The compensated equinus deformity is caused by either a structural or functional shortage of the gastrocnemius muscle. It creates an inability to achieve a range of 10 degree dorsiflexion of the foot to the leg when the knee is fully extended and the subtalar joint is in neutral position. The reduced range of motion will be made up for by pathological motion in other joints or segments.

A compensating equinus is one of the most important causes of treatment failure. Equinus influences may be distorting your diagnosis, disrupting or negating your treatment approaches and destroying your patient’s feet, legs, and body.

In fact, the compensating gastrocnemius equinus deformity forces the subtalar joint to use limited sagittal plane motion to compensate for it. This action forces the subtalar joint into a pronated position or even a subluxed position throughout the gait cycle. Clinically, this can be diagnosed simply by watching the patient stand and walk.

Measurements can be misleading due to compensation being divided among various segments of the feet and legs. For example, midtarsal joint oblique axis compensation can provide additional dorsiflexion of the forefoot on the rearfoot that ultimately becomes fixed in some patients. This can give a false over-estimation of the range of ankle dorsiflexion. Similar compensation can occur at the knee in the form of hyperextension.

In short, diagnosis can be tricky. That’s why some patients are given orthotics made from neutral position casts and have nothing but trouble with them. Signs and symptoms that may accompany orthotic therapy in patients with gastrocnemius equinus deformity are:

1. Pain and discomfort wearing orthoses even after a long adjustment period
2. Fracturing of orthotics
3. Flattening of orthotics
4. Sliding off the orthotic and development of medial and lateral ridges from them
5. Leg cramping
6. Retro-patella pain
7. Development of 1st MPJ pain

Appropriate treatment when you suspect gastocnemius equinus deformity is calf muscle stretching before and after dispensing of the orthotics. Casting for the fully compensated equinus deformity when combined with a fully compensated rearfoot varus is one of the only cases where a semi-weight bearing cast of most effective; otherwise you may have intolerance problems. Other less severe equinus deformities may require slight to moderate pronated of the neutral position cast. Heel raises may be of some value in severe cases if the patient will wear them during 90% of weight bearing activity. Other problems develop is the patient is in and out of the heel elevation. If in compliance, patient’s stretching exercises do not increase ankle dorsiflexion, a structural versus a functional equinus is present. This may indicate a need for surgical lengthening of the Achilles’ tendon. If surgical intervention is not deemed appropriate, then orthotics with heel raises and/or molded shoes with heel raises would be appropriate forms of therapy.

For the severe, fully compensated rearfoot varus equinus patient, a true flatfoot, non-weight bearing will be present. Molded orthopedic shoes are the recommended treatment. Due to the center of gravity being extremely medial during the gait cycle the molded shoe controls better than conventional shoes with or without orthotics. If for cosmetic reasons the patient wants orthotics the casts should be semi-weight bearing with the subtalar joint held as closely to the accommodative neutral as possible. An accommodative, soft, molded orthotic is only recommended appliance. Heel lifts should be used only if the patient will be in them 90% of the weight bearing time.

The fully compensated rearfoot varus equinus is a rare deformity. Trying to treat it like all other biomechanical deformities is foolish; full correction is impossible, not to mention intolerable. Great relief can be obtained with molded shoes or semi-weight bearing orthotics. If the equinus deformity is present, consideration of its destructive forces is imperative in designing prescription orthoses.