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Equinus Deformity

What is it?

 

Talipes equinus deformity is a condition in which the foot is held in a plantarflexed position. The patient will lack the ability to dorsiflex their foot up toward the leg. Commonly, this is due to tightness in the Achilles tendon, the soleus muscles, or gastrocnemium muscle. Other causes can be a boney block in the ankle, or leg length discrepancies.  All of these causes may be congenital or acquired.

 

 

Equinus deformity

 

Related Foot Issues

 

Because an equinus deformity requires a degree of compensation for successful mobility, a number of co-morbid conditions can develop. Some compensation methods involve flattening of the arch to gain ankle motion, toe walking, and even involvement at the knee or hip.

 

Common additional pathologies include:

  • Plantar fasciitis
  • Metatarsalgia
  • Bunions, hammertoes
  • Pressure sores
  • Shin splints, calf muscle cramping
  • Tendonitis
  • Ankle and foot pain

 

How Can Orthotics Help?

 

Custom prescribed foot orthotics aim to ensure proper, even weight distribution, and to control the foot as needed. The customization of each device means that various modifications can be made for appropriate, functional treatment. Orthotics are an important treatment option if surgery is not recommended. If prescribing orthotics for this type of patient, unique care must be taken in product selection and specification.

 

Orthotic Modifications for the Equinus Deformity

 

When a patient with an equinus deformity is treated with foot orthoses, the abnormal forces acting on the foot and lower extremity can cause problems with the orthoses. The two most common problems are irritation across the plantar arch, and irritation along the medial band of the plantar fascia.

 

The lack of ankle joint dorsiflexion can cause excessive pronation of the oblique midtarsal joint (OMTJ) and the subtalar joint (STJ). Because of the tendency of the equinus foot to pronate at the OMTJ, an orthosis that resists these motions may cause irritation transversely across the plantar aspect of the OMTJ. If you have dispensed an orthotic to a patient, and they complain of irritation along the transverse plantar arch, it is likely due to an undiagnosed equinus deformity (assuming it is not a correcting/manufacturing error).

 

The medial band of the plantar fascia may also become irritated by an orthosis if an equinus deformity exists. The equinus deformity causes an increase in pronation moment across the STJH and OMTJ during the gait cycle. This will increase tension in the medial band of the plantar fascia, causing it to bowstring. If this is severe enough, it will be irritated by the orthotic shell.

 

One of the best ways to determine whether the equinus deformity is contributing to orthosis irritation is to try adding a heel lift. This is placed plantar to the heel post of the orthosis inside the shoe.  Add a 1/8″ or/14″ lift and have the patient trial walk and see if the irritation is lessened. If the pain has decreased, then the irritation was likely caused by the equinus deformity, not the construction of the orthosis itself.

 

It is always impressive to see how sensitive some patients’ feet are to small changes in the heel height of the orthoses. Many patients who complain of very significant irritation get total relief with the addition of a 1/8″ heel lift. The lift effectively reduces tension in the Achilles tendon. This creates less OMTJ and STJ pronation occurring during the late midstance phase of gait.

 

If the patient is noted to have a signification equinus deformity during the biomechanical examination, specific shoe recommendations are also needed. The height of the heel of the shoe has as much to do with the orthosis irritation as the height of the orthosis.

 

Sport
Adding a heel raise, even of minimal thickness, can alleviate symptoms and ensure a tolerable and effective orthosis.

Example

 

Patient has pain in the plantar fascia and abductor halluces muscle belly area with both walking and standing; has only 1 degree of ankle dorsiflexion with the knee extended (a gastrocnemius equinus deformity). In this case, the practitioner must ensure that the orthosis and/or shoe have some increased heel height. This is to ensure maximum symptomatic relief and comfort.  If the patient’s shoes have an adequate difference between heel and forefoot height, specific modifications may not be needed (these types usually have a 3/8″ difference).

 

However, if the same patient is wearing their orthosis in a style of shoe with a relatively low heel height, then the orthosis will need to have an increased heel height.

 

In addition to foot orthotics, there are a variety of other non-surgical options aimed at alleviating symptoms. These can be used in conjunction with custom foot orthotics. These can include physiotherapy, night splints. More severe cases may require surgery.

 

 

 

 

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