Condition Spotlight: Ankle Equinus

diagram showing ankle equinus

Ankle equinus is a condition where the ankle joint is lacking flexibility and sits in a position that is called the plantarflexion. It involves a restriction in the movement of dorsiflexion, which involves pulling the toes upwards towards the skin bone.

To make it easier to understand this condition, let’s first have a look at the structure of the ankle joint.

The ankle joint, which is also known as the talocrural joint, is composed of the 2 leg bones called the tibia and the fibula, as well at the talus bone in the foot.

The ankle joint is a hinge joint, meaning that it primarily moves in 2 directions (plantarflexion and dorsiflexion) and has very little movement through any other directions, much like a door.

It is also known as a synovial joint, where the ends of the bones are protected by a smooth cartilage. Within the joint there is also a joint capsule that protects the joint itself, and within this joint capsule is what is called a synovial membrane. This membrane produces a fluid that lubricates the joint and allows it to move efficiently.

The ankle joint is very important through the gait cycle. Adequate movement through the ankle joint is crucial for everyday life, as well as ensuring your feet clear the ground when you are walking so that you don’t trip and fall over.

An ankle equinus may result in the person not being able to move through the phases of gait properly.

The 2 muscles that are commonly the cause of ankle equinus are the gastrocnemius muscle and the soleus muscle.

The gastrocnemius muscle

This is the biggest muscle at the back of the lower leg and acts at both the knee and the ankle joints.

It originates at the lateral (outer) condyle of the femur (thigh bone) and attaches onto the heel bone via the achilles tendon.

It is responsible for knee flexion and plantarflexion of the ankle joint.

The soleus muscle

This muscle sits behind the gastrocnemius in the lower leg.

It originates from the medial (inside) border of the tibia and also attaches to the heel bone via the achilles tendon.

Its role is to plantarflex the ankle joint.

What Causes an Ankle Equinus?

There are a number of causes that can be attributed to equinus of the ankle, which can include:

  • Tightness in the achilles tendon or the calf muscles, particularly the gastrocnemius and soleus muscles.
  • A tarsal coalition, which is a condition where there is an abnormal connection or fusion between 2 bones in the midfoot and the rearfoot. This fusion can be caused by bone, cartilage of fibrous tissues and is often referred to as a bar. This can limit movement through the rearfoot and midfoot joints, therefore affecting the ankle.
  • Bony blocks that have been caused by a previous fracture in or around the ankle or midfoot joints.
  • Trauma to the ankle joint through injury including an achilles tear and/or rupture or a severe ankle sprain that has resulted in torn ligaments.
  • Excessive wearing of high heeled shoes.
  • Some other health conditions can also cause tightness, such as diabetes, where prolonged excessive levels of blood sugars can damage tendons, or neurological disorders that cause muscle spasms.
  • A limb length discrepancy where one leg is longer than the other.
  • Being in a cast or on crutches for long periods of time.

In some cases it is a congenital condition, meaning that it has been present since birth. In other cases, it may advance over time or is acquired through a traumatic incident that has affected the position of the ankle or the achilles and calf muscles.

It can occur on one or both feet and the degree of equinus may differ between the feet. In children, it is often referred to as toe walking.

How is Ankle Equinus Diagnosed?

Often patients will be able to identify that their lower leg or ankles are not functioning properly, however sometimes it is more subtle and requires an accurate diagnosis.

In some cases, patients are unaware that they have an ankle equinus, as their presenting problems are elsewhere in the lower body.

To diagnose an equinus in the ankle, a thorough biomechanical assessment is completed. This involves looking at the range of motion of the ankle and foot joints while you are seated, as well as testing the strength of the muscles.

We will assess you for a limb length discrepancy as well. Standing assessments involve looking at the foot posture, the strength of the posterior leg muscles including testing your ability to perform a calf raise, as well as testing the flexibility of the calves and ankle using the lunge test.

Gait assessments will look at the way your body moves through the gait cycle to identify any abnormalities.  Those who have an ankle equinus tend to walk more on the forefoot and do not use the heel efficiently. Some people will not have the heel contact the ground at all, placing excessive pressure on the rest of the foot.

There are a few ways that the body tries to compensate for an ankle equinus including flattening out the arch of the foot to assist with stability and lifting the heel off the ground earlier.

At Watsonia Podiatry, we use our Zebris treadmill to assess where the forces are being placed on the feet.

In some cases, we may send you for scans such as an X-ray, ultrasound or MRI to see if we can identify the cause of the ankle equinus.

How can an ankle equinus affect the rest of the foot?

Those with an ankle equinus typically find a way to compensate for this, therefore treatment must not only focus on the ankle joint but the rest of the foot and lower leg as well.

Compensation pain or injuries can occur anywhere from the lower back down to the feet. If an ankle equinus is not properly diagnosed, this pain may not be able to be treated properly either.

Ankle equinus can lead to other conditions including:

How is an ankle equinus treated?

Treatment depends on a number of factors including your occupation, activity levels and the aetiology or ‘reason’ why you have an ankle equinus.

Treatment can include:

Heel lifts

Typically either 4mm or 6mm, these can be placed into your shoes to give your heel a stable platform and reduce pressure through the ankle, achilles tendon and posterior leg muscles.

Orthotics

Orthotics can provide correction and support for the foot and ankle.

As there are  a number of compensation injuries due to ankle equinus, orthotics can help to support the body from the feet up to the hips and redistribute pressure so that the lower body can function more efficiently.

A stretching and strengthening program

This will aim to target the gastrocnemius and soleus muscles, but will also provide general strengthening to the rest of the foot and lower leg.

This may include simple calf stretching and variations of calf raises.

Footwear modifications

This may involve changing the footwear that you wear most often if it is not appropriate for either your foot type or activity.

Wearing footwear that supports and cushions your feet is important in general and will help to avoid other pain or problems.

Night splints (in severe cases)

In some cases, night splints may need to be used to help reduce the severity of ankle equinus.

These are generally used more in children who are toe walking or if there is a genetic or health condition that means that conservative treatment will not work.

Surgery (in severe cases)

This is typically used as a last resort treatment when conservative options have failed.

Surgery may involve lengthening the achilles tendon, reconstructing the ankle, repairing damaged structures or treating a tarsal coalition.

Do you have an ankle equinus?

If you are suffering from any pain in you lower legs or feet and think you may have an ankle equinus, contact us today for an appointment with one of our podiatrists. We will work with you to find the most suitable treatment option and make your more mobile today.

Book in to see us by giving us a call on 03 9432 2689 or making an appointment online here.