Achilles Tendon Injuries
The Achilles tendon is among the most important functional parts of a person’s leg. According to the American Orthopaedic Foot & Ankle Society, “the Achilles tendon is the largest tendon in the body. It is formed by the merging together of the upper calf muscles [gastrocnemius/soleus], and inserts into the back of the heel bone [calcaneus].”1
The Achilles tendons, like other body tissues, become more rigid, less flexible, and more susceptible to injury as a person ages. However, injuries to the Achilles tendon are not common, affecting only 6% of inactive people. The most common cause of injury is repetitive stress on the tendon (ie, stress tendinopathy), especially during exercise. This painful condition accounts for approximately 11% of all running injuries and can be quite debilitating, preventing the sufferer from exercising and causing great difficulty walking, especially when the condition is acute.2
There are two types of Achilles tendinopathy—noninsertional and insertional—depending on which part of the tendon is affected.3 In noninsertional Achilles tendinopathy, fibers in the middle portion of the tendon have begun to degenerate, swell, and thicken. This type of injury tends to affect younger, more active patients. Insertional Achilles tendinopathy involves the lower portion of the heel, where the tendon attaches (inserts) to the heel bone. This type of injury can occur at any age, in patients who are very active and in those who are inactive.3
Repeated episodes of Achilles tendonitis can lead to the development of Achilles tendinosis, a chronic degenerative condition of the tendon that can lead to tendon tearing or rupture, which usually requires surgical repair.
Who Is at Risk?
In addition to runners, people who participate in dancing and sports such as tennis, football, and basketball are at high risk for injury. Using poor techniques while training for such sports or when running causes unnecessary pressure on the tendons. Making abrupt changes in training methods, such as an abrupt increase in the intensity of training or reducing the interval between 2 different sections of training, also can put strain on the tendon.4
There are several other factors that can put people at increased risk for Achilles tendon injuries. Some arthritic conditions, such as ankylosing and/or psoriatic arthritis, cause weakening of the tendons, making them prone to such injuries. Also, some people have genetically weak tendons, which make them vulnerable to this type of injury. Use of certain medications, such as fluoroquinolones (eg, ciprofloxacin and ofloxacin), also can increase the risk.
The primary presenting symptom of Achilles tendinopathy is pain/tenderness in the posterior heel and along the tendon. Pain is usually worse when first getting up and walking following a period of inactivity. Achilles tendinopathy is usually diagnosed by taking a careful history and palpating the level of swelling and/or tenderness of the tendon to help locate the exact area of involvement—usually 2 cm to 6 cm above the calcaneus (Figure 1).2,5 Thickening of the tendon is often noted. In some cases, asking patients to perform exercises that involve putting the Achilles tendon under pressure can help to determine the level of injury. One example of this is to have the patient try to stand or walk on his or her toes.
In some cases, baseline x-ray, magnetic resonance imaging, and bone scans may be indicated. Differential diagnoses include ruling out posterior tibialis ligament injury or Achilles tendon avulsion, inflammatory arthritides, plantar fasciitis syndrome, occult lesion, stress fracture of calcaneus, or sural neuritis.6
Rupture of the Achilles tendon can be diagnosed by squeezing the calf muscle when the patient is lying facedown on an exam table; if the foot does not move, the test is positive for an Achilles tendon rupture.
Depending on the level of injury, there are several conservative interventions that can be used to treat Achilles injuries.7 Conventional treatment usually consists of RICE (rest, ice, compression, and elevation) and nonsteroidal anti-inflammatory medication (NSAIDS), along with stretching and exercises.8 These methods are easy to perform and cost effective, with very good outcomes. In addition to facilitating repair of the injured area, the conservative methods involve identifying the etiological factors of the injury and attempting to correct them. When conservative interventions fail, there are a number of surgical options.
In most cases, the initial, acute treatment for Achilles tendinopathy starts with putting the tendon at rest. Exposing the patient to a lot of pressure, especially on the injured area, could worsen the injury and increase the pain felt by the patient. Therefore, patients should be advised against any exercises that expose the injured area to impact. Only light exercises are acceptable.9 Icing the injured tendon (15 minutes on/15 minutes off) is a useful way to reduce swelling, both immediately after injury and after exercise.10
The most commonly prescribed pain medications include acetaminophen or NSAIDs, such as ibuprofen. However, these agents should not be used for longer than 2 weeks because they can hinder the ability of the tendon to heal completely. Additionally, side effects such as gastrointestinal complications (stomach pain, ulcer, bleeding) and cardiac complications have been associated with these agents. Patients with pre-existing GI or cardiac issues should be advised to consult a medical specialist before taking these agents.11
Topical glyceryl trinitrate, usually used to treat angina, has been found to reduce the symptoms of noninsertional Achilles tendinopathy and improve function when used continuously for up to 12 weeks.12 In one study, 52 patients (68 tendons) treated for 6 months with topical glyceryl trinitrate therapy were followed for 3 years after cessation of therapy. Patients were asked about their pain scores, return to previous activity, the Victorian Institute of Sport Achilles tendon scale (VISA-A), asymptomatic patient outcomes, clinical assessment of tendon tenderness, and functional hop test. According to the study findings, the patients treated with glyceryl trinitrate had significantly less Achilles tendon tenderness (P=0.03), and greater improvement in VISA-A scores (P=0.04) than those in the placebo group; 88% (28 of 32 tendons) of patients were completely asymptomatic at 3 years (VISA-A score of 100) compared to 67% (24 of 36 tendons) of patients treated with rehabilitation alone (P=0.03 with Chi square analysis).13 The authors suggested that the mechanism of action of topical glyceryl trinitrate on chronic tendinopathies is more than an analgesic effect.