Ankle and Foot

Achilles Pain: Symptoms, Treatment and Biomechanics

Details

Published on Sunday, 04 July 2010 02:22

Written by David Micca, DPM, FACFAS, CWS, FAACWS

by David Micca, DPM, FACFAS, CWS, FCCWS

Podiatrist: Doctor specializing in Foot and Ankle disorders/ Foot & Ankle Surgeon

Achilles Anatomy:

The Achilles tendon is made up of two muscles of the calf, the gastrocnemius and the soleus. The gastrocnemius is the longer of the two muscles, the soleus is the shorter muscle.

These muscles combine to make up the calf. As they descend, they combine to form the Achilles tendon. Fibers of the Achilles tendon continue beyond the insertion to form the plantar fascia on the bottom of the heel. Fibers of the Achilles tendon attach to the back of the heel below the mid-level of the body of the heel.

The anatomical function of the Achilles is to allow the heel to rise and transfer weight of the foot onto the toes for propulsion. The anatomical function of Achilles rotation is to invert the heel (frontal plane motion) during plantarflexion of the foot.

Most tendons have a tendon sheath that produces fluid, called synovial fluid, that bathes the tendon in nutrition. The Achilles tendon does not have a true tendon sheath and is surrounded by a structure called paratenon, a thin layer of fibrous tissue that separates the Achilles tendon from surrounding soft tissue.

The absence of the tendon sheath allows the Achilles tendon to complete a larger range of motion (ROM). The absence of a tendon sheath limits the amount of circulation and synovial fluid that can be supplied to the tendon when injured. This lack of circulation is the reason why Achilles tendon ruptures heal so slowly.

Acute Achilles tendinitis

Acute Achilles tendinitis (also known as Albert's Disease) has an abrupt onset with pain 2-3 cm proximal to its insertion on the back of the heel. Most individuals with acute Achilles tendinitis can describe an injury or an overuse event that initiated the pain.

Symptoms of Acute Achilles Tendinitis

Symptoms of acute Achilles tendinitis occur at the beginning of an activity and are described as a sharp pain.

As the activity progresses and the Achilles tendon 'warms up', the Achilles pain begins to resolve. With excessive use, the tendon again becomes painful at the end of activity. For example, runners with Achilles tendinitis experience pain as they begin their run. The pain subsides while running only to recur near the end of their normal running distance.

Achilles tendinitis is a condition of irritation, swelling and inflammation of the large tendon in the back of the ankle. When tendinitis advances and the tendon erodes, the condition is called tendonosis. With tendonosis, the tendon's shape is disrupted, causing tiny tears. Small tears within the tendon make it susceptible to rupture. If these small tears are chronic, they will calcify over time causing a condition known as pericalcific tendinitis.

Achilles tendinitis is a common overuse injury that tends to occur in middle-age recreational athletes as well as people with predisposing biomechanical abnormalities such as Haglund’s deformity, fully compensated or partially compensated rearfoot varus, equinus, as well as other foot types.

Chronic Achilles tendinitis

Chronic Achilles tendonitis exhibits the same type of pain as acute Achilles tendinitis but the location of the pain is usually at the insertion of the Achilles tendon into the heel (see picture). Chronic Achilles tendinitis can also cause hypertrophy (enlargement) of the posterior heel. This hypertrophy at the back of the heel can occur by either an increased Philip-Fowler angle (an x-ray finding) and is considered a structural cause or due to abnormal frontal plane motion of the rear foot which causes “reactive” bone growth (hypertrophy). This occurs due to excessive motion (rubbing) of the posterior heel on the counter of the enclosed shoe back.

Chronic Achilles tendinitis does not improve with use, but rather shows a direct relationship with the duration of time spent on your feet; the more you use it, the more it hurts. This condition is also called Achilles tendonosis, which can lead to hypertrophy (enlargement) of the back of the heel and Achilles tendon.

In cases of chronic Achilles tendinitis it's important to differentiate between pain strictly due to the pull of the Achilles tendon and pain due to the enlargement of the posterior heel rubbing against the shoe called a pump bump or Haglund’s deformity. Oftentimes, this can be differentiated by determining when the pain occurs.

• If there is pain to the Achilles walking barefoot it is suggestive of Achilles tendinitis
• Pain to the posterior heel with enclosed shoes is usually due to a “pump bump” or Haglund’s deformity

Correcting the abnormal rear foot motion on the frontal plane can correct the inflammation associated with a Haglund’s deformity. Custom orthotics are often prescribed to correct the problem.

Another way to differentiate a pump bump from insertional Achilles tendinitis is by the location of pain. A Haglund's Deformity is usually found on the posterior-lateral heel while insertional Achilles tendonitis is central to the Achilles tendon and is directly posterior to the heel.

Treatment of acute and chronic Achilles tendinitis

We know that we need to weaken the calf muscle to allow the Achilles tendon an opportunity to heal.

In cases of chronic Achilles tendinitis, patients who do not respond to heel lifts and anti-inflammatory medications require a lengthening procedure of the Achilles tendon with or without a partial resection of the posterior heel.

In cases with minimal hypertrophy of the heel, lengthening of the tendon will suffice. Lengthening of the Achilles tendon may be performed through three 0.5cm incisions but does require a period of casting. Full recovery may take 6-8 months.

Endoscopic techniques are also available in a limited number of cases, correcting equinus with a procedure called an endoscopic gastrocnemius recession.

PRP or Platelet-Rich Plasma is also used for the treatment of Achilles tendinitis. PRP offers increased concentrations of the patient’s own plasma, which is harvested from centrifuged blood before it is injected into the injury site. PRP injections yield high concentrations of growth factors and other proteins that subsequently lead to enhanced healing of the Achilles tendon on a cellular level.

Biomechanics as it relates to the Achilles Tendon

Equinus is the most common contributing factor to Achilles tendonitis. Equinus refers to one who walks on his toes. Equinus can be determined by measuring the range of motion of the ankle with the knee flexed and extended.

By dorsiflexing the foot (moving the toes towards the leg) an angular measurement is established between these two lines. Normal range of motion of the ankle, to complete a normal gait cycle, is 10 to 15 degrees beyond 90 degrees. This means that the normal range requires the ankle to dorsiflex to 90 degrees plus an additional 10 to 15 degrees. An inability to complete this range of motion is termed equinus.

Other factors may contribute to an inability to reach 90 degrees, such as a bony block on the front of the ankle. This is called an osseous equinus.

Abnormal rearfoot motion, particularly rearfoot pronation, has been associated with many foot and leg pathologies. It can cause abnormal torgue on the Achilles, predisposing it to overuse syndrome and tendinitis. Control of abnormal rear foot pathology with functional orthotics ensures prevention of these conditions.