Much confusion surrounds the incidence and management of deformities of the forefoot because 3 different deformities are characterized by adduction of the forefoot: talipes varus (Figure 183-6), in which the entire foot is inverted and the forefoot is adducted; metatarsus varus (Figure 183-7), in which the forefoot is inverted and adducted while the hind foot and heel are in the normal position; and metatarsus adductus (Figure 183-8), in which the only finding is adduction of the metatarsals at the tarsometatarsal joints. The combined incidence of these 3 forefoot adductive deformities is in the neighborhood of 1 per 100 live births (the most frequent musculoskeletal congenital malformation), with metatarsus adductus being the most common and talipes varus the least common.

Talipes varus and metatarsus varus have been considered lesser degrees of clubfoot and are fixed deformities of the foot that require early treatment. The medial border of the foot is concave, with a widening of the space between the 1st and 2nd toes and a high medial longitudinal arch. The lateral border of the foot is convex, and the base of the 5th metatarsal bone is prominent.

Figure 183-6 Bilateral talipes varus. The entire foot is twisted inward on its longitudinal axis, and the forefoot is adducted. (Tachdjian MO. Pediatric Orthopaedics. 2nd ed. Philadelphia, PA: WB Saunders; 1990. Copyright © 1990, Elsevier, with permission.)

Figure 183-7 Bilateral metatarsus varus. The forefoot is inverted and adducted, the great toe is widely separated from the second toe, and the lateral border of the foot is convex. The hindfoot is in a neutral position. (Sharrard WJW. Paediatric Orthopaedics and Fractures. 2nd ed. Oxford, NY: Blackwell Scientific; 1979. Reprinted by permission of Blackwell Publishing Ltd.)

Figure 183-8 Metatarsus adductus. The forefoot is adducted but not inverted. (Ferguson AB. Orthopedic Surgery in Infancy and Childhood. 4th ed. Baltimore, MD: Williams & Wilkins; 1981. Reprinted by permission of Lippincott Williams & Wilkins.)

Metatarsus adductus can be associated with hip dysplasia (2% of cases); therefore a thorough hip evaluation is essential. A history of a crowded intrauterine environment, such as uterine fibroids, bicornate uterus, multiple gestation or oligohydramnios is often associated with metatarsus adductus.

The severity of metatarsus adductus may be graded by the heel bisector method. Normally, a line bisecting the heel falls between the 2nd and 3rd toes. The metatarsus adductus is considered mild if line falls through the 3rd toe, moderate if between the 3rd and the 4th toes, and severe if between the 4th and 5th toes. Flexibility of the forefoot should be assessed. A flexible foot might be defined as one in which the 2nd toe can be easily brought in line with or past the heel bisector.

In babies with limited flexibility of the forefoot, radiographic examination is necessary to rule out talipes varus and metatarsus varus.

When evaluating metatarsus adductus in the primary care physician's office, placing the child in a standing position on a copy machine and taking a photocopy of the soles of the feet is an easy way to assess the heel bisector position. Although it is somewhat subjective, this low-cost, no-risk method allows for tracking of the progression or improvement of the condition over time.

Metatarsus adductus is a functional deformity and requires no treatment because it corrects spontaneously, usually during the first year. Talipes varus and metatarsus varus are fixed deformities of the foot that require early treatment. Treatment consists of serial casting, long-leg splints that abduct the forefoot, or both. Abduction stretching exercises and out-flare last shoes may be used as an adjunct to cast treatment but should not be relied on as the only therapy. Primary care physicians see metatarsus adductus frequently and observe its resolution without treatment, whereas orthopedists are more likely to see talipes varus and metatarsus varus through referrals, sometimes unfortunately in late infancy when treatment results are less satisfactory.