Achilles Tendinopathy: Everything You Need to Know (And More)

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What you should know about Achilles tendinopathy to prevent its occurrence and to stop it in its tracks before it stops you.

By Jeffrey B. Kreher, MD, FAAP
Pediatrics & Internal Medicine
Primary Care Sports Medicine 

Member AMSSM

The Basics:
Pain in the area of the Achilles tendon goes by a multitude of names and overlapping conditions, including tendonitis, tendinosis, Haglund’s deformity, paratenonitis, and bursitis, among others. The focus of this article will include pain in the Achilles tendon in the midportion (approximately 2-6 cm up from the heel), or non-insertional, Achilles tendinopathy.


Tendinopathy is defined as a combination of pain, swelling, and impaired performance. Unfortunately, Achilles tendinopathy ranks as one of the biggest nuisances to sports medicine providers and athletes. Frequently, the acute injury will go on to be chronic (defined by most to be symptoms greater than six months).


An observational study found that at an average follow-up of eight years after initial nonsurgical management of acute or subacute (less than six months of symptoms)

Achilles tendinopathy:

  • approximately 30 percent had been operated on,

  • 84 percent had full recovery of their activity level, and

  • 94 percent had no symptoms or only mild pain with strenuous exercise; however,

  • 41 percent went on to develop symptoms in the uninvolved tendon (Paavola et al 2000).

Commonly, non-insertional Achilles tendinopathy presents as gradual onset of pain 2-6 cm up from heel insertion. Early on, pain is at the beginning and/or end of training with a period of relief mid workout. With continued stress and overuse, pain can progress and be present the entire workout and perhaps occur with periods of simple walking. A few functional tests include pain with standing on tiptoes (especially when stressed on a single leg and/or repetitively) and pain going up or down stairs. Additionally, morning pain can be present and is associated with increased disease activity. Your sports medicine provider should examine the entire lower extremity both standing and prone. Often, with tendinopathy there will be a tender area that moves through a “painful arc” as the foot is dorsi- and plantar-flexed.

The Achilles tendon is a merging of two calf muscles, the gastrocnemius and the soleus, and their tendons (or more formally, their aponeuroses) with a 90 degree spiral of the fibers. The tendon inserts on the heel bone, or calcaneus. It is surrounded by a layer of cells, or envelope, called the paratenon. The Achilles tendon is the strongest and thickest tendon in the body. It sustains forces 12.5 times body weight. Sports medicine physicians will no longer use the term tendinitis because the –itis implies inflammation which is not present in the classic understanding; rather, there is evidence of neurogenic inflammation that is not fully treated by nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (Advil™, Motrin™).


When viewed with a microscope, the injured tendon has prominent tendon degeneration and changes in the collagen fiber structure and arrangement. The microscopic changes are termed tendinosis. To complicate matters more there can be evidence of tendinosis in athletes without symptoms. Tendinosis most often is found 2-6 cm from the insertion of the tendon onto the heel because this area tends to have less blood flow compared to the rest of the tendon.


The diminished blood flow combined with repetitive microinjury leads to tendinosis and degeneration. However, recently it has been more widely reported that tendinosis leads to new vessels in the area of injury. These new vessels come with new nerves which are purported to be the source of pain along with the neurotransmitter glutamate. The mechanism behind soft tissue management systems such as Active Release Techniques (ART®) and augmented soft tissue methods include break down of adhesions caused by a faulty, or less desirable, attempt by the body to heal the damaged tendon.

Achilles tendinopathy is most commonly present in runners and those participating in other running sports, but does occur with other sports and frequently in less active people. A common stimulus is excessive and repetitive overload of the tendon, or cumulative microtrauma. Injury is felt to be due to nonuniform stresses across the tendon which can be made worse by a “whipping action” about the tendon. The “whipping action” is believed to result from an excessive motion of the hindfoot in the frontal plane as commonly seen with a lateral heel strike and excessive compensatory pronation (or rolling in of the ankle when viewed from behind).


injury has been associated with a multitude of purported risk factors. However, associations do not prove cause and effect in all cases; therefore, the athlete must be diligent in their search for a sports medicine physician, therapist, or chiropractor knowledgeable in biomechanics. Diagnosis of Achilles tendinopathy is easy. It is the search for and treatment of the underlying causes that is most important.

Risk factors for Achilles tendinopathy:

  • Excessive mileage

  • Sudden increase in intensity

  • Decreased recovery time between hard workouts

  • Change of running surfaces

  • Poor footwear

  • Age (>35 years old)

  • Increased body weight and height

  • Exposure to fluoroquinolones (an antibiotic class)

  • Muscle weakness

  • Muscle imbalance

  • Insufficient flexibility

  • Malalignment

  • Leg length discrepancy

  • Pes cavus (flat foot)

  • Lateral ankle instability

There are many less common causes of pain around the Achilles tendon (see below). Your sports medicine provider should check for the following: level of foot pronation, insufficiency of gastrocsoleus complex, hindfoot alignment, amount of ankle dorsiflexion, forefoot alignment, and subtalar movement. The terrible triad that often leads to Achilles tendinopathy includes weak gastrocsoleus complex, decreased ankle dorsiflexion (going up), and limited ankle and foot mobility. This will often lead to increased flexion of the knee and hip, further compounding the stress on the Achilles tendon.

Partial list of other pain sources around the Achilles:

  • Paratenonitis (painful area is fixed with movement of foot)

  • Achilles enthesopathy or insertional Achilles tendinopathy (located at tendon-bone junction)

  • Retrocalcaneal bursitis (most tender deep into Achilles tendon)

  • Superficial bursitis (more prominent heel pain)

  • Sever’s disease (heel pain present in adolescents)

  • Haglund’s deformity (very prominent heel bone and abnormal x-ray)

  • Complete Achilles rupture (acute onset with no or very limited ability to plantarflex)

  • Partial Achilles rupture (usually presents with an acute onset)

  • Anomalous soleus

  • Os trigonum syndrome (worse when on tip toes; common in dancers)

  • Peroneal tendon tenosynovitis and/or subluxation (more lateral to tendon)

  • Plantar flexor tenosynovitis (worse with plantar flexion of foot regardless of activity)

  • Tarsal tunnel syndrome

  • Achilles tendon tumors such as xanthomas (very rare)

  • Sural nerve neuroma

An X-ray should be done to rule out some of the other possible contributors, but is often of limited value. In the hands of an appropriately trained user, ultrasound is the most helpful tool for diagnosis and potentially in assisting treatment. MRI is helpful only in the rarely difficult to diagnose situations. Persistence of symptoms is the natural course and not necessarily an indication for more advanced imaging. Also, an abnormal ultrasound or MRI image with no symptoms is not necessarily an indication for treatment.

The best treatment is prevention, and the best prevention is a sensible training program which is going to vary with every athlete. Preventative loading and stress of the Achilles tendon includes static stretching with a wall, stairs, or 20 degree incline board. Eccentric training has also been found to be good in both prevention and treatment

Given the difficulty in treating Achilles tendinopathy, treatment should be sought early and aggressively. Unfortunately, there is sparse scientific evidence for any one therapy over others. Often, initial treatment will include relative rest. However, relative rest is not complete inactivity but rather avoidance of painful activities. NSAIDs (like ibuprofen and naproxen) are not any better than placebo pill (Astrom et al 1992). Ultrasound, deep friction massage, augmented soft tissue massage (ASTM), and Active Release Techniques (ART®) are anecdotally very helpful.


It is hypothesized that short-term use of a 12-15 mm heel lift and cryotherapy (ice therapy) are helpful. However, the heel lift was not found to be helpful in a randomized prospective trial, and it should only be short term to avoid perpetuating calf inflexibility (Lowdon et al 1984). Correction of the biomechanical deficits has no scientific evidence but still should definitely be considered in all athletes suffering from Achilles tendinopathy (or any tendinopathy).

Acutely, relative rest and minimizing immobilization is paramount. However, in rare cases of extreme pain with any walking, immobilization might be recommended. The recovery phase includes correction of biomechanical deficits such as mobilization of foot and ankle (subtalar and midtarsal), medial and lateral stretching of the tendon, strengthening of the proximal muscles such as the gluteals (or buttocks), multiplanar stretching, and most importantly eccentric strengthening of the gastrocnemius and soleus muscles. While initial studies were extremely promising, follow-up studies of eccentric strengthening continue to enforce the greatest benefit while not without occasional failures. Shoe wear should also be evaluated.

--Eccentric strengthening:
A Swedish physician, Dr Hakan Alfredson, is credited with advancing the study of eccentric training for treatment of Achilles tendinopathy. His initial studies showed unparalleled favorable results in treatment. Upon further study outside of Scandinavia, eccentric strengthening continues to be the most studied and beneficial conservative treatment. However, a systematic review of the studies could not determine the magnitude of effects due to variable study quality and methodologies (Kingma 2007).


Eccentric strengthening programs by definition lengthen a muscle while it is loaded and contracting. Eccentric muscle training is often painful; for example, prolonged downhill running produces more pain if muscles are not accustomed to such loading. A great majority of weight programs focus on concentric strengthening where the muscle is shortened as it is loaded.

Studies of eccentric strengthening reflect the varying theories concerning whether the rehabilitation should be painful or not. Also, there is variability in the amount of load provided and the speed with which the movements should be done.  Of note, the movements are not followed by calf raises in most studies. One lowers their heel down slowly and then unloads the calf only to step back up into the starting position with the uninjured leg. However, work with your sports medicine provider to find what works best for you, given that no one regimen has been proven better than the others. The most common recommendations are variations of the Alfredson’s heel-drop exercise program.

It must be stressed that the best result with eccentric training is in non-insertional Achilles tendinopathy—approximately 90% success. Results in insertional Achilles tendinopathy are much less favorable—approximately 30% success (Fahlstroem 2003).

--Advanced therapeutic options:
There are a few therapies that continue to be investigated with variable results. None of these therapies should be recommended exclusively, but rather be considered part of the toolbox of possible interventions.

If there is significant morning pain, a night splint can be considered. However, a recent study in British Journal of Sports Medicine found no additional benefit when night splints were used in addition to eccentric exercises (de Vos et al 2007). There was a recent report in American Journal of Sports Medicine showing benefit of low-energy shock-wave treatment added to eccentric exercises, but this is a randomized controlled trial from a single institution and awaits further validation (Rompe et al 2008). A study out of Germany found cryotherapy with compression better than cryotherapy alone (Knobloch et al 2008). Another study in American Journal of Sports Medicine found AirHeel brace™ treatment to be as effective as eccentric training but not of added benefit when combined with eccentric training (Petersen et al 2007). The following therapies need more study but have been found beneficial to some chronic sufferers: prolotherapy, ultrasound guided needle tenotomy, platelet-rich plasma injections, shockwave therapy, sclerosing agent injection, and topical glyceryl trinitrate (or nitroglycerin patches).

Peritendinous steroids continue to remain controversial. There is perhaps a short term benefit but no proven long term benefit. In addition, care must be taken to avoid injection into the tendon, as this has been associated with tendon rupture in rats.

One will also remember the high incidence of surgery with chronic Achilles tendinopathy. It is not uncommon to hear that surgery has better results than conservative therapy, but it must be remembered that the greater the reported benefit of surgery, the weaker the strength of the studies. That is not to say that some patients may be appropriately managed with surgery and have excellent outcomes.

The future of Achilles tendinopathy treatment lies in prevention with eccentric exercises. Another potential option is sclerosing agents. This entails injection of a chemical by ultrasound guidance that destroys the new vessel growth associated with tendinosis. As a result it is hypothesized that the nourishment to the nerve fibers and pain generators is lost and pain resolves. However, it must be noted that this remains a superficial treatment that does not address any potential underlying biomechanical cause(s). It is best to work with a cadre of sports medicine providers to tackle this nuisance or be brought to incapacity by this mythological weak area.

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date: February 16, 2009


The American Medical Society for Sports Medicine (AMSSM) was formed in 1991 to fill a void that has existed in sports medicine from its earliest beginnings. The founders most recognized and expert sports medicine specialists realized that while there are several physician organizations which support sports medicine, there has not been a forum specific for primary care non-surgical sports medicine physicians.



The American Medical Society for Sports Medicine (AMSSM) was formed in 1991 to fill a void that has existed in sports medicine from its earliest beginnings. The founders most recognized and expert sports medicine specialists realized that while there are several physician organizations which support sports medicine, there has not been a forum specific for primary care non-surgical sports medicine physicians.


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