The common deformities of the foot are those in which the parts affected are deformed or turned to an abnormal degree in the direction of their normal movements. Thus in talipes varus the foot is turned inward, hyperadducted; talipes valgus and flat-foot, turned out, hyperabducted; talipes equinus or hyperextended, talipes calcaneus or hyperflexed, and talipes cavus or increase of the arch of the foot. These deformities may be either congenital or acquired, and it is not always easy to separate the two. A deformity may be thought by the parents to have existed from birth, when it may have been caused by an infantile paralysis occurring before the period of walking.

Foot deformities likewise possess two characteristics which are marked, they are those of paralysis or weakness and contraction or strength. They are usually associated but sometimes separate. There can be a paralysis without contraction, but inasmuch as the muscular system is built on the principle of balance it is obvious that if one muscle or set of muscles is paralyzed it is only a question of time until the opposing muscles become contracted. In a similar manner if contraction exists as the most prominent element and perhaps the primary one, it will usually be found that the opposing muscles and ligaments are stretched and weakened.

These conditions furnish the indications for treatment. Where weakness is the predominant feature then support is to be given and contraction of the relaxed tissue favored. Where strength and contraction is predominant then operations and forcible measures are necessary to overcome them. Also, when in a contracted case the contracted tissues have been overcome, there still remains the weakness of the opposing tissues to be remedied. It may be possible to bring the foot to a perfectly normal position, but until the previously weakened and overstretched tissues have regained their tone normal function will not be possible.

While the deformities may be simple they are usually compound; thus an equinus may be associated with a varus or valgus, 'and is then called an equino-varus or equinovalgus. Cavus or hollow-foot and calcaneous or lowering of the heel are often associated, so that it is difficult to draw a line separating them.

Talipes Varus

Talipes varus in its most common form is congenital and is often associated with equinus or a drawing up of the heel. The prevailing deformity is one of adduction, with a certain amount of inward rotation (Fig. 595). The muscles favoring it are the tibialis anterior and tibialis posterior; therefore the tendons of these muscles are sometimes cut to prevent their drawing the foot upward and inward. Division of the plantar fascia is also often necessary. The main principles of treatment are to stretch the contracted tissues forcibly, either by manual or instrumental force, and then maintain the foot in its corrected position, often at first by plaster of Paris and later by apparatus, until the weakened opposing muscles have resumed their functions. This often takes so long that transplanting of tendons has been resorted to; thus the tendon of the tibialis anterior has been detached from its insertion on the inner side of the foot and transplanted to the outer side, so that the contracting force on the inner side of the foot is weakened, while the correcting force of the abducting muscles has been increased.

Fig. 595    Talipes equinovarus.

Fig. 595- - Talipes equinovarus.

If equinus is present either tenotomy of the tendo calcaneus (Achillis) or forcible stretching of it allows the heel to descend.