Equinus

Motion in the human body depends upon a fine balance between strength and flexibility. Muscles need to be strong enough to accomplish a given task, but they also need to be flexible enough to allow for normal range of motion. Loss of muscle flexibility can lead to injury. When the upward (dorsiflexion) range of motion of the ankle is limited, the term equinus is used to describe tightness in the calf and Achilles tendon.

Equinus is caused by soft tissue or bone pathology and caused by one or more of the following:

• Contracture or shortening of the Achilles tendon.
• Anterior ankle bone block.
• Posterior ankle contracture.
• Congential posterior ankle or tendo-Achilles contracture.

The presence of one or more of these conditions will limit the range of motion of the ankle resulting in equinus.

Folks with moderate to severe equinus will find a number of different foot problems as a result of a tight calf. These problems may include bunions, flat feet, hammer toes, tendonitis, heel pain and a host of other foot conditions. These problems evolve from our first steps as children and continue to develop through adulthood. Equinus contributes to the development of these problems by causing an imbalance between each of the muscle groups of the lower extremity.

Treatment of Equinus

The initial steps in treating equinus include the use of a heel lift and calf stretching exercises. Shoes with a higher heel are also helpful. Folks with equinus should also avoid going barefoot or in just their socks. Simply put, the lower the heel, the more problems you'll have with equinus related foot problems.

In some cases, surgical care is required to lengthen the Achilles tendon. This procedure can also be performed endoscopically and is called an endoscopic gastrocnemius recession. The following video shows the steps used to perform an endoscopic gastrocnemius recession. Two incisions are used, one on the medial and another on the lateral aspect of the calf. The obturator and cannula are passed between these two incisions.

An endoscopic gastrocnemius recession (EGR) is performed on an outpatient basis using a general anesthetic and thigh tourniquet. The procedure take approximately 15 minutes to complete. Patients are able to walk the same day of surgery. Follow-up care may include the use of compression hose to accommodate swelling and the use of an anticoagulant as a prophylactic measure to prevent deep vein thrombosis (DVT).

An alternative procedure to an EGR is a percutaneous Achilles tendon lengthening (TAL). A percutaneous TAL is performed with three 0.5 cm stab incision and often does not require suture closure. Each procedure has its advantages and disadvantages. The EGR is an ambulatory procedure meaning that patients can walk on the leg the same day of surgery. The disadvantage of the EGR is that it weakens the force of equinus by only 5-10%. A TAL has a significantly greater impact on equinus in that it can weaken to force of equinus up to 50%. The disadvantage of the TAL is that it is a non-ambulatory procedure and requires 6 weeks of non-weight bearing casting.

For more information regarding the biomechanical interaction of the leg, ankle and foot, be sure to view our pages on CT Band Syndrome.

EGR - endoscopic gastroc recession.

Equinus -  derived from the Latin word equus meaning horse. Horses are toe walkers. A horse’s hoof is actually its toes. And hence the comparison to humans with a tight calf.

TAL - tendo-Achilles lengthening.

The calf consists of two muscles, the gastrocnemius and the soleus. The origin of the gastrocnemius is above the knee on the posterior thigh (femur) and the origin of the soleus is below the knee on the lower leg (tibia). As these two muscles descend the leg from the knee to the ankle, they merge to form the Achilles tendon. The Achilles tendon inserts into the back of the heel bone (calcaneus). Equinus is said to be present if the range of motion at the ankle is limited due to tightness in the calf.

Normal range of motion in the ankle is measured by placing a person supine with their knees extended (straight) and force is applied to the forefoot, moving the toes and forefoot towards the knee.  This motion at the ankle is called dorsiflexion. To measure the range of motion, an imaginary line is drawn down the lateral (outside) side of the leg and foot. Range of motion is considered normal when the patient to be able to reach a 90 degree angle between the two lines plus an additional 10 degrees. Any measurement shy of 90 degrees would be considered equinus. Please note - accurate measurement of equinus requires positioning of several joints and requires some training to be performed accurately. This brief description is merely for sake of example.

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• Achilles Tendon Rupture

• Pronation

• Supination

• CT Band Syndrome

• Foot and Ankle Anatomy

This article was written by Jeffrey A. Oster, DPM and last updated 2/5/13.

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