.5% compared to non-surgical treatment where the re-rupture rate is ~40%.


Patients with Achilles tendon rupture may experience the following complications:

  • Re-rupture

Patients undergoing non-surgical treatment have a 10%–40% risk for re-rupture. Surgical treatment has a significantly less chance of re-rupture.

  • Complications with wound healing

Note that ~5%–10% of patients undergoing surgery are at risk for developing wound healing complications. Risk is higher for women if the patient is smoking or using steroids or if the patient had an open technique surgery. Smoking is the most common and crucial for wound-healing complications.

  • Sural Nerve Injury

Patients undergoing the percutaneous procedure are at more risk for developing sural nerve injury.


  1. Tarantino D, et al. J Funct Morphol Kinesiol. 2020;5:95. 

  2. Achilles Tendon Rupture. StatPearls. Available at:,Shamrock%3B%20Matthew%20Varacallo. Accessed on May 11, 2021. (,Shamrock%3B%20Matthew%20Varacallo)

  3. Aujla R, et al. Journal of Arthroscopy and Joint Surgery. 2018;5:139-144.

  4. Moon Y, et al. Arthrosc Orthop Sports Med. 2017;4:59-65.

  5. Boyd RP, et al. Br J Gen Pract. 2015;65:668-9.


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