What Is Metatarsus Varus?

Metatarsus varus, which is also called metatarsus adductus, describes a congenital condition causing the bones in the front of the foot, or the forefoot, to curve inward. It may equally affect one or both feet. There are several potential reasons why this condition might occur, and the severity of the problem usually can’t be estimated at birth. Instead, it is analyzed as babies grow, and the seriousness of the curve is judged by how rigid the bone structure in the forefoot is becoming. Some children with this malformation outgrow it, while others may require interventions like exercises, casting, or surgery.

Conditions like metatarsus varus are often said to cause pigeon toeing, a term that isn’t always used because it may have negative connotations. It is, however, a useful description for understanding the basic appearance of an affected foot, although the inward curvature should be understood as originating from the middle of the foot instead of from the heel. Patients with metatarsus varus have no malformation of the heel bones, unless they have additional defects.

This congenital problem has been attributed to a few potential causes. It can occur in utero due to a persistent breech position of the fetus, which may not allow bones in the forefoot to grow as straight as they should. Alternately, too little amniotic fluid has been associated with higher rates of metatarsus varus. Some physicians believe the curvature may result at any time a foot is squeezed into a position in the uterus where it cannot normally develop.

Newborns or slightly older infants are fairly easy to diagnose with this congenital defect due to the foot’s appearance. At first, it’s hard to predict what treatment, if any, is necessary. As the baby grows, sometimes the curving area stiffens, but in many infants the foot remains loose and metatarsus varus may self-correct. Doctors frequently recommend small exercises parents can do with babies to help encourage straighter growth and shaping of the forefoot bones. Corrective shoes might also be advised.

If stretching and therapeutic footware do not work, additional treatment may be considered when babies are between six and eight months old. The most recognized approach is to cast the baby’s foot or feet to slowly address the unusual growth pattern. A series of casts, replaced every one to two weeks, gradually assist with straightening. In many cases, this treatment for metatarsus varus is effective. It also has the advantage of occurring at a time when most babies are not yet walking.

For a small percentage of children, casting does not work completely, and the problem may remain. In these instances, doctors may recommend surgical correction. Usually, surgery isn’t attempted until patients are at least four years old.