Forefoot Varus and Supinatus

A forefoot varus is an osseous deformity of the forefoot occurring in about 1-2% of the population. While there is still some debate as to the aetiology (cause) of this condition, it has been suggested that a forefoot varus arises from the talus (a bone within your ankle joint and rearfoot) developing abnormally. The talus starts out inverted, plantarflexed and adducted, and as we develop, then slowly everts, dorsiflexes, and abducts until it reaches its end position. This rotation of the talus is usually complete by 6 years of age, although some people may take longer. It is therefore quite common to see children under 6 years of age with some degree of forefoot varus. For most people, the talus will end up in a position where the forefoot is level with the rearfoot in the frontal plane (looking from the front). If this movement is inadequate, then the person will have a forefoot varus and if it progresses beyond this point the person will end up with a different (but related) condition called a “forefoot valgus”.

A forefoot varus can be classified according to the amount of subtalar joint pronation that is available to compensate for the forefoot varus. These classes are: fully compensated, partially compensated, or uncompensated. Uncompensated means the foot does not and cannot pronate further at the subtalar joint in order to get the forefoot flat to the weightbearing surface. In this presentation, the heel (calcaneus) is usually perpendicular or even inverted relative to the weightbearing surface, the STJ is either in neutral or supinated, and the midtarsal joint is maximally pronated. The person may also have a plantarflexed 1st Ray as a compensation. A partially compensated forefoot varus means that the foot has some capacity to compensate through pronation of the subtalar joint, but not enough to do so fully. The heel can be everted and there is available pronation in the midtarsal joint. However, none of these are sufficient to allow the forefoot to lie fully level with the weightbearing surface. A fully compensated forefoot varus involves sufficient subtalar joint pronation and midtarsal pronation to allow full contact of the forefoot with the weightbearing surface. The heel is usually everted in this presentation. Each of these forms of forefoot varus will have its own presenting issues, particularly related to plantar pressures (pressures on the bottom of the foot) and which tissues are being stresses as a result of the movements involved and the capacity of that tissue to deal with that stress.

In the uncompensated forefoot varus, the person will have a foot that is relatively immobile at the midpoint of midstance and which not not well suited to dealing with absorbing shock during gait. It is often accompanied by a rearfoot varus, and in extreme cases, by talipes equinovarus (“club foot”). This person will bear weight on the lateral side (outside) of the foot, may have an abductory twist during gait, may have knee issues due to poor shock attenuation of the limb, an abductory twist and rotating the leg abnormally during gait.

A partially compensated forefoot varus will show a mixture of uncompensated and fully compensated signs and accompanying symptoms, depending on the degree of compensation available.

A fully compensated forefoot varus is associated with a foot that will be hypermobile at the midtarsal joint and forefoot during the midpoint of midstance, and particularly during the propulsive phase of gait. Possible complications of this condition may include Hallux Abducto Valgus (“bunions”), lesser toe deformities, skin lesions (corns and callus), plantarfasciopathy, sprains and tendinopathies, excessive internal rotation of the limb leading to knee, hip and groin issues, and low back pain due to lack of shock-absorbing capacity and disruption of the movement of the hallux (big toe) and the Windlass Mechanism.

It must be noted that just because someone has a forefoot varus does not mean that they will have pathologies as a result of it. In many cases, pathologies related to a forefoot varus depend largely on the capacity of the tissues to deal with the accumulated loads placed on them over time.

A forefoot varus cannot be corrected with exercises as it is an osseous (bony) deformity. Orthoses and/or modified shoes are absolutely essential for managing this condition, although surgery is also an option in extreme cases.

A forefoot varus looks very similar to another condition called a “forefoot supinatus”. A forefoot supinatus is a very common soft-tissue deformity due to contracted tissues. It is caused by over-pronation, meaning it is not the cause of over-pronation. If the actual cause of over-pronation is corrected, then a forefoot supinatus can be reversed, either by itself, or with the aid of foot mobilisation techniques.

It is important to be very careful when diagnosing forefoot varus, as correcting for a forefoot varus when one isn’t present can potentially be harmful, as the corrections can interfere with normal foot function and, ironically, lead to the medial arch not being able to support itself, amongst other things. Self-diagnosis must be avoided, and professional diagnoses sought if you suspect you have this condition.

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