Equinus

The equinus foot is a foot deformity that often occurs in children, but also in adults. The heel stands up and does not touch the ground

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The equinus foot - briefly explained

An equinus deformity (also called pes equinus) manifests itself in an abnormally increased flexion of the foot in the ankle. This misalignment of the feet occurs in children, but also in adults.

An equinus malalignment can be congenital or acquired, most often the equinus occurs as part of a neurological disease in which the interaction between nerves and muscles is disturbed, such as paralysis (due to infantile cerebral palsy - also called ICP - or polio - also called polio or a stroke). But also bony changes in the ankle, muscle diseases, tendon injuries or being bedridden can cause the formation of an equinus.

A malalignment of the equinus foot is treated depending on the cause. For conservative therapy (without surgery), physiotherapy treatments and stretching exercises as well as special splints (orthoses, night splints) are available. If the calf muscles or Achilles tendon are shortened, they can be surgically lengthened.

What is an equinus?

An equinus foot is a misalignment of the foot in which the foot can no longer be brought into a 90 degree position in the ankle while lying down with the knee joint extended (by an examiner, i.e. passively). The foot remains permanently in a bent position, which causes considerable problems when walking and standing. The foot can only be loaded on a small contact surface. Balance is difficult, especially when, as in most patients, other neurological disorders are also present. Often there are also combined malpositions of the feet, for example an abduction-flexor-flat foot or a clubfoot.

© W & B / Astrid Zacharias

Equinus position

The equinus foot is a misalignment of the foot in which the foot is held bent at the ankle (plantar flexion). There is a raised heel. A touchdown of the foot with the entire sole of the foot is not possible.

Cause: How does an equinus foot occur?

An equinus deformity can either be congenital or acquired. A congenital equinus is very rare. It is assumed that a forced posture of the embryo in the womb (breech position) can cause malpositions of the feet. It is found more frequently in connection with underlying neurological diseases or skeletal malformations.

The equinus foot malalignment is usually acquired; here, other diseases are in the foreground, which then lead to an equinus malalignment. This is therefore the result of a disease (so-called secondary deformity):

  • Neurogenic causes due to nerve damage

Damage to nerve tracts leads to paralysis of individual muscles or muscle groups (paresis). Nerve damage occurs, for example, in a stroke (apoplexy), infantile cerebral palsy or an infection with polioviruses (poliomyelitis, polio). However, permanent pressure on a nerve (especially in the area of ​​the fibula head) or a fracture can also cause nerve damage. Neuropathy can also damage the nerves.

  • Muscular or tendon-related causes

Muscle or tendon disorders can lead to an equinus deformity due to shortened calf muscles. Even after a rupture of the Achilles tendon (Achilles tendon rupture), the tendon can shorten, which then causes an equinus deformity.

  • Widespread scarring

If, for example, severe scarring occurs in the calf area due to burns or soft tissue injuries (e.g. a compartment syndrome), the tissue contracts (contracture). This pull in the calf area results in an equinus foot.

  • Due to storage

In bedridden people in need of care, for example, the lack of movement of the ankle joint for several days can lead to an equinus foot deformity.

Forms of an equinus

Every child first learns to walk on tiptoe. Doctors call this the physiological tiptoe of a toddler. If the tiptoe persists beyond this phase without a neurological or neuromuscular disease being present, one speaks of a habitual equinus.

As long as the equinus foot position is only available when walking or standing, without the calf muscles being irreversibly shortened, one speaks of a functional equinus foot. A typical example is the equinus foot, which is used to compensate for a difference in leg length. If there is a shortening of the calf muscles (contracture), which can no longer be compensated for, experts speak of a structurally fixed equinus foot. Causes can be spastic muscle activity, muscle damage after accidents or even scars.

Diagnosis: how is an equinus foot diagnosed?

The diagnosis of equinus foot is made by taking the medical history (anamnesis) and examining the patient. Here, attention is also paid to whether the doctor can still bring the foot into the so-called neutral-zero position while lying down - i.e. the position in which at least a 90 degree angle is reached in the ankle. If this is not possible, there is an equinus foot position. The gait pattern of those affected is clearly impeded by the equinus foot position. With a fixed equinus foot, the foot is only loaded in the front area, heel contact with the ground is not possible when standing. Compensation can be achieved by overstretching the knee joint, increasing flexion in the hip joint or counter-curving the lumbar spine. This can lead to significant unsteadiness in gait and discomfort in the adjacent joints.

An X-ray helps rule out bony causes such as osteoarthritis of the ankle, but the X-ray image is usually normal for neurological causes. A long-standing equinus foot can also lead to secondary changes in the skeleton of the foot.

Therapy: how can an equinus foot be treated?

  • Conservative treatment (without surgery)

A habitual equinus foot position in childhood can, under certain circumstances, correct itself under the increasing body weight of the growing child. If this is not the case, the equinus must be treated. Parents should discuss with their doctor at an early stage whether therapy is necessary. As long as the foot misalignment is not caused by shortened calf muscles, conservative treatment is possible with good results. Sometimes special stretching exercises under the guidance of a physiotherapist are sufficient.

If the calf muscles are threatened with shortening, a different treatment is usually necessary. For example, patients have to wear a lower leg walking cast for several weeks so that the position of the feet returns to normal. Then night splints and functional orthoses (walking splints) are often used.

Sometimes the doctor will also administer botulinum toxin to certain parts of the calf muscles to relax them. Botulinum toxin is also used to assess the possibilities and limits of functional treatment.

  • Operative treatment

If the equinus foot position is already structurally fixed, i.e. if the calf muscles are shortened or if there are bony changes, an operation is usually necessary to correct the deformity. Here, too, there are different treatment approaches. Basically, the Achilles tendon or the calf muscles can be lengthened. Lengthening the Achilles tendon is technically easier and leads to a greater increase in length. The disadvantage is a possible loss of strength. The procedures in which the calf muscles are lengthened are therefore considered to be gentler and more physiological.

More complex interventions are often necessary for bony changes.

All procedures carry a certain risk of relapse, especially in growing age. But they can be repeated several times. As a rule, intensive physiotherapeutic follow-up treatment is necessary after the operation.

Our expert: Professor Markus Walther

© Schön Kliniken Munich Harlaching

Our advisory expert:

Professor Markus Walther, specialist in orthopedics and trauma surgery, head of the department for foot and ankle surgery at the Schön Klinik Munich-Harlaching.

Swell:

  • Fritz U. Niethard, Pediatric Orthopedics: Spitzfuß, p. 178 f., 2nd edition, 2010, Thieme-Verlag
  • S. Breuch, H. Mau, D. Sabo, Clinic Guide Orthopädie: Spitzfuß / Hängefuß, p. 716 f, 5th edition, 2006, Urban and Fischer Verlag
  • F. Hefti, Pediatric Orthopedics in Practice, 3rd edition, 2015, Springer Verlag

Important note: This article contains general information only and should not be used for self-diagnosis or self-treatment. He can not substitute a visit at the doctor. Unfortunately, our experts cannot answer individual questions.

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